Fabrication of slicer optics of Mid Infrared Spectrometer with an Image Slicer (MIRSIS) for ground-based astronomy

Mid Infrared Spectrometer with an Image Slicer (MIRSIS) is a compact mid-infrared spectrometer with an image slicer as a testbed of techniques for efficient observations with next generation telescopes. MIRSIS is a]Omicron band spectrometer for ground-based observations. Optics of MIRSIS is mostly composed of reflective ones. A key point of the development of MIRSIS is a fabrication of slicer optics, which consists of slice mirrors, pupil mirrors and pseudo slit mirrors. It is necessary to develop fabrication technique of slicer optics, because shapes and alignment of these mirrors are special. Here it is also important to choose the design matched to the processing method. In this paper, we report our fabrication of the slicer optics elements in detail. As a result, we achieved the slice mirror with the micro-roughness of RMS 12nm and the angle accuracy of under 0.0041deg, the pupil mirror with the micro-roughness of RMS 20nm and the shape accuracy of PV 3micron, and the pseudo slit mirror with the angle accuracy of 0.02deg. All of the parts fabricated satisfy the required specification.