Astigmatism Compensation in the Czerny–Turner Spectrometer

By distorting the plane grating into a concave cylinder, astigmatism found normally in the Czerny-Turner spectrometer can effectively be eliminated. The level of distortion would require metal grating blanks to avoid shearing stresses. The stigmatic principle has recently been demonstrated on a low resolution, uv illuminator patterned after the Czerny-Turner spectrograph. For the illuminator, it was desired that the image integrity of the circular entrance aperture be maintained at the focal plane. There is good reason to believe that medium resolution (approximately 1 A) instruments employing this stigmatic principle would maintain their resolution.