HOLOGRAPHIC OPTICAL-ELEMENT FABRICATION USING CHALCOGENIDE LAYERS

Investigations in the field of diffractive optical element (DOE) fabri cation using optical methods and registering media based on chalcogeni de vitreous semiconductors are reviewed. The peculiarities of the holo graphic diffraction grating (HDG) fabrication processes using such res ists are investigated and the factors that influence the groove profil es are determined. Ways of optimizing media parameters, exposure, and treatment processes are shown. High-quality HDGs are obtained with spa tial frequencies in the range 600 to 3600 mm(-1), diffraction efficien cies of 80 to 85% in polarized light, and a stray light level of 10(-6 ). The processes of Fresnel lense formation by the holographic method with the consequent diffraction pattern transfer into the substrate ar e developed and investigated. This provides an opportunity to obtain b inary lenses with high numerical apertures and small sizes. The result s of investigations of the fabrication processes of DOEs with blazed p rofiles are discussed. Most promising is the method of direct DOE reco rding using a sharply focused laser beam, which enables one to obtain kinoform elements with micrometer-sized distant zones. Additional trea tment methods (wet or dry) enable one to obtain blazed gratings using the initial HDG with a symmetrical profile fabricated on the base of t he chalcogenide layers.