Angstrom resolution optical profilometry for microscopic objects

An instrument capable of recording the amplitude and phase of reflected light with a phase resolution of better than X/3000 and the lateral resolution of a confocal scanning microscope was built. The instrument is based on a commercial microscope body and uses the regular interference contrast optics. The modifications consisted of adding a coherent (heterodyne) detector and a confocal laser scanning system. Two-dimensional surface images of amplitude, slope, and profile were taken with a step height resolution of typically 0.5-2 A. The instrument is described, and its characteristics for surface profilometry are discussed. © 1987 Optical Society of America.