Applications of Mo/Si multilayer mirrors for the moon-based extreme ultraviolet Camera (EUVC) require not only the
minimal residual stress, but also little stress changes in the temperature environment on lunar surface. Hence, we deposit
the 16.5 nm period Mo/Si multilayer mirror with a low as-deposited residual stress of -36 Mpa (compressive). The in-situ
and real time stress tests are measured in the temperature cycling range from 20 °C to 130 °C. The results indicate that
the stress gradually increases to the maximum of -100 MPa when heating up to 105 °C, then it gradually relaxes to 10
Mpa after thermal cycling to 130 °C. Such stress change has little influence on the performance of the Mo/Si multilayer
Star sensor is a special high accuracy photoelectric sensor. Attitude acquisition time is an important function index of star sensor. In this paper, the design target is to acquire 10 samples per second dynamic performance. On the basis of analyzing CCD signals timing and star image processing, a new design and a special parallel architecture for improving star image processing are presented in this paper. In the design, the operation moving the data in expanded windows including the star to the on-chip memory of DSP is arranged in the invalid period of CCD frame signal. During the CCD saving the star image to memory, DSP processes the data in the on-chip memory. This parallelism greatly improves the efficiency of processing. The scheme proposed here results in enormous savings of memory normally required. In the scheme, DSP HOLD mode and CPLD technology are used to make a shared memory between CCD and DSP. The efficiency of processing is discussed in numerical tests. Only in 3.5ms is acquired the five lightest stars in the star acquisition stage. In 43us, the data in five expanded windows including stars are moved into the internal memory of DSP, and in 1.6ms, five star coordinates are achieved in the star tracking stage.
This paper (SPIE Paper 60310G) was removed from the SPIE Digital Library on 8 August 2008 upon learning that portions of the paper are identical or similar to material contained in a Master's Thesis by Taeyoung Choi at South Dakota State University in 2002 titled "IKONOS Satellite on Orbit Modulation Transfer Function (MTF) Measurement using Edge and Pulse Method," without attribution or credit to the source.
As stated in the SPIE Publication Ethics Guidelines, "SPIE defines plagiarism as the reuse of someone else's prior ideas, processes, results, or words without explicit attribution of the original author and source, or falsely representing someone else's work as one's own. Unauthorized use of another researcher's unpublished data or findings without permission is considered to be a form of plagiarism even if the source is attributed. SPIE considers plagiarism in any form, at any level, to be unacceptable and a serious breach of professional conduct."
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A novel auto-focusing technique using a self imaging approach is developed for an aerospace camera having large aperture and long focus. Its optical system consists of an emitting system, receiving system, and two penta-prisms. Emitting system has three parts: a light source, beamsplitter, and aim slit. The receiving system includes a field lens, two separate lenses, and CCD. Using two little penta-prisms instead of a large planar mirror makes the autofocus system simple and compact. CCD was used as photoelectric converting device. A defocused signal is acquired by measuring the change of the two slit self-images position imaged on the CCD. A simple and compact construction of the auto-focusing system was proposed. The algorithm to calculate the moving of the slit-self images position was analyzed in order to achieve subpixel position estimation. The results of the experiments show a ±10μm focusing precision. The system demonstrates high resolution, easy adjustment and high reliability.