Method for determining the optical axis and (n(e), n(o)) of a birefringent crystal.

Abstract

There is a phase difference between s and p polarizations when a circularly polarized heterodyne light beam is reflected from a birefringent crystal. It can be measured accurately with a common-path heterodyne interferometric technique. We have derived an equation that describes the relationship between the phase differences and n _e, n _o, and α. Two groups of solutions for (n _e, n _o) can be obtained from this equation by the phase measurements performed at three incident angles under moderate conditions. Each group consists of three pairs of solutions for (n _e, n _o). Finally, by justifying with physical conditions, we obtained the correct solution for (n _e, n _o). Azimuth angle α of the birefringent crystal optical axis can also be determined. And the feasibility of this method is demonstrated.