A TOMOGRAPHY IMAGING SYSTEM USING TWO TYPES OF SENSORS
MUSTAFA MUSBAH ELMAJRI
A project report submitted in partial fulfilment of the
requirements for the award of the degree of
Master of Engineering (Electrical-Mechatronics & Automatic Control)
Faculty of Electrical Engineering
Universiti Teknologi Malaysia
MAY 2008
iii
“This project report dedicated to the memory of my late beloved
grandmother and father
(May Allah grant them eternal rest, Aameen),
and to my affectionate mother”
iv
ACKNOWLEDGMENT
Praise is to Allah, the Cherisher and Sustainer of the worlds. With his
permission I have completed this thesis.
My deep appreciation and heartfelt gratitude goes to my supervisor, Dr.
Sallehuddin Bin Ibrahim for his kindness, constant endeavor, and guidance and the
numerous moments of attention he devoted through out this work.
I extend my deepest gratitude to Miss. Noorfaizah Binti Mohammad Rohi,
Mrs. Norhalimatul Sadiah Hj Kamaruddin, Mr. Mohd Amri B Md Yunus and Mr.
Mohd Daud Bin Isa who have spent a lot of their precious time to guide, advice and
support me to finish this project.
Special thanks goes also to the lab assistant, Abang Faiz for his help and
cooperation willing to stay at night throughout the progress of this project.
Family support plays a vital role in the success of any individual. I would
like to convey a heartfelt thanks to my family, my brothers, my sisters, my nephews
and nieces for their endless love, emotional support and belief in me. Without them I
would never come up to this stage.
v
ABSTRACT
Process tomography is a technique to realize flow imaging in a process vessel
or pipeline by using the sensor system. This technique involves using tomographic
imaging methods to manipulate data from sensors in order to collect sufficient
information about the flow in the pipeline. This project is about the construction of a
simple imaging system using two types of sensors namely optical sensors and
electrodes (forming electrodynamic sensors) with halogen bulbs as light sources.
These sensors complement each other. The images from both sensors can be
analyzed to determine the precise distribution of objects in the pipe. The sensors are
suitably arranged around an 80mm x 80mm x 40mm transparent square pipe. The
amount of sensors must be sufficient so that the accuracy and resolution of the image
is good. The more sensors used the better as it enhanced the resolution and provide
an accurate image of the object distribution. The sensors are connected to simple
signal conditioning circuits which are then linked to a data acquisition system (DAS).
The DAS is then connected to a computer which then displays the images of objects
flowing in a pipe detected by the system.
vi
ABSTRAK
Proses tomografi adalah suatu teknik untuk mendapatkan imej aliran dalam
sebuah paip atau talian paip menggunakan system penderia. Teknik ini melibatkan
penggunaan kaedah-kaedah pengimejan tomografi untuk memanipulasi data daripada
penderia-penderia untuk memungut maklumat yang secukupnya tentang aliran dalam
paip. Projek ini adalah tentang pembinaan system pengimejan ringkas menggunakan
dua jenis penderia yakni penderia optik dan elektrodinamik (yang membentuk
penderia elektrodinamik).
Lampu halogen menjadi sumber cahaya. Penderia-
penderia ini saling melengkapi antara satu sama lain. Imej-imej daripada kedua-dua
penderia boleh dianalisis untuk menentukan agihan yang jitu tentang objek dalam
paip. Penderia-penderia diatur dengan sesuai di sekeliling paip segiempat 80mm x
80mm x 40mm yang transparen.
Bilangan penderia mesti secukupnya supaya
ketepatan dan kebezajelasan imej adalah elok. Lebih banyak penderia yang
digunakan adalah lebih baik kerana ia menguatkan kebezajelasan dan mendapatkan
imej yang tepat tentang agihan objek. Penderia-penderia itu disambung ke litar-litar
penyesuaian isyarat yang ringkas yang disambungkan ke system perolehan data
(DAS). DAS disambungkan ke sebuah computer yang kemudian memaparkan imejimej objek yang mengalir dalam paip yang dikesan oleh system.
vii
TABLE OF CONTENTS
CHAPTER
1
TITLE
PAGE
TITLE
i
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENTS
iv
ABSTRACT
v
ABSTRAK
vi
CONTENTS
vii
LIST OF FIGURES
xi
LIST OF ABBREVIATIONS
xiv
LIST OF APPENDICES
xv
INTRODUCTION
1.1
Process Tomography
1
1.2
Project background
3
1.3
Problem Statements
4
1.4
Objective of the project
6
1.5
Scope of work
6
1.6
The Thesis Outline
7
viii
2
LITERATURE REVIEW
2.1
An Overview of process Tomography
9
2.2
Tomography Sensors
10
2.2.1
11
2.2.2 Electrical Resistance Tomography (ERT)
13
2.2.3
Electrical Impedance Tomography (EIT)
14
2.2.4
Ultrasonic Tomography
15
2.2.5
X-ray tomography
15
2.2.6
Optical Tomography
16
2.2.7
Electrical Charge Tomography
17
2.3
Application of Process Tomography
19
2.4
Optical Projection
22
2.5
Fiber Optics
24
2.5.1 Single-mode fibre
26
2.5.2 Multimode fibres
27
2.5.3
27
2.6
3
Electrical Capacitance Tomography (ECT)
Fiber Optics Applications
Particles Charging Mechanism
29
HARDWARE DESIGN
3.1
Introduction
30
3.2
Pipe Design
30
3.3
Optical Tomography System
32
3.3.1
Selection of Optical Sensor
34
3.3.2
Light Source
36
3.3.3
Signal Conditioning Circuit
37
3.3.3.1 Current to Voltage Circuit Converter
38
ix
3.3.3.2
3.4
First and Second Stage Amplifier
Electrodynamic Tomography System
41
3.4.1
Electrodynamic Sensor
43
3.4.2
Signal conditioning circuit for
electrodynamic
sensor
4
44
3.5
The Data Acquisition System
48
3.6
Complete Hardware Design
50
SOFTWARE DESIGN
4.1
Introduction
51
4.2
Concentration Profile
51
4.3
Linear Back Projection Technique
52
4.4
Sensitivity Maps
54
4.4.1
Optical Sensitivity Maps
54
4.4.2
Electrodynamic Sensitivity Maps
56
4. 5
5
39
Programming Structure
59
RESULTS
5.1
Introduction
60
5.2
Circuit Testing
61
5.3
Concentration Profile from the Offline Data
65
5.3.1 Concentration Profile during No-Flow
Condition
66
5.3.2 Concentration Profile during Full-flow
Condition
67
x
5.3.3 Concentration Profile during Object at the
middle
68
5.3.4 Concentration Profile during 20mm PVC Pipe
6
dropped close to the Pipe wall
69
5.3.5 Concentration Profile during transparent rod
70
5.3.6 Concentration Profile during Two Objects Flow
71
CONCLUSION AND FUTURE RECOMMENDATION
6.1
Conclusion
73
6.2
Suggestions for Future Works
75
REFERENCES
76
Appendices A-E
79-133
LIST OF FIGURES
FIGURE
DESCRIBTION
PAGE
2.1
Overview of process tomography
10
2.2
ECT measurement circuits
12
2.3
Diagram showing the electrical model of EIT
14
2.4(a)
Orthogonal type parallel projections
23
2.4(b)
Rectilinear type parallel projections
23
2.4(c)
Combination of orthogonal and rectilinear projections
23
2.4(d)
Three fan beam projections
23
2.4(e)
Four fan-beam projections
24
2.5
Single and multimode fibers
25
2.6
Types of fiber propagation and dispersion
26
3.1
Pipe design
31
3.2
Optical Imaging System
32
3.3
Fiber optics arrangement
33
3.4
BPX65 photodiode
35
3.5
MR16 halogen lamp
37
3.6
Schematic circuit of receiver
38
3.7
Current to Voltage Converter
38
3.8
Buffer
40
3.9
Third stage signal amplifier
40
3.10
The optical imaging system being tested
41
3.11
An array of sensors in clockwise order
42
3.12
Block diagram of an electrical charge sensing system
44
3.13
A photo of the electrodynamics circuits
45
3.14
Non-inverting voltage follower
46
xii
3.15
Non-inverting voltage amplifier
47
3.16
Connection of sensors to the PC
49
3.17
The complete hardware system.
50
4.1
Back projection
53
4.2
Theoretical concentration matrix tomogram. (a) 2D view and
(b) 3D view
54
4.3(a-d)
Sensitivity maps for an 8 sensors
55
4.3(e-h)
Sensitivity maps for an 8 sensors
56
4.4
The pipe co-ordinates model
57
4.5
Sensitivity map of sensor 1
57
4.6
3D sensitivity map of sensor 1
58
5.1(a)
Output 1
61
5.1(a-b)
Output 2 and Output 3
62
5.2
Average output using hand touch
63
5.3
The hand is fixed at the electrode for period of time
63
5.4
Output signal when the sensor receiving surrounding lights
64
5.5
Optical output when the light not blocked
64
5.6
The optical output when light is blocked
65
5.7
The concentration profile for the no-flow condition (a) Obtained
from electrodynamic system and (b) Obtained from optical system
5.8
The concentration profile for the full-flow condition (a) Obtained
from electrodynamic system and (b) Obtained from optical system
5.9
66
67
The concentration profile when the square wood bar is inserted at
the middle (a) Obtained from electrodynamic system and (b)
Obtained from optical system
5.10
68
The concentration profile when the 20mm PVC pipe is inserted
close to wall of the pipe (a) Obtained from optical system and (b)
Obtained from electrodynamic system
5.11
69
The concentration profile for transparent rod (a) Obtained from
electrodynamic system and (b) Obtained from optical system
70
xiii
5.12
The concentration profile for the two objects (a) Obtained from
optical system (b) Obtained from electrodynamic system
72
xiv
LIST OF ABBREVIATIONS
A
-
Area of the capacitor plate
AC
-
Alternating Current
C
-
Capacitance
dp
-
Distance Between Two Plates
DAS
-
Data Acquisition System
DC
-
Direct Current
ECT
-
Electrical Capacitance Tomography
EIT
-
Electrical Impedance Tomography
ERT
-
Electrical Resistance Tomography
LBP
-
Linear Back Projection
NMR
-
Nuclear Magnetic Resonance
PC
-
Personal Computer
PET
-
Positron Emission Tomography
PVC
-
Polyvinyl Cloride
Q
-
Quantity of charge in coulombs
Rf
-
Feedback resistance
V
-
Voltage in volts
τ
-
Time constant
ε0
-
Permittivity Of Free Space
εr
-
Permittivity Of The Dielectric
xv
LIST OF APPENDICES
APPENDIX
A
TITLE
Schematic Diagram for the Electrodynamic Transducer
Circuit
B
Data Sheet for TL084A
C
Data Sheet for LF351
D
Data Sheet for BPX65 Series
E
Software Program
PAGE
CHAPTER 1
INTRODUCTION
1.1
Process Tomography
There are various definition ns for the word ‘Tomography’. The word is
derived from the Greek words; ‘Tomo’ which means ‘to slice’ or ‘cutting’ section,
and ‘Graph’ that means ‘image’ or ‘drawing’.
The Oxford English defines
tomography as: Radiography in which an image of a predetermined plane in the body
or other object is obtained by rotating the detector and the source of radiation in such
a way that points outside the plane giving a blurred image. Most people associate
tomography with complex systems which are used to obtain images of internal parts
of the human body. The development of tomography instrumentation started in
1950’s, and has led to the invention of a number of imaging equipments for
processes in the1970’s. The concept of tomography is not restricted to the medical
field only, but exceeded to include industrial applications, where tomography has
been developed, over the last twenty years, to be a reliable tool for imaging various
industrial applications, such as chemical, oil, gas, food processing, biomedical,
pharmaceuticals, and plastic products manufacturing. This field of application is
commonly known as Industrial Process Tomography (IPT) or simply Process
Tomography (PT). In addition to the use of tomography in the medical and industrial
fields, it is also used in the fields of archaeology, biology, geophysics, materials
science and other sciences. In most cases it is based on the mathematical procedure
called tomographic reconstruction.
2
In general, process tomography is a field to investigate the distribution of
objects in a conveying pipe by placing several sensors around the vessel without
interrupting the flow in the pipe; to acquire vital information in order to produce two
-or three- dimensional images of the dynamic internal characteristics of process
systems. The output signal from the sensors will be sent to the computer via an
interfacing system. The computer will receive the signal from the respective sensors
to perform data processing and finally construct a cross-section flow image in the
pipe through image reconstruction algorithms. With further analysis, the same signal
can be used to determine the concentration, velocity and mass-flow rate profile of the
flows over a wide range of flow regimes by providing better averaging in time and
space through multi-projections of the same observation. Such information can
assist in the design of process equipment, verification of existing computational
modelling and simulation techniques, or to assist in process control and monitoring.
Currently, there are several tomography techniques available for studying
complex multiphase phenomena. These include for example, infrared, optical, X-ray
and Gamma-ray tomography systems, positron emission tomography (PET),
magnetic resonance imaging (MRI), and sonic or ultrasonic tomography system.
Although process tomography is a technique still in its infancy, but it has the
potential for enabling great improvements in efficiency and safety in process
industries, while minimizing waste and pollution in a range of applications. It can be
used to obtain both qualitative and quantitative data needed in modelling a multi
fluid flow system.
Optical tomography is an attractive method since it may prove to be less
expensive, have a better dynamic response, and more portable for routine use in
process plant other than radiation-based tomographic methods such as positron
emission, nuclear magnetic resonance, gamma photon emission and x-ray
tomography.
Its performance is also independent of temperature, pressure and
viscosity of fluid (S. Ibrahim et al., 2000).
3
The electrodynamic models basically relate the charge on a particle to the
voltage on a sensor. These models are developed based on the fact that many
flowing materials pick up charge during transportation, primarily by virtue of friction
of fine particles amongst themselves and abrasion on the wall of the conveyor.
Although charge generation on solids is well know from electrostatics, it is
not generally possible to calculate the magnitude of charge generated solely based on
the properties of the material and the process in which it is involved.
However, it is known that the magnitude of charge generated depends on
different parameters. It has been established that the magnitude of charge acquired
by solids depends upon the moisture content of the atmosphere, the particles size
distribution and the velocity with which the particles move and/or impinges onto
surface.
1.2
Project background
Process tomography provides several methods of obtaining the concentration
profile of a process. It has become one the vast growing technologies nowadays, and
it can be applied to many types of processes and unit operation, including pipelines,
stirred reactors, fluidized beds, mixers, and separators. Depending on the sensing
mechanism used, it is non-invasive, inert, and non-ionizing.
The main target of this project is to develop a tomography system by using
optical sensors with two halogen bulbs as light sources for visualization of solid
flow, the extracted results then will be compared with the results obtained from
electrodynamic sensors on the same process.
Several researches had been carried
4
out to investigate the performance of process tomography in obtaining the data from
the process pipeline.
The accuracy of the image obtained is dependant on the
number of sensors used and the projection technique applied.
