Efficient optimal design of smooth optical freeform surfaces using ray targeting

An optimization design method is proposed for generating smooth freeform reflective and refractive surfaces. In this method, two optimization steps are employed for ray targeting. The first step aims to ensure the shape of the target illumination, and the second step is employed to further improve the irradiance uniformity. These two steps can provide significant savings of time because the time consuming Monte Carlo raytracing is not used during the optimization process. Both smooth freeform reflective surfaces and smooth freeform refractive surfaces can be designed, and the target illumination could be achieved just by controlling the positions of several hundred predefined rays on the target plane with these two steps. The simulation results and the experimental tests show that this optimization design method is robust and efficient.