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A compact shape-measurement module based on a thin compound-eye camera with multiwavelength diffractive pattern projection for intraoral diagnosis

We have proposed a compact three-dimensional shape-measurement system for intraoral diagnosis, in which multiwavelength pattern projectors based on diffractive optical elements (DOEs) are integrated in the lens gaps of a compound-eye camera. We have built a prototype module with blue and green pattern projectors in both sides of the compound-eye camera to increase in-plane spatial resolution. With the two projectors, the stripe pitch was reduced to 0.73 mm in average from about 1.4 mm for one wavelength. Root-mean-square (rms) error of the measured depth map of a plane board was 0.27 mm at the distance of 40 mm. The rms errors for the measured results of the gums and teeth of a plaster figure and an examinee were 0.37 and 0.40 mm, respectively.