This article reports design and measurement results of a novel 3D laser measurement system delivered to SBST, Singapore, in February 2003. According to our knowledge, it is the first fast laser scanning system worldwide using optical fibers to separate the laser scanner from the temperature sensitive measurement electronics. Together with an angle encoder triggered measurement electronics the result is a simple and robust scan hardware, because no temperature control is needed since all sensitive parts can be mounted inside of the vehicle. The second feature of the system is an automatic alignment of the 3D laser scanner data with the rails. Therefore no additional information about the position of the vehicle towards the rails or about the track is necessary. The rail detection algorithm is executed in real time on a dual Pentium computer. The overall measurement accuracy under normal environment conditions is 3 to 10 mm standard deviation for distances up to 10 m

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

This paper presents a large aperture micro scanning mirror (MSM) array especially developed for the novel 3D-laser camera Fovea3D. This 3D-camera uses a pulsed ToF technique with 1MVoxel distance measuring rate and targets for a large measurement range of 30 ... 100m and FOV of 120 degrees x60 degrees at video like frame rates. To guarantee a large reception aperture of >= 20mm, large FOV and 3200 Hz bi-directional scanning frequency at the same time, a hybrid assembled MSM array was developed consisting of 22 reception mirrors and a separate sending mirror. A hybrid assembly of frequency selected scanner elements and a driving in parametric resonance were chosen to enable a fully synchronized operation of all scanner elements. For position feedback piezo-resistive position sensors are integrated on each MEMS chip. The paper discusses details of the MEMS system integration including the synchronized operation of multiple scanning elements

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