Radiometric performance ofSecond Generation Global Imager (SGLI)
using integrating sphere
Taichiro Hashiguchi, Yoshihiko Okamura,
Kazuhiro Tanaka, Yukinori Nakajima
Japan Aerospace Exploration Agency

Koichi Suzuki

JASTECS Corporation

Takashi Sakashita, Takahiro Amano
NEC Corporation

SPIE Remote Sensing 2016 at Edinburgh, United Kingdom

Sep. 26, 2016

1

Contents
GCOM overview
SGLI specification
Strategy of SGLI radiometric testTraceability of SGLI radiometric test
SGLI VNR radiometric test
SGLI IRS radiometric test
SummaryRadiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK2

Global Change Observation Mission(GCOM)
overview
 Long-term observation of the earth’s environment
 5 years of each satellite's mission life and 13 years in total.
 Two satellite series;
 GCOM-W :Microwave observation for WATER CYCLE using AMSR2(AMSR-E follow on)
 GCOM-C :Optical multi-channel observation for RADIATION BUDGET
and CARBON CYCLE using SGLI (GLI follow on)
GCOM-C(CLIMATE)AMSR2GCOM-W(WATER)

SGLI

GCOM-W1 “SHIZUKU”
was launched on May 18,
2012.
SensorAdvanced Microwave Radiometer 2(AMSR2)
Passive Microwave Observation
Water vapor, soil moisture etc

SensorSecond-generation Global Imager(SGLI)
Optical Observation 380nm – 12 micron
Cloud, Aerosol, Vegetation, Chlorophyll etc

Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK3

GCOM-C overview
SGLI VNR
ELU

SGLI IRSELUSGLI IRSSRU

SGLI VNR
SRU+Y
deep
space+X
flightdirection+ Z earth

SGLI
VNR
IRS
SRU
ELU

Second-generation Global Imager
Visible and Near Infrared Radiometer
Infrared Scanning RadiometerScanning Radiometer Unit
Electronic Unit

GCOM-COrbit
Parameters

Mission Life

Local sun timesun-synchronous, ground track repeat, near-circularorbit
10:15 – 10:45 at descending node

Altitude above equator

798 km at Equator

Inclination

98.6 degrees

Orbit Type> 5 years
Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK4

Second-generation Global Imager (SGLI)
Overview
Non Polarized
Observation Telescopes(24deg FOV x 3)

SolarDiffuserEarthView Window

Polarized
Observation
Telescopes(55deg FOVx 2)

Sun Cal.
WindowAbout1.5m

About
1.4m

About
1.5m

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

DeepSpaceWindow

About
0.7m

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 250m, Swath 1400km
Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK5SGLI Specification• The SGLI features are 250m (VNR-NP & SW3) and 250/500m (TIR) spatial resolution andpolarization/along-track slant view channels (VNR-PL), which will improve land, coastal,250m over the Land or coastal
and aerosol observations.
area, and 1km over offshore

SGLI channels
GCOM-C SGLI characteristics
Lmax
SNR at Lstd
IFOVλ∆λL
std
Sun-synchronous
VNR-NP, VNR-PL,VNR-NP, VNR-PL,VNR-NP, VNR-PL,Orbit(descending local time: 10:30)
CH
IRS-SWIIRS-SWI: nm
IRS-SWI : SNRm
Altitude 798km, Inclination 98.6deg:W/m2/sr/µm
IRS-TIR: µm
IRS-TIR: NE∆T
IRS-TIR: Kelvin
Mission Life
5 years
VN1380
1060
210
250
250
Push-broom electric scan (VNR)
Scan
VN24121075
250400250
Wisk-broom mechanical scan (IRS)
VN34431064400300
250
1150km cross track (VNR-NP & VNR-PL)
VN44901053120400
250
Scan width
VN55302041350250
250
1400km cross track (IRS-SWI & IRS-TIR)
Multi-angle
VN6565203390400
250Digitalization 12bit
obs. for202362400
250
673.5nm and VN7 673.5
Polarization
3 polarization angles for VNR-PLVN8673.52025210250
250
868.5nm
Along track
Nadir for VNR-NP, IRS-SWI and IRS-TIR,
VN9763
1240
350
1200
250/1000
400
250
VN10 868.5
20830
direction+45 deg and -45 deg for VNR-PL

On-board
calibration

VNR-NP, VNR-PL: Solar diffuser, LED, Lunarcal. maneuvers, and dark current bymasked pixels and nighttime obs.
IRS-SWI: Solar diffuser, LED, Lunar, and darkcurrent by deep space window
IRS-TIR: Black body and dark current by deepspace window

VN11P1
P2
SW1
SW2
SW3
SW4T1T2868.5
673.5
868.5
1050
1380
1630
2210
10.8
12.0

2020202020200
500.70.730253057831.9300
300Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK

