the characteristics of reflectance patterns generated when a laser beam strikes a machined surface contain adequate information to determine the degree of surface finish. an extensive development endeavor has established equipment and procedures required to properly extract data from reflectance patterns to obtain a repeatable correlation between the gleaned information and surface finish. two types of reflective patterns have been utilized: diffracted reflection from single-point-turned periodic surfaces, and diffuse reflection from radom-ground or honed surfaces. surface finishes ranging from 0.025 to 2 micrometers (1 to 80 microinches), aa, have been measured by using visible laser radiation on the finer surfaces and infrared lasers on rougher materials. using this method to measure a surface finish provides a noncontact procedure and does not require critical alignment, as is often the case when using a stylus instrument on curved surfaces. data have been obtained by making full-pattern scans, then integrating the area under the curves, and by measuring the intensity ratio at two predetermined points. calibration curves have been developed that produce straight lines on log-log graph paper. also, production inspection equipment has been fabricated to measure the surface finish of parts by the ratio method. (era citation 04:001282)