Abstract Measurement of surface roughness on mechanical components, which may incorporate also critical profiles, using diffused light techniques is a very complex problem. This paper describes a new optoelectronic device employing a diode laser and an array of discrete photodetectors placed on an arc of circle and interfaced with a data acquisition board. The device allows an extended range of roughness measurements; it is compact, easy to be used and almost insensitive to external noise and vibrations. It provides an estimation of the surface quality parameters comparing the scattered light at two different ranges of angles thereby overcoming many of the earlier limitations. The experiment has evidenced that there is a good agreement between measurement results and theoretical model usually applicable to normally distributed surfaces.