Laser direct writing method based on large-area multi-step binary optical element

Abstract

The invention discloses a laser direct writing method based on large-area multi-step binary optical element, which comprises the following steps: processing a 2N-order step data document into a gray BMP image with gray values starting from G0=0 to G2<N>-1=2<N>-1, decomposing the gray BMP image according to exposure metering accumulation formula P=P1+P2+....Pn, Pn=2<n-1>*P1 (n<=N), expressing the exposure metering of all the 2<N>step exposure through separately or accumulatively combination, to realize the covering of the exposure metering of all the steps by maximally overlapping N exposures (P=P1+P2+....Pn) at the position area in the Y stepping direction. The exposure metering of each step is decomposed into X and Y two-dimension unit meterings which are superposed. By adopting the mode of scanning the synchronous pulse triggering exposure, on one hand, the exposure metering is accurately controlled, on the other hand, the photoetching efficiency is improved, all the data are written only once in an entirely digital manner, alignment nesting is not required, and the error probability brought in the middle links can be reduced.

Description

technical field

[0001] The invention relates to the technical field of multi-step microstructure preparation, in particular to a laser direct writing method based on a large-area multi-step binary optical element. Background technique

[0002] Based on the diffraction theory of light waves, binary optical devices use computer-aided design to etch relief structures with two or more step depths on the substrate or the surface of traditional optical devices, forming pure phase, coaxial reproduction, and extremely high diffraction A class of diffractive optical elements with high efficiency. Generally, the two-step binary optical element has symmetrical positive and negative first-order diffracted light, and the theoretical efficiency of the first-order diffracted light is 40.5%. The theoretical diffraction efficiency of more than 4 multi-step binary optical elements is 81%. The theoretical diffraction efficiency of the meta-optical element is 96%. Binary optical elements have...

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