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Advanced Dispersed Fringe Sensing Algorithm for Coarse Phasing Segmented Mirror TelescopesSegment mirror phasing, a critical step of segment mirror alignment, requires the ability to sense and correct the relative pistons between segments from up to a few hundred microns to a fraction of wavelength in order to bring the mirror system to its full diffraction capability. When sampling the aperture of a telescope, using auto-collimating flats (ACFs) is more economical. The performance of a telescope with a segmented primary mirror strongly depends on how well those primary mirror segments can be phased. One such process to phase primary mirror segments in the axial piston direction is dispersed fringe sensing (DFS). DFS technology can be used to co-phase the ACFs. DFS is essentially a signal fitting and processing operation. It is an elegant method of coarse phasing segmented mirrors. DFS performance accuracy is dependent upon careful calibration of the system as well as other factors such as internal optical alignment, system wavefront errors, and detector quality. Novel improvements to the algorithm have led to substantial enhancements in DFS performance. The Advanced Dispersed Fringe Sensing (ADFS) Algorithm is designed to reduce the sensitivity to calibration errors by determining the optimal fringe extraction line. Applying an angular extraction line dithering procedure and combining this dithering process with an error function while minimizing the phase term of the fitted signal, defines in essence the ADFS algorithm.
Document ID
20130012648
Acquisition Source
Jet Propulsion Laboratory
Document Type
Other - NASA Tech Brief
Authors
Spechler, Joshua A.
(California Inst. of Tech. Pasadena, CA, United States)
Hoppe, Daniel J.
(California Inst. of Tech. Pasadena, CA, United States)
Sigrist, Norbert
(California Inst. of Tech. Pasadena, CA, United States)
Shi, Fang
(California Inst. of Tech. Pasadena, CA, United States)
Seo, Byoung-Joon
(California Inst. of Tech. Pasadena, CA, United States)
Bikkannavar, Siddarayappa A.
(California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 27, 2013
Publication Date
April 1, 2013
Publication Information
Publication: NASA Tech Briefs, April 2013
Subject Category
Astronomy
Report/Patent Number
NPO-47688
Distribution Limits
Public
Copyright
Public Use Permitted.
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