TIR RXI collimator.

A metal-less RXI collimator has been designed using the Simultaneous multiple surface method (SMS). Unlike conventional RXI collimators, whose back surface and parts of the front surface have to be metalized, this collimator is completely metal-free, made only of plastic (PMMA). The collimator’s back surface is designed as a grooved surface providing two TIR reflections for all rays impinging on it. One advantage of the design is the lower manufacturing cost, since there is no need for the expensive process of metalization. More importantly, unlike conventional RXI collimators, this design performs good colour mixing, as well as being very insensitive to the source non-uniformities. The experimental measurements of the first prototype show good agreement with the simulated design.