Abstract

The methods currently used for evaluating the resolving power of a plane diffraction grating are: recording the shape and halfwidth of a spectral image by the 546.1-nm mercury line or 632.8-nm He–Ne laser, and measuring the flatness of the diffracted wavefront interferometrically. The method discussed in this paper is that the plane grating under test is measured using a real-time digital wavefront interferometer, the relative intensity distribution of the spectral image is calculated, and the resolution is obtained. The main advantages of this method are: (1) the resolution is free of the errors introduced by the instrument in the conventional resolving power test; (2) the relationship between the resolution and the shape of the diffracted wavefront is made clear.

© 1986 Optical Society of America