9881-26

Proto Flight Model (PFM) development statusof Visible and Near-Infrared Radiometer (VNR)
on the Second-Generation Global Imager (SGLI)
6 April 2016
T. Sakashita, S. Tsuida, T. Amano, K. Shiratama (NEC)Kazuhiro Tanaka (JAXA)
10th SPIE Asia-Pacific Remote Sensing Symposium

Earth Observing Missions and Sensors: Development, Implementation, and Characterization IV
New Delhi, India, 4-7 April 2016

Contents

 GCOM mission and satellite
 SGLI specification (SGLI-VNR and SGLI-IRS) SGLI VNR Current Status
 Test Results of VNR
 VNR Geometric Test VNR Radiometric Test
 NP Polarization Sensitivity
 PL Polarization Measurement
 Conclusion
2© NEC Corporation 2015

Global Change Observation Mission (GCOM) Global observation satellite system as JAXA’s GEOSS contribution.
 2 satellite series for 5 years, total 13 years observation.
 GCOM-W Microwave radiometer observation for WATERCYCLE using AMSR2 (AMSR-E follow on)
 GCOM-C Opticalmulti-channel
observation
forRADIATION BUDGET and CARBON CYCLE using SGLI(GLI follow on)
GCOM-C(CLIMATE)

GCOM-W(WATER)AMSR2GCOM-W “SHIZUKU”
was launchedon May 18, 2012.
Sensor3

Advanced Microwave Radiometer 2(AMSR2)
Passive Microwave Observation
Water vapor, soil moisture etc© NEC Corporation 2015

GCOM-Cis scheduled forlaunch in 2017.
Sensor

SGLISecond Generation Global Imager(SGLI)
Optical Observation 380nm – 12 micron
Cloud, Aerosol, Vegetation, Chrolophl etc

SGLI on GCOM-C1 satellite
SGLI IRSELUSGLI VNR
ELU+X+Y
deep
space

flightdirection+Z earth

SGLI VNR
SRU

SGLI IRS
SRU

4Mission Life> 5 years

Solar Paddle> 4000w （End of Life）

Mass

about 2,000kg© NEC Corporation 2015

SGLI Second Generation Global Imager
VNR Visible and Near Infrared Radiometer
IRS Infrared Scanning Radiometer
SRU Scanning Radiometer Unit
ELU Electronic UnitSGLI (Second Generation Global Imager)
Non Polarized
Observation Telescopes(24deg FOV x 3)

Solar
Diffuser

Polarized
Observation
Telescopes(55deg FOVx 2)

EarthView Window

Sun Cal.
Window

About
1.4m

About
1.7m

About
1.3m

Visible and Near Infrared Radiometer(SGLI-VNR)
Sensor Unit

5DeepSpace
Window

About
0.6m

Infrared Scanning Radiometer(SGLI-IRS)
Features

SGLI VNR

Non Polarized Observation （11ch）, IFOV 250m, Swath 1150km
Polarized Observation（2ch）, IFOV 1km, Swath 1150km

SGLI IRS

Shortwave Infrared （SWI 4ch）, IFOV 250m/1km, Swath 1400km
Thermal Infrared （TIR:2ch）, IFOV 500m, Swath 1400km© NEC Corporation 2015

SGLI Specification• The SGLI features are 250m (VNR-NP & SW3) and 500m (TIR)
spatial resolution and polarization/along-track slant view
channels (VNR-PL), which will improve land, coastal, and aerosol
250m over the Land or coastal
observations.
area, and 1km over offshore
SGLI channels

GCOM-C SGLI characteristics

Orbit
Mission LifeScan
Scan width
Digitalization
Polarization
Along track
direction

