Spectroscopic Holographic Diffraction Grating

The diffraction grating is a dispersive element in the diffraction spectral devices. It is an optical surface ofa metal or a transparent material, which is one method or another deposited groove in a certain way dividing the front of the incident light wave on the coherent beams and change their amplitude and phase. The interference of these coherent beams of light determines the resulting distribution of radiation energy in space and spectroscopic characteristics of the grating. 

More recently, in the spectral devices used only ruled diffraction gratings, which grooves cut with the help of special machines with diamond cutters. These gratings are parallel grooves, spaced at equal distances; the shape of the cross section is determined by the cutting edge profile of the diamond cutter. Form of groove may be different but the grating elements – the grooves – are repeated in a strictly equal intervals called the period of the grating. 

Recently, a new manufacturing technology of diffraction gratings was developed by forming the interference pattern of laser radiation in photoresist. These are called holographic diffraction gratings. If the grating deposited on a plane surface, such ones are called plane. If grooves are shown in a concave spherical surface, such concave grating. They have a focusing effect. In the modern spectral devices are used both plane and concave diffraction gratings. 

HoloGrate, JSC at manufacturing of holographic diffraction gratings uses unique inorganic photoresist of own development. This photoresist possesses low light scattering level and high resolution. The technology based on the use of such photoresist allows to producing quasi-sinusoidal groove profile holographic diffraction gratings with the various form and curvature of a surface (one of the profiles is on the picture below). At present time HoloGrate carries out research on obtaining the holographic diffraction gratings with predetermined triangular groove profile and rectangular one using the ion etching.