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Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. Single freeform surface design for prescribed input wavefront and target irradiance
 Journal of the Optical Society of America. A, Optics, image science, and vision 34 (2017), No.9, pp.14901499 ISSN: 10847529 ISSN: 07403232 ISSN: 15208532 
 Bundesministerium für Bildung und Forschung BMBF 031PT609X 

 English 
 Journal Article 
 Fraunhofer IOF () 
Abstract
In beam shaping applications, the minimization of the number of necessary optical elements for the beam shaping process can benefit the compactness of the optical system and reduce its cost. The single freeform surface design for input wavefronts, which are neither planar nor spherical, is therefore of interest. In this work, the design of single freeform surfaces for a given zeroetendue source and complex target irradiances is investigated. Hence, not only collimated input beams or point sources are assumed. Instead, a predefined input ray direction vector field and irradiance distribution on a source plane, which has to be redistributed by a single freeform surface to give the predefined target irradiance, is considered. To solve this design problem, a partial differential equation (PDE) or PDE system, respectively, for the unknown surface and its corresponding ray mapping is derived from energy conservation and the raytracing equations. In contrast to former PDE formulations of the single freeform design problem, the derived PDE of MongeAmpere type is formulated for general zeroetendue sources in Cartesian coordinates. The PDE system is discretized with finite differences, and the resulting nonlinear equation system is solved by a rootfinding algorithm. The basis of the efficient solution of the PDE system builds the introduction of an initial iterate construction approach for a given input direction vector field, which uses optimal mass transport with a quadratic cost function. After a detailed description of the numerical algorithm, the efficiency of the design method is demonstrated by applying it to several design examples. This includes the redistribution of a collimated input beam beyond the paraxial approximation, the shaping of point source radiation, and the shaping of an astigmatic input wavefront into a complex target irradiance distribution.