Real-time measurement of optical thickness by three-channel homodyne interferometry

Vincenzo Greco; C. Iemmi; S. Ledesma; Giuseppe Molesini; Franco Quercioli

doi:10.1117/12.194329

15 November 1994 Real-time measurement of optical thickness by three-channel homodyne interferometry

Vincenzo Greco, C. Iemmi, S. Ledesma, Giuseppe Molesini, Franco Quercioli

Proceedings Volume 2248, Optical Measurements and Sensors for the Process Industries; (1994) https://doi.org/10.1117/12.194329
Event: Optics for Productivity in Manufacturing, 1994, Frankfurt, Germany

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.

Citation Download Citation

Vincenzo Greco, C. Iemmi, S. Ledesma, Giuseppe Molesini, and Franco Quercioli "Real-time measurement of optical thickness by three-channel homodyne interferometry", Proc. SPIE 2248, Optical Measurements and Sensors for the Process Industries, (15 November 1994); https://doi.org/10.1117/12.194329

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