衍射光学元件灰度掩模板激光制作系统研究

Study on fabrication of grayscale mask for diffractive optical elements

根据灰度掩模的制作理论,提出了由PP8000胶片输出仪、远心成像透镜组、平行准直He-Cd激光器构成的精缩投影曝光灰度掩模制作系统.通过灰度掩模平面不同位置处提供可变的透过率,经一次光刻后得到所需的衍射光学元件.该系统不仅可采用黑白胶片制作高分辨率灰度掩模板,还可根据彩色灰度等效理论,利用彩色等效胶片实现256灰度级的扩展细分,以进一步提高灰度掩模板制作的分辨率.对于16台阶灰度掩模,其分辨率可以从0～255扩展到0～1280灰度级.利用该系统给出了二元光栅精缩后的感光图片.

The design principle of diffractive optics and three basic ways to fabricate grayscale masks are briefly introduced. By laws of grayscale fabrication, a projective-exposure system in precise-epitome way with PP8000 color film recorder is designed successfully. A variable transmittance is provided to different position on grayscale mask plane and the required diffractive optical elements can be obtained after one-time exposure. With this system, not only high-resolution grayscale mask can be fabricated with black-white film, but also subdivision with 256 grayscale level can be extended for further improving fabrication resolution of grayscale mask by a color equivalent film based on color grayscale equivalent theory. For 16-step grayscale mask, its resolution can be extended from 0~255 to 0~1280 grayscale level. The sensitive patterns minified by binary grating are also given with the system.