A 200 Hz compact range image sensor using a multi-spot laser projector

Abstract

In this paper, a high-speed range image sensor using a multi-spot laser projector is constructed. Several high-speed range image sensors have been developed recently. Their sampling rate is around the video rate (30 Hz or so) and a faster sensor is required such as the 1 ms vision developed by Ishikawa for measurement of ordinary images. The proposed sensor has achieved 200 Hz measurement. It consists of a commercially available laser projector and a high-speed CCD camera. The distance to each projected spot is measured by triangulation. To achieve fast measurement, each spot image is searched in one line (epipolar line). The laser projector is rotated by 14 deg. and consequently, the number of pixels assigned to each spot is magnified by more than 4 times. The number of pixels of the constructed sensor is 361 and its measurement range is 800-2000 mm. Although the acquired range image is sparse, the proposed sensor is thought to be adequate for several applications such as robot vision because of its high-speed imaging and compactness. Some characteristics such as measurement errors are discussed, and the effectiveness of the proposed sensor is verified by experiments.