Gloss inspection of metallic products by diffractive optical element based sensor

A sensor was developed to measure the gloss of curved metal objects. The crucial pan of the sensor is a diffractive optical element (DOE). The advantages of the present sensor are non-contact measurement mode, normal incidence of the probe light, and possibility to measure gloss of curved surfaces. The sensor yields information also on the surface texture, such as finishing marks, of curved metal surfaces. The operation of the sensor was verified by measuring draw-off pipes of water cranes, which were obtained from metal industry.