ABSTRACT
Diffraction gratings for optical spectroscopy are made by ruling grooves either on a transparent surface to obtain a transmission phase grating or metal surface to obtain a reflection phase grating. Holographic and dielectric gratings are produced using photolithography. Master diffraction gratings are ruled with mechanically controlled ruling engines. H. Rowland is considered to be the father of modern ruled diffraction grating. Commonly used ruled diffraction gratings are the relatively inexpensive metalized replicas of the master diffraction gratings. Replica gratings are made by pouring a plastic solution over an original grating, evaporating the solvent, and removing the resulting film, which has the grooves of the original grating impressed upon it. A blazed holographic grating has a saw-tooth groove profile, which has higher efficiency than that of a holographic grating with sinusoidal groove profile. Multilayer dielectric gratings could be designed for any wavelength using appropriate materials.
