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Segmented lens mount for projection optics

: Kalkowski, G.; Damm, C.; Peschell, T.; Leitel, A.; Kunze, N.

Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
OptiFab 2003. Technical digest
Bellingham/Wash.: SPIE, 2003
ISBN: 0-8194-5104-5
OptiFab <2003, Rochester/NJ>
Conference Paper
Fraunhofer IOF ()
lens mount; projection lens; injection molding; OUTSERT technology

Since mechanical accuracy is of major importance in the field of optics, piece production is still prevailing and implementations of techniques of mass producti on are a challenge. Using injection molding of plastic elements onto sheet metal s (e.g. so-called OUTSERT-technology) provides a new approach to resolve this issue. Clearly, such a technique could save spacers and retainer rings as well as process time in assembly and allow an economical production of optics mounts at high production rates, if the required mechanical accuracy can be met. For a mob ile projection application, the lens barrel of a fix-focus projection lens has b een realized in this technology. The design is based on a segmented lens cage w ith fixed and loose plastic bearings parts for each optical element. Important f or accurate lens alignment is a 3-fold symmetry of the cage. Due to the symmetrical layout, reproducibility of the injection molding process is of greater impor tance than absolute mechanical accuracy. A careful characterization of the const ituent parts has been performed, using non-contacting 3d-shape measurements. The data obtained so far reveal satisfying results with respect to reproducibility and selected dimensions of the lens seats. Also, tilt deviations of the lens sur faces in the assembled mount were determined. Further, a preliminary measurement of the Modulation Transfer Function (MTF), to check the optical performance, ha s been obtained and shows encouraging results.