We design the optical unit for an imaging time-of-flight scanner camera based on partially steerable micro mirrors. This new class of 3D cameras enables video frame rates and-in conjunction with the accompanying user software-online real-time selection of regions of interest. The challenges for the optical design comprise (i) sufficient light collection from close-up objects, (ii) maximizing optical efficiency for objects at large distances, (iii) reduction of the dynamical range of signal returns and (iv) minimization of parasitic scattering. We present a solution based on coaxial beam guidance, where the emitted beam first passes a beam splitter, is then deflected by a dedicated emission mirror in the center of a point-symmetrical, synchronized arrangement of five micro mirrors and final ly passes a protective spherical glass cover. The mirror assembly is slightly displaced from the center of the dome in order to establish a secondary focus for parasitic reflections at the inside of the cover. The light scattered at the target surface which reaches the mirror array is directed towards an assembly of rhomboid prisms. These prisms reshape the distributed mirror array aperture such that a small lens with high numerical aperture suffices to focus the light onto a fast, small-area avalanche photo diode, thus maximizing the acceptance angle of the detector and permissible misalignments of the element mirrors

We report on the design and fabrication of a novel all-glass four-channel beam splitter based on a Kösters prism for use in space. The Kösters prism, which consists of three pairs of individual prisms, is used to separate an incoming telescope beam into four spectral channels (λ = 800–1700 nm) with the goal to obtain a multi-band photometry of cosmic sources in the optical/near-infrared bands. We performed optical design studies to evaluate the influence of geometrical tolerances of the six individual prisms on the image quality. A stray light analysis revealed the impact of the composition on the overall optical performance. Mechanical design studies benchmarked possible mounting strategies. We considered optical adhesives, soldering and clamping. The influence of the mechanical loads during a rocket launch as well as thermal loads at 140 K (the operation temperature of the optical element) were studied. We optimized the coating properties of the prisms by considering the results from the optical design study as well as the technological requirements for the direct bonding of the prisms. Bonding strategies to realize the prism pairs were developed and successfully tested. A demonstrator Kösters prism was manufactured and is ready to validate its optical performance.

As the scientific field of the freeform optics is newly developing, there is only a small number of approved starting systems for the imaging lens design. We investigate the possibility to generate starting configurations of freeform lenses with the Simultaneous Multiple Surface (SMS) method. Surface fit and transfer to the ray tracing program are discussed in detail. Based on specific examples without rotational symmetry, we analyze the potential of such starting systems. The tested systems evolve from Scheimpflug configurations or have arbitrarily tilted image planes. The optimization behavior of the starting systems retrieved from the 3D- SMS is compared to classical starting configurations, like an aspheric lens. Therefore we evaluate the root mean square (RMS) spot radius before and after the optimization as well as the speed of convergence. In result the performance of the starting configurations is superior. The mean RMS spot diameter is reduced about up to 17.6 % in comparison to an aspheric starting configuration and about up to 28 % for a simple plane plate