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Proceedings Paper

Real-time measurement of optical thickness by three-channel homodyne interferometry
Author(s): Vincenzo Greco; C. Iemmi; S. Ledesma; Giuseppe Molesini; Franco Quercioli
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Paper Abstract

A homodyne interferometer is described, using a He-Ne laser source and working in Twyman- Green configuration. By means of proper retardation plates and polarizing beam splitters, three signals at 90 degree(s) phase lag are made available. Such signals are digitized and fed into a desktop computer. Fitting procedures and computing algorithms are then implemented working out a phase angle; monitoring such a phase provides information on the optical path difference between the two arms of the interferometer. The general features of the approach are reviewed; examples of application are given, monitoring the fine displacement of mechanical parts and measuring the optical thickness variation of a soap film in air.

Paper Details

Date Published: 15 November 1994
PDF: 5 pages
Proc. SPIE 2248, Optical Measurements and Sensors for the Process Industries, (15 November 1994); doi: 10.1117/12.194329
Show Author Affiliations
Vincenzo Greco, Istituto Nazionale di Ottica (Italy)
C. Iemmi, Istituto Nazionale di Ottica (Italy)
S. Ledesma, Istituto Nazionale di Ottica (Italy)
Giuseppe Molesini, Istituto Nazionale di Ottica (Italy)
Franco Quercioli, Istituto Nazionale di Ottica (Italy)

Published in SPIE Proceedings Vol. 2248:
Optical Measurements and Sensors for the Process Industries
Christophe Gorecki; Richard W. T. Preater, Editor(s)

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