Study of low-threshold mechanisms for modifying the structure of thin chromium films under the action of supershort laser pulses

This paper discusses a thermochemical method for recording information, based on local laser oxidation of thin chromium films, followed by etching of the unirradiated region. This method is an alternative to laser photolithography and direct laser removal of a chromium film. It is mainly used to fabricate diffraction optical elements. The thermochemical method of recording information lacks the thermal and hydrodynamic distortions of the pattern that characterize laser ablation, while the number of process operations is substantially less than in photolithography. Diffraction optical elements are currently used in large telescopes, microlens arrays, laser optics, etc. The main requirement on all types of diffraction optical elements is high spatial resolution. The search for methods of increasing the resolution of diffraction optical elements is the main motivation for studying the structure of irradiated chromium films. © 2011 Optical Society of America.