Fabrication of high quality grisms for infrared observation

本研究的目的是设计和制造用于红外光谱观测的高质量光栅。提出的想法是在格栅表面机械地产生光栅图案，并利用硅的各向异性蚀刻化学形成三角形光栅槽。本文通过实验研究了(1)利用刻划机在光刻胶薄膜上机械刻蚀光栅掩模图案的过程，(2)制备用于刻蚀的SiO_2光栅掩模的过程，以及(3)利用晶体取向对单晶硅进行各向异性刻蚀形成预先确定的锯齿槽轮廓的过程，并构建了红外光栅的标准制作工艺。采用该标准工艺，设计并制作了覆盖6ma左右红外区域的硅格栅。实验结果表明，在光栅表面形成的光栅在沟槽形状的图形精度和各面光洁度、平整度等方面均优于传统的机械直纹光栅，证明了所提出的红外光栅加工工艺的有效性。

The purpose of this research is to design and fabricate high quality grisms for infrared spectroscpopic observations. The proposed idea is to generate grating patterns mechanically onto the surface of a grism and form triangularly shaped grating grooves chemically utilizing anisotropic etching of silicon.Here, (1) the process of shaping grating mask patterns mechanically onto the photoresist thin film which is coated onto the grism surface by using a ruling engine, (2) the process of forming SiO_2 grating mask for etching, and (3) the anisotropic etching process of single crystal silicon to form pre-determined saw-tooth groove profile utilizing crystal orientation, are examined experimentally, and standard process of fabricating infra-red grisms is constructed.By adopting this standard process, a silicon grism which covers around 6mum infrared region is designed and fabricated. The grating formed on the grism surface is found to be superior to the conventional mechanically ruled gratings in the figure accuracy of the goove shape and the smoothness and flatness of each facet, and the effectiveness of the proposed process of fabricating infrared grisms is proved.