Fabry-Perot Scanning Spectrometer
PRODUCT DESCRIPTION
OPTRA developed a hyperspectral
imaging system for the long wave
infrared (LWIR) based on a tunable firstorder Fabry-Perot Scanning Spectrometer
(FPSS). This system was developed
under a U.S. Army SBIR Phase II
contract. The system is intended for
standoff passive infrared detection of
chemical agent plumes with the
capability of identifying not only the
agent species but also its spatial location.
The FPSS operates over 8 to 12
µm with a spectral resolution of 1% of
the wavelength. The etalon operates in
the first order which supports coverage
of the entire spectral range without the
requirement for additional filters for
order sorting. This spectral range hosts
resonance bands for most known
chemical agents as well as a large
number of industrial compounds. The
FPSS has a 22 degree field of view and a
spatial resolution of 0.11 degrees. The
key components of the FPSS system are
the collection optics, a tunable FabryPerot etalon, piezo-electric actuators,
optical position sensors, a closed-loop
positioning system, an uncooled
microbolometer focal plane array, a
digital frame grabber card, and a userfriendly Graphical User Interface (GUI).
Fabry-Perot Scanning Spectrometer
Advantages
• Highly efficient spectral coverage over the
full 8 to 12 µm spectral range without the
need for additional filters
•
Use of low cost yet sensitive uncooled
microbolometer focal plane array
•
Use of OPTRA’s NanoGageTM optical
position sensors to measure plate separation
and correct for piezo nonlinearity and
hysteresis
Applications
• Chemical and biological agent detection
•
Toxic industrial chemical detection
•
Fugitive emissions monitoring
•
Remote airborne surveillance
TECHNICAL SPECIFICATIONS
Functional Specifications
SPECIFICATION
Wavelength range
Spectral resolution
Spatial resolution
Field of view
Intermediate field of view
Frame rate
FPA size
Entrance aperture
NESR per pixel per frame
VALUE
8 – 12 µm
1% (e.g. 100 nm FWHM at 10 µm)
0.11 degrees
22 degrees diagonal across the FPA
0.11 degrees per pixel
15 Hz
160 × 120 pixels, 50 µm square
1 inch diameter
1.4 × 10-6 W/cm2sr cm-1
Operational Specifications:
SPECIFICATION
Operating temperature
OPTRA’s NanoGage Position Sensor used
to measure the plate separation of the FPSS
VALUE
0 to 40ºC
Physical Specifications:
SPECIFICATION
Size
Weight
VALUE
12″ × 6″ × 7.5″
10 lbs
Measured (red) and Modeled (blue) FPSS Transmission Spectra
(measurements taken using OPTRA’s J-Series FTIR Modulator)
1
FSR = 548.3FSR:
cm-1
Transmission
Transm ittance
0.8
548.3 cm -1
12mµm
FWHM
= 8.34
FW
HM : 8.34
cmcm
-1-1atat12
icron
Order = 1
0.6
Order: 1
m odel
m easured
0.4
0.2
0
0.7
0.8
0.9
1
W Wavelength
avelength (cm
)
(cm)
1.1
1.2
1.3
x 10
-3