On-board
calibration

6Sun-synchronous(descending local time: 10:30)
Altitude 798km, Inclination 98.6deg
5 years (3 satellites; total 13 years)
Push-broom electric scan (VNR)
Wisk-broom mechanical scan (IRS)
1150km cross track (VNR: VN & P)
1400km cross track (IRS: SW & T)
12bit
Multi-angle
3 polarization angles for P
obs. for673.5nm andNadir for VN, SW and T,
868.5nm+45 deg and -45 deg for P
VN: Solar diffuser, LED, Lunar cal maneuvers,and dark current by masked pixels andnighttime obs.
SW: Solar diffuser, LED, Lunar, and darkcurrent by deep space window
T: Black body and dark current by deepspace window© NEC Corporation 2015



CHVN, P, SW: nm
T: m

VN1
VN2
VN3
VN4
VN5
VN6
VN7
VN8
VN9
VN10
VN11
P1
P2
SW1
SW2
SW3
SW4
T1
T2

380
412
443
490
530
565
673.5
673.5
763
868.5
868.5
673.5
868.5
1050
1380
1630
2210
10.8
12.0

101010102020202012202020202020200
50
0.70.7

Lstd

Lmax

VN, P:
W/m2/sr/m
T: Kelvin
60
210
75
250
64
400
53120
41350
3390
2362
25210
40
350
83030
300
25250
30
300
57248
8103
350
1.9
20300
340
300
340

SNR at Lstd

IFOV

VN, P, SW:
SNRm
T: NET
250
250
400
250
300
250
400
250
250
250
400
250
400
250
250
250
250/1000
1200
400
250
200
250
250
1000
250
1000
500
1000
150
1000
57
250
211
1000
0.2
250/500
0.2
250/500
optionVisible and Near Infrared Radiometer (VNR)
VNR Non-Polarized (NP) sensor
 24deg FOV each for 3 NP sensors. (total 70deg, nadir looking) 11 lines Band pass filter(BPF) on the 11 line 6000pix CCD

VNR Polarized (PL) sensor
 55dev FOV with +/-45deg tilting mechanism. (forward, backward and nadir looking) 3 polarization filter on the same design CCD with NP sensor for 3 pol. directions

7© NEC Corporation 2015

SGLI VNR Current Statuscompletedcompleted

PL sub-unit

VNR SRU

Geometric

Geometric

Integration

Radiometric

Alignment

Vib. & ShockSRU-ELU Interface

RadiometricPol. sensitivity

NP/PL sensor Phase

NP sub-unit

Vib & Shock8ongoing

Stray light

Stray lightPol. measurement

NP sub assembly

PL sub assembly

Thermal vacuum

Thermal vacuum© NEC Corporation 2015

Radiometric
Thermal vacuum←NOWVib. & Acoustic

Final performance

Current StatusVNR SRU Onboard Configuration＋Z

earth＋X

flightdirection

VNR SRU
＋Y

deep
space

PL

March 2016, TSUKUBA

9© NEC Corporation 2015

NP

Geometric Test NP/PL sensor Performance Test by CollimatorGeometric test
Polarization sensitivity of NP sensor
Muller Matrix for PL sensor
Stray light test / Stray light correction model

NP sensor
Collimator

Rotation Stage

Rotation Stage : 6-axis (3-linear, 3-rotation)

10© NEC Corporation 2015

Radiometric Test (Integrating Sphere) Radiometric Performance Test by Integrating Sphere ; BaSO4, Spectralon(option)
Radiometric test for NP/PL sensor
Radiometric test for SRU

NP sensor

Integrating Sphere

Simple rotation stage

11© NEC Corporation 2015

Thermal Vacuum Test Thermal Vacuum Test
Geometric test for NP/PL sub-unit
Radiometric test for NP/PL sub-unit

6m Space chamber

Sub-Unit
IR panels

Collimator
Rotation stage

Collimator and Rotation stage are setting in the 6mφ Space chamber in TSUKUBA
Test condition : 6 (2-ambient, 4-vacuum)

12© NEC Corporation 2015

Geometric Performance (Alignment) CCD view angle measurements and verification
Ambient and Thermal Vacuum environment