Parallel beam
projection technique produced limited number of data obtained and may had a
problem with beam convergence and aliasing effect. A research conducted by Soh
(Soh, 2000) had proved that such problems may be minimized with the application of
fan beam projection technique. The technique will produce a significant number of
data and this will improve the accuracy of the image obtained (R. Abdul Rahim et
al., 2004b)
For this project, the image reconstruction is based on Linear Back Projection
(LBP) algorithm. The LBP algorithm was originally designed for x-ray tomography,
and then became the simplest and most common used in image reconstruction.
Flow imaging measurements can be either done using on-line (real time) or
off-line. For on-line measurements, many performance aspects must be considered
such as hardware performance, data acquisition system, and algorithm performance.
The quality of images obtained depends on the number of sensors used in
measurements. The input channel of the data acquisition system has to be increased
with the increase in the number of sensors used.
1.3
Problem statement
Nowadays, various pipes and vessels are used in process, and it is difficult to
know what type of flow is inside them. Systems have to be developed whereby the
controller is able to view objects within these pipes without interrupting the flow.
5
The process tomography system requires the knowledge of various
disciplines such as instrumentation process, and optics to assist in the design and
development of the system.
The way around this problem would be to place sensing electronics around
the actual pipe or vessel, where the system having two types of sensors; eg optical
and electrodynamic enable comparison to be made.
By using these sensing
electronics, we are able to take measurements and recreate an image of what is
contained within. Electronics of this nature needs to be created such that it is
affordable and easy to operate. A voltage-to-current converter is used to inject the
input current source, while other pairs of electrodes are able to pick this up and
convert this signal into a voltage measurement. Various types of voltage-to-current
converters need to be built, implemented and tested for suitability and sensitivity.
Thereafter, a synchronous detection systems needs to be tested together with the
voltage-to current converter via the sensing electrodes.
This project to investigate the process tomography, and how can be used to
construct an image of a solid object in a transparent square pipe. In selecting the
appropriate optical sensor, the characteristics of the light source and sensor must be
investigated. Based on this, the transmitter, receiver and signal conditioning circuit
of the system will be designed and realized physically. The signal conditioning
circuit will be combined with the data acquisition system. Image reconstruction will
be done using MATLAB.
The process involves projecting a light beam through some medium from one
boundary point and detecting the level of light received at another boundary point.
The Electrodynamic transducer was constructed by using a copper rod as a sensor in
order to detect the electrostatic charges of the flowing objects through the pipe.
6
1.4
i.
Objective of the Project
To search for material about the optical and electrodynamic sensors and
hardware fabrication.
ii.
To design and implement signal conditioning circuits that are effective for
receiving and processing the signals.
iii.
To understand the image reconstruction algorithm.
iv.
To obtain data for image reconstruction.
v.
To display the concentration profiles for object flow using MATLAB
Software.
vi.
1.5
To analyze the data so as to understand the flow regimes.
Scope of work
In order to achieve the aim of this project, that is to investigate the flow
regimes (image reconstruction) due to dropping particles in pipe based on
tomography concept, the scope of this project need to be understood, where it
includes the following points:
i.
Familiarization with the operation and performance of electrodynamic and
optical tomographic systems.
ii.
Construct an 80mm x 80mm transparent square pipe for system evaluation.
iii.
To design an electrodynamic system and an optical system prototype that can
be used to measure the solid object flow.
iv.
To design, construct, and test signal conditioning circuits to process the
signals obtained from sensors.
v.
Compare images from electrodes and optical tomography data.
7
vi.
Reconstruction of cross sectional images by using MATLAB Software in
order to determine the concentration profiles of the solid object flowing
inside the pipe.
1.6
The Thesis Outline
The layout of this report is as follows:
Chapter 1 gives a brief introduction to process tomography. Next, project
background, problem statements, objective of the project and scope of the study are
presented in this chapter.
Chapter 2 mainly discusses the literature review that is related to this study. It
consists of an overview of process tomography, the significance of developing the
system and a historical review about the evolvement of the process. Typical sensors
used in process tomography are also discussed. This chapter provides a brief insight
on the optical and electrodynamic tomography systems.
Chapter 3 describes the hardware development process which includes the
fabrication of a transparent pipe to house the fibre optic cables and sensors, the
specification of the optical sensor and the design of the signal conditioning circuits in
order to obtain vital output signal.
Chapter 4 gives a thorough explanation on software development.
This
includes the modelling of the process, the sensitivity models of optical and
electrodynamic sensors and a description of the developed software.
8
Chapter 5 presents the results obtained from the experiments done on the
developed system. The results obtained are discussed and a conclusion was drawn
based on the analysis.
Several experiments had been carried out in order to
investigate the system performance in many aspects such as the accuracy of the
system.
Chapter 6 contains the conclusions from this project and some suggestions for
future work and development are given in order to improve the system ability.
CHAPTER 2
LITERATURE REVIEW
2.1
An Overview of process Tomography
The use of process tomography is analogous to the application of medical
tomographic scanners to examine the human body. Development of the process to be
applied in an industrial field gave the word 'tomography' a well-defined term, which
means a cross-sectional image of a particular area, while, process tomography means
a cross-sectional image of a process. In a more specific definition, R. Abdul Rahim
had defined process tomography as a technique involving the use of instruments
which provide a cross sectional profile of the distribution of materials in a process
vessel or pipeline (R. Abdul Rahim et al. 1995).
These images are required to investigate the solids behaviour within the
conveyor. Furthermore, this technique can be manipulated as a flow sensor to
determine the solids mass flow rate. The design of a process tomography system
depends on how the measurement will be made.
The sensing system is considered the heart of any tomographic technique,
where the measurement section can be subdivided into four main parts: the sensors,
10
the signal conditioning circuit, the data acquisition system and the image
reconstruction algorithm. Figure 2.1 illustrates the system configurations;
Figure 2.1: Overview of process tomography
From the knowledge of the material distributions profile, internal models of
the process can be derived and used as an aid to optimize the design of the
process. This promises a substantial advance on present empirical methods of a
process design that depends on the input/output measurements which provides
only a limited amount of information about the detailed internal behaviour of the
process.
2.2 Tomography Sensors
Many types of sensors can be used in tomography systems; they depend on
the applications, where each tomography technique has its type of sensor being used.
There are two types of sensors; “hard-field” and “soft-field” sensors. A “hard-field”
sensor is equally sensitive to the parameters it measures in all positions throughout
the measurement volume. Its sensitivity is also independent of the distribution of the
measured parameters inside and outside measurement region. For a “soft-field”
sensor, the sensitivity of the measurement parameter depends on the position in the
sensing volume, as well as on the distribution of parameters inside and outside the
11
region (Chan, 2002). Soft-field sensors include capacitance, magnetic and electrical
charge sensors. Optical sensors are categorized as hard-field sensors.
Various forms of tomography are being investigated around the world. All
tomographic techniques are concerned with extracting the information to form a
cross-sectional image, which can then be analyzed to monitor and possibly control
the process. The tomography sensors used in industrial process will be discussed in
this chapter.
2.2.1 Electrical Capacitance Tomography (ECT)
Capacitance sensors are now widely used for industrial multi-component flow
processes. The basic technique principle of ECT can be described by considering a
parallel plate capacitor. The capacitance between these plates is dependent upon the
dielectric permittivity, the area of the plates and the distance between those plates.
This can be represented by the following equation:
C=
ε 0ε r A
dp
Where C is capacitance, ε 0 is permittivity of free space, ε r is permittivity of
the dielectric, A is area of the plate and dp is the distance between those plates. By
changing any of these parameters, the capacitance value would also be changed.
There are two types of measurement circuits suitable for ECT. They are the
charge/discharge circuit and the AC based circuit, due to their immunity to stray
capacitance. As shown by Yang (2003), the main difference between these two types
of circuits lies in the positions of the demodulators. In a charge / discharge circuit, as
shown in block diagram form in Figure 2.2(a), the demodulator precedes any of the
12
signal amplification. For the AC-based circuit in Figure 2.2(b), the AC signal from
the measured capacitance is amplified and thereafter demodulated.
Figure 2.2: ECT measurement circuits
(a) Block diagram of a charge / discharge circuit
(b) Block diagram of an AC-based circuit
The sensors are in the form of electrodes which are symmetrically mounted
on the outside of an insulating pipe or vessel. The sensing electronics then takes
measurements for all possible combination pairs of electrodes. Specifically for
capacitance tomography measurements, the surface of the electrode needs to be
sufficiently large to provide sufficient signal.
The advantages of this technique are non-intrusiveness of the measurement
inside the reactor, inexpensive, and fast in measurement speed. The disadvantages
are that the ETC has limited applications, and cannot produce high definition image
boundaries compared to a tomography system that used electromagnetic radiation
like optical, as well as the sensitivity for the measured properties is not constant
within the investigated area.
13
2.2.2
Electrical Resistance Tomography (ERT)
The technique is based on automated measurement and computerized analysis
of electrical resistivity changes caused by natural or man-made processes. Because
the electrical resistance of soil and rock is dependent on soil type, fluid saturation,
and chemistry, electrical resistance tomography can be used to monitor or detect
subsurface processes such as water infiltration, underground tank leaks, and steam or
electrical heating during soil cleanup operations.
The distinction between EIT and ERT is that the former uses both magnitude
and phase components of the measure electrodes whereas the latter uses only the
magnitudes [Daniels, 1996]. The ERT technique is of great potential in industry
process monitoring because of its advantage, such as visualisability, high temporal
resolution, low cost, no radiation hazard, etc. ERT has been employed as a
visualization tool for mixing processes, multi-phase flow and aqueous-based
separation in chemical engineering [Wang, 1999].
The accuracy of the technique is restricted by its complexity in sensor
modelling, noise reduction and image reconstruction. The fact that the electrodes
make electrical contact with the fluid limits the type of material from which they can
be fabricated. The limited number of measurements and the presence of electrical
noise cause difficulties in obtaining solutions. Additionally, the applied electrical
fields are ‘soft’ so that complex (e.g. iterative) reconstruction algorithm may be
needed to reduce image distortion. Compensation may be needed to increase
sensitivity near the center of the image [Dyakowski, 1996].
14
2.2.3
Electrical Impedance Tomography (EIT)
Electrical impedance tomography (also called applied potential tomography)
is a non-invasive inverse method which is able to determine the electrical impedance
(conductivity) of a medium by making voltage and current measurements at the
boundaries of the object, as initial data for image reconstruction. This technique is
mainly used in industry to recreate images of the contents within a pipe or vessel;
this helps the operator to visualize the internal behaviour of industrial processes,
where the process used a conducting fluid to carry immiscible fluid and solids which
possessed different bulk conductivities. There are various applications whereby
impedance tomography is used in medical imaging and measurement purposes.
`
Electrical impedance tomography (EIT) involves the measurement of changes
in both the resistance, and the reactive components from the multi electrode sensor of
the system or material. An electrical model of a typical impedance system is shown
in Figure 2.3. This alteration of impedance is due to the type of material under
investigation. This type of measurement is made possible due to the different
electrical resistivities of the various types of materials.
Figure 2.3: Diagram showing the electrical model of EIT
15
2.2.4 Ultrasonic Tomography
Ultrasonic sensors have been successfully applied in flow measurement, nondestructive testing and widely used in medical imaging (Hoyle and Xu, 1995). The
ultrasonic system is based upon interaction between the incident ultrasonic waves
(frequency of 18 kHz to 10 kHz) and the object to be imaged, where the interaction
may be sensed to yield information about the object or field. As the suspended
solids’ concentration fluctuates, the ultrasonic beam is scattered and the received
signal fluctuates in a random manner about a mean value. This type of sensor can be
used for measuring the flow velocity. Two pairs of sensors are required in order to
obtain the velocity using cross correlation method.
There are two types of ultrasonic signals that are usually used. They are the
continuous signal and the pulsed signal. The pulsed system is used to avoid the
standing wave patterns that can exist within the pipes. Using the ultrasonic method in
air is very inefficient due to the mismatch of the sensors’ impedance as compared
with air’s acoustic impedance. New types of sensor are continually being developed
but the effective ones are expensive. However, it is difficult to collimate and
problems occur due to reflections within enclosed spaces, such as metal pipe
(Sallehuddin, 2000).
2.2.5
X-ray tomography
The X-ray imaging technique can be divided into two categorises; X-ray
transmission radiography, and X-ray transmission tomography. For X-ray
transmission radiography, the image is static and it does not provide a continuous
imaging of the object. In X-ray transmission tomography, the objective is to obtain
images or slices through an object at different depth and is obtained by carefully
16
computed and controlled relative motion of the X-ray source and the detector during
the exposure. This technique is also known as computerized tomography.
The needed equipments for X-ray transmission tomography are bulky and a
high element of danger is involved due to the presence of ionizing radiation. This
factor makes it inappropriate for tomographic flow imaging in an industrial
environment.
2.2.6
Optical Tomography
Optical tomography involves projecting a beam of light source (e.g. LED,
infra-red, or halogen bulb) through a medium from one boundary point and detecting
the level light received at another boundary using a sensor (e.g. phototransistor,
photomultiplier, or photodiode) (Abdul Rahim, 1996). The voltage generated by the
sensor is related to the amount of attenuation in the path of the beam, caused by the
flow regime using a proper electronic circuit where the circuit is capable of
measuring physical parameters that contain information of the flow regime. The
analogue signal then is converted into digital form before being passed into the
measurement system in order to perform the analysis. Optical tomography is an
attractive method since it is conceptually straightforward and relatively inexpensive,
has a better dynamic response and can be more portable for routine use in process
plant than other radiation based tomographic techniques.
The optical sensor provides a sufficiently wide bandwidth that enables
measurement to be performed on high-speed flowing particles. Therefore, the optical
sensors can be applied in the process tomography that is to produce concentration
profiles and velocity profiles for the solids transported by gas and liquid. Optical
fibers exhibit high linearity when used to measure solid flow rates and show good
17
agreement between predicted and measured values for the spatial filtering effect
(Sallehuddin, 2000). Yang and Szuster (1996) had been developed a low-cost serial
data transmission link using transputer link adaptor chips and optical fibers for data
communication between sensing electronics and an image reconstruction computer.
Its major problem is due to the physical size of the transmitter and receiver
which limit the resolution that can be obtained. Another disadvantage of optical
sensor is in obtaining resolution caused by limitation of space for sensor replacement
whereby sensors can not be arranged too close to each other to avoid reflection.
Based on a research done by R. Abdul Rahim, the optical fibers are proven to exhibit
good linearity when used to measure solid flow rate.
2.2.7
Electrical Charge Tomography
Electrical charge tomography is also known as electrodynamics tomography.
The term ‘electrodynamics’ is use to describe the effect of a moving charge as
opposed to electrostatics where the charge is stationary. Pneumatically conveyed
particulate matter such as solids and powders acquires charge during the
transportation by several processes such as symmetrical charge separation and
frictional charging. An electrical charge sensor derives its signal by sensing the
random changes in induced charge caused by the turbulent nature of the flow
(Gregory, 1987). A further advantage of electrodynamics for imaging is that it has a
much narrower ‘slice width’ than conventional long electrode technique (Beck and
William, 1995).
