Process for mfg. multi-phase diffraction optic element

Abstract

A process for preparing multi-phase optical diffraction element includes sputtering Cr film on substrate, exposing the nagative photoresist on the back to form mask, determining the positions of each steps, etching ultraviolet transmitting substance (SiO2) with reactive ions, etc. Its advantages are low precision requirement of masks except the first one, and high diffraction efficiency.

Description

technical field [0001] The invention belongs to the field of information science and technology, and specifically relates to a process for manufacturing a multi-phase diffractive optical element. Background technique [0002] Binary optics, or binary diffractive optics, was first proposed abroad by Veldcamp et al. at the Massachusetts Institute of Technology (MIT) in the late 1980s. The control of the phase in the binary optical element is to approach the ideal value by generating multiple steps. For example, the phase step is 2π, you can press L=2, 4, 8,..., 2 m , (m is a positive integer) equal division method to divide, this method is geometrically equivalent to the surface of any shape can be approached by multi-step plane. In the existing manufacturing process, this binary phase step is easily completed by microelectronics technology: a simple black and white mask can be exposed and etched to produce two levels of steps, such as another mask, repeated exposure And et...

AI Technical Summary

Problems solved by technology

In the existing manufacturing process of diffractive optical elements, as the number of steps increases, the pattern structure of the reticle becomes finer and more difficult to guarantee the accuracy of overlay. Therefore, when the number of phases reaches 16, the process It is difficult to guarantee the engraving accuracy

Although the theoretical diffraction efficiency of the 16-phase optical element can reach 99%, it is difficult for the device efficiency to exceed 90%.

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