-50

50
0-50

θy（arcsec）-100
100 50 0 -50 -100
θx（arcsec）
100m60 239pixel-100
100 50 0 -50 -100
θx（arcsec）

pm0 3000pixel

100
50
0-50

-100
100 50 0 -50 -100
θx（arcsec）
ambient1
nominal1
coldhotnominal2ambient20-50

θy（arcsec）

010050θy（arcsec）

50

p60 5765pixel-100
100 50 0 -50 -100
θx（arcsec）
100
m60 5760pixel
vacuumambient

500-50θy（arcsec）

100
θy（arcsec）

p60 234pixel-100
100 50 0 -50 -100
θx（arcsec）

Deviation between
ambient and vacuum(about 250m for PL-1km)

Note
View angles are stable in thermal vacuum condition. (20~30℃)
The deviation between ambient and vacuum is due to the change of focal length.
The data for geometric model are acquired.
13© NEC Corporation 2015

Geometric Performance (MTF) MTF defocus
Following figures show the MTF defocus trend data.
Data point : PL2 sensor, +60° of pol. angle, +27.5° of view angle
10080

90
MTF [%]

MTF [%]

90100
p60 +27.5°CT

70
6050

p60 +27.5°AT
ambient1

80

nominal1

70

coldhot

60

nominal2

50

40ambient2

40-0.3 -0.2 -0.1 0 0.1 0.2 0.3
Defocusing Position [mm]-0.3 -0.2 -0.1 0 0.1 0.2 0.3
Defocusing Position [mm]The ambient data are the corrected value due to the vacuum shift of focal length

NOTE
MTF defocus is stable in thermal vacuum condition. (20~30℃)
MTF peak is almost 0 defocusing position, it means CCD position is suitable.
MTF value attains high resolution of >80%.
14© NEC Corporation 2015

Radiometric Performance (Linearity)
 Linearity error
Test condition : TVT nominal2 data, 0.3Lstd ~ Lmax of radiance
Plot data : worst deviation values
4.0%

Linearity Error

3.5%
3.0%
2.5%

NPR

2.0%

NPN

1.5%

NPL
Spec

1.0%
0.5%
0.0%
VN1 VN2 VN3 VN4 VN5 VN6 VN7 VN8 VN9 VN10 VN11

Comment
The data satisfies within 2%. (requirement)
The final data will acquire at the final performance test of SRU PFT.

15

© NEC Corporation 2015

Radiometric Performance (SNR) SNR
PL sub-unit TVT results in TVT tests.
PL2 ＠TVT nominal2
4000

S/N

3000
2500+60°

20000°

1500

‐60°

1000

Lstd
Target

500
0050

100

150

200

250

Radiance [W/m2/str/um]

300

350

S/N @Lstd

3500

1000
900
800
700
600
500
400
300
200
100
0

PL1_+60°
PL1_0°
PL1_-60°
PL2_+60°
PL2_0°
PL2_-60°
Targetnom1

cold

hotnom2

Comment
The SNR data satisfies >500.
(SNR 500 comes form polarization accuracy requirements)
The final data will acquire at the final performance test of SRU PFT.

16© NEC Corporation 2015amb2

Polarization Sensitivity for NP sensor

Polarization sensitivity

Polarization measurements using the linear polarizer.
a) Polarization sensitivity
Polarization sensitivity of NPR VN10b) Polarization direction
Polarization Uniformity of NPR VN10 +12deg
Measured value

1.04

Fitting curve

4%
3%
2%
1%
0%

-12

1.02
10.98
0.96
0.94
090

180

2703605.0%
4.0%

0View angle[deg]61211010090807060-12Rotation angle[deg]Polarization sensitivity exceeds
3% target in RED and NIR channels
as predicted from EM test results.
 Sensitivity Model req.
in the retrieval algorithm.

