GHRS Instrument Handbook
Design and Construction of the GHRS
Table 6.1: Properties of GHRS Gratings
Note that the "CD" gratings are cross-dispersers for the echelles. CD-A has a focal length of 1460 mm and CD-B has a focal length of 1340 mm. Note also that the "M" gratings are holographic and that the blaze angle quoted formally is that which correctly predicts the center of the wavelength region the grating is optimized for. G140L is a ruled grating. "Ech-A" and "Ech-B" refer to two modes of operation that use the same echelle grating but different cross-dispersers and detectors.