9881-26 proto flight model (pfm) development status of ... · channels (vnr-pl), which will improve...

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)

9881-26

10th SPIE Asia-Pacific Remote Sensing SymposiumEarth Observing Missions and Sensors: Development, Implementation, and Characterization IV

New Delhi, India, 4-7 April 2016

2 © NEC Corporation 2015

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


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 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-Cis scheduled forlaunch in 2017.

GCOM-C(CLIMATE)

SensorAdvanced Microwave Radiometer 2 (AMSR2)

Passive Microwave ObservationWater vapor, soil moisture etc

SensorSecond Generation Global Imager(SGLI)

Optical Observation 380nm – 12 micronCloud, Aerosol, Vegetation, Chrolophl etc

GCOM-W(WATER) AMSR2

SGLIGCOM-W “SHIZUKU” was launched on May 18, 2012.


SGLI on GCOM-C1 satellite

SGLI Second Generation Global ImagerVNR Visible and Near Infrared RadiometerIRS Infrared Scanning RadiometerSRU Scanning Radiometer UnitELU Electronic Unit

Mission Life > 5 years

Solar Paddle > 4000w （End of Life）

Mass about 2,000kg

SGLI IRSELU

+X

flight direction+Y

+Z earth

deepspace

SGLI VNRELU

SGLI IRSSRU

SGLI VNRSRU


SGLI (Second Generation Global Imager)

PolarizedObservationTelescopes(55deg FOVx 2)

Non PolarizedObservation Telescopes(24deg FOV x 3)

SolarDiffuser

About1.7m

About1.3m

Infrared Scanning Radiometer(SGLI-IRS)

EarthView Window

DeepSpaceWindow

About1.4m

About0.6m

Sensor Unit Features

SGLI VNRNon Polarized Observation （11ch）, IFOV 250m, Swath 1150kmPolarized Observation（2ch）, IFOV 1km, Swath 1150km

SGLI IRSShortwave Infrared （SWI 4ch）, IFOV 250m/1km, Swath 1400kmThermal Infrared （TIR:2ch）, IFOV 500m, Swath 1400km

Visible and Near Infrared Radiometer(SGLI-VNR)

Sun Cal.Window


SGLI Specification

SGLI channels

CH

Lstd Lmax SNR at Lstd IFOV

VN, P, SW: nmT: m

VN, P: W/m2/sr/m

T: Kelvin

VN, P, SW: SNR

T: NETm

VN1 380 10 60 210 250 250VN2 412 10 75 250 400 250VN3 443 10 64 400 300 250VN4 490 10 53 120 400 250VN5 530 20 41 350 250 250VN6 565 20 33 90 400 250VN7 673.5 20 23 62 400 250VN8 673.5 20 25 210 250 250VN9 763 12 40 350 1200 250/1000VN10 868.5 20 8 30 400 250VN11 868.5 20 30 300 200 250P1 673.5 20 25 250 250 1000P2 868.5 20 30 300 250 1000

SW1 1050 20 57 248 500 1000SW2 1380 20 8 103 150 1000SW3 1630 200 3 50 57 250SW4 2210 50 1.9 20 211 1000T1 10.8 0.7 300 340 0.2 250/500T2 12.0 0.7 300 340 0.2 250/500

•The SGLI features are 250m (VNR-NP & SW3) and 500m (TIR)spatial resolution and polarization/along-track slant viewchannels (VNR-PL), which will improve land, coastal, and aerosol observations.

GCOM-C SGLI characteristics

OrbitSun-synchronous(descending local time: 10:30)Altitude 798km, Inclination 98.6deg

Mission Life 5 years (3 satellites; total 13 years)

Scan Push-broom electric scan (VNR)Wisk-broom mechanical scan (IRS)

Scan width 1150km cross track (VNR: VN & P)1400km cross track (IRS: SW & T)

Digitalization 12bitPolarization 3 polarization angles for PAlong track direction

Nadir for VN, SW and T, +45 deg and -45 deg for P

On-board calibration

VN: Solar diffuser, LED, Lunar cal maneuvers, and dark current by masked pixels and nighttime obs.