This type of sensor has been widely used to measure powder flow in many
industries. It is a non-intrusive method that can measure phase density and velocity
on industrial pneumatic conveying systems where the solid-to-gas ratio is low and
18
the solids turbulently conveyed (Shackleton, 1982). Shackleton surveyed several
different methods of mass-flow rate measurement and discusses the limitations
associated with these methods. The sensing electrodes are passive elements. Electric
fields generated by the presence of charged particles and their movement produce a
fluctuating field in the electrode.
The major problem in applying this sensing technique lies in relating the
solid concentration to be measured to the magnitude of the charge signal, which
depends upon the physical properties of the particles (size, shape, distribution,
conductivity, permittivity, chemical composition, moisture content and so on) and
the conveying conditions (pipe size, pipe wall roughness, line temperature and so
on). The concentration and the velocity of solids are also known to be factors
contributing to the magnitude of the charge signal. It is, therefore, extremely difficult
to interpret measurement results except when all the above parameters are well
defined and constant (Yan, 1996).
Despite the aforementioned drawback, this sensing technique offers the most
inexpensive and the simplest means of measuring solids flows in pipelines. Because
electrodynamic sensors respond only to moving solids in the pipe, the measured
concentration data enjoys a large degree of immunity from the effects of solids
accretion which adversely affect other techniques (Yan 1996).
Monitoring the electrostatic nature of the flow with two electrodes spaced at
distance L apart allows measurements of flow velocity to be made using crosscorrelation techniques. Such a system requires minimal electronics and is physically
small. The electrodes are simple, consisting of metal pins or socket inserted into
suitable non-conducting receptacles.
19
2.3
Applications of Process Tomography
Process tomography is applied widespread in medical range. Through the
invented technology, the physicians are enabled to see through the human body for
any pathological abnormalities non-invasively and to make diagnostic decisions
rapidly, which facilitated the treatment of the detected diseases.
The Medical imaging goes back to 1985, when German physicist W.C.
Roentgen discovered X-rays haphazardly.(Lihong V. Wang, 1998). Roentgen
discovered the greatest and most important achievement in the history of mankind
medical diagnosis using an X-ray allowing doctors to diagnose bone fractures
without surgery using x-rays to detect foreign objects in the human body and the
development of diagnostic X-ray to enable doctors fencing of the blood vessels and
biological members in the body Rights.
Scientists and researchers have discovered many areas for the use of X-ray
applications. In the medical field could become doctors diagnose bone fractures and
portray human organs as well as the use of these rays in the treatment of cancerous
tumours. So some people tend to regard this discovery unique scientific revolution in
disease diagnosis, because X-rays penetrate new softball, on the contrary can not
penetrate solid objects, which facilitates bone appearance and the discovery of
fractures.
Contemporary medical imaging began with the invention of computerized
tomography in the 1970s. G.N. Hounsfield in England produced the first computer
reconstructed images experimentally based on the theoretical foundation laid by
A.M. Cormack in the United States.
20
The intrinsic nature of computerized tomography is built on the basis that if
an object is viewed from a number of different angles, then it is possible to
reconstruct a cross-sectional image of it. Different imaging modalities are used to
detect different aspects of biological tissues through a variety of contrast
mechanisms. X-ray imaging primarily detects electron while in magnetic resonance
imaging (MRI), proton density and its associated relaxation properties are detected.
The use of these areas went too far the medical field, where for the time being
entered in various industrial applications such as measuring the thickness of solid
substances and pieces of industrial survey revealed flaws can be detected visually
preserve the quality of production. X-rays are also used in airports to screen
passengers and baggage detection of banned substances.
Various electrical based tomography techniques have been applied
successfully for the monitoring of different industrial processes (S.F.A. Bukhari and
W.Q. Yang, 2001). For example, Electrical Resistance Tomography has been tested
for measuring hydraulic conveyors, solids/liquid mixtures, liquid-gas flows and
liquid/liquid flows. Electrical Charge Tomography has been used to investigate
pneumatic conveyors, fluidized beds, package contents checking, oil-gas flows and
combustion imaging.
The Electro Magnetic Tomography applications can be seen in metallurgical
processes, whereas, Radiation Tomography techniques, such as gamma-ray and x-ray
have been applied in gas/solid/liquid processes. Optical diffraction techniques have
been employed in mixing, heating of viscous fluids, flames and density fields near
impeller blades.
Position emission tomography (PET) is another technique which was
employed for particle tracking, useful for steady state separation and solid mixing.
Nuclear magnetic resonance (NMR) imaging technique has been applied in various
21
processes for measuring concentration profiles. In this method, the parameters
measured are the nuclear spin density of chemical species. NMR imaging can
provide high resolution but the technique is very costly.
The approach offers instrumentation simplicity, since there is no need for
phase detection without compromising the ability to distinguish between absorbers
and scatterers. Therefore, a large array of sources and detectors can be implemented
to increase resolution in optical tomography
S. Ibrahim et al. (2000) had investigated the application of optical
tomography in industrial process control system. The study had shown that optical
tomography can be used to provide feedback information on the process for plant
control either for alarm function or alarm malfunction detection.
Optical tomography is desirable method, whereas it may prove to be less
expensive, have a better dynamic response and be more portable for routine in
process plant that other radiation-based tomographic methods such as positron
emission, nuclear magnetic resonance, gamma photon emission and x ray
tomography. Its performance is also independent of temperature, pressure and
viscosity of the fluid. From the study, they came into a conclusion that optical
tomography system has several advantages compared to other systems. The optical
beams travel in straight lines which simplifies tomographic image reconstructions.
The optical approach to process tomography has the advantages of being
conceptually simple and inexpensive.
Meanwhile, the electrodynamics sensor is known to have a high spatial
filtering bandwidth, which makes it very useful for velocity determination (Rahmat,
1996). It is interesting to investigate its sensitivity and limitations as a sensor for
measurement of concentration, velocity and volume flow rates in tomography
system.
22
2.4
Optical Projection
In practical systems, several projections are needed to reduce aliasing which
occur when two particles intercept the same view. There are two major types of
projection techniques, namely the parallel projection and the fan beam projection,
including a various projection techniques which had been investigated by (Ibrahim et
al, 1999). These are: (a) two orthogonal projections consisting of several parallel
views, (b) two rectilinear projections consisting of several parallel views inclined at
45ͦ to one another, (c) a combination of two orthogonal and two rectilinear
projections, (d) three fan-beam projections, and (e) four fan-beam projections.
For the two orthogonal projections, each projection provides a number of
light beams, which are parallel and equally spaced to each other. The light emitters
and detectors are arranged on a one-to-one basis, i.e. each emitter has a
corresponding detector. Figure 2.4(a). Similarly, in the rectilinear projections, the
transmitters and receivers are also positioned on a one-to-one basis.
At one particular scanning angle, a single source illuminates its associated
detectors simultaneously and the data are collected by the detectors corresponding to
various angles. These are termed fan beam projection. Fan beam projection was
found to provide more projected data since one emitter is capable to provide several
data provided that the beam angle is large enough to be received by the adjacent
receivers. If every condition was fulfilled, then the fan beam projection may produce
data of 2n where n is number of sensor used.
23
(a) Orthogonal type parallel projections
(c) Combination of orthogonal and
rectilinear projections
(b) Rectilinear type parallel projections
(d) Three fan beam projections
24
(e) Four fan-beam projections.
Figure 2.4(a-e): Types of projections for optical tomography.
2.5
Fiber Optics
An optical fiber is a thin glass strand designed to guide a light along its length
by total internal reflection. A single hair-thin fiber is capable of transmitting trillions
of bits per second. In addition to their huge transmission capacity, optical fibers offer
many advantages over electricity and copper wire. Light pulses are not affected by
random radiation in the environment, and their error rate is significantly lower.
Fibers allow longer distances to be spanned before the signal has to be regenerated
by expensive "repeaters." Fibers are more secure, because taps in the line can be
detected, and lastly, fiber installation is streamlined due to their dramatically lower
weight and smaller size compared to copper cables.
25
Fiber optics is the branch of applied science and engineering concerned with
such optical fibers. Optical fibers are widely used in fiber-optic communication,
which permits digital data transmission over longer distances and at higher data rates
than other forms of wired and wireless communications. They are also used to form
sensors, and in a variety of other applications.
An optical fiber is a cylindrical dielectric waveguide that transmits light along
its axis, by the process of total internal reflection. The fiber consists of a core
surrounded by a cladding layer. To confine the optical signal in the core, the
refractive index of the core must be greater than that of the cladding. The boundary
between the core and cladding may either be abrupt, in step-index fiber, or gradual,
in graded-index fiber. The operating principle of optical fibers applies to a number of
variants including multi-mode optical fibers, single-mode optical fibers, graded index
optical fibers, and step-index optical fibers. Because of the physics of the optical
fiber, special methods of splicing fibers and of connecting them to other equipment
are needed.
Figure 2.5: Single and multimode fibers
Since light travels at different angles for different paths (or modes), the path
lengths of different modes are different. Thus different rays take a shorter or longer
26
time to travel the length of the fibres. The ray that goes straight down the centre of
the fiber core without reflecting arrives at the end of the fiber first ahead of the other
rays. Thus, light entering the fiber at the same time exits the other end at different
times. The light has spread out in time and this is called modal dispersion.
Figure 2.6: Types of fiber propagation and dispersion
2.5.1
Single-mode fibre
Single mode cable is a single stand of glass fiber with a diameter of 8.3 to 10
microns that has one mode of transmission. Since this fiber carries only one mode,
modal dispersion does not exist. This fiber with a core diameter less than about ten
times the wavelength of the propagating light cannot be modelled using geometric
optics because it obscures how optical energy is distributed within the fiber.
Single mode fiber is used in many applications where data is sent at multifrequency, so only one cable is needed (single-mode on one single fiber). Single-
27
mode fiber gives a higher transmission rate and up to 50 times more distance than
multimode, but it also costs more.
2.5.2 Multimode fibres
Multi-mode cable has a little bit bigger diameter, with a common diameters in
the 50-to-100 micron range for the light carry component. In a step-index multimode
fiber, rays of light are guided along the fiber core by total internal reflection. Rays
that meet the core-cladding boundary at a high angle, measured relative to a line
normal to the boundary, greater than the critical angle for this boundary, are
completely reflected. The critical angle, minimum angle for total internal reflection,
is determined by the difference in index of refraction between the core and cladding
materials. Rays that meet the boundary at a low angle are refracted from the core into
the cladding, and do not convey light and hence information along the fibre. In other
words, incident rays which fall within the acceptance cone of the fibre are
transmitted, whereas those which fall outside of the acceptance cone are lost in the
cladding.
2.5.3
Fiber Optics Applications
In recent years it has become apparent that fiber-optics are steadily replacing
copper wire as an appropriate means of communication signal transmission. They
span the long distances between local phone systems as well as providing the
backbone for many network systems. Other system users include cable television
services, university campuses, office buildings, industrial plants, and electric utility
companies.
28
A fiber-optic system is similar to the copper wire system that fiber-optics is
replacing. The difference is that fiber-optics use light pulses to transmit information
down fiber lines instead of using electronic pulses to transmit information down
copper lines.
The first commercial applications for fiber optics were for medical purposes.
Bundled fibers can deliver illumination light to remote regions of the body, and carry
coherent (understandable) images back out to the doctor. More recently, medical
fibers have been used as a remote delivery system for high-powered laser energy.
Using small fiber optic bundles, the powerful self-cauterizing properties of the laser
could be delivered to the patient without having to manipulate the bulk of the laser
itself. However it is in communications where fibers have made the most significant
advances. Long distance telephone cables, sometimes several inches in diameter and
containing hundreds or even thousands of paired wires, have been replaced by a
single-fiber cable. Because the light transmitting fiber is immune to electronic noise
the fiber can carry thousands more conversations with better sound quality.
When selecting a fibre for a particular application, the user should know in
advance what optical wavelength range will be required to transmit through the fiber.
The material that makes up the core of the fiber can then be selected, based on its
transmission characteristics. Working in the UV, around 300 to 400 nm, one will
probably have to use a quartz or silica core fiber. Glass and plastic will not transmit
very efficiently much below 400 nm. Working in the visible or Near Infra-Red, than
one will probably be able to use a glass or a plastic fiber. These will transmit from
about 400 nm to 1500 nm. They are considerable less expensive, easier to work with
and consequently easier to obtain than UV.
29
2.6
Particles Charging Mechanism
Solid materials charging is a well known phenomenon as early as 600 B.C.
The phenomenon of electrification was first noticed when pieces of amber were
rubbed briskly. For centuries, the word electricity had no meaning other than the
ability of some substances to attract or repel lightweight objects after being rubbed
with a material such as silk or wool. However, there was little progress until the
English scientist William Gilbert in 1600 described the electrification of many
substances and coined the term electricity from the ancient Greek word for amber,
elektron.
In comparatively recent times, when the properties of flowing (current)
electricity were discovered, the term static came into use as a means of
distinguishing a charge that was at rest from one that was in motion. However, today
the term is used to describe phenomena that originate from an electric charge,
regardless of whether the charge is at rest or in motion.
The charge generation on solid and powder is well known, the detailed
electrification mechanisms are less well established (Shockleton 1982). According to
(Shockleton 1982), the solid and powders involved in industry are not pure clean
substances and the level of electrification is affected by surface contamination,
impurities or adsorbed or absorbed materials, rather than the basic chemical
construction of the solids or powder. It is not generally possible to calculate the
magnitude of the charge generation from the properties of the material and the details
of the process in which it is involved. However, some useful empirical data does
exist which provides some guidelines on the electrification levels that can be reached
with certain materials.
It has bean established that the magnitude of the charge acquired by solids
depends upon the moisture content of the atmosphere, the particle size distribution
and the velocity with which the particle moves and/or impinges onto surfaces
(Shockleton 1982).
CHAPTER 3
HARDWARE DESIGN
3.1
Introduction
This chapter will describe the hardware development process which includes the
fabrication of a transparent square pipe to place the fibre optic cables and
electrodynamic sensors, the specification of the optical sensor, the design of the signal
conditioning circuits for both optical and electrodynamic tomography systems as well as
their principles of operations.
3.2
Pipe Design
In this project, an 80mm x 80mm x 40mm transparent square pipe will be used as
a conveyor. The system employs two halogen bulbs as light sources. 16 sensors (8
31
electrodes and 8 photodiodes) are arranged on top of each other with 30mm apart. For
optical system, an eight holes are drilled on two sides of the pipe circumference (4 holes
on each side) to locate the fiber optics according to their physical diameter which is
2.2mm. The other 8 holes are drilled on the other two sides to allow the light to pass
through them; whereas area surrounding the source of light was blacked out.
For electrodynamic technique, eight equally spaced sensing electrodes are
installed around the pipe. Two electrodes are placed on each side of the four sides of the
pipe. The electrode generally consists of a conductor structure and insulated from the
wall to minimize boundary problems. The Figure 3.1 below illustrates the pipe that was
constructed.
