Fabrication of Diffractive Optical Lens for Beam splitting Using LIGA Process

A LIGA process to fabricate the eight-level diffractive optical lens array for beam splitting is presented. The pattern of diffractive optical lens with two focal points is designed with an optimal rotation-angle method and realized through silicon etching, nickel electroplated and hot embossing process. Fabrication errors resulted from complex kinoform structure and micrometer-range feature size are taken care by tetraethoxysilane oxide etching and special designed de-mold techniques so that high quality diffractive optical lens can be fabricated. A PMMA-based diffractive optical lens is measured to confirm the optical properties. Comparing the measurement results and the simulation results, it is found that a PMMA-based diffractive optical lens with excellent optical properties are obtained. The diffraction efficiency error is only 5.19% and the uniformity error is 1.52%