"3D shape measurement technique for multiple rapidly moving objects," Opt. Express, (2011)

Y. Wang*, S. Zhang, and J. H. Oliver, "3D shape measurement technique for multiple rapidly moving objects," Opt. Express,  19(9), 8539-8545, 2011; doi: 10.1364/OE.19.008539

Recently proposed binary defocusing techniques have led to ultrafast speed 3D shape measurement, but they are generally limited to measurement of a single object at a time. Introducing additional gray coded patterns for point-by-point phase unwrapping could permit simultaneous multiple-object measurement. However, when the objects are moving rapidly, the displacement between the first captured pattern and the last can be significant, and pose challenges related to the precisely designed gray codes. This paper presents a new phase unwrapping strategy that combines the conventional spatial phase unwrapping with the gray code to resolve motion related phase unwrapping problems. A system with a speed of 5,000 Hz was developed to verify the performance of the proposed technique.

"Superfast phase-shifting method for 3-D shape measurement," Opt. Express, (2010)

[25] S. Zhang, D. van der Weide, and J. Oliver "Superfast phase-shifting method for 3-D shape measurement," Opt. Express18(9), 9684-9689, 2010. (Selected for July 6, 2010 issue of The Virtual Journal for Biomedical Optics); doi: 10.1364/OE.18.009684

Recently introduced DLP Discovery technology allows for tens of kHz binary image switching, which has great potential for superfast 3-D shape measurement. This paper presents a system that realizes 3-D shape measurement by using a DLP Discovery technology to switch binary structured patterns at very high frame rates. The sinusoidal fringe patterns are generated by properly defocusing the projector. Combining this approach with a phase-shifting method, we achieve an unprecedented rate for 3-D shape measurement: 667 Hz. This technology can be applied to numerous applications including medical science, biometrics, and entertainment.