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Proceedings Paper

Stray light suppression in InGaAs/GaAsSb type-II FPA
Author(s): Sundararajan Balasekaran; Masaki Migita; Takahiko Kawahara; Ken-ichi Machinaga; Kouhei Miura; Hiroshi Inada; Yasuhiro Iguchi; Tsukuru Katsuyama
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Paper Abstract

Stray light in focal plane array (FPA) deteriorates the accuracy of hyper spectral imaging. Multiple reflections between FPA window and peripheral region of a sensor chip are considered to be the major sources of stray light. One idea for suppressing the stray light is to shield the incident light on the peripheral region of the sensor chip by narrowing the FPA window. However, it is limited by the tolerance of assembly. In this study we have examined an epoxy coating on the peripheral region such as ROIC contact pad area, AlN substrate and bonding wire. Sensor chip with InGaAs/GaAsSb type-II quantum well structures, which has the cut-off wavelength of 2.35 μm, 320×256 pixels were bonded to ROIC through indium bumps, assembled to AlN substrate and to a four stage TEC. To avoid the degradation by the stress to the chip and bonding wire, low elastic modulus epoxy was selected. Stray light suppression was confirmed by the sensor signal output of epoxy coated samples, 3% contrast improvement was achieved. Further, reliability test of 10,000 heat cycles between -75°C and 25°C was carried out. No degradations were found in sensor characteristics of the epoxy coated sample. These results suggest that the epoxy coating in SWIR FPA is effective in suppressing the stray light and suitable for hyper spectral imaging.

Paper Details

Date Published: 13 February 2016
PDF: 8 pages
Proc. SPIE 9755, Quantum Sensing and Nano Electronics and Photonics XIII, 97551Z (13 February 2016); doi: 10.1117/12.2213971
Show Author Affiliations
Sundararajan Balasekaran, Sumitomo Electric Industries, Ltd. (Japan)
Masaki Migita, Sumitomo Electric Industries, Ltd. (Japan)
Takahiko Kawahara, Sumitomo Electric Industries, Ltd. (Japan)
Ken-ichi Machinaga, Sumitomo Electric Industries, Ltd. (Japan)
Kouhei Miura, Sumitomo Electric Industries, Ltd. (Japan)
Hiroshi Inada, Sumitomo Electric Industries, Ltd. (Japan)
Yasuhiro Iguchi, Sumitomo Electric Industries, Ltd. (Japan)
Tsukuru Katsuyama, Sumitomo Electric Industries, Ltd. (Japan)

Published in SPIE Proceedings Vol. 9755:
Quantum Sensing and Nano Electronics and Photonics XIII
Manijeh Razeghi, Editor(s)

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