300
250
300
248
103
50
20340
340

200
250
250
500
150
57
211
0.2
0.2

250
1000
1000
1000
1000
250
1000
250/1000
250/1000

6TIR: 500m resolution is also usedStrategy of SGLI radiometric test
 Objectives
 To confirm that SGLI was integrated radiometrically as designed
 To characterize radiometric performance
 To obtain the parameters of Level 1 ground processing Test Methods
 Use three integrating spheres for each wavelength range and radiancelevel in SGLI radiometric test
 【VNR】 0.38 – 0.87 μm
 Barium sulfate and Spectralon integrating spheres• Take advantage of the performance of the each integratingsphere 【IRS】 1.05 – 2.21 μm
 Gold-coated integrating sphere• To control the humidity by clean boothRadiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK7

Strategy of SGLI radiometric test- Specifications of integrating spheres -Monitor
detector

200mm

1000mmMonitordetector
1000mmMonitor
detector

Inner diameter
Aperture diameter
Sphere coating on inner wall
lamp configuration
lamp number of halogen
Max voltage per halogen lamp
lamp number of xenon
Attenuator
Lamp control
Thermal cooling
Monitor detector
Used black body to calibrate

Barium sulfate
integrating sphere

Spectralon
integrating sphereGold-coatedintegrating sphere1000 mm
280 mmBarium sulfate

500 mm
200 mmPTFE1000 mm
300 mm
Gold12 (500W)
100V
nonenone
voltage control
Air circulation with fan
Silicon photodiodeFixed-point black body of Copper (1358K)
Fixed-point black body of Pt-C (2011K)3 (220 W) and 1 (150 W)
22V
2
Mechanical attenuatorcurrent control
Air circulation with fan
Silicon photodiode8 (50 W) and 8 (10 W)
12Vnonenone
current control
Air circulation with fan
InGaAsFixed-point black body of Copper (1358K)
Fixed-point black body of zinc (692K)-Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK8

Strategy of SGLI radiometric test
- Representative radiance level 【Barium sulfate integrating sphere】
・It has good characteristics (stability,reproducibility) in the visible region.
⇒Used to characterize the absoluteperformance of VNR【Spectralon integrating sphere】
・To achieve the high radiance inthe short wavelength by turningon the xenon lamp.

1,000【Gold-coated integrating sphere】
・It has high reflectance and flatin the infrared region.
・It is hydrophobic, no water
vapor absorption of the wall in
1.38 μm

Spectralon was briefly measured by FieldSpec

VNR

IRS

3.00

100

2.00
Gold 2.98A(50W)x4

10

VN01 VN03 VN05

VN07
VN08
PL01

VN10
VN11
PL02

SW02

1.50
SW04

1.00
0.50

1300

VN02 VN04 VN06

500

VN097000.00
900 1100 1300 1500 1700 1900 2100 2300
Wavelength [nm]
SW01

SW03

Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK

Spectral response

Radiance [W/m^2/Str/um]

2.509Strategy of SGLI radiometric test

- Uniformity of the spectral radiance at the aperture in VNR test-Radiance uinformity [%]

2.00%
1.00%

BaSO4 VN01
BaSO4 VN02
BaSO4 VN03
BaSO4 VN10
Spectralon VN01
Spectralon VN02
Spectralon VN03
Spectralon VN10

0.00%
-1.00%-2.00%-4.0-3.0-2.0-1.0 0.0
1.0Angle [degree]

2.0

3.0

4.0

【Barium sulfate integrating sphere】
 Amplitude of the non-uniformity in each band is various.
 Radiance uniformity is less than 0.6% except VN01(380nm).
 It has good characteristics (stability, reproducibility) in the visible
region.
⇒Used for the absolute performance Gain, Stability, SNR【Spectralon integrating sphere】
 Amplitude of the non-uniformity in each band is almost same and flat Radiance uniformity is less than 0.5% all band.
⇒ Used to characterize the relative performance of VNR
 Photo response non-uniformity(PRNU), linearity
Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK10

Strategy of SGLI radiometric test
- VNR test case -【Barium sulfate integrating sphere】(a)Lamp set VN01 VN02 VN03 VN04 VN05 VN06 VN07 VN08 VN09 VN10 VN11 PL01 PL0290.0V x 12○○○85.0V x 12△
79.0V x 12○△○
71.3V x 12◎□○
62.3V x 12○□△◎51.9V x 12□△○48.7V x 12○
45.5V x 12○◎◎◎43.5V x 12◎39.7V x 12□○○○
38.1V x 12○35.1V x 12○◎◎
32.5V x 12□○◎○○
30.5V x 12○○
27.7V x 12□○○
24.8V x 12△○○
19.4V x 12◎：Lmax level□□□
17.3V x 12△：Lstd level□◎
16.0V x 12□：0.3Lstd level○
14.5V x 12□
12.5V x 12△□
10.1V x 12□

