1 December 2006 Solar-light shielding using a near-hemispherical lens for a star sensor
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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.
© (2006) Society of Photo-Optical Instrumentation Engineers (SPIE)
Hiroyuki Kawano, Hiroyuki Kawano, Haruhiko Shimoji, Haruhiko Shimoji, Shoji Yoshikawa, Shoji Yoshikawa, Katsumasa Miyatake, Katsumasa Miyatake, Kazumori Hama, Kazumori Hama, Shuji Nakamura, Shuji Nakamura, } "Solar-light shielding using a near-hemispherical lens for a star sensor," Optical Engineering 45(12), 124403 (1 December 2006). https://doi.org/10.1117/1.2402101 . Submission:


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