Some recent advances on superfast 3D shape measurement with digital binary defocusing techniques

•Presented all the newly developed binary defocusing techniques.•Thoroughly compared all these methods.•Demonstrated great potential for high-speed, as well as high-accuracy 3D shape measurement using binary defocusing techniques.

The digital binary phase-shifting technique has been demonstrated for its merits over the conventional sinusoidal phase-shifting method in terms of measurement speed and simplicity. Yet, the measurement depth range is small when a squared binary method is used. Our recent research focuses on improving its measurement accuracy without sacrificing measurement speed, and increasing its depth range without losing measurement quality. This paper will summarize our recent work on the following three major areas: (a) realization of kHz 3D shape measurement with binary phase-shifting methods; (b) binary pattern improvement with pulse width modulation and binary dithering/halftoning techniques; and (c) applications of superfast 3D shape measurement techniques. Principle of each technique will be presented, and experimental results will be shown to verify its performance.