Joong-Ki Jeong

Measurement of partially specular objects by controlling imaging range

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.

Profile measurement of a partially specular object using spatial light modulation

When specular objects are imaged on visual sensors, the acquired images usually suffer from saturation and blooming problem of imaging sensors. These problems are critical to apply optical profiling methods based on structured light to specular surface objects. In this paper, a structured-light-based profiling system combined with a spatial light modulator in the pattern projection side is proposed to obtain the profile of partially specular surfaces. As each pixelpsilas transmittance can be independently and selectively controlled, the spatial light modulator can project a series of coded patterns, and prevent the image sensor from being saturated by controlling the lighting intensity. In this way, a series of projected pattern is well imaged on image sensors, and the pattern correspondence is correctly extracted based on images with good quality. Finally 3-D profile is obtained from the correspondence. The system configuration and transmittance control scheme are explained. This idea is verified on experimental results, in which both the pattern correspondence and 3-D shape are successfully extracted from the partial specular areas which are not normally measurable due to saturation.