Regularities of Influence of Electron-beam Technology Modes on the Performance Characteristics of Optical Elements

Abstract

Experimental researches and new regularities of influence of electron-beam processing modes on quantitative indexes of quality of surface layers of optical glass and ceramics elements are carried out: purity and smoothness of surface-the surface of optical glass elements is completely free of defects, at the same time, there is an increase of purity class, the reduction of microroughness to 0.4-1.3 nm; thickness of melted layer; structural change and chemical composition; squeezing tension and thickness of strengthened layers-in the optical ceramics elements there appear compression tensions up to 30-70 MPa in strengthened surface layers of 90-210 microns thick. Optimal modes of electron-beam technology are found (thermal impact density 7•10 6-8•10 8 W/m 2 of electron beam, travel speed 5•10-3-5•10-2 m/s), which improve the performance characteristics of optical elements: increase of microhardness of the surface and increase of the strength of surface layers, as well as spectral transmission coefficient; increase of elements stability to external thermal and mechanical influences by their exploitation. Herein, there is a temperature increase of surface layers of elements and a rise in their thermal physical properties: volumetric heat capacity, thermal conductivity coefficient, thermal coefficient of linear expansion. The obtained experimental research results and developed on their basis methods of improvement of performance characteristics of optical elements found their practical use and introduction in a wide range of Ukrainian enterprises, which allowed to increase the accuracy and broaden measurement ranges of impulsive range finders for 7-15 %; to increase the probability of flawless performance of optical fairings of infrared guidance and observation devices and fiber-optic beam guides of laser medical devices while performing at 10-20 %.

Determination of Optimal Modes of Electron-Beam Micro-Treatment of Surfaces in Optic Elements

“…The equations of the mathematical model of the process of heating and rolling the considered element (in a moving coordinate system associated with the heat source) have the same representation [6,14]:…”

“…Using (10) and ( 18) and taking into account (6), finally, to solve the original problem, we obtain an expression for T(x,t), that allows to calculate the effect of the electron beam parameters on the temperature field in a thin-film optical element: Mathematical model of the process of heating a thin large-size plate. For the considered thin large-size plate, the following conditions are met (Fig.…”

“…As practice has shown [3,6,7], the most erratic, environmentally friendly, and easily controllable way of optical element treatment is the electron-beam method. The possibilities of using the moving elementary beam of the tape form were displayed for polishing elements from optical glass and obtaining high purity surfaces with minimal roughness, as well as to strengthen elements from optical ceramics and obtain surfaces with increased microhardness and thickness of reinforced layers by tens of microns.…”

Electronic Beam Technology in Optoelectronic Instrumentation: High-quality Curved Surfaces and Microprofile Creation in Different Geometric Shapes

“…To find the optimal coefficient values of the approximant polynomium (6), you need to use the standard searching method of nonlineary optimization. This is due to the fact that the calculation of the minimized functiongradient, and, moreover,Hesse matrix (the second derivatives) is quite ambiguous, and, in addition, the presence of the so-called "cavities" is not excluded in the used form of approximating function -all this requires the choice of the most effective methods of numerical optimization in the function of some considered variables.A specialized package of applications [4,5,11] was used on purpose, which contains the most effective methods of numerical optimization in various functions and which allow varying input, choose the most appropriate method of optimization in the dialog mode.…”

“…In the result of practical research, it was proved that the most convenient, environmentally friendly and manageable way of processing optical elements is the electronic beam method of processing the surfaces of elements [3,4].With the help of a moving electronic beam in a tape shape,one can get surfaces of high purity optical glass with minimal roughness (polishing of flat elements). However, the widespread use of a single electronic beam for the processing of curved surfaces of optical elements (concave, convex, cylindrical, spherical, etc.)…”