Patent ID: 6943893

Claim:
An optical heterodyne surface plasma wave detecting method for measuring changes in dielectric coefficient or refractive index attributed to a test object on a total reflective component, the total reflective component having an interface with the test object, the detecting method comprising the steps of: a) processing a coherent light beam from a two-frequency orthogonal polarized coherent light source to form a reference light beam and a signal light beam, each of the reference light beam and the signal light beam having correlated P 1 and P 2 components, the correlated P 1 and P 2 components having two different frequencies and parallel polarization directions; b) directing the signal light beam to the total reflective component such that two surface plasma waves are generated at the interface; c) detecting the reference light beam and light which is reflected from the total reflective component so as to obtain an optical heterodyne reference signal and an optical heterodyne test signal, respectively; and d) comparing the optical heterodyne test signal with the optical heterodyne reference signal to determine changes in at least one of amplitude and phase of the optical heterodyne test signal relative to the optical heterodyne reference signal.