Improvement of Performance Characteristics of Optical Elements by Using Finishing Electron Beam Treatment

Abstract

The optimal parameters of the electron beam ranges are found (heat density Fn = 7∙10^6...8∙10^8 Wt/m^2 and travel speed V = 5∙10^(-3) ... 5∙10^(-2) m/s), within which there is improvement of performance characteristics of optical elements: the area occupied by negative defects reduces in 1,8…2,7 times and its purity increases, the flatness remains; residual microroughnesses decrease from 30…40 nm to 0,5…1,2 nm on it; its microhardness increases in в 1,3…1,7 times and the hardened layers 210…230 µm thick are formed; there comes the change of layers structure and their homogenization, silicon-oxygen grid becomes closer to quartz glass, the light scattering coefficient reduces by 10…30 %, and coefficient of infrared radiation transmittance increases up to 2…5 %; the resistance of the elements to the external thermal and mechanical effects is increased.