Separated Aperture Optical Telescopes with small satellite formation flying
- Paper number
IAC-06-B5.4.02
- Author
Mr. Norihide Miyamura, University of Tokyo, Japan
- Year
2006
- Abstract
High resolution remote sensing is required for Earth observation and astronomy. For example, large aperture telescopes which indicate effective aperture of 10 meters or larger in diameter is required to realize high resolution in astronomy. Monolithic mirrors of such a large size are not feasible to manufacture in the near future. Furthermore, on-orbit thermo-mechanical drift and vibration environment in launching cause misalignment of optical system and degradation of the resolution especially for large aperture telescopes. On the other hand, separated aperture telescopes consist of individual small aperture sub-telescopes whose images are combined into single image in beam combining telescope. This system can form a large aperture telescope on orbit with individual small aperture telescope. Thus, separated aperture telescopes system has a possibility to extend a small satellite remote sensing mission. In this paper, I conduct a study on the feasibility of a large aperture imaging telescope composed of small aperture sub-telescopes with small satellite formation flying. During this study, I compare the performance of separated telescopes system with existing large aperture monolithic telescope. I suggest a mission which has advantages to separated telescopes system. Then, I extract technological problems to realize separated aperture telescopes. I suggested a Michelson design which has some advantages over Fizeau design for separated telescopes system. Michelson design can relax the accuracy of position control and measuring distance. Then I constructed a mathematical model of the system including dynamics of satellites and optical performance of instrument. To compare the performance of the separated telescope system with monolithic mirror telescope, I calculated the system MTF and estimate acquired image for each system. Separated aperture telescopes system can extend the cutoff frequency almost as same as that of theoretical monolithic large aperture telescope if wide field aberration is solved. However, in separated aperture system, MTF has complicated shape. Zero MTF can be seen below the maximum cutoff spatial frequency. In this paper, the Michelson-type separated optical imaging telescope with small satellite formation flying is proposed. Maximum MTF cutoff frequency can be extended with this system. Zero MTF below the maximum cutoff spatial frequency means the degradation of combined image. Therefore post-processing of acquired image or a new mission which require high cutoff frequency and permit zero MTF below the maximum cutoff frequency should be studied for future work. I am currently conducting a study on these problems.
- Abstract document