The image slicer for the Subaru Telescope High Dispersion Spectrograph

We report on the design, manufacturing, and performance of the image slicer for the High Dispersion Spectrograph (HDS) on the Subaru Telescope. This instrument is a Bowen-Walraven type image slicer providing five 0.3 arcsec x 1.5 arcsec images with a resolving power of R= 110,000. The resulting resolving power and line profiles are investigated in detail, including estimates of the defocusing effect on the resolving power. The throughput in the wavelength range from 400 to 700 nm is higher than 80%, thereby improving the efficiency of the spectrograph by a factor of 1.8 for 0.7 arcsec seeing.