A new scanning heterodyne interferometer scheme for simultaneous mapping of topography and effective local reflection coefficient of a surface

摘要

Among many optical diagnostic techniques, scanning two-beam interferometer (STBI) scheme is very important because it can provide an image of the 3-dimensional structure of a surface under test (SUT) with extremely good depth resolution. In a STBI, one of the two beams is used for probing the surface, a probe beam (PB), and the other beam is used as the reference beam (RB). In general, scanning of PB over a surface results in both phase and amplitude modulation caused by variations of the height and the effective local reflection coefficient (ELRC) of the SUT. In a conventional STBI scheme, however, cannot distinguish the phase change and amplitude change if they vary at the same time. Therefore, a conventional STBI has limited applications in surface diagnostic especially for a surface with materially inhomogeneous.