Simple method for improving the sampling in profile measurements by use ofthe Ronchi test

We present a simple method for increasing the number of data points obtaine d during performance of profilometric measurements with the Ronchi test. Th e method is based on multiple ronchigram acquisitions that are superimposed after a few very simple data-processing operations. The measurement method , experimental setup, and data processing are described in detail from the ronchigram to the measured profile, and experimental results for a concave surface of an spherical ophthalmic lens are provided. The radius of curvatu re values measured for that surface are compared with the ones obtained wit h a high-precision radioscope, showing very good agreement and demonstratin g capability of the technique to measure topographic profiles of reflective samples. (C) 2000 Optical Society of America OCIS codes: 120.3930, 120.394 0, 120.4800, 120.6650, 120.4290.