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.

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

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