Assessment of surface texture from analysis of the signal visibility of a laser Doppler anemometer

A prospective new optical non-contact method for the assessment of surface texture is presented. A dual-beam laser Doppler anemometer is employed and the parameter “fringe visibility” is used as an indication of surface asperity size and geometry. The method was tested on specimens resulting from three different manufacturing processes, i.e. grinding, milling and turning, which possessed a range of R_a values from 0.025 to 50 μm. Both static and dynamic measurement configurations were examined.The experimental data are complemented by a review of the theoretical considerations and a computer model which considers the quantitative effects of variation in the relative asperity size, i.e. fringe spacing, and collection optics.