Figure 3.1: Pipe design
32
3.3
Optical Tomography System
Practically, the optical tomography system is better than many other approaches
to tomographic imaging such as x-ray tomography and nuclear magnetic resonance. The
system is split into several parts to show how the system works from the light source till
the final imaging process, the concentration profile. Optical fibers detect the light which
is then transmitted to photodiodes. The particle’s projected area is proportional to the
amount of signal lost. The signal lost is detected as voltage which is proportional to the
particle size. Amplitude of the received light is compared with the amplitude of light
when no obstruction in the light path for the same sensor.
In this project, the halogen light source will supply 4 parallel light beams for
each side of the pipe, which the fiber optics are housed on them. This results in the
cross section of the pipe being interrogated by a total of 8 beams. The 8 sensors are
connected to the analogue sensing electronics circuit (a signal conditioning circuit to
convert the information into an electrical signal) and then digitized (data acquisition
system in order to convert signal into computer codes) before its being reconstructed and
visualized. The basic structure of the optical system is shown in Figure 3.2.
Figure 3.2: Optical Imaging System
33
The arrangement of the fiber optics around the wall of the pipe is illustrated in
Figure 3.3.
Figure 3.3: Fiber optics arrangement
The photo-detector will generate an electrical current within a range of micro
Amperes that propagates to the intensity of the received light; then the current is being
fed into electronic device to perform signal measurement. Nevertheless, the output
signal is dependent on the position of the component boundaries within their sensing
zone. The measured data are then transferred to a computer through a computer data
acquisition system.
regarding to the flow.
Computer software is used to obtain the concentration profile
34
3.3.1
Selection of Optical Sensor
In order to select the optical sensor for process tomography application, it is
necessary to consider the characteristics and requirements of the process. Various
aspects of consideration are required, including the conveyor’s physical characteristics,
size of the process (conveyor’s diameter), range of conveying rate, and type of materials
to be conveyed and cost of the system. The sensor radiation characteristic and receiver
responsiveness at the required wave length must also be taken into consideration. In
order to have a detector that can detect the halogen beam due to the required wave
length (wavelength response by detector), the detector radiation and responsivity must
be matched with the light emission wavelength.
There are a wide range of different light spectrum photo sensors. To obtain an
optimized and accurate reading, the selection of light detector must be unique to the
exposed light spectrum and provide a fast setting time. In addition, the type of detector
selected must consider the detector's noise limit (smallest signal that can be handled),
leakage current, mating electronics, packaging constraints, signal-to-noise ratio,
frequency bandwidth and the cost (Abdul Rahim et al., 2005).
The photodiode is selected because it gives:
i.
High speed response
ii.
Improve linearity
iii.
Low leakage current
iv.
Low noise
The measure of sensitivity is the ratio of radiant energy (in watts) incident on the
photodiode to the photo-current output in amperes. It is a typical responsivity curve that
35
shows A/W as function of wavelength. The detector radiation and responsivity must be
matched with the light emission wavelength.
photodiode is around 850nm.
The maximum responsivity of the
That means the detector can adapt the emission
wavelength which below its range, 750nm.
In this project the BPX 65 photodiode is used to detect the halogen light via the
optical fiber. The optical fiber that was chosen is made from plastic. The photodiode
are configured to operate in photoconductive mode (current operating mode) where the
photodiodes are working in reverse biased.
Figure 3.4: BPX65 photodiode
The principle of this project is based on the light beams transmitting in a straight
line to receivers. The sensor output voltage depends on the blockage effect when objects
intercept the light beams. There are two assumptions in this model as follows:
36
i.
All incident lights on the surface of object are fully absorbed by the
object
ii.
3.3.2
Light scattering and beam divergence effect are neglected.
Light Source
MR16 (sometimes referred to as MR-16) is a standard format for halogen
reflector lamps made by a variety of manufactures. MR16 lamps consist of a halogen
capsule (bulb) integrated with a pressed glass reflector. The reflector of an MR16 lamp
is 2 inches (50mm) in diameter. The reflector controls the direction and spread of light
cast from the lamp. MR16 lamps are available with different beam angles from narrow
spot lights of as small as 7 degrees to wide flood lamps of 60 degrees. "MR" refers to
multifaceted reflector, indicating that this reflector is usually shaped with multiple small
facets. This multifaceted reflector gives a soft edge to the area illuminated by the lamp.
The reflector has an aluminium coating that reflects all light.
A halogen bulb is often 10 to 20 percent more efficient than an ordinary
incandescent bulb of similar voltage, wattage, and life expectancy. Halogen bulbs may
also have two to three times as long a lifetime as ordinary bulbs, sometimes also with an
improvement in efficiency of up to 10 percent. The Halogen tungsten filament lamps
used are standard 12V 50W MR16 lamps shown:
37
Figure 3.5: MR16 halogen lamp
3.3.3
Signal Conditioning Circuit
This circuit function is to improve the signal quality and compensate the noise
produced from the circuit. This circuit will include the current to voltage converter,
buffer circuit and the filter circuit. The measuring circuits function to improve signal
that is received from the photodiode BPX 65.
The signal conditioning circuit of optical system is consist of three stages which
are: Current to Voltage circuit converter, First level circuit Amplifier and Second level
circuit Amplifier. The complete circuit is illustrated in Figure 3.6:
38
Figure 3.6: Schematic circuit of receiver
3.3.3.1 Current to Voltage Circuit Converter
BPX 65 photodiode will receive light from halogen lamps through the optical
fibers and convert it to a current signal. Photodiode act as a transducer which changes
non-electrical signal into an electric signal. As the needed signal is voltage, so another
current to voltage converter is used. This circuit below is the first level for circuit
measurement. Current to voltage converter circuit is as shown in Figure 3.7.
Figure 3.7: Current to Voltage Converter.
39
3.3.3.2 First and Second Stage Amplifier
This First level amplifier is an inverter amplifier. This type of amplifier is widely
used around the global. The circuit output is figured out by multiplying input and
constant gain which is set by the R1 resistance and feedback resistance Rf. Gain can be
measured using this formula:
A=V0/V1 =-Rf/R1
3.1
The first level amplifier acts as buffer and provides a DC gain of 10. This circuit
will eliminate any differential voltage to load. The 10 KHz bandwidth is chosen for the
system, hence,
ω=2πf
3.2
=2π (10x103)
= 62.81 k rad/s
Time constant, τ = 1 / ω
3.3
1.59 x 10-5 s
τ = CR and R is fixed 1M
C= τ/R
= 15.91 pF
3.4
40
Figure 3.8: Buffer
The output of second stage is connected to the following stage. To get the higher
output signal the third stage amplifier is being used (Figure 3.9). This circuit provides a
gain of 14.7 and the corner frequency is 10.61 kHz.
Figure 3.9: Third stage signal amplifier.
41
The optical imaging system is shown in Figure 3.10. The picture illustrates the
3rd Output signal on the oscilloscope monitor when the light is not blocked.
Figure 3.10: The optical imaging system being tested
3.4
Electrodynamic Tomography System
Electrodynamics or formerly known as electrical charge tomography system is
based on several sensors that are sensitive to electrical charge induced to their sensing
electrodes. Pneumatically conveyed matter such as solids acquires charges during the
transportation between several processes such as symmetrical charge separation and
frictional charging. There are many advantages of using electrical charge transducer
such as robust, low cost and have the potential to be used for process tomography,
whereby several identical transducers are positioned around the vessel being
42
interrogated. These provide data which are used to re-construct dynamic images of the
movement of the material being monitored (Green et al, 1997).
In this system, the positions of electrodynamic sensors at the measured cross
section through the pipe are shown in Figure 3.11 below.
Figure 3.11: An array of sensors in clockwise order
43
3.4.1
Electrodynamic Sensor
Electrodynamic sensors are basically passive charge to voltage converters. The
operation of electrodynamic sensor is based the concept of Coulomb' theory of charge
established as in equation below:
Q=CV
3.5
Where Q is the quantity of charge in coulombs, C is a capacitance in farads and
V is voltage in volts.
The corresponding voltage level can be known if there is any amount of charge
Q with the capacitance C fixed (Hezri, 2002). There are two variations of
electrodynamic sensors depending on their sensing electrodes; these are the ring type
elecirode sensors and discrete electrodynamic sensors.
Electrodynamic sensors derive their signals by sensing the random changes in
induced charge arising from the turbulent nature of the flow. Dry solids moving through
a conveyor will generate static electric charge depending on factors such as the size,
shape and type of materials. The electrostatic charge can be detected using electrodes
and converted into voltage signal by the electrodynamic transducers (Azrita, 2002).
44
3.4.2
Signal conditioning circuit for electrodynamic sensor
The associated electronics part consists of signal conditioning circuitry and is
used to convert the detected quantity of charge (i.e electrostatic charge) into its
equivalent voltage signal, which is modified into three forms such as AC voltage,
rectified voltage and average voltage as shown in Figure 3.12. This part of the
transducer comprises the signal amplifiers, a buffer, filters and rectifiers of the circuit.
Figure 3.12: Block diagram of an electrical charge sensing system
The complete circuit of electrodynamic transducer is shown in Appendix A, and
the photo of an electrodynamic sensors constructed during this project is shown in
Figure 3.13:
45
Figure 3.13: A photo of the electrodynamics circuits
The electrode consists of metal conductor, which is electrically insulated form
the surrounding conveyor and provide a capacitance to earth (GND). This capacitance is
not very well defined due to the way it is formed, but it has a value of approximately
1pF.
In order that measurements are made with very similar capacitance the input
circuit of capacitor, Cl connected between input and earth. The value of C1 is 4.7 pF. The
passing charge particles induce charge, Qi into the electrode resulting in a voltage Vi.
The input resistor R1 provides a path for current to flow into and out of the capacitance
Cl formed between electrode and ground.
46
The current flow through the resistor result in the voltage, which provides the
input to the integrated circuit amplifier (IC1), connected as a non-inverting voltage
follower. Figure 3.14 shows typical non-inverting voltage follower. In the voltage
follower configuration no resistors or capacitors exist. The output of this amplifier is fed
back to the negative input pin.
Figure 3.14: Non-inverting voltage follower
The value of gain for OP-AMP1 is 1, where Vo=Vi for non- inverting voltage
follower. Thus,
Av =
Vo Vo
=
=1
Vi Vo
3.6
And the bandwidth is 3 MHz (referring to data sheet TLO84CN).
The output of the voltage follower is used as a guard voltage for the input circuit,
to non-inverting voltage amplifier (OP-AMP2). Figure 3.15 shows typical non-inverting
voltage amplifier.
47
AC coupling functions is used as a filter to block passage of DC voltages from
one stage to another. In other word, AC coupling will only let the AC signal to pass into
the next stage of the circuit.
Figure 3.15: Non-inverting voltage amplifier
The pair of back-to-back Zener diodes is an attempt to prevent large voltage
discharges, which occur in a conveyor, from damaging the transducer amplifiers. The
time constant of the coupling circuit in the second stage is 1 second, providing high pass
network with lower cut-off frequency of 0.167Hz. Output 1 (0/P1) is the output of this
stage, which is used for cross-correlation measurement and as the input to the following
stage.
The third stage of the circuit is to precision rectifier composed of two operational
amplifiers (OP-AMP3 and OP-AMP4) are AC coupled to the preceding amplifier. This
AC coupling removes any long-term drift in OP-AMP2 arising for example from
changes in the input bias current with temperature. The summing amplifier, OPAMP4
has capacitance, C6 connected across its feedback resistor, R12. This low pass filter
attempts to make the rectified voltage pulses have the same waveform as the induced
charge when performing the spatial filtering test. The output of this stage (O/P2) is
available for the spatial filtering test and as the directly coupled input to the low pass
filter circuit OP-AMP5.
48
This circuit provides smoothing for the preceding stage and its output (O/P3) is
termed the average output. A variable resistor is used to offset any bias voltage so that
the output is zero volts for zero input.
The ICs used in the electrodynamic circuit are the TLO84CN by ST. Basically,
the TL084 choice of JFET input operational amplifier are chosen because it provides
wide bandwidths and fast slew rate with low input bias currents, input offset currents
and supply currents. The IC is compatible with the industry standard MC1741, MC1458
and MC3403/LM324 bipolar products. It also has an operating current temperature of 0
to 70°C.
3.5
The Data Acquisition System
In this research the sensors are interfaced to a desktop computer (PC) via a data
acquisition card. The data acquisition card used for interfacing is a high performance 64channel single ended data acquisition board (DAS- 1 800HC) from Keithley Metrabyte
Instruments. This data acquisition card is capable of performing analogue input
sampling at 333 kHz. Out of the available 64 channels, 16 channels are enough for
producing concentration profiles. Therefore 16 channels are sampled (8 for optical
system and another 8 for electrodynamic system).
DAS- 1800 board is installed into the PC through the I/O connectors of the PC's
Mainboard. The 16 sensors are connected to DAS-1800 using electrical wires to connect
each output of the sensors individually.
49
The connection of sensors to the PC interfaced by DAS- 1800 and its accessories
is shown in Figure 3.16.
Figure 3.16: Connection of sensors to the PC
50
3.6
Complete Hardware Design
A complete hardware design is made by combining all modules that have been
discussed in this chapter. Figure 3.17 shows the complete hardware system that was
used.
Figure 3.17: The complete hardware system.
CHPTER 4
SOFTWARE DESIGN
4.1
Introduction
This chapter will explain the process taken to obtain the concentration profile
of the solid objects conveyed inside the pipe. The processes include the task to
obtain the model that represent the behavior of the sensing system interrogating the
pipe circumference, the algorithm used to relate the flow and the sensor reading.
4.2
Concentration Profile
The main objective of this research is to obtain the concentration profiles of
the solid materials by using data obtained from the tomography measurement. The
process of reconstructing image begins after receiving the output data (voltage) from
the sensors (i.e photodiodes and electrodynamics). The Linear back projection image
algorithm is used to obtain these profiles. For optical sensors, any obstacle (object)
that cross the light path will reduce the signal output of the corresponding light
52
path’s detector. A preamp is used over each detector to convert the photodiode
current to voltage. In case of electrodynamics technique, the signal output for each
electrode will increase from zero volts to an equal magnitude of the electrostatic
charge of the object which passing through the pipe. All the outputs reading will be
captured by using data acquisition system (DAS).
Through the DAS, signals
produced by both of systems are available for image processing using MATLAB
software.
4.3
Linear Back Projection (LBP) Technique
To reconstruct the cross-sectional image from the projection data, linear back
projection (LBP) algorithm has been used. The measurements obtained at each
projection are projected back along the same line, assigning the measured value to
each point in the line (R. Abdul Rahim et al., 2002). Among the many algorithms,
(LBP) is the most fundamental principle used for image reconstruction in
tomography processes. Though the principle is simple, the implementation is quite
complicated. The principle claimed that each projection results in shadows around
the boundary at opposite direction of projection if there is an object between the two
boundaries. The shadows effect is know as ‘projection’ or sometime it is called as
projection data. Projection contain a set of measurements where the number of
measurement is depends on the amount of sensors on the boundary. To construct the
image, all the projections are back projected to its original direction. All the spaces
lay on the projected ray are mark with corresponding ray’s amplitude. Then, the
back projected rays are superimposed in order to obtain the image.
projection scheme is illustrated in Figure 4.1.
