MYLRAD Final Presentation
Demonstrator Study for Micro-Laser-Ranging Device
ESA Contract No. 18497/04/NL/MV
Hartmut Henkel
Bodo Bernhardt
von Hoerner & Sulger GmbH
von Hoerner-System GmbH
Schwetzingen, Germany
Innovation Triangle Initiative (ITI) Final Presentations’ Day
Monday, 21 November 2005, Fresnel 1 and 2, ESTEC
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
Outline of Presentation
Introduction
Ranging Principles
MYLRAD Principle
Hardware
Testing
Specifications reached with the 1st MYLRAD Breadboard
Outlook
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
What is MYLRAD?
. . . a Micro-Laser-Ranging Device
Micro (µ)
Laser
Ranging
Device
↔
↔
↔
↔
can be built very small, light-weight, low power
works optically
purpose: distance measurement
nice hardware
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
Motivation
Precision distance measurement (ranging)
is required in various space scenarios:
I
Satellite–satellite docking →
sat1.fig
I
Catching defunct satellites
I
Establishing satellite formations →
sat2.fig
I
Landing manoeuvres
(planets, moons, asteroids. . . ) →
I
3 D imaging, scanning
from Landers or Rovers
land1.fig
Cooperative vs. non-cooperative targets
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
How the MYLRAD project started. . .
I
vH&S patent for precision time delay measurement
I
Broad applications for space identified. . .
I
. . . like laser ranging
I
Interested customer (EADS Astrium Limited)
I
But development risk
I
ESA’s brilliant ITI programme
I
Opportunity to study and build a demonstrator
I
Project Start September 2004
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
General ranging principle
Based on the speed of light in vacuum: 299 792 458 m/s
I
Laser beam is sent out
I
Reflected at target
I
Received by optics and detector
I
Delay time measured
10 m
1 cm
↔
↔
66.7 ns
67 ps
Two variants:
I
Lidar = Light Detection and Ranging
I
Radar = Radio Detection and Ranging
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
Lidar vs. Radar
Principle
Transmitter
Focusing
Steering
Pointing
Miniaturisation
Absorption
Lidar
Radar
optical
laser
lens/mirror
mirror
better
easier
atmosphere
RF
RF transmitter
antenna (array)
moving antenna
less critical
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
Two main Lidar principles
Typical scenarios:
Pulse Mode
Periodic Modulation
Carrier
pulse (tp < 5 ns)
square wave tper = 250 ns
Peak power
Laser
Receiver
Distance
Complexity
high
solid-state
wide-band
delay
high
much lower
semiconductor
narrow-band
phase shift
lower
↓
MYLRAD
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
Block diagram of a scanning MYLRAD application
Rotating Unit
on Mast
Angular
Sensor
Mirror
Sensor
Frontend
Elevation Data
Scan
Drive
Scan Control
Laser Beam
Laser
Driver
Time Delay
Digitizer
Range
Data
3−D
Terrain
Mapper
Patent vH&S
Planetary
Surface
Photo
Diode
Piezo
Motor
Amplifier
Azimuth
Driver
Rotation Control
lidar−blk1.fig
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
How to measure time delay?
Various possible solutions, e. g.:
I
Counter: “stop watch”
needs high-frequent clock
(1 cm ≡ 15 GHz)
I
Analog integrator: →
high time resolution
but weak absolute precision
Voltage
t
Take the best of both:
I
Coarse timing by clock (quartz, e. g. 70 MHz)
I
Fine timing by analog interpolator
The Noise-Shaping Synchroniser (NSS) by vH&S does this.
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
How the Noise-Shaping Synchroniser (NSS) works
I
I
I
I
I
Transmit and receive modulated light beam
Synchronise received signal pulse on master clock
This introduces sub-clock delay error
Remember error in analog integrator
Shift next input pulse to compensate for this error
Master Clock
Signal Pulse
Input
Phase
Shifter
Sampling
Flip−Flop
Synchronous
Output
Phase Control
Analog
Integrator
nssloop1.fig
Sub−Clock Sampling Error
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
NSS signals
Integr.
t
Error
Input
Clock
Output
I
Output pulse train is synchronous with master clock.
I
Sub-clock precise timing is contained in output pulse pattern.
I
Frontend has “noise shaping” characteristics.
I
Final range result is calculated by digital signal processing
“decimation filter”.
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
Block diagram of the MYLRAD breadboard
Master
Clock
Generator
Master
Clock
Moveable
Mirror
Clock
Divider
Carrier
Laser
Driver
Laser
Diode
Target
Cal. Light
NSS
Narrow
Band
Amplifier
Limiter
1
0
0
1
0
1
0
1
0
1
0
1
0
1
Photo
Diode
APD
Receiver
Optics
Decimation
Filter
Laser
Optics
Bandpass
Filter
Digital
Range Result
concept1a.fig
Design supported by numerical simulations:
I NSS, optics with APD and parallax/range effects
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
How the MYLRAD demonstrator breadboard looks like
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
MYLRAD in operation
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
Top view to MYLRAD components
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
Testing
MYLRAD has been characterised by many tests:
I Static precision, total range, static noise
I Dynamic performance (moving targets)
I Stability and Drift
Various test targets:
Rotating
Gray Target
Rotating
Sector Wheel
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
Retro Reflector
vH&S vH-S
MYLRAD breadboard specifications
Specifications resulting from tests:
Parameter
Value
Comment
Laser power
Modulation
Measurement rate
Measurement range
Range extension
Static range resol.
Beam divergence
Power consumption
15 mW
4 MHz
1000 results/s
0.5 m – 30 m
0.5 m – 7 km
5 mm – 30 mm
0.7 mrad
< 2.5 W
average
up to 20 k results/s
non-cooperative targets
cooper. targets, extrapol.
over 0.5 m – 30 m range
depending on collimator
breadboard, 30 mW laser
. . . can be further improved!
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
Future developments towards Space
I
Design Elegant Breadboard/Engineering Model of MYLRAD
I
Qualification of laser diode
I
Qualification of COTS circuits
(e. g. limiting amplifier)
I
Coaxial transmitter/receiver →
arrangement (no parallax)
Laser
I
APD
Frontend
Amplifier
mylrad−coax1.fig
Design of MYLRAD integrated scanner system
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S
Finally. . .
I
I
I
Big thanks to ESA for ITI and for making this study possible!
Big thanks to João Pereira do Carmo (ESTEC) for study
leading and support!
And thank you very much for your interest!
Greetings from Schwetzingen!
H. Henkel, B. Bernhardt
MYLRAD
ESTEC, Noordwijk, 2005-11-21
vH&S vH-S