COMMON-PATH OPTICAL HETERODYNE PROFILOMETER - A CONFIGURATION

A novel configuration that combines a Linearly polarized He-Ne laser a nd a birefringent lens to produce a common-path polarized optical hete rodyne profilometer with respect to the heterodyned P and S waves has been set up. In this profilometer a linear polarized frequency-stabili zed He-Ne laser was used with an acousto-optical modulator to replace the Zeeman laser as the light source that had two polarization eigenst ates in different temporal frequencies. The proposed interferometer sh ows a more symmetric and ideal common-path structure than the conventi onal optical heterodyne profilometers with the Zeeman laser. The phase error aroused by the elliptical polarization and the nonorthogonality of the two eigenpolarization modes of the Zeeman laser can be reduced . The system's resolution in the vertical direction reaches 2 Angstrom , and in a 27-mu m scanning range the repeatability of the surface pro file measurements is shown to be 5 Angstrom. (C) 1998 Optical Society of America.