Constant Deviation Monochromator Grating
Constant deviation monochromator gratings are used in scanning monochromators where the grating is rotated and scans the signal from the entrance slit across the exit slit. The deviation angle between the incident signal and diffracted signal remains constant.
The main advantage of a constant deviation concave grating over a plane grating is that it removes the need for collimating and focusing optics, reducing the number of optical elements and increasing throughput. It also allows more compact instrument designs.