With the advancements of ultra-high-precision micro-optics fabrication technologies, it is now possible to fabricate integral field units (IFUs) with slicer mirror width of 30 m or less. This paper describes a 36-um machined image slicer IFU (MISI-36) for the Diffraction-Limited near-IR Spectropolarimeter (DL-NIRSP) of the Daniel K. Inouye Solar Telescope (DKIST). MISI-36 has a unique 2-section image slicer design, and is consists of a monolithic image slicer block with 112 micro slicer mirrors, a parabolic collimator, a monolithic flat mirror array consists of 112 fold mirrors, and a monolithic spherical mirror array consists of 112 spherical mirrors. We have successfully fabricated a prototype device using Canon Inc.’s diamond-cutting CNC, and conducted a preliminary performance evaluation using an experimental bench-top spectrograph similar to the spectrograph of DL-NIRSP. We will present the optical design and optical performances of the MISI-36 prototype.
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