Soft diaphragms for apodization of powerful laser beams

'Soft' diaphragms have become widely used elements for beam apodization in high-power laser facilities. New types of soft diaphragms are reported. For the diaphragms of the first type a smoothed profile of the transmission coefficient T(r) is formed due to the laser beam energy dissipation on small-scale optical inhomogeneities introduced into the diaphragm aperture, 2r0. The laser shot-blasted technology for the surface and volume processing of the transparent dielectric plates in order to produce, in plates' apertures, the dissipation regions with the specified transmission profiles is discussed. Soft diaphragms with light diameters of 2r0 equals 10 divided by 100 mm are under development. The damage threshold of the proposed diaphragms is comparable to that of optical glass. Low energy absorption in diaphragms makes them applicable for the pulse-repetitive and cw lasers of different wavelengths. Apodizers of the second type present the cells with a profiled absorbing liquid layers. When using the bleachable dye solutions the diaphragm contrast K equals T(O)/T(r0) may exceed 103. Such cells combine the functions of a passive shutter and a soft diaphragm, and can be used in master oscillator and amplifiers' cascades in high power laser facilities.