INSTRUMENT DEVELOPMENT STATUS AND PERFORMANCES OF HYPERSPECTRAL IMAGER SUITE (HISUI) -Onboard Data Correction- Jun Tanii Japan Space Systems , Tokyo, Japan Akira Iwasaki The University of Tokyo, Tokyo, Japan Yoshiyuki Ito NEC Corporation, Tokyo, Japan WE3.09.1 #2513 International Geoscience and Remote Sensing Symposium 2014 July 13 th -18 th , 2014 Québec, Canada
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INSTRUMENT DEVELOPMENT STATUS AND PERFORMANCES OF
HYPERSPECTRAL IMAGER SUITE (HISUI) -Onboard Data Correction-
Jun Tanii Japan Space Systems , Tokyo, Japan
Akira Iwasaki The University of Tokyo, Tokyo, Japan
Yoshiyuki Ito NEC Corporation, Tokyo, Japan
WE3.09.1 #2513
International Geoscience and Remote Sensing Symposium 2014 July 13th-18th, 2014 Québec, Canada
VNIR SWIR Spatial Scanning Push broom type by satellite moving Same as left IFOV (Spatial resolution) 48.5 urad (30 m) 8.1 urad (5 m) FOV (swath width) 48.5 mrad (30 km) 144.7 mrad (90 km) Observation frequency < 4.36 ms < 0.73 ms Wavelength region and number of bands / Center wave length
▐ Design for The Telescope and Spectrograph Telescope
TMA ( off-axis three mirror anastigmat type ) • The diameter of telescope is approximately 30cm and the F-number is 2.2. It is matched for the ground sampling distance(GSD) of 30 meters.
Spectrograph Two Aberration-corrected Offner type Grating spectrographs VNIR spectrograph and SWIR spectrograph High diffraction efficiency Equal interval of Spectral Sampling Minimize the wavelength shift/ smile/ keystone Robust in alignment against temperature change Stable temperature control within +/-1K in orbit to minimize the
wavelength shift.
1. HISUI Instrument Overview
Page 9
▐ Design for The Telescope and Spectrograph Detector
• Cooler and Dewar • SWIR detector is integrated inside the dewar • and cooled down to 145K using Stirling-type cryocooler.
Design of Hyperspectral Sensor Unit 1. HISUI Instrument Overview
Flight Model of Hyperspectral Sensor Unit
10
Optical Calibrator
Telescope (TMA)
Slit
VNIR Grating Spectrometer
(Offner)
SWIR Grating Spectrometer
(Offner)
Si-CMOS 2D-Detector MCT
2D-Detector
Stirling Cooler
1. HISUI Instrument Overview
Page 11
Onboard Data Correction and Compression
▐ Function of HELU (Hyper Electronics Unit) for Digital Data Data correction of items as follows;
• Offset-Gain-Non linearity • PRNU (Photo Response Non-Uniformity) • Smile distortion (using weight-coefficients during the binning)
In order to reduce data size, • data binning in spectral direction 4 pixels in VNIR 2 pixels in SWIR • lossless data compression
Observation Mode: With Onboard Data Correction and Data Compression Calibration Mode: Without Onboard Data Correction nor Data Compression ( Onboard Calibration with Lamps, Vicarious Calibration, ……)
2. Onboard Data Correction
Page 12
Flow of Onboard Data Correction in HELU
2. Onboard Data Correction
Page 13
2. Onboard Data Correction
Onboard Radiometric Correction
Radiance:W(W/m2/sr/μm)
Raw Data of Detector pixel :X (DN)
Calculation formula 1W = A(X-C)^2 +B(X-C)
Calculation formula 2W = A(X-C)^2 +B(X-C)•For low response pixel• For low radiance band
Calculation formula 3W = A1X+B1, W=A2(X-C-50)*for bad linearity pixel
Offset
2 3
1
Formulae for non Linearity/Offset Correction
Page 14
2. Onboard Data Correction
Onboard Radiometric Correction Examples of PRNU/Gain Correction
Correction Parameter Table: install into Ground Data Processing System
2. Onboard Data Correction
Page 20
Spectral Performance
Wavelength shift of Flight Model (expected) VNIR <0.06nm SWIR <0.11 nm including launch and space environment conditions Onboard spectral calibrator monitors the wavelength shift.
After Launch Vibration Test Negligible Negligible Offset
Thermal Vacuum Test <0.058nm <0.106nm Variable
Total <0.06nm <0.11nm Expected
Value Onboard
Onboard Calibrator 0.2nm 0.625nm
Spectral Performance : Wavelength shift of evaluation model
2. Onboard Data Correction
Page 21
Conclusions Onboard Data Correction of Hyperspectral Sensor of HISUI The validation tests of Onboard Data Correction function have been
completed using the data of functional evaluation model of Instrument. The smile performance after correction is very well. The method of Onboard Data Correction has been established. Status of HISUI Instrument Analyzing test results, FM is expected to achieve the spectral
performance better than specifications. The critical parts of FM, such as the telescope, the spectrographs and
the detectors, have been manufactured and the integration & tests of the sensor is proceeding .
▐ Acknowledgements HISUI project proceeds under the contract with METI (Ministry of Economy, Trade and
Industry).
3. Conclusions
Page 22
Thank you very much for your attention !
Page 23
Test Data of Evaluation Model(Spectral Calibration Accuracy at Normal Temp.)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0 125 250 375 500 625 750 875 1000
Sp
ectr
al
Ca
lib
rati
on
Accu
racy
(n
m)
Pixel No. (CT derection)
Caribration Accuracy (Spectral) in VNIR Region
435nm546nm
-1.25
-1
-0.75
-0.5
-0.25
0
0.25
0.5
0.75
1
1.25
0 125 250 375 500 625 750 875 1000
Sp
ect
ral
Ca
lib
rati
on
Acc
ura
cy (
nm
)
Pixel No. (CT direction)
Caribration Accuracy (Spectral) in SWIR Region
1014nm1129nm1530nm
VNIR SWIR
3. Design of Flight Model
Spectral Performance
72.272.25
72.372.35
72.472.45
72.572.55
72.672.65
72.772.75
72.872.85
72.9
10 15 20 25 30 35 40
Wav
elen
gth p
ositi
on(P
ixel N
o) at
546
nm
Temp(C)
a) Temperature shift of Hg-Ar lamp line by VNIR spectrometer assembly
33C-> 13C-> 33C-> 20C
a
f
e
d
c
b
Onboard Temp. Range
24
VNIR :Wavelength Shift vs. Temp. (Thermal Vacuum Test)
<0.23pixel =0.58nm
≦0.023pixel /2degC
3. Design of Flight Model
Spectral Performance
22.322.35
22.422.45
22.522.55
22.622.65
22.722.75
22.822.85
22.922.95
23
10 15 20 25 30 35 40
Wav
elen
gth p
soiti
on(P
ixel N
o.) a
t 101
4nm
Temp(C)
b) Temperature shift of Hg-Ar lamp line by SWIR spectrometer assembly
33C->13C-> 33C->20C -> 22Ca
f
e
d
c
b
25
SWIR :Wavelength Shift vs. Temp. (Thermal Vacuum Test)