WINERED: optical design of warm infrared echelle spectrograph ver.0.7

摘要

We are developing a near-infrared (λ = 0.9 - 1.35μm) high-resolution (Rmax=100,000) spectrograph "WINERED" with several unique approaches. We employed the classical cross-dispersed configuration because it provides the best balance between system throughput, alignment tolerances, and image quality (thus, high spectral resolution). Our design has three characteristics: 1) a ZnSe immersion Echelle grating is used to realize a compact optical system even with R=100,000, 2) a VPH (Volume Phase Holographic) grating is used as a cross-disperser, which makes the camera optics smaller and brings higher throughput than the classical reflective grating, 3) as an additional mode, a reflective Echelle grating can be substituted to the immersion grating to cover a wider wavelength range with R=30,000. We found a good compact design solution with good performance: spots are all well within 2 x 2 pixels on the entire detector array for all three modes.