Optical Design of A Compact Imaging Spectrometer for STSAT3

Abstract

A compact imaging spectrometer (COMIS) for use in the STSAT3 microsatellite is currently under development. It is scheduled to be launched into a low Sun-synchronous Earth orbit (~700 km) by the end of 2010. COMIS was inspired by the success of CHRIS, which is a small hyperspectral imager developed for the ESA microsatellite PROBA. COMIS is designed to achieve nearly equivalent imaging capabilities of CHRIS in a smaller (65 mm diameter and 4.3 kg mass) and mechanically superior (in terms of alignment and robustness) package. Its main operational goal will be the imaging of Earth's surface and atmosphere with ground sampling distances of ~30 m at the 18~62 spectral bands (4.0~1.05 μm). This imaging will be used for environmental monitoring, such as the in-land water quality monitoring of Paldang Lake, which is located next to Seoul, South Korea. The optics of COMIS consists of two parts: imaging telescope and dispersing relay optics. The imaging telescope, which operates at an f-ratio of 4.6, forms an image (of Earth's surface or atmosphere) onto an intermediate image plane. The dispersion relay optics disperses the image and relay it onto a CCD plane. All COMIS lenses and mirrors are spherical and are made from used silica exclusively. In addition, the optics is designed such that the optical axis of the dispersed image is parallel to the optical axis of the telescope. Previous efforts focused on manufacturing ease, alignment, assembly, testing, and improved robustness in space environments.

Environmental Test Results of a Flight Model of a Compact Imaging Spectrometer for a Microsatellite STSAT-3

“…최종 우주 공간에서의 시스템 MTF 값을 확보하기 위하여, 각 개발 단계 별로 MTF 공차 할당을 수행하게 된다. 표 2는 우주공간에서 검출기 차단 주파수의 반에 해당하는 나이퀘 스트 주파수인 38.5 line-pair per mm(lp/mm)에서 29%의 시 스템 MTF를 확보하기 위한 COMIS 시스템의 MTF 공차 할 당을 보여주고 있다 [7] . 광학 설계 MTF는 38.5 lp/mm에서…”

“…소형영상분광기(COMIS, compact imaging spectrometer)는 과학기술위성3호의 부탑재체로 지표면 및 대기 과학을 연구 할 목적으로 개발된 분광 카메라이다 [7][8][9] . COMIS는 고도 700 km의 태양 동기 궤도 상공에서 27 m 지상 해상도를 갖고 관측 폭 28 km의 지표면 및 대기를 관측하게 된다.…”

Compact Zoom Lens Design for a 5x Mobile Camera Using Prism

“…To correct the residual aberrations, we use two aspheric lenses. The aspheric surface has many design parameters, so aberrations can be well corrected [14][15].…”

Optical Skin-fat Thickness Measurement Using Miniaturized Chip LEDs: A Preliminary Human Study

“…In our previous study, we constructed a sensor module with a packaged chip LED at a 770 nm wavelength and tested its performance using two layer tissue phantoms [7][8].…”