Stress-optic modulator: A novel device for high sensitivity linear birefringence measurements

Year: 2001

Authors: Brandi F., Polacco E., Ruoso G.

Autors Affiliation: INFN, Sezione di Pisa, via Livornese 582/a, 56010 S Piero a Grado (PI), Italy; Dipartimento di Fisica, Piazza Torricelli 1, 56100 Pisa, Italy; Dipartimento di Fisica \’Galileo Galilei\’, INFN, via Marzolo 8, 35131 Padova, Italy; Department of Physics and Astronomy, Laser Centre, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, Netherlands; INFN-Laboratori Nazionali di Legnaro, via Romea 4, 35020 Legnaro, Italy

Abstract: In this paper we present a device, called the stress-optic modulator (SOM), that allows us to perform high sensitivity measurements of linear birefringence with low frequency signal. The SOM can be used as a polarization modulator in a heterodyne detection scheme to measure the ellipticity induced on a linearly polarized laser beam. Its operation makes use of the strain produced on a glass window by two blocked PZTs, thus enabling a careful control of the stress and of the anisotropy induced on the isotropic glass. A sensitivity of 3 x 10(-8) Hz(-1/2) for an ellipticity signal at the frequency of 1 Hz is obtained. For long term operation of the device a drawback arises from the drift of the spurious birefringences present in the optical system. Through the use of an active feedback system this quasi-static anisotropy can be compensated, enabling much longer integration times without degradation of the sensitivity.

Journal/Review: MEASUREMENT SCIENCE & TECHNOLOGY

Volume: 12 (9)      Pages from: 1503  to: 1508

KeyWords: Birefringence; Elasto-optical effects; Eellipsometers; Stress-optic modulators (SOM)

DOI: 10.1088/0957-0233/12/9/317

Citations: 30
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