A DISPLACEMENT MEASUREMENT SYSTEM, UTILIZING A WOLLASTON INTERFEROMETER

A dual interferometric displacement measurement system is presented wh ere a Wollaston prism interferometer is employed in conjunction with a normal Michelson interferometer. The system operates without the use of external polarizers, apart from those associated with the Wollaston prism interferometer itself It is shown that an optical path differen ce induced in the Michelson interferometer can be detected using the W ollaston prism in a normal interferometer arrangement. Further, the in terference pattern produced by the Wollaston prism interferometer chan ges in a measurable, linear fashion as the optical path difference fro m the Michelson interferometer alters. A simple theoretical analysis o f the system is presented and used to derive a computer model of the o ptical arrangement. Results from an experimental implementation of the system, using a Wollaston prism with a beam separation of 0.5 degrees and a superluminescent diode, of wavelength 825 nm, as a light source , are included and compared to the results from the computer model. (C ) 1998 Elsevier Science Ltd. All rights reserved.