Continuous surface relief micro-optical elements fabricated on photographic emulsions by use of binary and halftone masks

We investigated the fabrication of continuous surface relief micro-optical elements, using binary and halftone masks, on photographic emulsions. Smoothly varying relieves were obtained recording gray-scale patterns by means of two photographic techniques. The first one involved the defocused image of a binary mask. In the second technique, a halftone mask printed at high screen frequency was used. The influence of some processing parameters on the formation of the surface relief was studied. The use of suitable values of these parameters permitted to enhance the optical performance of fabricated micro-optical elements. A description of the design, fabrication and test of microlenses, microlens arrays and sinusoidal gratings, is shown. Results are discussed.