Hybrid method of free-form lens design for arbitrary illumination target.

We propose a hybrid method of free-form illumination design for an arbitrary target form, imposing no restriction on the boundary of the irradiance distribution. Smooth continuous surfaces and continuous irradiance distributions are achieved with two independent steps. Initial solutions of the illumination problem are obtained with the method of supporting paraboloids, and final solutions are acquired by numerically solving the elliptic Monge-Ampére equations. Lenses, which are able to produce complex irradiance distributions, can be achieved with this method and fabricated in practice. The feasibility of this approach is demonstrated by some examples with experimental results.