Spatial coherence radar applied for tilted surface profilometry

Mitsuo Takeda, FELLOW SPIE The University of Electro-Communications 1-5-1 Chofugaoka, Chofu Tokyo 182-8585, Japan Abstract. A new method of spatial coherence profilometry is demonstrated. The surface profile is measured by shifting the spatial degree of coherence gradually in its own space of existence, and modulating its phase angle. In each point of the sample we analyze the change of light intensity versus the phase of a Fresnel zone pattern used as the intensity distribution of an incoherent quasimonochromatic source. The tilt of the surface is measured by gradually shifting the Fresnel zone plate on its transverse plane. This shift of the light source rotates the spatial degree of coherence around the coordinate origin until the condition of maximum interference visibility is fulfilled. The method works without any mechanical movement and a quasimonochromatic light illuminates the interferometric system. Experimental demonstration of the new method is presented. © 2003 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.1542893]