The back
53
Figure 4.1: Back projection.
In (LBP) algorithm, the concentration profile is generated by combining the
voltage measured by each sensor with the computed sensitivity map (S. Ibrahim et
al., 1999).
To reconstruct the image, each sensitivity map is multiplied by its
corresponding sensor reading. This is just like back projecting each sensor reading
to image plane individually. Consequently, a m(n×n) matrix is obtained, in which
the m represents the number of obtained projection and the n is the reconstructed
image resolution of the used sensitivity matrix. The same elements in these matrices
are summed up to provide the back projected voltage distributions. This is process
can be expressed mathematically as:
Where Vij is the voltage distribution in 8×8 matrix, V sn is the voltage for nth
sensor, Sn is the sensitivity map for nth sensor and m is the total number of sensors
used at each stream.
For electrodynamic system the limitation of linear back projection is exposed
clearly in Figure 4.2. Very low estimation of solids concentration at the centre of the
pipe even though we have assumed uniformly distributed solids of equal charge in
each and every pixel, (the measured value for each sensor assumed to be one volt).
54
(a)
(b)
Figure 4.2: Theoretical concentration matrix tomogram. (a) 2D view and (b) 3D view
The theoretical concentration distribution is shown as tomogram where the
variation in darkness relates to solid's concentration variation in the conveyor pipe.
4.4
Sensitivity Maps
The cross section of the circular pipe has to be mapped onto a rectangular
array of pixels. The cross section can be mapped onto any number of rectangular
arrays of pixels. The more number of pixels the better the resolutions of the images,
although large number of pixels results in very low sensor outputs which is
undesirable for certain application.
4.4.1 Optical Sensitivity Maps
The sensitivity matrix for each sensor consists of an 8x8 matrix containing 64
numerical values, many of which are zeros. Through this algorithm, 8 sensitivity
55
matrices with 8x8 dimensions are calculated.
Each sensor corresponds to one
sensitivity map. If the beam of the sensor being considered passes through a pixel
within the pipe, the pixel has a sensitivity of one, otherwise zero. Based on this
algorithm, the sensor voltage for each projection is multiplied with the sensitivity
map.
In order to obtain the concentration profile, the sensitivity map for each
sensor’s projection has to be determined first and an assumption of the straight path
of emitter beam is used. The sensitivity map for each sensor’s projection is shown
below. T1, T2, T3...T8 denote the eight transmitted light beams. Four parallel and
equally spaced projections are placed at each side. R1, R2, R3, R4, R5, R6, R6, R7
and R8 denote receivers 1, 2,3,4,5,6,7 and 8 respectively.
56
Figure 4.3: (a) – (h): Sensitivity maps for an 8 sensors.
4.4.2
Electrodynamic Sensitivity Maps
To calculate the sensitivity map of each sensor, we have to define the coordinates of the pipe. In this work the centre of the pipe is chosen as the origin i.e.
(0,0) rectangular coordinate value as shown in Figure 4.4.
57
Figure 4.4: The pipe co-ordinates model
Knowing the longitudinal dimensions of the pipe and the angle of each
sensor with respect to the origin, it becomes easy to calculate the rectangular
coordinates by using one of the mathematical methods. The MATHCAD software
was used to calculate sensitivity models for all electrodynamic sensors.
The sensitivity map of sensor 1 is shown in Figure 4.5 and its equivalent three
dimensions (3D) format is shown in Figure 4.6.
58
0.552
0.679
0.881
1.245
2.111
7.475
7.475
2.111
0.543
0.664
0.848
1.16
1.769
3.007
3.007
1.769
0.518
0.621
0.765
0.973
1.262
1.549
1.549
1.262
0.483
0.564
0.666
0.793
0.930
1.031
1.031
0.930
0.444
0.504
0.575
0.652
0.723
0.769
0.769
0.723
0.404
0.449
0.498
0.546
0.587
0.611
0.611
0.587
0.367
0.401
0.435
0.466
0.491
0.505
0.505
0.492
0.334
0.359
0.383
0.405
0.421
0.430
0.430
0.422
Figure 4.5: Sensitivity map of sensor 1
Figure 4.6: 3D sensitivity map of sensor 1
59
4.5
Programming Structure
The concentration profile of the object will be displayed offline through the
developed software. In this project, the algorithm was constructed using the Matlab
programming language. The program was selected due to its simple structure that
provides a complete application development environment.
The offline visualization was performed for the purpose of result evaluation.
The user should have had the data collected during the experiment. The data must be
entered manually into the program.
CHAPTER 5
RESULTS
5.1
Introduction
In this chapter, the results obtained from the experiments are presented and
discussed. There are several experiments done to evaluate two different tomography
systems, (i.e. electrodynamic & optical tomography systems) which developed in this
project. Solid objects with various dimensions and shapes were inserted inside the
pipe and the data received from each sensor are keyed in into the application
program to obtain the concentration profile of the object. The result will be verified
in terms of their accurateness.
The ability of both systems in detecting and
recognizing the location of objects in the flow pipe is investigated.
5.2
Circuit Testing
The electronic circuits were tested to ascertain whether they can be used for
measurement purpose.
61
Testing process took place in different circumstances and different objects by
using the probe of the oscilloscope screen. For electrodes that are used to detect the
charge induced by moving particle, in primary level of testing the output were being
observed by the touching of the hand.
The discrete electrodnamic sensors have three output electrical signals which
have different applications. The three outputs are namely the AC output signal
(O/P1), the rectified output signal (O/P2) and the averaged output signal (O/P3). The
shape of each stage is shown in Figure 5.1 below:
(a)
62
(b)
(c)
Figure 5.1: (a) : Output 1, (b): Output 2 and (c): Output 3.
When no object flows throw the pipeline, the tested electrodes cannot sense
any electrical charge, so the output voltage value for each electrodynamic sensor was
supposed to be zero volt. The small reads shown on the monitor of the oscilloscope
are the noise generated by the circuit. The figure 5.2 shows the average output after
using the hand touch method:
63
Figure 5.2: Average output using hand touch.
In the case of using a finger to touch the electrode for several seconds, it is
noted that the amount of signal increased as observed on the oscilloscope screen.
Figure 5.3 below shows that:
Figure 5.3: The hand is fixed at the electrode for period of time.
The hand also used to block the light source to reach the receivers. The
output of the optical sensors where the room lights were turned on is shown in Figure
5.4.
64
Figure 5.4: Output signal when the sensor receiving surrounding lights
From the Figure 5.4, we note that the wave form of the signal is not smooth;
because of the light is not focused on the mirror of the photodiode. The shape of the
output improves by increasing the amount of light received by the optical sensors.
The Figure 5.5 shows the wave form when the fiber optic is housing close to
photodiode and the halogen source is turned on.
Figure 5.5: Optical output when the light not blocked.
65
When light is totally blocked, the output voltage decreases even up to zero
volt. Figure 5.6 illustrates that.
Figure 5.6: The optical output when light is blocked.
5.3
Concentration Profile from the Offline Data
The objective of this experiment is to get the offline output voltage level at
each detector of the two systems for various flow conditions. The types of flow
evaluated are no flow condition, full-flow condition, and single object flow with
different sizes and locations.
66
5.3.1
Concentration Profile during No-Flow Condition
The concentration profile obtained from electrodynamic system for the noflow condition is shown in Figure 5.7(a). Figure 5.7(b) is the concentration profile
obtained from optical system for the same condition.
(a)
(b)
Figure 5.7: The concentration profile for the no-flow condition.
(a) Obtained from electrodynamic system. (b) Obtained from optical system.
During no-flow condition, the concentration profile displays a uniform
concentration throughout the pipe circumference which exhibit that there are no
object flowing inside the pipe. Ideally, all the pixels that represent the pipe should
display the same colour code. The slight difference in case of electrodynamic system
occurs as the result of noise.
67
5.3.2 Concentration Profile for Full-flow Condition
To represent a full-flow condition, a square wood bar with dimensions a little
smaller than the dimensions of the pipe was used. The concentration profile obtained
shows a uniform value for the whole map since the sensors acquired the same value of
data.
This condition happens because in optical process tomography, the output
obtained by the sensor during full-flow condition is 0 V because the beam was totally
block by the object and thus, cannot be received by the sensor at the other end. When
the sensor reading is multiplied with the sensitivity value, it will return a 0 value. Figure
5.8 (a,b) shows the result for full-flow condition.
(a)
(b)
Figure 5.8: The concentration profile for the full-flow condition.
(a) Obtained from the electrodynamic system. (b) Obtained from the optical system.
68
5.3.3
Concentration Profile of Object flowing in middle of the pipe
The concentration profile presented in Figure 5.9(a) generated from data sets
obtained when inserting a 60mm × 60mm square wood bar at the middle of the pipe.
For the electrodynamic system, the charge sensed by the sensors almost same.
However, the matter is different in the case of optical system, where the object at that
specific location was blocking the beam projected from four emitters (i.e. T2, T3, T6
and T7), and thus, cannot be received by the sensors R2, R3, R6 and R7 respectively at
the other end.
(a)
(b)
Figure 5.9: The concentration profile when the square wood bar is inserted at the middle
(a) Obtained from the electrodynamic system. (b) Obtained from the optical system.
69
5.3.4
Concentration Profile of a 20mm PVC pipe dropped close to the pipe wall
Figures 5.10 (a,b) show the result for 20mm PVC pipe inserted into the pipe.
From the figure we cane see that the optical sensors R3 and R8 were detect the object.
The concentration profile presented in Figure 5.10(b) shows that the PVC pipe was
dropped so close to the third electrodynamic sensor S3. The sensor sensed high charge
compared to others.
(a)
(b)
Figure 5.10: The concentration profile when the 20mm PVC pipe is inserted close to
wall of the pipe
(a) Obtained from the optical system. (b) Obtained from the electrodynamic system.
70
5.3.5
Concentration Profile during transparent rod
In this condition, a transparent object was used.
Figure 5.11 shows the
concentration profiles result. Because of physical aspect, the rod image can not be
reconstructing clearly using optical system Figure 5.11(b). This problem is caused due
smearing effect of the LBP [Sallehuddin, 200]. By increasing the number of projection,
we can reduce this phenomenon but can not be eliminated completely.
Use of
electrodynamic system has more efficiency in such conditions; where the
electrodynamic sensors senses the charge carried by the object regardless of its
transparency.
(a)
(b)
Figure 5.11: The concentration profile for a transparent rod
(a) Obtained from the electrodynamic system. (b) Obtained from the optical system.
71
5.3.6
Concentration Profile of Two Objects Flow
The concentration profile obtained from the optical system for two objects flow
is shown in Figure 5.12(a). From the figure we note that although the two orthogonal
projections systems provide a small amount of error, there is aliasing in the image,
which occurs when two particles intercept the same view resulting in the ambiguity of
the location of some particles. This is due to the fact that the tow projections system
produces insufficient information which leads to the lack of image resolution and
aliasing [Daniels, 1992].
This Confusion of the location of objects is disappears if we had a look to the
concentration profile obtained from electrodynamic system, Figure 5.12(b), where it is
clear that one of the objects is located at the upper right corner close to sensors S1and
S2, while the other one dropped at opposite corner not too close to the pipe wall,
whereas the sensors S5, S6 could not sense high amount of charge.
72
(a)
(b)
Figure 5.12: The concentration profile for the two objects condition.
(a) Obtained from the optical system. (b) Obtained from the electrodynamic system.
CHAPTER 6
CONCLUSION AND FUTURE RECOMMENDATION
6.1
Conclusion
The objective of this project has been achieved through the measurement
using two types of tomography systems (i.e. optical & electrodynamic techniques).
For optical system, two halogen bulbs are used as light sources, the light beam
assumed to be parallel projections. Eight photodiodes are used as receivers to detect
the solid objects flowing inside a square pipeline. Eight electrodes are housed
around the same pipe to detect the charges carried by the objects. Signal conditioning
circuits to process the signals obtained from sensors are designed and constructed.
The concentration profiles of the solid objects flowing inside the pipe are obtained
using MATLAB software.
The goal of a combining both of the systems with each other is to make
comparison between them in performance and accuracy in measuring objects with
different characteristics.
74
The concentration profiles obtained from the optical system show a
significant error where the dimension of the object can not be determined due to
insufficient number of sensors used, where the number of used sensors is a crucial
factor that determines the accuracy of the concentration profile obtained.
There is another important factor that makes the concentration profile not
sufficient to be interpreted accurately; this factor is the lower order of sensitivity
matrix. By adding the number of sensors, as well as the number of projections, the
system will be more accurate.
By the results, it also became clear that the optical system unworkable for
measuring transparent objects. This matter consider as one of limitations of using
optical system.
On the other hand, the electrodynamic sensors which are the integral part of
electrical charge tomography system have shown high sensitivity to presence of
charge within its sensing zone. We also note that some of the obstacles facing the
implementation of the optical system could be bypassed in the electrodynamic
system; since the electrodynamic system is not affected by different shape of the
object and its physical properties as much influenced by the charge carried by the
object. For example, electrodynamic system capable to sense transparent objects,
whereas, optical system was unable.
One of the limitations faces the electrodynamic system is noise.
Noise
occurrence may cause by wire connections as well as external environment of the
circuit which affect the circuit response in many ways. The signal detected by the
electrodynamic sensors is too small compared to the noise.
75
Although the electrodynamic system has high accuracy when detecting
objects flowing close to the sensors, yet, it cannot sense the charge of the objects
flowing at the middle of the pipe.
6.2
Suggestions for Future Works
i.
The signal conditioning part should be improved to be more noise
resistant.
ii.
Compressing the size of the signal conditioning circuit, such as by
using improved PCB design software.
iii.
Increase the number of sensors that should be used in both
tomography systems in order to enhance the system performance.
iv.
A less costly photodiode can be investigated in order to decrease the
budget.
v.
The system algorithm can be enhanced to obtain the flow velocity.
vi.
The mass flow rate can be calculated by integrating both velocity
profile and the concentration profile.
vii.
Increase the number of the pixels to enhance resolution.
REFERENCES
Chan Kok San (2002). “Real Time Image Reconstruction for Fan Beam Optical
Tomography System”. Universiti Teknologi Malaysia: B.Eng. Thesis.
Hakilo Ahmed Sabit (2005). “Flow Regime Identification Of Particles Conveying In
Pneumatic Pipeline Using Electric Charge Tomography And Neural Network
Techniques”. Universiti Teknologi Malaysia: Master Eng. Thesis.
Daniels, A.R. (1996). “Dual Modality Tomography for the Monitoring of Constituent
Volumes in Multi-Component Flows”. Sheffield Hallam University: Ph.D. Thesis.
Dyakowski T. (1996) “Process tomography applied to multi-phase flow
measurement”. Meas. Sci. Technol., 7, pp.343-353.
Mazidah Binti Tajjudin (2005). “Fan Beam Optical Tomography”. Universiti
Teknologi Malaysia, Master Eng. Thesis.
