Measurement of partially specular objects by controlling imaging range - art. no. 671808

When specular surface is imaged on a group of CCD cells, the image usually suffers from saturation and blooming problem. This problem is a serious obstacle to applying optical profiling methods based on structured light to specular objects. In this paper, a phase-based profiling system combined with a spatial light modulator in the imaging part is proposed to measure three dimensional shape of partially specular Surfaces. The spatial light modulator prevents the image sensor from being saturated. In this way, projected fringes are well imaged and their phase information is correctly extracted. The system configuration and transmittance control scheme are explained in sequence. This idea is verified by experimental results, in which phase information is successfully extracted from the areas which are not normally measurable due to saturation.