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Optical Engineering

Solar-light shielding using a near-hemispherical lens for a star sensor
Author(s): Hiroyuki Kawano; Haruhiko Shimoji; Shoji Yoshikawa; Katsumasa Miyatake; Kazumori Hama; Shuji Nakamura
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Paper Abstract

We have developed a light-shielding technique for a star sensor that can shorten the baffle length. We achieved a baffle length of 120 mm, two-thirds that of a conventional two-stage baffle. The key idea is that the first lens of the imaging optics is designed as a near-hemispherical (NHS) lens that can work as an angle filter; high-incidence-angle rays are not permitted to be transmitted but low-incidence-angle rays from stars can be. A star sensor system with the new light-shielding technique onboard the SERVIS-1 satellite was launched in October 2003 as an experimental device. Though the in-orbit data verified its fundamental performance in capturing star images, undesirable solar background noise was observed in two corners of the field of view. Ray-trace simulations revealed that slight scattered light on the specular baffle surface entered the NHS lens and reached the corners of the image sensor through a multireflection path inside the lens. We redesigned the baffle and confirmed that stray light was reduced below maximum acceptable levels in a ground test. The star sensor with redesigned baffles is planned to be installed as the main attitude sensor for the SERVIS-2 satellite to be launched in 2008 or later.

Paper Details

Date Published: 1 December 2006
PDF: 9 pages
Opt. Eng. 45(12) 124403 doi: 10.1117/1.2402101
Published in: Optical Engineering Volume 45, Issue 12
Show Author Affiliations
Hiroyuki Kawano, Mitsubishi Electric Corp. (Japan)
Haruhiko Shimoji, Mitsubishi Electric Corp. (Japan)
Shoji Yoshikawa, Mitsubishi Electric Corp. (Japan)
Katsumasa Miyatake, Mitsubishi Electric Corp. (Japan)
Kazumori Hama, USEF (Japan)
Shuji Nakamura, USEF (Japan)

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