Discontinuous free-form lens design for prescribed irradiance

Abstract

For the problem of point source forming prescribed irradiance, a new, to the best of our knowledge, method-variable separation mapping method is presented, which establishes separately the correspondence between variables on the light source and the target plane. The role played by the optical surfaces is then to redirect the light rays to their corresponding target points. The surface of the lens is determined by first calculating the surface points and then their normal vectors. Considering that normal deviations are produced in the surface construction process, a normal deviation control method is also presented to restrict the deviation. With this normal deviation control method, discontinuities are introduced onto the lens surface. From these mapping and normal control methods, a fast and efficient algorithm has been developed for several prescribed irradiance problems with simple nonrotational shape of the illuminated region.

Overall Illuminance Uniformity of IRED Lighting in Nighttime CCTV

“…Reflective surface efficiency is not very high, since it is impossible to cover the whole source emergence spatial angle without any occlusion. Because of this, a lens based on refraction and/or total internal reflection of the freeform surface lens has an potential advantage [5][6][7].…”

Freeform lens collimating spectrum-folded Hadamard transform near-infrared spectrometer

“…Meanwhile, the advanced manufacturing technology makes it feasible to fabricate such a freeform surface, either by injection casting, ion implantation and flying cut with high performance at present [15][16][17].…”

New approach to construct freeform surface by numerically differential formulation

“…To alleviate the discontinuous issue of freeform, Wang et al 2 introduced the variable separation mapping strategy to take into account the normal deviation of the curve below a present value. The surface curve was regenerated with tangent vectors along the curve perpendicular to the normal vector, thus eliminating the accumulated normal deviation.…”