Surface plasmon resonance heterodyne interferometry for measuring physical parameters

Abstract

A light beam is incident on the boundary surface between the thin metal film of a surface-plasmon-resonance (SPR) apparatus and the test medium. If the incident angle is equal or very near to the resonant angle, then the phase difference between p- and s- polarizations of the reflected light is related to the associated physical parameter. The phase difference can be measured accurately by the heterodyne interferometry. If the relation between the phase difference and the associated physical parameter is specified, the associated physical parameter can be estimated with the data of the phase difference. This method has the advantages of both common-path interferometry and heterodyne interferometry.