Method for calculating a refractive optical element forming given illuminance distribution and wavefront

In the geometrical optics approximation, we consider a method for calculating a refractive optical element with two freeform surfaces, which transforms an incident beam with a plane wave-front into an output beam with a required wavefront and generating a required illuminance distribution. As examples, optical elements forming given illuminance distributions and (converging and diverging) spherical wavefronts are designed. The presented examples demonstrate the good performance of the method.