AN f/3.5 MEDIUM-DISPERSION GRATING SPECTROGRAPH

摘要

The Meinel spectrograph is a medium-dispersion grating instrument with an aperture of f/3.5. The average reciprocal dispersion is 20.6 A/mm and 10.3 A/mm in the first- and second-order spectra, respectively. In the first order it has a wavelength coverage from 3317 A to 8468 A and a resolution of 0.5 A. The spectrograph was built around an optical design of Dr. A. B. Meinel of the Yerkes Observatory. The collimating and camera elements utilize spherical reflecting surfaces, and the aberrations of the complete optical system are com¬pensated by a Schmidt-type correction mirror. The mechan¬ical features of the spectrograph were designed and built by the U.S. Naval Research Laboratory. Because of its excellent f/number, the spectrograph has found numerous applications where either light levels were low or exposures in the micro-second time region were required.