Mohamad Zakuan Bin Hassan (2006). “Optical Tomography For Measuring Solid
Flow”. Universiti Teknologi Malaysia: B.Eng. Thesis.
Mohd Amri B Md Yunus (2005). “Imaging Of Solid Flow In a Gravity Flow Rig
Using Infra-Red Tomography”. Universiti Teknologi Malaysia, Master Eng. Thesis.
Mohd Fua’ad Rahmat (1996). “Instrumentation Of Particle Conveying Using
Electrical Charge Tomogaphy” Sheffield Hallam University: Ph.D. Thesis.
77
R. Abdul Rahim, K.S. Chan, J.F. Pang, L.C.Leong (2004b). “Optical Tomography
System Using Switch mode Fan Beam Projection: Modeling Techniques”.
R. Abdul Rahim, N. Horbury, F.J. Dickin, R.G. Green, B.D. Naylor, T.P. Pridmore,
(1995). “Optical Fibre Sensor for Process Tomography use on Pneumatic
Conveyors”.
R. A. Williams, M. S. Beck, (1995). Principles, techniques and applications”.
Butterworth-Hienemann Ltd.
Sallehuddin Ibrahim. (2000). “Measurement of gas bubbles in a vertical water
column using optical tomography”. Ph.D Thesis, Sheffield Hallam University.
S. Ibrahim, R.G. Green, K. Dutton and Abdul Rahim R. (2000). “Application Of
Optical Tomography in Industrial Process Control System”. IEEE. 493 – 498.
S. Ibrahim, R.G.Green, K.Dutton, R. Abdul Rahim, K.Evans and A.Goude. (1999).
“Optical sensor configurations for Process Tomography”. Meas.Sci. Teachnol.
1079-1086.
S.F.A. Bukhari and W.Q. Yang, (2004). “Tomographic Imaging Technique for Oil
Separator Control. 3rd International Symposium on Process Tomography”. Poland.
Wang, M., Dorward, A., Vlaev, D, and Mann, R. (1999), “Measurement of gasliquid mixing in a stirred vessel using electrical resistance tomography (ERT)
Proceedings of the 1st World Congress on Industrial Process Tomography”, Buxton,
UK.78-83.
Yang, W.Q. and Peng, L. (2003). “Image reconstruction algorithms for electrical
capacitance tomography”. Meas. Sci. Technol Journal. Vol.14.P.R1-R13.
Yvette Shaan-Li Susiapan 2007. “A Flame Imaging System Using Optical Sensors”.
Universiti Teknologi Malaysia, Master Eng. Thesis.
APPENDIX A
(Schematic Diagram for the Electrodynamic Transducer Circuit)
APPENDIX B
(Data Sheet for TL084A)
TL084
TL084A - TL084B

GENERAL PURPOSEJ-FET
QUAD OPERATIONAL AMPLIFIERS
.
..
.
..
.
WIDE COMMON-MODE (UP TO VCC+) AND
DIFFERENTIAL VOLTAGE RANGE
LOW INPUT BIAS AND OFFSET CURRENT
OUTPUT SHORT-CIRCUIT PROTECTION
HIGH INPUT IMPEDANCE J–FET INPUT
STAGE
INTERNAL FREQUENCY COMPENSATION
LATCH UP FREE OPERATION
HIGH SLEW RATE : 16V/µs (typ)
N
DIP14
(Plastic Package)
D
SO14
(Plastic Micropackage)
P
TSSOP14
(Thin Shrink Small Outline Package)
DESCRIPTION
ORDER CODES
The TL084, TL084A and TL084B are high speed
J–FET input quad operationalamplifiers incorporating
well matched, high voltage J–FET and bipolar transistors in a monolithic integrated circuit.
The devicesfeaturehigh slew rates, low input bias and
offset currents, and low offset voltage temperature
coefficient.
Part Number
Temperature
Range
TL084M/AM/BM
–55 C, +125 C
TL084C/AC/BC
D
P
•
•
•
o
o
o
o
•
•
•
0 C, +70 C
•
•
•
–40 C, +105 C
TL084I/AI/BI
Package
N
o
o
Examples : TL084CN, TL084CD
PIN CONNECTIONS (top view)
Output 1 1
14 Output 4
Inverting Input 1 2
-
-
13 Inverting Input 4
Non-inverting Input 1 3
+
+
12 Non-inverting Input 4
11 VCC -
VCC + 4
Non-inverting Input 2 5
+
+
10 Non-inverting Input 3
Inverting Input 2 6
-
-
9
Inverting Input 3
8
Output 3
Output 2 7
January 1999
1/11
TL084 - TL084A - TL084B
SCHEMATIC DIAGRAM (each amplifier)
VCC
Non- inver ting
input
I nverting
input
1 0 0Ω
2 0 0Ω
Output
1 0 0Ω
30k
8.2k
1.3k
1.3k
35k
35k
1 0 0Ω
VCC
ABSOLUTE MAXIMUM RATINGS
Symbol
VCC
Value
Unit
Supply Voltage - (note 1)
Parameter
±18
V
V
Vi
Input Voltage - (note 3)
±15
Vid
Differential Input Voltage - (note 2)
±30
V
Ptot
Power Dissipation
680
mW
Output Short-circuit Duration - (note 4)
Toper
Operating Free Air Temperature Range
Tstg
Storage Temperature Range
Notes :
2/11
Infinite
TL084C,AC,BC
TL084I,AI,BI
TL084M,AM,BM
0 to 70
–40 to 105
–55 to 125
o
–65 to 150
o
C
C
1. All voltage values, except differential voltage, are with respect to the zero reference level (ground) of the supply voltages where the
zero reference level is the midpoint between VCC+ and VCC–.
2. Differential voltages are at the non-inverting input terminal with respect to the inverting input terminal.
3. The magnitude of the input voltage must never exceed the magnitude of the supply voltage or 15 volts, whichever is less.
4. The output may be shorted to ground or to either supply. Temperature and /or supply voltages must be limited to ensure that the
dissipation rating is not exceeded.
TL084 - TL084A - TL084B
ELECTRICAL CHARACTERISTICS
VCC = ±15V, Tamb = 25oC (unless otherwise specified)
Symbol
TL084I,M,AC,AI,
AM,BC,BI,BM
Parameter
Min.
Vio
DV io
Iio
Iib
Avd
SVR
ICC
Input Offset Voltage (R S = 50Ω)
o
TL084
Tamb = 25 C
TL084A
TL084B
TL084
Tmin. ≤ Tamb ≤ Tmax.
TL084A
TL084B
Typ.
Max.
3
3
1
10
6
3
13
7
5
TL084C
Min.
Max.
3
10
mV
13
10
10
Input Offset Current *
o
Tamb = 25 C
Tmin. ≤ Tamb ≤ Tmax.
5
100
4
5
100
4
pA
nA
Input Bias Current *
o
Tamb = 25 C
Tmin. ≤ Tamb ≤ Tmax.
20
200
20
30
400
20
pA
nA
Large Signal Voltage Gain (RL = 2kΩ, VO = ±10V)
Tamb = 25oC
Tmin. ≤ Tamb ≤ Tmax.
50
25
200
25
15
200
Supply Voltage Rejection Ratio (R S = 50Ω)
o
Tamb = 25 C
Tmin. ≤ Tamb ≤ Tmax.
80
80
86
70
70
86
V/mV
dB
Supply Current, per Amp, no Load
Tamb = 25oC
Tmin. ≤ Tamb ≤ Tmax.
mA
1.4
2.5
2.5
1.4
Input Common Mode Voltage Range
±11
+15
-12
±11
+15
-12
CMR
Common Mode Rejection Ratio (RS = 50Ω)
o
Tamb = 25 C
Tmin. ≤ Tamb ≤ Tmax.
80
80
86
70
70
86
Output Short-circuit Current
o
Tamb = 25 C
Tmin. ≤ Tamb ≤ Tmax.
10
10
40
10
10
40
10
12
10
12
12
13.5
10
12
10
12
12
13.5
8
16
8
16
±VOPP
Output Voltage Swing
o
Tamb = 25 C
Tmin. ≤ Tamb ≤ Tmax.
SR
tr
KOV
GBP
Ri
THD
en
∅m
VO1/VO2
o
µV/ C
Input Offset Voltage Drift
Vicm
Ios
Unit
Typ.
V
dB
mA
60
60
60
60
V
RL
RL
RL
RL
=
=
=
=
2kΩ
10kΩ
2kΩ
10kΩ
Slew Rate (Vin = 10V, RL = 2kΩ, CL = 100pF,
o
Tamb = 25 C, unity gain)
V/µs
Rise Time (Vin = 20mV, RL = 2kΩ, C L = 100pF,
Tamb = 25oC, unity gain)
0.1
0.1
Overshoot (Vin = 20mV, RL = 2kΩ, C L = 100pF,
o
Tamb = 25 C, unity gain)
10
10
Gain Bandwidth Product (f = 100kHz,
Tamb = 25oC, Vin = 10mV, R L = 2kΩ, C L = 100pF)
Input Resistance
Total Harmonic Distortion (f = 1kHz, AV = 20dB,
RL = 2kΩ, C L = 100pF, Tamb = 25oC, VO = 2VPP)
Equivalent Input Noise Voltage
(f = 1kHz, Rs = 100Ω)
2.5
2.5
µs
%
MHz
2.5
4
10
12
2.5
4
12
10
Ω
%
0.01
0.01
15
15

√
Hz
nV
Phase Margin
45
45
Degrees
Channel Separation (Av = 100)
120
120
dB
* The input bias currents are junction leakage currents which approximately double for every 10oC increase in the junction temperature.
3/11
TL084 - TL084A - TL084B
MAXIMUM PEAK-TO-PEAK OUTPUT
VOLTAGE VERSUS FREQUENCY
MAXIMUM PEAK-TO-PEAKOUTPUT
VOLTAGE (V)
30
V CC =
R L = 2kΩ
15V
25
T a m b = + 25° C
S ee Fig ure 2
20
V CC =
10V
15
10
V CC =
5V
5
0
100
1K
10K
100K
1M
10M
MAXIMUMPEAK-TO-PEAK OUTPUT
VOLTAGE (V)
MAXIMUM PEAK-TO-PEAK OUTPUT
VOLTAGE VERSUS FREQUENCY
30
25
V CC = 15V
20
VCC = 10V
15
10
V CC =
0
100
1K
15
Ta mb = -55 C
10
5
Ta mb = +125 C
10k
40k
100k
400k
1M
4M
10M
FREQUENCY (Hz)
30
25
VOLTAGE (V)
MAXIMUM PEAK-TO-PEAK OUTPUT
MAXIMUM PEAK-TO-PEAK OUTPUT
VOLTAGE VERSUS LOAD RESISTANCE
VCC = 15V
Tamb = +25°C
See Figure 2
20
15
10
5
0
0.1 0.2
0.4
0.7 1
2
LOAD RESISTANCE (k
4/11
4
Ω)
7
10
MAXIMUM PEAK-TO-PEAKOUTPUT
VOLTAGE (V)
15V
1M
10M
30
25
20
15
R
L
= 1 0 kΩ
R
L
= 2 kΩ
10
VC C =
5
15 V
S e e F i g u re 2
0
-7 5
-5 0
- 25
0
25
50
75
-50
125
T E MP ER AT U R E ( ° C )
MAXIMUM PEAK-TO-PEAK OUTPUT
VOLTAGE VERSUS SUPPLY VOLTAGE
MAXIMUM PEAK-TO-PEAKOUTPUT
VOLTAGE (V)
MAXIMUMPEAK-TO-PEAK OUTPUT
VOLTAGE (V)
VCC =
R L = 2kΩ
S ee Figure 2
0
100K
MAXIMUM PEAK-TO-PEAK OUTPUT
VOLTAGE VERSUS FREE AIR TEMP.
30
20
10K
FREQUENCY (Hz)
MAXIMUM PEAK-TO-PEAK OUTPUT
VOLTAGE VERSUS FREQUENCY
25
5V
5
FREQUENCY (Hz)
Ta mb = +25 C
R L= 10kΩ
Tamb = +25 C
See Figure 2
30
25
RL = 10 kΩ
Tamb = +25°C
20
15
10
5
0
2
4
6
8
10
12
SUPPLY VOLTAGE ( V)
14
16
TL084 - TL084A - TL084B
INPUT BIAS CURRENT VERSUS
FREE AIR TEMPERATURE
LARGE SIGNAL DIFFERENTIAL
VOLTAGE AMPLIFICATION VERSUS
FREE AIR TEMPERATURE
100
1000
INPUT BIAS CURRENT (nA)
V CC =
15V
400
DIFFERENTIAL VOLTAGE
AMPLIFICATION (V/V)
10
1
0.1
0.01
-50
200
100
40
20
V CC =
10
4
VO =
2
R
L
15V
10V
= 2k Ω
1
-25
0
25
50
75
100
-75
125
-50
-25
0
25
50
75
125
100
TEMPERATURE (°C)
TEMPERATURE (°C)
LARGE SIGNAL DIFFERENTIAL
VOLTAGE AMPLIFICATION AND PHASE
SHIFT VERSUS FREQUENCY
TOTAL POWER DISSIPATION VERSUS
FREE AIR TEMPERATURE
180
DIFFERENTIAL
VOLTAGE
AMPLIFICATION
(left s ca le)
PHASE SHIFT
(right s ca le )
10
90
R = 2kΩ
L
C L = 100pF
V CC = 15V
T amb = +125 C
1
100
1K
10K
0
100K
1M
10M
TOTAL POWER DISSIPATION (mW)
DIFFERENTIAL VOLTAGE
AMPLIFICATION(V/V)
250
100
225
V CC =
200
No signal
No load
175
150
125
100
75
50
25
0
-75
-50
FREQUENCY (Hz)
1.6
No signal
No load
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
V CC =
15V
1.2
1.0
0.8
0.6
0.4
0.2
0
-50
-25
0
25
50
TEMPERATURE (°C)
0
25
50
75
100
125
SUPPLY CURRENT PER AMPLIFIER
VERSUS SUPPLY VOLTAGE
2.0
1.8
-75
-25
TEMPERATURE (°C)
SUPPLY CURRENT PER AMPLIFIER
VERSUS FREE AIR TEMPERATURE
1.4
15V
75
100
125
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
Tamb = +25°C
No signal
No load
2
4
6
10
12 14
8
SUPPLY VOLTAGE ( V)
16
5/11
TL084 - TL084A - TL084B
VOLTAGE FOLLOWER LARGE SIGNAL
PULSE RESPONSE
INPUT AND OUTPUT VOLTAGES
(V)
COMMON MODE REJECTION RATIO
VERSUS FREE AIR TEMPERATURE
COMMON MODE MODE REJECTION
RATIO (dB)
89
R L = 1 0 kΩ
88
VC C =
15V
87
86
85
84
83
-75
-50
-25
0
25
50
75
100
125
6
4
OUTP UT
INPUT
2
0
VCC = 15V
R L = 2 kΩ
C L= 100pF
Tam b = +25 C
-2
-4
-6
0
0.5
OUTPUT VOLTAGE VERSUS
ELAPSED TIME
2
2.5
3
3.5
EQUIVALENT INPUT NOISE VOLTAGE
VERSUS FREQUENCY
28
70
24
90%
16
12
8
V
4
0
t
0
CC
= 15V
R L = 2k Ω
10%
-4
VCC = 15V
A V = 10
60
OVERSHOOT
20
EQUIVALENT INPUT NOISE
VOLTAGE (nV/VHz)
OUTPUT VOLTAGE (mV)
1.5
TIME (µs )
TEMPERATURE (°C)
0.1
Tamb = +25°C
r
R S = 100 Ω
T amb = +25°C
50
40
30
20
10
0
0.2
0.3
0.5
0.4
0.6
10
0.7
40
100
TIME ( µs)
1
TOTAL HARMONIC DISTORTION
(%)
400
1k
4k
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION VERSUS
FREQUENCY
V VCC = = 15V
15V
CC
0.4
11
AA
V V= =
VV
= 6V
(rms)
OO
(rms) = 6V
0.1
0.04
T amb
T amb= =+25°C
+25°C
0.01
0.004
0.001
100
400
1k
4k
10k
FREQUENCY (Hz)
6/11
1
40k
100k
10k
40k 100k
TL084 - TL084A - TL084B
PARAMETER MEASUREMENT INFORMATION
Figure 1 : Voltage Follower
Figure 2 : Gain-of-10 Inverting Amplifier
10k Ω
1k Ω
-
-
eI
1/4
eo
TL084
1/4
eo
TL084
RL = 2kΩ
CL = 100pF
eI
RL
CL = 100pF
TYPICAL APPLICATIONS
AUDIO DISTRIBUTION AMPLIFIER
f O = 100kH z
1/4
1M
Ω
TL0 84
Output A
1 µF
1/4
-
TL0 84
1/4
Input
TL084
100k
Ω
Output B
Ω
100k Ω
100k
V CC+
1OO µF
100k
Ω
1/4
TL0 84
Output C
7/11
TL084 - TL084A - TL084B
TYPICAL APPLICATIONS (continued)
POSITIVE FEEDBACK BANDPASS FILTER
16 k Ω
16 k Ω
22 0p F
220pF
43k Ω
43 k Ω
43 k Ω
Input
22 0pF
1/4
TL08 4
22 0p F
43 k Ω
30 k Ω
43 k Ω
30 k Ω
1/4
TL 08 4
43 k Ω
-
1/4
1/4
TL08 4
TL 084
1 .5 k Ω
1 .5 k Ω
Output B
Ground
Output A
OUTPUT A
SECOND ORDER BANDPASS F ILT ER
fo = 100kHz ; Q = 30 ; Gain = 4
8/11
OUTPUT B
CASCADED BANDPASS F IL TER
fo = 100kHz ; Q = 69 ; Gain = 16
TL084 - TL084A - TL084B
PACKAGE MECHANICAL DATA
14 PINS - PLASTIC DIP
Dimensions
a1
B
b
b1
D
E
e
e3
F
i
L
Z
Min.
