New class of optical apodizing diaphragms on the basis of dyed polymers

A new class of apodizing diaphragms, obtained by gradient photobleaching of initially uniform dyed polyurethaneacrylate films by the adapted penumbra technique, is proposed. Two types of intracavity soft apertures are proposed: apodizing selectors that should be used with a separate Q switch, and selectors combined with an optical switch (a single element contains a passive Q switch and an apodizing selector of transverse modes of the cavity). Soft apertures of the first type, produced on the basis of polyurethaneacrylate doped with the dithiobenzyl nickel complex, were used for transverse-mode selection in a Nd³⁺:YAG laser.