Synthesis and Investigation of Diamond Diffractive Optical Elements

摘要

The fabrication of diamond-based optical elements for high-power CO_2 lasers is of particular interest because of the low optical absorption coefficient of this material in combination with it's very high thermal conductivity and the weak temperature dependence of refractive index. Recent advances in gas-phase synthesis have made it possible to fabricate polycrystalline CVD diamond films (DF) whose optical and thermal properties are close to those of single crystal diamond material, whereas they are far cheaper. As a result, these sophisticated materials are applied more and more to tasks dominated till now by other materials. Such examples for this are windows for high-power CO_2 lasers in the 5-20 kW domain and beam-splitters. Recently new techniques have been proposed for antireflective structuring of DF surface as well as for generation of phase microrelief to manufacture diamond diffractive optical elements (DOEs) for the far IR range. The realisation of DOE by UV-laser ablation has been considered. Using of ion-chemical etching and plasma etching is considered later. The present paper is devoted to further development of considered approaches. The realization of diamond diffractive optical elements (DOEs) is considered, able to focus an incoming CO_2 laser beam into certain pregiven focal domains. Results of experimental investigation of designed DOEs are presented and discussed.