0.51
1.39
Millimeters
Typ.
Max.
1.65
Min.
0.020
0.055
0.5
0.25
Inches
Typ.
0.065
0.020
0.010
20
0.787
8.5
2.54
15.24
0.335
0.100
0.600
7.1
5.1
0.280
0.201
3.3
1.27
Max.
0.130
2.54
0.050
0.100
9/11
TL084 - TL084A - TL084B
PACKAGE MECHANICAL DATA
14 PINS - PLASTIC MICROPACKAGE (SO)
Dimensions
A
a1
a2
b
b1
C
c1
D
E
e
e3
F
G
L
M
S
10/11
Min.
Millimeters
Typ.
0.1
0.35
0.19
Max.
1.75
0.2
1.6
0.46
0.25
Min.
Inches
Typ.
0.004
0.014
0.007
0.5
Max.
0.069
0.008
0.063
0.018
0.010
0.020
o
45 (typ.)
8.55
5.8
8.75
6.2
0.336
0.228
1.27
7.62
3.8
4.6
0.5
0.334
0.244
0.050
0.300
4.0
5.3
1.27
0.68
0.150
0.181
0.020
8 o (max.)
0.157
0.208
0.050
0.027
TL084 - TL084A - TL084B
PACKAGE MECHANICAL DATA
14 PINS - THIN SHRINK SMALL OUTLINE PACKAGE
Dim.
Millimeters
Min.
Typ.
A
Inches
Max.
Min.
Typ.
1.20
A1
0.05
A2
0.80
b
c
D
4.90
0.05
0.15
0.01
1.05
0.031
0.19
0.30
0.007
0.15
0.09
0.20
0.003
0.012
5.10
0.192
4.50
0.169
8o
0o
0.75
0.09
E
1.00
5.00
6.40
E1
Max.
4.30
e
4.40
0o
l
0.50
0.60
0.039
0.196
0.041
0.20
0.252
0.65
k
0.006
0.173
0.177
0.025
8o
0.0236
0.030
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the
consequences of use of such information nor for any infringement of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this pub lication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support
devices or systems without express written approval of STMicroelectronics.
 The ST log o is a trademark of STMicroelectronics
 1999 STMicroelectronics – Printed in Italy – All Rights Reserved
STMicroelectronics GROUP OF COMPANIES
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 http://www.st.com
11/11
This datasheet has been download from:
www.datasheetcatalog.com
Datasheets for electronics components.
APPENDIX C
(Data Sheet for LF351)
LF151
LF251 - LF351
WIDE BANDWIDTH
SINGLE J-FET OPERATIONAL AMPLIFIER
■ INTERNALLY ADJUSTABLE INPUT OFFSET
VOLTAGE
■ LOW POWER CONSUMPTION
■ WIDE COMMON-MODE (UP TO VCC+) AND
DIFFERENTIAL VOLTAGE RANGE
■ LOW INPUT BIAS AND OFFSET CURRENT
N
DIP8
(Plastic Package)
■ OUTPUT SHORT-CIRCUIT PROTECTION
■ HIGH INPUT IMPEDANCE J–FET INPUT
STAGE
■ INTERNAL FREQUENCY COMPENSATION
■ LATCH UP FREE OPERATION
■ HIGH SLEW RATE : 16V/µs (typ)
D
SO8
(Plastic Micropackage)
DESCRIPTION
ORDER CODE
These circuits are high speed J–FET input singleoperational amplifiers incorporating well matched,
high voltage J–FET and bipolar transistors in a
monolithic integrated circuit.
The devices feature high slew rates, low input bias
and offset currents, and low offset voltage temperature coefficient.
Package
Part Number
LF351
LF251
LF151
Temperature Range
0°C, +70°C
-40°C, +105°C
-55°C, +125°C
N
D
•
•
•
•
•
•
N = Dual in Line Package (DIP)
D = Small Outline Package (SO) - also available in Tape & Reel (DT)
PIN CONNECTIONS (top view)
March 2001
1
8
2
7
3
6
4
5
12345678-
Offset null 1
Inverting input
Non-inverting input
VCCOffset null 2
Output
VCC+
N.C.
1/9
LF151 - LF251 - LF351
SCHEMATIC DIAGRAM
INPUT OFFSET VOLTAGE NULL CIRCUIT
ABSOLUTE MAXIMUM RATINGS
Symbol
VCC
Parameter
Supply voltage - note
LF151
1)
2)
Vi
Input Voltage - note
Vid
Differential Input Voltage - note 3)
Ptot
Power Dissipation
Output Short-circuit Duration - note
4)
Toper
Operating Free-air Temperature Range
Tstg
Storage Temperature Range
1.
2.
3.
4.
2/9
LF251
LF351
Unit
±18
V
±15
V
±30
V
680
mW
Infinite
-55 to +125
-40 to +105
-65 to +150
0 to +70
°C
°C
All voltage values, except differential voltage, are with respect to the zero reference level (ground) of the supply voltages where the zero reference
level is the midpoint between VCC + and VCC -.
The magnitude of the input voltage must never exceed the magnitude of the supply voltage or 15 volts, whichever is less.
Differential voltages are the non-inverting input terminal with respect to the inverting input terminal.
The output may be shorted to ground or to either supply. Temperature and/or supply voltages must be limited to ensure that the dissipation rating
is not exceeded
LF151 - LF251 - LF351
ELECTRICAL CHARACTERISTICS
VCC = ±15V, Tamb = +25°C (unless otherwise specified)
Symbol
Typ.
Max.
Input Offset Voltage (Rs = 10kΩ)
Tamb = +25°C
Tmin ≤ Tamb ≤ Tmax
3
10
13
Input Offset Voltage Drift
10
Iio
Input Offset Current- note 1)
Tamb = +25°C
Tmin ≤ Tamb ≤ Tmax
5
100
4
Iib
Input Bias Current -note 1
Tamb = +25°C
Tmin ≤ Tamb ≤ Tmax
20
200
20
Avd
Large Signal Voltage Gain (RL = 2kΩ, Vo = ±10V)
Tamb = +25°C
Tmin ≤ Tamb ≤ Tmax
50
25
200
Supply Voltage Rejection Ratio (RS = 10kΩ)
Tamb = +25°C
Tmin ≤ Tamb ≤ Tmax
80
80
86
Vio
DVio
SVR
Parameter
ICC
Supply Current, no load
Tamb = +25°C
Tmin ≤ Tamb ≤ Tmax
Vicm
Input Common Mode Voltage Range
CMR
IOS
SR
tr
Kov
GBP
Ri
THD
en
∅m
1.
µV/°C
pA
nA
nA
V/mV
dB
1.4
+15
-12
Common Mode Rejection Ratio (RS = 10kΩ)
Tamb = +25°C
Tmin ≤ Tamb ≤ Tmax
70
70
86
Output Short-circuit Current
Tamb = +25°C
Tmin ≤ Tamb ≤ Tmax
10
10
40
10
12
10
12
12
13.5
12
16
Tmin ≤ Tamb ≤ Tmax
Unit
mV
±11
Output Voltage Swing
Tamb = +25°C
±Vopp
Min.
3.4
3.4
mA
V
dB
mA
RL =
RL =
RL =
RL =
2kΩ
10kΩ
2kΩ
10kΩ
Slew Rate
Vi = 10V, RL = 2kΩ, CL = 100pF, Tamb = +25°C, unity gain
Rise Time
Vi = 20mV, RL = 2kΩ, CL = 100pF, Tamb = +25°C, unity gain
Overshoot
Vi = 20mV, RL = 2kΩ, CL = 100pF, Tamb = +25°C, unity gain
Gain Bandwidth Product
f = 100kHz, Tamb = +25°C,Vin = 10mV, RL = 2kΩ, CL = 100pF
60
60
V
V/µs
µs
0.1
%
10
MHz
2.5
4
Input Resistance
1012
Total Harmonic Distortion ( f = 1kHz, Av = 20dB
RL = 2kΩ, CL = 100pF, Tamb = +25°C,Vo = 2Vpp)
0.01
Ω
Equivalent Input Noise Voltage
RS = 100Ω, f = 1KHz
15
nV
-----------Hz
Phase Margin
45
Degrees
The input bias currents are junction leakage currents which approximately double for every 10°C increase in the junction temperature.
MAXIMUM PEAK-TO-PEAK OUTPUT
3/9
LF151 - LF251 - LF351
VOLTAGE versus FREQUENCY
VOLTAGE versus FREQUENCY
MAXIMUM PEAK-TO-PEAK OUTPUT
VOLTAGE versus FREQUENCY
MAXIMUM PEAK-TO-PEAK OUTPUT
VOLTAGE versus FREE AIR TEMP.
MAXIMUM PEAK-TO-PEAK OUTPUT
VOLTAGE versus LOAD RESISTANCE
MAXIMUM PEAK-TO-PEAK OUTPUT
VOLTAGE versus SUPLY VOLTAGE
MAXIMUM PEAK-TO-PEAK OUTPUT
INPUT BIAS CURRENT versus FREE AIR
4/9
LF151 - LF251 - LF351
TEMPERATURE
AMPLIFICATION versus FREE AIR TEMP.
LARGE SIGNAL DIFFERENTIAL VOLTAGE
AMPLIFICATION AND PHASE SHIFT versus
FREQUENCY
TOTAL POWER DISSIPATION versus FREE AIR
TEMPERATURE
SUPPLY CURRENT PER AMPLIFIER versus
FREE AIR TEMPERATURE
SUPPLY CURRENT PER AMPLIFIER versus
SUPPLY VOLTAGE
LARGE SIGNAL DIFFERENTIAL VOLTAGE
COMMON MODE REJECTION RATIO versus
5/9
LF151 - LF251 - LF351
FREE AIR TEMPERATURE
VOLTAGE FOLLOWER LARGE SIGNAL PULSE
RESPONSE
OUTPUT VOLTAGE versus ELAPSED TIME
EQUIVALENT INPUT NOISE VOLTAGE versus
FREQUENCY
TOTAL HARMONIC DISTORTION versus FREQUENCY
6/9
LF151 - LF251 - LF351
PARAMETER MEASUREMENT INFORMATION
Figure 1 : Voltage Follower
Figure 2 : Gain-of-10 inverting amplifier
TYPICAL APPLICATION
(0.5Hz) SQUARE WAVE OSCILLATOR
HIGH Q NOTCH FILTER
7/9
LF151 - LF251 - LF351
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC DIP
Millimeters
Inches
Dim.
Min.
A
a1
B
b
b1
D
E
e
e3
e4
F
i
L
Z
8/9
Typ.
Max.
Min.
3.32
0.51
1.15
0.356
0.204
0.020
0.045
0.014
0.008
0.065
0.022
0.012
0.430
0.384
0.313
2.54
7.62
7.62
3.18
Max.
0.131
1.65
0.55
0.304
10.92
9.75
7.95
Typ.
0.100
0.300
0.300
6.6
5.08
3.81
1.52
0.125
0260
0.200
0.150
0.060
LF151 - LF251 - LF351
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC MICROPACKAGE (SO)
Millimeters
Inches
Dim.
Min.
A
a1
a2
a3
b
b1
C
c1
D
E
e
e3
F
L
M
S
Typ.
Max.
Min.
1.75
0.25
1.65
0.85
0.48
0.25
0.5
0.1
0.65
0.35
0.19
0.25
Typ.
Max.
0.026
0.014
0.007
0.010
0.069
0.010
0.065
0.033
0.019
0.010
0.020
0.189
0.228
0.197
0.244
0.004
45° (typ.)
4.8
5.8
5.0
6.2
1.27
3.81
3.8
0.4
0.050
0.150
4.0
1.27
0.6
0.150
0.016
0.157
0.050
0.024
8° (max.)
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the
consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from
its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications
mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information
previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or
systems without express written approval of STMicroelectronics.
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9/9
This datasheet has been download from:
www.datasheetcatalog.com
Datasheets for electronics components.
