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Proceedings Paper

Source modulation for phase shifting in static and dynamic speckle shearing interferometry
Author(s): J.-R. Huang; Helen D. Ford; Ralph P. Tatam
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Paper Abstract

Direct injection-current modulation of a diode laser source is demonstrated for phase-stepping, heterodyning and stroboscopic illumination in a shearing interferometer. The techniques are proposed as an alternative to the use of mechanical phase-shifters such as piezoelectric transducers, offering the advantages of ease of implementation, extended measurement bandwidth and elimination of active elements from the measurement head. The phase-stepping and heterodyning techniques require the interferometer to be unbalanced, which introduces an unwanted magnification mismatch into the shearing interferometer. A compensation technique using a block of high refractive-index material is described, and experimental demonstrations of each of the three techniques are presented.

Paper Details

Date Published: 17 July 1996
PDF: 12 pages
Proc. SPIE 2860, Laser Interferometry VIII: Techniques and Analysis, (17 July 1996); doi: 10.1117/12.276315
Show Author Affiliations
J.-R. Huang, Cranfield Univ. (United Kingdom)
Helen D. Ford, Cranfield Univ. (United Kingdom)
Ralph P. Tatam, Cranfield Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 2860:
Laser Interferometry VIII: Techniques and Analysis
Malgorzata Kujawinska; Ryszard J. Pryputniewicz; Mitsuo Takeda, Editor(s)

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