An Optical Ultrahigh‐Resolution Cross‐dispersed Echelle Spectrographwith Adaptive Optics11Observations here were made at the Starfire Optical Range 1.5 m telescope, operated by the Directed Energy Directorate, Air Force Research Laboratory.

Abstract

ABSTRACTA prototype cross‐dispersed optical echelle spectrograph of very high resolution has been designed and built at Steward Observatory and tested at the Starfire Optical Range 1.5 m telescope. It is the first spectrograph to take advantage of diffraction‐limited images provided by adaptive optics in order to achieve a potential resolving power of R ∼ 600,000. The wavelength coverage in a single exposure is about 300 Å, which is approximately 100 times that of conventional spectrographs operating at comparable resolution. This was achieved by recording 60 cross‐dispersed orders across the 18 × 18 mm2 area of the CCD detector. The total efficiency of the system, including the sky and telescope transmission, spectrograph, and CCD detector, is measured to be 1.3% at peak, much higher than that of other ultrahigh‐resolution spectrographs. Sample stellar spectra with R ∼ 250,000 are presented.