While the images are narrow in the spectral direction, they suffer from a large amount of astigmatism inherent in this type of grating system. This lends itself naturally to use with linear or area detector arrays. While astigmatism is reduced, which increases throughput, the resolution of a flat-field spectrograph is never as great as for a Rowland Circle spectrograph. The advantage of flat-field spectrographs lies in achieving compact spectrometers with no moving parts. For image formation, see Fig.
Spectral resolution is optimized for a planar spectrum.
Image formation would be similar to Fig. The angle between the slits remains constant as the grating is rotated to scan wavelengths. Ruled concave gratings are usually blazed as a natural consequence of the ruling process, and some holographic gratings can be blazed by ion milling. Please contact us which grating has the best performance for your specifications. The Richardson Grating Laboratory can design a custom concave grating to best suit your specifications.