SW: Solar diffuser, LED, Lunar, and dark current by deep space window

T: Black body and dark current by deep space window

Multi-angle obs. for 673.5nm and 868.5nm

250m over the Land or coastal area, and 1km over offshore

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


SGLI VNR Current Status

Integration

Alignment

SRU-ELU Interface

Radiometric

Thermal vacuum

Vib. & Acoustic

Final performance

VNR SRU

Geometric

Radiometric

Vib. & Shock

Stray light

Pol. measurement

PL sub assembly

Thermal vacuum

PL sub-unitNP sub-unit

Geometric

Vib & Shock

Radiometric

Pol. sensitivity

Stray light

NP sub assembly

Thermal vacuum

NP/P

L se

nsor

Pha

se

completed completed ongoing

←NOW


Current Status

VNR SRU Onboard Configuration

＋Xflight direction

＋Ydeep space

＋Zearth

VNR SRU

PL NP

March 2016, TSUKUBA


NP/PL sensor Performance Test by CollimatorGeometric testPolarization sensitivity of NP sensorMuller Matrix for PL sensor Stray light test / Stray light correction model

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

Geometric Test

Collimator

Rotation Stage

NP sensor


Radiometric Test (Integrating Sphere)

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

Integrating Sphere

Simple rotation stage

NP sensor


Thermal Vacuum Test

Thermal Vacuum TestGeometric test for NP/PL sub-unitRadiometric test for NP/PL sub-unit

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

6m Space chamber

IR panels

Collimator

Rotation stage

Sub-Unit


CCD view angle measurements and verificationAmbient and Thermal Vacuum environment

NoteView 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.

Geometric Performance (Alignment)

ambient1nominal1coldhotnominal2ambient2

-100

-50

0

50

100

-100-50050100

θy（

arcs

ec）

θx（arcsec）

p60 234pixel

-100

-50

0

50

100

-100-50050100

θy（

arcs

ec）

θx（arcsec）

m60 239pixel -100

-50

0

50

100

-100-50050100

θy（

arcs

ec）

θx（arcsec）

pm0 3000pixel

-100

-50

0

50

100

-100-50050100

θy（

arcs

ec）

θx（arcsec）

p60 5765pixel

-100

-50

0

50

100

-100-50050100

θy（

arcs

ec）

θx（arcsec）

m60 5760pixel

vacuum

ambient

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


MTF defocusFollowing figures show the MTF defocus trend data. Data point : PL2 sensor, +60° of pol. angle, +27.5° of view angle

NOTEMTF 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%.

Geometric Performance (MTF)

The ambient data are the corrected value due to the vacuum shift of focal length

40

50

60

70

80

90

100

-0.3 -0.2 -0.1 0 0.1 0.2 0.3

MT

F[%

]

Defocusing Position [mm]

p60 +27.5°CT

40

50

60

70

80

90

100

-0.3 -0.2 -0.1 0 0.1 0.2 0.3M

TF

[%]

Defocusing Position [mm]

ambient1nominal1coldhotnominal2ambient2

p60 +27.5°AT


Radiometric Performance (Linearity)

Linearity errorTest condition : TVT nominal2 data, 0.3Lstd ~ Lmax of radiancePlot data : worst deviation values

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

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

4.0%

VN1 VN2 VN3 VN4 VN5 VN6 VN7 VN8 VN9 VN10VN11

Lin

eari

ty E

rror

NPRNPNNPLSpec


Radiometric Performance (SNR)

SNRPL sub-unit TVT results in TVT tests.

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

0

500

1000

1500

2000

2500

3000

3500

4000

0 50 100 150 200 250 300 350

S/N

Radiance [W/m2/str/um]

PL2 ＠TVT nominal2

+60°0°‐60°LstdTarget

0100200300400500600700800900

1000

nom1 cold hot nom2 amb2

S/N

@L

std

PL1_+60°

PL1_0°

PL1_-60°

PL2_+60°

PL2_0°

PL2_-60°

Target


Polarization Sensitivity for NP sensor

Polarization measurements using the linear polarizer.a) Polarization sensitivity b) Polarization direction

Polarization sensitivity exceeds3% target in RED and NIR channelsas predicted from EM test results. Sensitivity Model req.

in the retrieval algorithm.

