3D imaging using a unique refractive optic design to combine moire and stereo

Phase shift measurement on a Moire image is a very effective approach for gathering a full-field 3D data. The limitations of this approach include: (1) The data is gathered over multiple images as the Moire pattern is phase shifted (one of the gratings is shifted for each of the multiple images). Thus, the data gathering can be effected by things such as motion blurring due to the requirement for multiple images. (2) The phase measurement has a two pi ambiguity which makes it difficult to analyze data with step discontinuities. To eliminate the need to take multiple images as the grating is shifted, we have developed a refractive element system that simultaneously produces multiple Moire images of the same scene. The system is adjusted so that each of the simultaneous images provide a different Moire phase. From these multiple simultaneous images, accurate subfringe information can be extracted using standard phase calculating techniques. An added advantage of this optical design is that the images have a stereo disparity which is a function of the distance from the lensing system. This stereo disparity can be used to eliminate the two pi ambiguity problem that plagues other phase calculating techniques. This presentation reviews the optical arraignment that provides the multiple simultaneous Moire images and presents a mathematical description.