Abstract
The present study theoretically demonstrates a high dynamic range optical interference measurement approach based on phase change of the amplitude modulated (AM) wave envelope obtained by on-axis heterodyne interference, which can measure thicknesses from sub-wavelength to several millimeters. First, the AM light wave generated by on-axis heterodyne interference is split into two AM light waves. The sample thickness is obtained from the position of the interference fringes, produced by interfering with the transmitted AM light wave through the sample and reference AM wave. Furthermore, the proposed measurement approach is simplified via 4-beam optical interference using circularly polarized heterodyne-modulated waves.
Funder
Japan Society for the Promotion of Science