Showa Optronics Co., Ltd.

High-precision narrow-band
optical filters for global observation
100Transmittance (%)

80

Atsuo Kurokawa○, Yasuhiro Nakajima, Shinji Kimura, Hiroshi Atake,Showa Optronics Co., Ltd.

60

Yoshihiko Okamura, Kazuhiro Tanaka,
Japan Aerospace Exploration Agency

40Shunji Tsuida, Kenichi Ichida, Takahiro Amano,
NEC TOSHIBA Space Systems, Ltd.

200300400

500

600700wavelength (nm)800900Showa Optronics Co., Ltd.

Outline◎Back Ground・Optical Filters on GCOM-C1 Satellite・Specification and Important Factor for VN Filters・Benefits of High-Precision Band Pass Filter◎Preliminary Study of Manufacturing Filters

・Coating Methods
・Film Thickness Distribution and Coating Equipments
・Error of Center Wavelength (CWL) Uniformity◎Results and Discussion

・CWL Error & Error of CWL Uniformity
・Spectrum Shift Caused By Telecentric Error
・Controlling CWL Distribution◎Summary

Showa Optronics Co., Ltd.

Optical Filters on GCOM-C1 satellite
VN filters(Optical filters)

GCOM‐C1 satellite

SGLI‐‐VNR unit

SGLI‐‐IRS unit

SGLI‐VNR‐VN
telescopes
SGLI : Second Generation global Imager
VNR : Visible & Near infrared RadiometerVN : Visible & Near infrared
P : Polarimetry
I R S : InfraRed Scanner
SW : ShortWave infrared
T : Thermal infrared
FOV=70deg,

Swath=1150km

Showa Optronics Co., Ltd.

Specification and Important Factor for VN Filters
Table. Main Specifications for pass band characteristics of VN filters
unit VN1 VN2 VN3 VN4 VN5 VN6 VN7,8 VN9 VN10,11
Nominal value nm 380.0 412.0 443.0 490.0 530.0 565.0 673.5 763.0 868.5
Centernm ±1.5 ±1.6 ±0.9 ±1.0 ±1.1 ±2.3 ±1.3 ±1.5±1.7
Tolerance
Wavelength% ±0.4 ±0.4 ±0.2 ±0.2 ±0.2 ±0.4 ±0.2 ±0.2±0.2(CWL)
nmPP 0.70.71.11.21.31.01.61.42.1
Uniformity%PP 0.18 0.18 0.24 0.24 0.24 0.18 0.24 0.180.24
FWHM
nm101010102020201220Band widthTolerance
nm ±1.0 ±1.0 ±1.0 ±1.0 ±2.0 ±2.0 ±2.0 ±1.0±2.0000

1

Intensity (a.u.)

5050Transmittance(%)

1001001Intensity (a.u.)Transmittance(%)

100100

Actual size of filters：：82mm××1mm
Intensity Spectrum of an observation target5050000> 0.18%pp

0.18%pp

Wavelength

Wavelength

Poor CWL uniformity

Good CWL uniformity

Showa Optronics Co., Ltd.

Benefits of High-Precision Band Pass Filter
・High-accurate Center Wavelength
・Optimized transmission band width→ High Signal-to-noise ratio→ Enable High-precision monitoring
Increase accuracy of environmental change prediction
・Good Uniformity over the entire effective area of substrate→ increases filter size for large line sensors→ reduces the number of telescope maintaining FOV→ saves weight of satellite

Showa Optronics Co. Ltd.

Outline◎Back Ground・Optical Filters on GCOM-C Satellite・Specification and Important Factor for Filters
・Benefits of High-Precision Band Pass Filter◎Preliminary Study of Manufacturing Filters

・Coating Methods
・Film Thickness Distribution and Coating Equipments
・Error of Center Wavelength (CWL) Uniformity◎Results and Discussion

・CWL Error & Error of CWL Uniformity
・Spectrum Shift Caused by Telecentric Error
・Controlling CWL Distribution◎Summary

Showa Optronics Co., Ltd.

Coating Methods

PLASMA SOURCEElectron Beam
Physical Vapor Deposition

Plasma Ion AssistedDeposition

Dual Ion Beam
Sputtering Deposition(EB)(PIAD)(IBSD)

Packing density
Spectral shift
Internal stress
Productivity

EB
Low
Significant< 100MPa
HighPIADHigh
Negligible
250MPaHighIBSDHigh
Negligible> 350MPa
Low

Showa Optronics Co., Ltd.

Film Thickness Distribution and Coating Equipments
Z

Spherical substrate holder

Substrate
P

850mm

Spherical holder
Optimized shadow mask

θ φrtilt=22.5deg.

