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We propose theoretical consideration and computer modeling of information pit recording and etching processes in chalcogenide vitreous semiconductors. We demonstrate how to record and develop information pits with the necessary shape and sizes in chalcogenide photoresists using gaussian laser beam and selective etching. It has been shown that phototransformed region cross-section could be almost trapezoidal or parabolic depending on the photoresist material optical absorption, recording beam power, exposure, etchant selectivity and etching time. Namely, during the laser illumination and thermal heating caused by it, photosensitive material is the quasi-equilibrium microscopic mixture of the transformed and non-transformed phases with different optical absorption coefficients: temperature dependent near the absorption edge "transformed" coefficient e α and almost independent coefficient . If after thermal heating, the photo-transformed region "bleaches" and the pit depth increases more rapidly under the following laser power increasing. If , the photo-transformed region "darkens" and the pit depth increases sub-linearly or even saturates under the following laser power increasing. Thus, almost parabolic or flattened pits appear in the case , whereas the pits with elongated tops appear in the case . After illumination, the spatial distribution of photo-transformed material fraction was calculated

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High efficient holographic diffraction gratings with spatial frequencies from 600 to 3600 mm-1 have been recorded using As 40 S 60-х Se х (х = 0, 10, 20) photoresist layers and He-Cd laser operating at the wavelength λ = 440 nm. The investigation of the grating relief made by atomic force microscopy revealed that As 40 S 60-x Se x resists allows one to record grating originals with profiles of various heights depending on the resist chemical composition, its etching and exposure times. We obtained typical spectral and angular dependences of the first order diffraction efficiency for the grating with the high modulation depth and groove profile close to the sinusoidal one. Comparing the recorded gratings with different spatial frequencies, exposure and etching times, we determined optimal recording conditions (exposure and etching times) in order to obtain gratings with the high diffraction efficiency.