Wide-band phase-shifting fringe projector on the basis of a tailored free-form mirror

Phase-shifting fringe projection is an effective method for three-dimensional shape measurements. Conventional fringe projection systems utilize a digital projector that images fringes into the measurement plane. The performance of such systems is limited to the visible spectral range (VIS), as most projectors experience technical limitations in ultraviolet (UV) or infrared (IR) spectral ranges. However, for certain applications these spectral ranges are of special interest. A novel fringe projector was developed on the basis of a single-tailored free-form mirror. The free-form mirror generates a sinusoidal fringe pattern by redistribution of light. Phase shifting can be realized by a slight rotation of the free-form mirror. In this system, the fringe pattern is generated by illuminating the free-form surface and not by the classical imaging technique. As the system is based on a single mirror, it is wavelength-independent in a wide spectral range and therefore applicable in UV and IR spectral ranges. Additionally it does not feature any chromatic aberrations. We present the design and an experimental setup of this novel fringe projection system. Fringe projection is realized in different wavelength ranges (VIS and UV) and the advantage of fringe projection in the UV spectral range can be shown for certain materials.