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Use of anomolous thermal imaging effects for multi-mode systems control during crystal growthReal time image processing techniques, combined with multitasking computational capabilities are used to establish thermal imaging as a multimode sensor for systems control during crystal growth. Whereas certain regions of the high temperature scene are presently unusable for quantitative determination of temperature, the anomalous information thus obtained is found to serve as a potentially low noise source of other important systems control output. Using this approach, the light emission/reflection characteristics of the crystal, meniscus and melt system are used to infer the crystal diameter and a linear regression algorithm is employed to determine the local diameter trend. This data is utilized as input for closed loop control of crystal shape. No performance penalty in thermal imaging speed is paid for this added functionality. Approach to secondary (diameter) sensor design and systems control structure is discussed. Preliminary experimental results are presented.
Document ID
19900008594
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Wargo, Michael J.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
September 6, 2013
Publication Date
June 1, 1989
Publication Information
Publication: JPL, Proceedings of the Second Noncontact Temperature Measurement Workshop
Subject Category
Solid-State Physics
Accession Number
90N17910
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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