Simple visual focusing and alignment technology for digital lithography

A simple visual focusing and alignment technology for digital lithography, which requires only one imaging system to capture both focusing and alignment information, is proposed. Firstly, the Brenner function and the global search method were chosen among the various sharpness evaluation functions, achieving visual precision focusing. Then, the mutual mapping relationship between DMD plane and CCD plane was established by image alignment technique, realizing the visualized precision alignment. Finally, a digital lithography system based on the proposed method was built and experimentally verified, by which the preparation of a grating with a line width of 1.35 μm was achieved, reaching the limit of the system resolution, and the alignment accuracy of the method reached 0.2 μm. Moreover, the mapping exposure experiments showed that the pre-exposure patterns could be converted between DMD and CCD planes, and the visualization of microstructure preparation was truly realized. This method improves the convenience of microstructure preparation and can greatly meet the needs of material scientists regarding microstructure preparation.