Evaporation source

SourceX

Y

Shadow masks to correct
the CWL distributiona) The geometry diagram and pictures of the spherical holder with a shadow mask
Z

Substrate

tilt=0deg.

Flat substrate holder

P

850mm

Flat holder
θOptimized shadow mask

φ=θrhSource

Shadow masks to correct
Ythe CWL distributionb) The geometry diagram and pictures of the flat holder with a shadow mask
Evaporation sourceX

Showa Optronics Co., Ltd.

Error of CWL Uniformity
Error = 0%

Error = 0%1515mm15mm

1510+2.5%0mm

Error = 4.0%pp

0-50%

+2.5%

-40

-2.5%
-30-20-1000mm

1020

Error = 0.05%pp

0mm
0-5-10-15mm-50mm-15-50105530405050mmc)c) Spherical holder with a shadow mask

0%-10-2.5%-15mm-50mm-15-50-40-30-20-1000mm102030405050mmd)d) Flat holder with a shadow mask

3 telescopes were required almost similar performance→ 3 filters that have almost similar spectral characteristics are essential
・High-accurate CWL
・Optimized transmission band width・Good CWL uniformity over the entire area of the substrate

Showa Optronics Co., Ltd.

Outline◎Back Ground・Optical Filters on GCOM-C Satellite・Specification and Important Factor for Filters
・Benefits of High-Precision Band Pass Filter◎Preliminary Study of Manufacturing Filters

・Coating Methods
・Film Thickness Distribution and Coating Equipments
・Error of Center Wavelength (CWL) Uniformity◎Results and Discussion

・CWL Error & Error of CWL Uniformity
・Spectrum Shift Caused By Telecentric Error
・Controlling CWL Distribution◎Summary

Showa Optronics Co., Ltd.

0.10
0.10

●：Optical Monitor▲：Time Controlled

0.00
0.00

‐-0.10
0.10
VN1
VN2
VN3
VN4
VN5
VN6
VN7
VN8
VN9
VN10
VN11

-0.20
‐0.20

Error
uniformity(%)(%)
Errorofof CWLCWL uniformity

CWL error of each band(measurement at center of a substrate)
0.20
0.20
0.15
0.15
0.10
0.10

Spec=0.18%pp●：PIAD with Flat holder▲：IBSD

0.20

Error of CWL uniformity (%)

CWL error (%)

CWL error (%)

0.20
0.20

Spec=±±0.2%

CWL Error & Error of CWL Uniformity

0.15

0.10

0.05

0.00

-50

-25
025Position on the substrate (mm)50× × × × × × × × × × × × × × × ×× × × × ×

Cross marks ; measurement points on the substrate

0.00
0.00

CWL distribution along the length ofthe VN1 filter (area of 100mm××1mm)

VN1VN2VN3VN4VN5VN6VN7VN8VN9VN10VN110.050.05

Error of CWL uniformity along the longer
direction of each band (area of 82mm××1mm)

Showa Optronics Co., Ltd.

Spectrum Shift Caused by Telecentric Error
AOI
AOI=0°
increasing

AOI=0°

AOI=0°
AOI
increasing

Filter Substratetransmittance [%] (%)
Transmittance

1009080706050403020100350

450 wavelength550
wavelength [nm]650750The wavelength spectrum shifts to shorter wavelength

Showa Optronics Co., Ltd.

Controlling CWL Distribution

300mmφError of CWL uniformity (%)

0.20

0.15

0.100.050.00-50

The shape of the optimized Shadow mask025-25Position on the substrate (mm)Control of CWL distribution50

Showa Optronics Co., Ltd.

Outline◎Back Ground・Optical Filters on GCOM-C Satellite・Specification and Important Factor for Filters
・Benefits of High-Precision Band Pass Filter◎Preliminary Study of Manufacturing Filters

・Coating Methods
・Film Thickness Distribution and Coating Equipments
・Error of Center Wavelength (CWL) Uniformity◎Results and Discussion

・CWL error & Relative CWL Uniformity
・Spectrum Shift Caused by Telecentric Error
・Controlling CWL Distribution◎Summary

Showa Optronics Co., Ltd.

SummaryNarrow-band optical filters with・CWL error of better than ±0.1%
・CWL uniformity of better than 0.1%pp
over an area of 100 mm × 1 mm were achieved
The possibility of compensating a spectrum shift
due to a telecentric error of optical lens bycontrolling CWL distribution was demonstrated

Showa Optronics Co., Ltd.

Thank you for your time100

1-22-1 Hakusan Midori-ku Yokohama 226-0006 Japana-kurokawa@soc-ltd.co.jp
http://www.soc-ltd.co.jp

Transmittance (%)

806040

200
300

400

500

600
700
wavelength (nm)800900