【Spectralon integrating sphere】
Lamp set(b) Xenon Halogen VN01 VN02 VN03 VN04 VN05 VN06 VN07 VN08 VN09 VN10 VN11 PL01 PL02On x 2On x 2-10A x 2
9A x 2
9.6A x 2
9.0A x 27.0A x 2
6.0A x2

○○

○*○

○
○

○
○

○

○

○*
○

○*
○

○
○
○* Only Linearity measurement by CCD electrical shutter There are many measurement cases tocharacterize VNR performance using
integrating sphere.
 Per band, telescope , angle of viewand radiance level The lighting time of lamps becomes longer.
 The radiance degradation of integrating
sphere occurs compared to calibration
by FPBB(Fixed-point black body).

 The merit of using two integrating spheres is to reduce the lighting time of the lamp.
 Prevent radiance degradation of the lamp by distributing the load using two
integrating spheres.
Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK11

Strategy of SGLI radiometric test- Matrix of SGLI radiometric test -VNR
IRSRadiometric characterization
Barium sulfate
Spectralon
Gold-coatedintegrating sphere integrating sphere integrating sphere
Gain○○
Dynamic range○○
Stability○○
Photo response non-uniformity (PRNU)○○
Linearity by change of the lamp set○○
Linearity by CCD electrical shutter○
Linearity by attenuator function○SNR○○ Absolute performance of VNR are characterized by using barium sulfate integrating sphere.
 Relative performance of VNR are characterized by using Spectralon integrating sphere.
 The consistency of two integrating spheres in VNR test is confirmed by linearityperformance.
 IRS performance are characterized using by gold-coated integrating sphere.
Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK12

Traceability of SGLI radiometric test
IRS

SGLI

VNR

Gold-coatedBarium sulfate

IntegratingSphere

IntegratingSphere

Integrating SphereRadiometerStandard Spectral Radiometer
SW02-04

VN06-11

SW01

ZnCu

Fixed-Point Black Body

VN01-05

SGLI sensors are calibrated byintegrating spheres of working standard.
Spectralon
Integrating
SphereRelativeradianceTransfer
Radiometer

Integrating spheres of working
standard are traceable to each FPBB.

Pt-C

FPBBs of primary standard aretraceable to the national standard.
NationalStandard

Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK13

VNR radiometric performance summary VNR final radiometric test finished in Aug. 2016
 We used barium sulfate and Spectralon integrating sphere The performances of each band center pixel were characterized andsatisfied the requirement
Integrating SNR, gain, dynamic range, stability,Sphere
PRNU, linearity
VNR-SRU
 All pixel and band performance
under calculation
 The radiometric parameters will be
implemented in ground system

Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK

VNR PRNU (Photo response non-uniformity) results- preliminary - Using the Spectralon integrating sphere The measurements were carried out at Lmax, Lstd level for five angle ofview for VNR-NP
 The data at Lmax, Lstd level were corrected of the uniformity of radianceat the aperture and connected The residual of Lmax and Lstd PRNU satisfied the requirement of 1%p-p(a) Lmax VN01 right telescope(c) Lmax VN01 right telescope

105
100959085

105
100
959085PRNU(b)

250 500 750 1000 1250 1500
Pixel

250 500 750 1000 1250 1500
Pixel

PRNU

0250 500 750 1000 1250 1500
Pixel

+10°
+5°0°
-5°
-10°

(d)

Lstd VN01 right telescope(after correction and connecting)

Lstd VN01 right telescope(before correction and connecting)1051009590850+10°+5°0°-5°-10°+10°+5°0°-5°-10°105
1009590850250 500 750 1000 1250 1500
Pixel+10°+5°0°-5°-10°(e) PRNU error VN01 right telescope
PRNU error [%]0This band is 0.4 %p-p(after correction and connecting)

PRNU

PRNU

(before correction and connecting)

4.0
3.0
2.0
1.0
0.0
-1.0
-2.0
-3.0
-4.00

Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK250500

750 1000 1250 1500
PixelVNR Linearity results- preliminary - Using the barium sulfate and Spectralon integrating spheres
 The linearity is defined as deviation from the first order polynomial
 The requirement is less than ±2% between 0.3Lstd and Lmax
 The linearity is measured by three methods
 The changing lamp set method using barium sulfate integrating sphere The CCD electrical shutter method of VNR function
 The mechanical shutter method using attenuator function of the Spectralon integratingsphere

Linearity Error [%] The consistency between different methods and spheres were verified
4.0
3.0
2.0
1.0
0.0
-1.0
-2.0
-3.0-4.0

VN08 right telescope

Linearity by change the lamp set
Linearity by CCD electrical shutter
Linearity by attenuator function