0.94

0.96

0.98

1

1.02

1.04

1.06

0 90 180 270 360

Nor

mal

ized

out

put

Rotation angle[deg]

Polarization Uniformity of NPR VN10 +12deg

Measured value

Fitting curve0%

1%

2%

3%

4%

5%

-12 -6 0 6 12

Pola

riza

tion

sens

itivi

ty

View angle[deg]

Polarization sensitivity of NPR VN10

60

70

80

90

100

110

120

-12 -6 0 6 12

Pola

riza

tion

angl

e (°

)

View angle[deg]

Polarization angle of NPR VN10

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

VN1 VN2 VN3 VN4 VN5 VN6 VN7 VN8 VN9 VN10VN11

Pmax, Pmin NPR Pmax

NPN Pmax

NPL Pmax

NPR Pmin

NPN Pmin

NPL Pmin


Polarization Sensitivity for NP sensor (Model)

Model parameter ρc, ρmax for Stokes Q and U componets

chxy1tan max2

max2

22

yxyx

ch

chl

Qcos 2

1 cos 21 sin 21 cos 2

ρc : Pol. sensitivity of CCD+BPFρl : Pol. sensitivity of telescopeρmax : Pol. sensitivity of telescope (maximum)xch : channel (pixel) location for AT directiony : pixel location for CT directionymax : pixel location for CT direction (maximum)

-U

-U

+U

+U

-Q-Q

+Q

+Q

x_axis

y_axis

6000pixel1pixel

xch

-y

θ

Imaging plane

45°

Coordinate definition

0.0%

0.5%

1.0%

1.5%

2.0%

VN1 VN2 VN3 VN4 VN5 VN6 VN7 VN8 VN9 VN10 VN11

NPR

NPN

NPL

ρmax

-1.0%

0.0%

1.0%

2.0%

3.0%

4.0%


NPR

NPN

NPL

ρc


Modeling errors from 5 view angles data (3 for model, 2 for verification)

ResultsQ, U modeling are realized with sufficientaccuracy comparing to the req.

Relative errors between bands : <0.4%Band-common errors : <0.6%

Polarization Sensitivity for NP sensor(Model Accuracy)

0.00%

0.10%

0.20%

0.30%

0.40%


Relative ErrorCommon Error

Q element

0.00%

0.10%

0.20%

0.30%

0.40%


Relative ErrorCommon Error

U element

The model and the Modeling error of NPR VN10

-0.4%

-0.3%

-0.2%

-0.1%

0.0%

0.1%

0.2%

0.3%

0.4%

-5%

-4%

-3%

-2%

-1%

0%

1%

2%

3%

-12 -6 0 6 12

Q, U

View angle [deg]

Q measurements

U measurements

Q modeling

U modeling

ΔQ

ΔU

ΔQ, Δ

Uρmax :1.73%ρc :3.30%

Modeling error (σ)

0.0%

0.1%

0.2%

0.3%

0.4%


Relative Error

Common Error

Polarization sensitivity


Target AccuracyPol. ratio (ΔP/Pstd) : <4%Pol. direction : <1.3°Incident light : standard radiance of Lstd, standard pol. ratio of 5% at any direction

Results from the PL sensor test (PL2, view angle of +0.5°, at Lstd Input)

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.

Polarization Observation Accuracy for PL sensor

-8%-6%-4%-2%0%2%4%6%8%

0 90 180 270 360

Acc

urac

y of

Pol

. rat

ioΔP

/P

Rotation angle of 5% Polarizer[deg]

Accuracy of Polarization Ratio

-3

-2

-1

0

1

2

3

0 90 180 270 360

Acc

urac

y of

Pol

. dir

ectio

n [d

eg]

Rotation angle of 5% Polarizer[deg]

Accuracy of Polarization direction


Conclusion

Test results of VNR-SRU PFM met the requirement.

Precise sensor models are analyzed for the data processingGeometric 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 2017

9881-26 proto flight model (pfm) development status of ... · channels (vnr-pl), which will improve...

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