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Proceedings Paper

The experiment to detect equivalent optical path difference in independent double aperture interference light path based on step scanning method
Author(s): Chaoyan Wang; Xin-yang Chen; Lixin Zheng; Yuanyuan Ding
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Paper Abstract

Fringe test is the method which can detect the relative optical path difference in optical synthetic aperture telescope array. To get to the interference fringes, the two beams of light in the meeting point must be within the coherence length. Step scanning method is within its coherence length, selecting a specific step, changing one-way’s optical path of both by changing position of micro displacement actuator. At the same time, every fringe pattern can be recorded. The process of fringe patterns is from appearing to clear to disappearing. Firstly, a particular pixel is selected. Then, we keep tract of the intensity of every picture in the same position. From the intensity change, the best position of relative optical path difference can be made sure. The best position of relative optical path difference is also the position of the clearest fringe. The wavelength of the infrared source is 1290nm and the bandwidth is 63.6nm. In this experiment, the coherence length of infrared source is detected by cube reflection experiment. The coherence length is 30μm by data collection and data processing, and that result of 30μm is less different from the 26μm of theoretical calculated. In order to further test the relative optical path of optical synthetic aperture using step scanning method, the infrared source is placed into optical route of optical synthesis aperture telescope double aperture. The precision position of actuator can be obtained when the fringe is the clearest. By the experiment, we found that the actuating step affects the degree of precision of equivalent optical path. The smaller step size, the more accurate position. But the smaller the step length, means that more steps within the coherence length measurement and the longer time.

Paper Details

Date Published: 6 November 2014
PDF: 6 pages
Proc. SPIE 9272, Optical Design and Testing VI, 92721E (6 November 2014); doi: 10.1117/12.2071804
Show Author Affiliations
Chaoyan Wang, Shanghai Astronomical Observatory (China)
Xin-yang Chen, Shanghai Astronomical Observatory (China)
Lixin Zheng, Shanghai Astronomical Observatory (China)
Yuanyuan Ding, Shanghai Astronomical Observatory (China)

Published in SPIE Proceedings Vol. 9272:
Optical Design and Testing VI
Yongtian Wang; Chunlei Du; José Sasián; Kimio Tatsuno, Editor(s)

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