The general conditions for the production of stigmatic images with concave or plane gratings are derived. Several practical methods of realizing these conditions have been devised using a cylindrical lens with plane mirrors, or a concave mirror alone, between the slit and the grating.
HAROLD T. SMYTH, "Some Stigmatic Grating Mountings," J. Opt. Soc. Am. 25, 312-314 (1935)