-6Polarization angle of NPR VN10120
Polarization angle (°)

Normalized output

1.065%-60View angle[deg]612Pmax, Pmin

NPN Pmax

3.0%

NPL Pmax

2.0%

NPR Pmin

1.0%

NPN Pmin

0.0%

NPL PminVN1 VN2 VN3 VN4 VN5 VN6 VN7 VN8 VN9 VN10 VN1117© NEC Corporation 2015

NPR PmaxPolarization Sensitivity for NP sensor (Model)
Model parameter ρc, ρmax for Stokes Q and U componets
Q

11cos 2cos 21 y  xch   tan 1  ρcρlρmax
xchyymax

xch 2  y 2l  2 max2xch  ymax

: Pol. sensitivity of CCD+BPF: Pol. sensitivity of telescope: Pol. sensitivity of telescope (maximum): channel (pixel) location for AT direction: pixel location for CT direction: pixel location for CT direction (maximum)+Q

Imaging planex_axis+U-U

1pixel-Q

xch

NPR
1.0%

NPN
NPL

0.5%
0.0%
VN1 VN2 VN3 VN4 VN5 VN6 VN7 VN8 VN9 VN10 VN114.0%
3.0%

ρc2.0%

NPR

1.0%

NPN
NPL

VN1 VN2 VN3 VN4 VN5 VN6 VN7 VN8 VN9 VN10 VN11y_axis

+U

-U

1.5%

ρmax

-1.0%
45°

-Q

-y

2.0%

0.0%

6000pixel

θ+Q
18

sin 2cos 2© NEC Corporation 2015

Coordinate
definition

Polarization Sensitivity for NP sensor(Model Accuracy)
Modeling errors from 5 view angles data (3 for model, 2 for verification)

3%

0.4%

2%

0.3%

Q measurements

1%

0.2%

U measurements

0%

0.1%

-1%

0.0%

-2%

-0.1%

-3%

-0.2%

-4%

-0.3%

-5%

-0.4%
-12-606View angle [deg]12Q modeling

ΔQ, ΔUQ, UThe model and the Modeling error of NPR VN10U modeling
ΔQΔU
ρmax :1.73%
ρc:3.30%

0.40%
0.30%

Q element

Relative Error
Common Error

0.20%
0.10%
0.00%
0.40%
0.30%

VN1 VN2 VN3 VN4 VN5 VN6 VN7 VN8 VN9 VN10 VN11U element

Relative Error
Common Error

0.20%
0.10%
0.00%

Results
Q, U modeling are realized with sufficient 0.3%
0.2%
accuracy comparing to the req.
0.4%

VN1 VN2 VN3 VN4 VN5 VN6 VN7 VN8 VN9 VN10 VN11Polarization sensitivity

Relative Error
Common Error

0.1%

Relative errors between bands : <0.4%
Band-common errors : <0.6%19© NEC Corporation 2015

0.0%

VN1 VN2 VN3 VN4 VN5 VN6 VN7 VN8 VN9 VN10 VN11Modeling error (σ)

Polarization Observation Accuracy for PL sensor
Target Accuracy
Pol. ratio (ΔP/Pstd) :<4%
Pol. direction :<1.3°
Incident light : standard radiance of Lstd, standard pol. ratio of 5% at any direction

Accuracy of Polarization Ratio

8%6%4%2%0%-2%-4%-6%-8%090180270
Rotation angle of 5% Polarizer[deg]Accuracy of Pol. direction [deg]Accuracy of Pol. ratio ΔP/P Results from the PL sensor test (PL2, view angle of +0.5°, at Lstd Input)

360

Accuracy of Polarization direction

32
10-1-2-3090
180
270
Rotation angle of 5% Polarizer[deg]360CommentMeasurement accuracy of pol. is realized within the target mostly. (initial analysis)
The final analysis of the accuracy will carry out applying the SRU radiometric data.

20© NEC Corporation 2015

ConclusionTest results of VNR-SRU PFM met the requirement.
Precise sensor models are analyzed for the data processing
Geometric modelRadiometric gain
Polarization sensitivity model of NP sensor
Mueller Matrix for PL sensor

The final VNR test is now ongoing before the delivery to thesatellite system.
Mechanical Environmental Test (Vibration and Acoustic Excitation)
Final Performance Test (Integrating Sphere, Calibration Test , … etc)

Target launch in 201721

© NEC Corporation 2015