APPENDIX D
(Data Sheet for BPX65 Series)
Silizium-PIN-Fotodiode
Silicon PIN Photodiode
BPX 65
Wesentliche Merkmale
• Speziell geeignet für Anwendungen im Bereich
von 350 nm bis 1100 nm
• BPX 65: Hohe Fotoempfindlichkeit
• Hermetisch dichte Metallbauform (TO-18),
geeignet bis 125 oC1)
Features
• Especially suitable for applications from
350 nm to 1100 nm
• BPX 65: high photosensitivity
• Hermetically sealed metal package (TO-18),
suitable up to 125 oC1)
Anwendungen
• Schneller optischer Empfänger mit groβer
Modulationsbandbreite
Applications
• Fast optical sensor of high modulation
bandwidth
Typ
Type
Bestellnummer
Ordering Code
Gehäuse
Package
BPX 65
Q62702-P27
18 A3 DIN 41870, planes Glasfenster, hermetisch
dichtes Gehäuse, Lötspieβe im 2.54-mm-Raster
(2/10”), Anodenkennzeichnung: Nase am
Gehäuseboden
18 A3 DIN 41870, flat glass lens, hermetically sealed
package, solder tabs 2.54 mm (2/10”) lead spacing,
anode marking: projection at package bottom
1)
Eine Abstimmung der Einsatzbedingungen mit dem
Hersteller wird empfohlen bei TA > 85 °C.
1)
For operating conditions of TA > 85 °C please contact
us.
2000-01-01
1
OPTO SEMICONDUCTORS
BPX 65
Grenzwerte
Maximum Ratings
Bezeichnung
Parameter
Symbol
Symbol
Wert
Value
Einheit
Unit
Betriebs- und Lagertemperatur
Operating and storage temperature range
Top; Tstg
– 40 ... + 80
°C
Löttemperatur (Lötstelle 2 mm vom Gehäuse
entfernt bei Lötzeit t ≤ 3 s)
Soldering temperature in 2 mm distance from
case bottom (t ≤ 3 s)
TS
230
°C
Sperrspannung
Reverse voltage
VR
50
V
Verlustleistung, TA = 25 oC
Total power dissipation
Ptot
250
mW
Kennwerte (TA = 25 °C, Normlicht A, T = 2856 K)
Characteristics (TA = 25 °C, standard light A, T = 2856 K)
Bezeichnung
Parameter
Symbol
Symbol
Wert
Value
Einheit
Unit
Fotoempfindlichkeit, VR = 5 V
Spectral sensitivity
S
10 (≥ 5.5)
nA/Ix
Wellenlänge der max. Fotoempfindlichkeit
Wavelength of max. sensitivity
λS max
850
nm
Spektraler Bereich der Fotoempfindlichkeit
S = 10% von Smax
Spectral range of sensitivity
S = 10% of Smax
λ
350 … 1100
nm
Bestrahlungsempfindliche Fläche
Radiant sensitive area
A
1.00
mm2
Abmessung der bestrahlungsempfindlichen
Fläche
Dimensions of radiant sensitive area
L×B
1×1
mm
Abstand Chipoberfläche zu Gehäuseoberfläche
Distance chip front to case surface
H
2.25 … 2.55
mm
Halbwinkel
Half angle
ϕ
± 40
Grad
deg.
IR
1 (≤ 5)
nA
Dunkelstrom
Dark current
BPX 65: VR = 20 V
2000-01-01
L×W
2
OPTO SEMICONDUCTORS
BPX 65
Kennwerte (TA = 25 °C, Normlicht A, T = 2856 K)
Characteristics (TA = 25 °C, standard light A, T = 2856 K) (cont’d)
Bezeichnung
Parameter
Symbol
Symbol
Wert
Value
Einheit
Unit
Spektrale Fotoempfindlichkeit, λ = 850 nm
Spectral sensitivity
Sλ
0.55
A/W
Quantenausbeute, λ = 850 nm
Quantum yield
η
0.80
Electrons
Photon
Leerlaufspannung, Ev = 1000 Ix
Open-circuit voltage
VL
320 (≥ 270)
mV
Kurzschluβstrom, Ev = 1000 Ix
Short-circuit current
IK
10
µA
Anstiegs und Abfallzeit des Fotostromes
Rise and fall time of the photocurrent
RL= 50 Ω; VR = 5 V; λ = 850 nm; Ip = 800 µA
tr, tf
12
ns
Durchlaβspannung, IF = 100 mA, E = 0
Forward voltage
VF
1.3
V
Kapazität, VR = 0 V, f = 1 MHz, E = 0
Capacitance
C0
11
pF
Temperaturkoeffizient von VL
Temperature coefficient of VL
TCV
– 2.6
mV/K
Temperaturkoeffizient von IK
Temperature coefficient of IK
TCI
0.2
%/K
Rauschäquivalente Strahlungsleistung
Noise equivalent power
VR = 20 V, λ = 850 nm
NEP
3.3 × 10–14
Nachweisgrenze, VR = 20 V, λ = 850 nm
Detection limit
D*
3.1 × 1012
2000-01-01
3
W
-----------Hz
cm × Hz
-------------------------W
OPTO SEMICONDUCTORS
BPX 65
Relative Spectral Sensitivity
Srel = f (λ)
Photocurrent IP = f (Ev), VR = 5 V
Open-Circuit-Voltage VL = f (Ev)
Total Power Dissipation
Ptot = f (TA)
Dark Current
IR = f (VR), E = 0
Capacitance
C = f (VR), f = 1 MHz, E = 0
Dark Current
IR = f (TA), VR = 20 V, E = 0
Directional Characteristics
Srel = f (ϕ)
2000-01-01
4
OPTO SEMICONDUCTORS
BPX 65
Chip position (2.7)
Radiant sensitive area
1.1 .9
0
1.1
0.9
5.5
5.0
ø4.8
ø4.6
ø0.45
14.5
12.5
2.54
spacing
Maßzeichnung
Package Outlines
ø5.6
ø5.3
5.3
5.0
GET06013
Cathode (SFH 402, BPX 65)
Anode (SFH 482)
Maße in mm, wenn nicht anders angegeben / Dimensions in mm, unless otherwise specified.
2000-01-01
5
OPTO SEMICONDUCTORS
This datasheet has been download from:
www.datasheetcatalog.com
Datasheets for electronics components.
APPENDIX E
(Software Program)
s1= [0.552
0.543
0.518
0.483
0.444
0.404
0.367
0.334
0.6795
0.6641
0.6212
0.5641
0.5047
0.4496
0.401
0.3593
0.8806
0.8484
0.7652
0.6668
0.5753
0.4981
0.435
0.3836
1.245
1.16
0.9732
0.7932
0.6521
0.5464
0.4666
0.4052
2.111
1.769
1.262
0.9304
0.7236
0.5872
0.4918
0.4216
7.475
3.007
1.549
1.031
0.7691
0.6113
0.5059
0.4306
7.475
3.007
1.549
1.031
0.7691
0.6113
0.5059
0.4306
2.111
1.769
1.262
0.9304
0.7236
0.5872
0.4918
0.4216];
s2 =[0.4216
0.4306
0.4306
0.4216
0.4052
0.3836
0.3593
0.3344
0.4918
0.5059
0.5059
0.4918
0.4666
0.4350
0.4010
0.3677
0.5872
0.6113
0.6113
0.5872
0.5464
0.4981
0.4496
0.4045
0.7236
0.7691
0.7691
0.7236
0.6521
0.5753
0.5047
0.4440
0.9304
1.0310
1.0310
0.9304
0.7932
0.6668
0.5641
0.4835
1.2620
1.5490
1.5490
1.2620
0.9732
0.7652
0.6212
0.5187
1.7690
3.0070
3.0070
1.7690
1.1600
0.8484
0.6641
0.5435
2.1110
7.4750
7.4750
2.1110
1.2450
0.8806
0.6795
0.5520];
s3 =[0.3344
0.3593
0.3836
0.4052
0.4216
0.4306
0.4306
0.4216
0.3677
0.4010
0.4350
0.4666
0.4918
0.5059
0.5059
0.4918
0.4045
0.4496
0.4981
0.5464
0.5872
0.6113
0.6113
0.5872
0.4440
0.5047
0.5753
0.6521
0.7236
0.7691
0.7691
0.7236
0.4835
0.5641
0.6668
0.7932
0.9304
1.0310
1.0310
0.9304
0.5187
0.6212
0.7652
0.9732
1.2620
1.5490
1.5490
1.2620
0.5435
0.6641
0.8484
1.1600
1.7690
3.0070
3.0070
1.7690
0.5520
0.6795
0.8806
1.2450
2.1110
7.4750
7.4750
2.1110];
s4 =[0.3344
0.3677
0.4045
0.4440
0.4835
0.5187
0.5435
0.5520
0.3593
0.4010
0.4496
0.5047
0.5641
0.6212
0.6641
0.6795
0.3836
0.4350
0.4981
0.5753
0.6668
0.7652
0.8484
0.8806
0.4052
0.4666
0.5464
0.6521
0.7932
0.9732
1.1600
1.2450
0.4216
0.4918
0.5872
0.7236
0.9304
1.2620
1.7690
2.1110
0.4306
0.5059
0.6113
0.7691
1.0310
1.5490
3.0070
7.4750
0.4306
0.5059
0.6113
0.7691
1.0310
1.5490
3.0070
7.4750
0.4216
0.4918
0.5872
0.7236
0.9304
1.2620
1.7690
2.1110];
s5 =[0.4216
0.4918
0.5872
0.7236
0.9304
1.2620
1.7690
2.1110
0.4306
0.5059
0.6113
0.7691
1.0310
1.5490
3.0070
7.4750
0.4306
0.5059
0.6113
0.7691
1.0310
1.5490
3.0070
7.4750
0.4216
0.4918
0.5872
0.7236
0.9304
1.2620
1.7690
2.1110
0.4052
0.4666
0.5464
0.6521
0.7932
0.9732
1.1600
1.2450
0.3836
0.4350
0.4981
0.5753
0.6668
0.7652
0.8484
0.8806
0.3593
0.4010
0.4496
0.5047
0.5641
0.6212
0.6641
0.6795
0.3344
0.3677
0.4045
0.4440
0.4835
0.5187
0.5435
0.5520];
s6 =[0.5520
0.6795
0.8806
1.2450
2.1110
7.4750
7.4750
2.1110
0.5435
0.6641
0.8484
1.1600
1.7690
3.0070
3.0070
1.7690
0.5187
0.6212
0.7652
0.9732
1.2620
1.5490
1.5490
1.2620
0.4835
0.5641
0.6668
0.7932
0.9304
1.0310
1.0310
0.9304
0.4440
0.5047
0.5753
0.6521
0.7236
0.7691
0.7691
0.7236
0.4045
0.4496
0.4981
0.5464
0.5872
0.6113
0.6113
0.5872
0.367
0.4010
0.4350
0.4666
0.4918
0.5059
0.5059
0.4918
0.3344
0.3593
0.3836
0.4052
0.4216
0.4306
0.4306
0.4216];
s7 =[2.1110
7.4750
7.4750
2.1110
1.2450
0.8806
0.6795
0.5520
1.7690
3.0070
3.0070
1.7690
1.1600
0.8484
0.6641
0.5435
1.2620
1.5490
1.5490
1.2620
0.9732
0.7652
0.6212
0.5187
0.9304
1.0310
1.0310
0.9304
0.7932
0.6668
0.5641
0.4835
0.7236
0.7691
0.7691
0.7236
0.6521
0.5753
0.5047
0.4440
0.5872
0.6113
0.6113
0.5872
0.5464
0.4981
0.4496
0.4045
0.4918
0.5059
0.5050
0.4918
0.4663
0.4350
0.4010
0.3677
0.4216
0.4306
0.4306
0.4216
0.4052
0.3836
0.3593
0.3344];
s8 =[2.1110
1.7690
1.2620
0.9304
0.7236
0.5872
0.4918
0.4216
7.4750
3.0070
1.5490
1.0310
0.7691
0.6113
0.5059
0.4306
7.4750
3.0070
1.5490
1.0310
0.7691
0.6113
0.5059
0.4306
2.1110
1.7690
1.2620
0.9304
0.7236
0.5872
0.4918
0.4216
1.2450
1.1600
0.9732
0.7932
0.6521
0.5464
0.4666
0.4052
0.8806
0.8484
0.7652
0.6668
0.5753
0.4981
0.4350
0.3836
0.6795
0.6641
0.6212
0.5645
0.5047
0.4496
0.4010
0.3593
0.5520
0.5435
0.5187
0.4835
0.4440
0.4045
0.3677
0.3344];
s1a=10.321*s1; % 10.321 is measured value s1.
s2a=11.031*s2; % 11.031 is measured value s2 and so on...
s3a=1.501*s3;
s4a=0.59*s4;
s5a=2.992*s5;
s6a=3.2*s6;
s7a=0.390*s7;
s8a=0.73*s8;
s = s1+s2+s3+s4+s5+s6+s7+s8; % Total sensitivity map for 8X8 imaging.
lbp = s1a+s2a+s3a+s4a+s5a+s6a+s7a+s8a; % Linear back Projection imaging.
% plot 2-d and 3-d concentration.
h1=figure;
subplot(2,2,1)
imagesc(s)
axis off
colorbar('vert')
title(['2-D Concentration sensitivity map 8X8'],...
'FontSize',12,'FontName','Times New Roman','FontWeight','Bold')
xlabel(['Colunm 1-13 -->'],...
'FontWeight','Bold')
ylabel(['Row 1-13 -->'],...
'FontWeight','Bold')
zlabel(['sensor 1 output (v)'],...
'FontWeight','Bold')
subplot(2,2,2);
surfc(s)
colorbar('vert')
title(['3D concentration sensitivity map 8X8'],...
'Fontsize',11,'fontname','arial narrow','fontWeight','bold');
zlabel(['Output/V'],...
'Fontsize',10,'Fontname','book man oldstyle','FontWeight','bold');
ylabel(['S4
S3'],...
'Fontsize',10,'Fontname','book man oldstyle','FontWeight','bold')
xlabel(['S2
S1']),...'Fontsize',10,'Fontname','book man oldstyle','FontWeight','bold')
axis ([0 12 0 12 0 15])
grid off
subplot(2,2,3)
imagesc(lbp)
axis off
colorbar('vert')
title(['2-D Concentration using lbp tomography'],...
'FontSize',12,'FontName','Times New Roman','FontWeight','Bold')
xlabel(['Colunm 1-13 -->'],...
'FontWeight','Bold')
ylabel(['Row 1-13 -->'],...
'FontWeight','Bold')
zlabel(['sensor 1 output (v)'],...
'FontWeight','Bold')
subplot(2,2,4)
surfc(lbp)
colorbar('vert')
title(['3D Concentration using lbp tomography'],...
'Fontsize',11,'fontname','arial narrow','fontWeight','bold');
zlabel(['Output/V'],...
'Fontsize',10,'Fontname','book man oldstyle','FontWeight','bold');
ylabel([''],...
'Fontsize',10,'Fontname','book man oldstyle','FontWeight','bold')
xlabel(['']),...'Fontsize',10,'Fontname','book man oldstyle','FontWeight','bold')
axis ([0 16 0 16 0 100])
grid on