0.3Lstd0

Lstd

500

1000

1500

2000
[DN]

2500

3000

Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UKLmax

3500

4000

16

IRS radiometric performance summary IRS final radiometric test is ongoing We used gold-coated integrating sphere The performances of initial test were characterized and satisfied therequirement
 SNR, gain, dynamic range, stability, PRNU, linearity
 The radiometric parameters of final performance are implemented inground system
IntegratingSphere

IRS-SRU

Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UKIRS PRNU (Photo response non-uniformity) results
 Using the gold-coated integrating sphere IRS PRNU of initial test satisfied the requirement within 10% of themaximum value
SW01
0.3Lstd

1Lstd

1Lmax

1.0
0.9
0.8
13PixelSW03

0.3Lstd

1Lstd

450.9

1Lmax

1.00.9123Pixel

45SW04

1.11Lmax

1.0

1Lstd

0.3Lstd

0.8

PRNU

PRNU

1.1

2SW02

1.1

PRNU

PRNU

1.1

0.3Lstd

1Lstd

1Lmax

1.0
0.9
0.8

0.8
1 2 3 4 5 6 7 8 9 1011121314151617181920
Pixel

123
PRNU

Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK

45

IRS Linearity results

0.3Lstd Lstd0

Linearity Error [％]

SW01

Lmax

Linearity Error [％]5432
10-1-2-3-4-550

0.3Lstd5432
10-1-2-3-4-5
Lstd
010100150200
Radiance[W/m2/str/μm]

SW032500.3Lstd
5432
10-1-2-3-4-5Lstd
020Lmax
Linearity Error [％]Linearity Error [％] Using the gold-coated integrating sphere The linearity is defined as deviation from the first order polynomial
 The requirement is less than ±2% between 0.3Lstd and Lmax

203040
Radiance[W/m2/str/μm]

50

5432
10-1-2-3-4-50.3Lstd

0Lstd
2 4SW02406080
Radiance[W/m2/str/μm]

SW04

Lmax

100Lmax

6 8 10 12 14 16 18 20Radiance[W/m2/str/μm]

Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK

19

IRS final radiometric test environment

0.05340.0533 The humidity sensitivity experiment wasperformed using transfer radiometer of 1.38μm.

 IRS final test and radiance calibration ofintegrating sphere by FPBB are needed tocontrol same environment (temp. and humi.)
Transfer radiometer of 1380nm [V]in clean booth
55.0
Humidity[％]

54.5

0.053254.00.0531

53.50.0530

53.00.0529

52.50.0528

52.00.0527

51.50.0526

51.00.0525

50.50.0524
10:00:00

 SW02 (1.38 μm) data is affected by water
vapor variation.

Humidity[％]Transfer radiometer of 1380nm [V]TransferRadiometerof 1.38μm

50.0
12:00:00
Time

14:00:00

Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK20

IRS final radiometric test preliminary result

444240
9:00

12:00 15:00 18:00 21:00
2016/9/20~21 Time(JST)Absolute Humidity

10.0
9.5
9.0
8.5
8.0
6:00

9:00

0:00

SW03

5 0.3Lstd
43210-1-2-3-4-5Lstd
010203040
Radiance [W/m2/str/μm]

Lmax

Linearity Error [％]

SW02
Lmax
5 0.3Lstd
432
10-1-2-3-4-5Lstd
0204060
80
100
Radiance [W/m2/str/μm]
SW04
Lmax
5 0.3Lstd
432
10-1-2-3-4-5Lstd
0 2 4 6 8 10 12 14 16 18 20
Radiance [W/m2/str/μm]

Linearity Error [％]

48
46

6:00

Absolute Humidity[g/m^3]

Humidity

SW01
Lmax
5 0.3Lstd Lstd
432
10-1-2-3-4-5050
100
150
200
250
Radiance[W/m2/str/μm]

Linearity Error [％]Temperature

24.5
24.0
23.5
23.0
22.5
22.0
21.5
21.0
20.5

Humidity [%]Temperature [℃]Linearity Error [％]IRS-SRU

 This linearity data was measured on 21 Sep.
Gold-coatedIntegrating Sphere  Detailed evaluation is ongoing.

50

12:00 15:00 18:00 21:00 0:00
2016/9/20~21
Time(JST)performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK
Radiometric21

Summary The SGLI radiometric tests were carried out in the strategy andtraceability using three integrating spheres.
 The integrating spheres were used depending on the wavelength
range and the radiance level of SGLI.
 Preliminary test results indicate to achieve the required radiometricperformance. Further detailed evaluation is ongoing.
 It is necessary to evaluate all the pixel and band characterizations.
 The radiometric parameters will be derived from final radiometricperformance.

Radiometric performance of SGLI using integrating sphere @SPIE RS 2016, Edinburgh, UK22