Design of optical elements with TIR freeform surface

A novel method for the design of total internal reflection based (TIR) optical elements generating complex two-dimensional narrow-angle light distributions is presented. The method consists of two parts: computation of a piecewise smooth solution and its subsequent approximation by a spline surface. Examples of TIR optical elements designed using the proposed approach are discussed. The simulation results demonstrate high performance of the proposed method: the luminous efficacy of the optical elements is 91.8% and the relative root-mean-square error is less than 8.6%.