Abstract
A multiple optical paths grating projector for high-speed shape measurement is proposed in this paper. The prototype projector has three optical paths produced with half mirrors. A grating plate and an LED device are placed on the end of each optical path. The image of the grating plate is projected onto the object by a focal lens when the corresponding LED lights up. Three grating plates are placed on the respective optical path. The positions of the grating plates are adjusted in such a way that the projected grating patterns are shifted at intervals of 1/3 periods of the grating pitch. This projector can shift the phase of the projected grating patterns quickly with switching the position of lighted LED. The evaluated maximum response speed of phase shifting using this projector is 600 kHz. High-speed shape measurements are performed with a high-speed camera and this projector. As experimental results, shape measurement of a milk crown was performed in 5 kHz with phase-shifting speed of 15 kHz and shape measurement of a rotating fan was performed in 10 kHz with phase-shifting speed of 30 kHz. It was demonstrated that the proposed multiple optical paths grating projector was available for high-speed shape measurement.
