Pattern projection in the short-wave infrared (SWIR): Accurate, eye-safe 3D shape measurement

3D sensors based on pattern projection are a popular measuring instrument for the three-dimensional acquisition of people, e.g., for identification purposes or for human-machine interaction. State-of-the-art sensors typically project the pattern(s) at a wavelength of 850 or 940 nm. Although illumination at these wavelengths is barely perceptible or completely imperceptible to the human eye, almost 80 or 50% of the incident radiation reaches the retina. In order to make the 3D measurement of faces not only free of disturbance, but also to make it considerably easier to fall below the limits for retinal exposure, the short-wave infrared (SWIR) is well suited. For instance, at a wavelength of 1450 nm, only a negligible portion of the incident radiation hits the lens of the eye, let alone the retina. Since the terrestrial solar spectrum has a minimum in this wavelength range, the susceptibility to natural ambient light is also reduced. Therefore, we have developed an SWIR 3D scanner, which we present and characterize in this article.