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Automatic evaluation of interferogramsA system for the evaluation of interference patterns was developed. For digitizing and processing of the interferograms from classical and holographic interferometers a picture analysis system based upon a computer with a television digitizer was installed. Depending on the quality of the interferograms, four different picture enhancement operations may be used: Signal averaging; spatial smoothing, subtraction of the overlayed intensity function and the removal of distortion-patterns using a spatial filtering technique in the frequency spectrum of the interferograms. The extraction of fringe loci from the digitized interferograms is performed by a foating-threshold method. The fringes are numbered using a special scheme after the removal of any fringe disconnections which appeared if there was insufficient contrast in the holograms. The reconstruction of the object function from the fringe field uses least squares approximation with spline fit. Applications are given.
Document ID
19840013223
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Becker, F. (NASA Headquarters Washington, DC United States)
Date Acquired
September 4, 2013
Publication Date
September 1, 1982
Publication Information
ISSN: 0374-1257
Subject Category
Optics
Report/Patent Number
NAS 1.15:76953
REPT-74
NASA-TM-76953
Accession Number
84N21291
Funding Number(s)
CONTRACT_GRANT: NASW-3541
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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