Optical Heterodyne Interferometer Using the Intermode Beat of a Two-mode Stabilized He-Ne Laser

Abstract

High-resolution heterodyne Michelson interferometer has been built using the intermode beat of a two-mode stabilized He-Ne laser. To facilitate the precision phase measurement, the high-frequency beat signal of 724MHz is down-converted to the intermediate frequency by means of single sideband suppressed carrier modulation technique. The digital phasemeter based on sampling the saw-tooth wave of the intermediate frequency provides nanometer resolution. In addition, periodic nonlinearity error caused by leakage of the polarization components in the interferometer optics is evaluated.