Integral field spectroscopy (IFS) is an observational method for obtaining spatially resolved spectra over a specific field of view (FoV) in a single exposure. In recent years, near-infrared IFS has gained importance in observing objects with strong dust attenuation or at a high redshift. One limitation of existing near-infrared IFS instruments is their relatively small FoV, less than 100 arcsec2, compared with optical instruments. Therefore, we developed a near-infrared (0.9 to 2.5 μm) image-slicer type integral field unit (IFU) with a larger FoV of 13.5×10.4 arcsec2 by matching a slice width to a typical seeing size of 0.4 arcsec. The IFU has a compact optical design utilizing off-axis ellipsoidal mirrors to reduce aberrations. Complex optical elements were fabricated using an ultra-precision cutting machine to achieve root mean square surface roughness of less than 10 nm and a P-V shape error of less than 300 nm. The ultra-precision machining can also simplify the alignment procedures. The on-sky performance evaluation confirmed that the image quality and the throughput of the IFU were as designed. In conclusion, we successfully developed a compact IFU utilizing an ultra-precision cutting technique, almost fulfilling the requirements.

中文翻译：

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超精密金刚石切割近红外宽视场整体视场单元研制

积分场光谱 (IFS) 是一种在单次曝光中获得特定视场 (FoV) 空间分辨光谱的观测方法。近年来，近红外 IFS 在观测具有强尘埃衰减或高红移的物体方面变得越来越重要。与光学仪器相比，现有近红外 IFS 仪器的局限性之一是其 FoV 相对较小，小于 100 arcsec2。因此，我们通过将切片宽度与0.4角秒的典型视宁尺寸相匹配，开发了一种近红外（0.9至2.5μm）图像切片器型积分场单元（IFU），其FoV为13.5×10.4角秒2。IFU 具有紧凑的光学设计，利用离轴椭球面镜来减少像差。使用超精密切割机制造复杂的光学元件，表面粗糙度均方根小于 10 nm，PV 形状误差小于 300 nm。超精密加工还可以简化对准程序。空中性能评估证实了 IFU 的图像质量和吞吐量符合设计。总之，我们利用超精密切割技术成功开发了紧凑型IFU，几乎满足要求。