An Optical Ultrahigh Resolution Spectrograph with the Adaptive Optics

A prototype optical wavelength ultrahigh resolution echelle cross-dispersed spectrograph has been tested at the Starfire Optical Range (SOR) 1.5 m telescope (Woolf et al. 1995; Ge et al. 1996). To our knowledge this is the first high resolution spectrograph to take advantage of the diffraction limited images produced by an adaptive optics system. Because of the sharpened images produced by the adaptive optics at visible wavelength, about r0/D ~ 1/15 in the seeing-dominant domain, the narrow slits necessary for high resolution can be used without a large loss of light. This is a great advantage when compared with conventional high resolution spectrographs (e.g. Lambert et al. 1990; Diego et al. 1995). In addition, the smaller image widths inherent with the adaptive optics system allow the orders to be spaced closer together on the chip, allowing more orders to be observed simultaneously.