396 RWTH Publication No: 229989        2014        IGPM396.pdf
TITLE Solving the Monge-Ampère Equations for the Inverse Reflector Problem
AUTHORS Kolja Brix, Yasemin Hafizogullari, Andreas Platen
ABSTRACT The inverse reflector problem arises in geometrical nonimaging optics: Given a light source and a target, the question is how to design a reflecting free-form surface such that a desired light density distribution is generated on the target, e.g., a projected image on a screen. This optical problem can mathematically be understood as a problem of optimal transport and equivalently be expressed by a secondary boundary value problem of the Monge-Ampère equation, which consists of a highly nonlinear partial differential equation of second order and constraints. In our approach the Monge-Ampère equation is numerically solved using a collocation method based on tensor-product B-splines, in which nested iteration techniques are applied to ensure the convergence of the nonlinear solver and to speed up the calculation. In the numerical method special care has to be taken for the constraint: It enters the discrete problem formulation via a Picard-type iteration. Numerical results are presented as well for benchmark problems for the standard Monge-Ampère equation as for the inverse reflector problem for various images. The designed reflector surfaces are validated by a forward simulation using ray tracing.
KEYWORDS inverse reflector problem, elliptic Monge-Ampère equation, B-spline collocation method, Picard-type iteration
DOI 10.1142/S0218202515500190
PUBLICATION Mathematical Models and Methods in Applied Sciences
Volume 25, Issue 5, pp. 803-837, 2015