International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Existing experimental researches show that in order to prevent the destruction of optical elements of modern opto-electronic devices (discs as the light filter linings for IR devices, the input protective windows of laser sighting systems for observation in IR areas of the spectrum, semispherical fairings of IR devices for homing and observation of objects, lightguides for laser medical devices, etc.), electron beam method becomes promising, as it provides cleaning of surfaces, increases their microhardness, makes them more resistant to external influences. The results of experimental studies to improve the properties of the surface layers of elements from optical ceramics after their processing with a moving electron beam with a heat density Fn = 106…1.6∙107 W/m2 and moving speed V = 10-3…10-1 m/s (increase in the surface microhardness from 1.2 … 2.9 GPa (raw elements) to 5.7 … 6.4 GPa (processed elements), the occurrence of hardened layers with a thickness of 210… 230 microns). It has been established that the improvement of these properties leads to an increase in the resistance of elements to external thermal effects: an increase of 1.3…1.7 times the critical values of external heat flows and their exposure times, exceeding which leads to the destruction of elements and the failure of devices for the studied range of change of external pressure is 105…107 Pa; increasing the maximum allowable values of thermoelastic stresses in elements from 50…140 MPa to 160…370 MPa at heating temperatures of 300…1200 K.

Based on the electron-beam technology we suggest the method that increases accuracy and extends the ranges of optoelectronic device measurement, and also increases the probability of their trouble-free operation under conditions of external thermal and mechanical actions. The method is based on the developed experimentally-statistical models to determine the complex influence of parameters of the electron beam on the physical-mechanical properties and optical characteristics in the surface layers of optical elements. at At the stage of device manufacturing this method allows forming a database of the superior physical and mechanical properties and the optical characteristics in the surface layers of optical elements depending on the electron beam parameters, by choosing the optimal regimes of their electron-beam processing, that allow maximizing the metrological characteristics of the devices.

The optimum ranges of the electron beam parameters change (density of heat exposure and speed of movement), within which there is a substantial improvement (more than 2 … 3 times) of the basic properties of the surface layers of the optical elements are found. The tests of the optical windows of laser rangefinders under intensive external heating and hemispherical optical fairings of IR devices at supersonic blowing by air flow and axisymmetric rotation that simulate real operating conditions, have shown that in the case of processed by electron beam optical windows and fairings it reduces the number of their destruction and increases the reliability of the devices during the operation, taking into account the impact of external-heat.

The results of experimental studies of the influence of electron beam parameters (density of heat action, the speed of movement) on the properties of the surface layers of the elements of optical ceramics (changes in the structure of the material through the thickness of the element, the amount of surface microhardness, values of residual thermal stresses in the layers, the thickness of the hardened layers, their stability to external thermal and mechanical stresses) are. The optimum range of parameters of the beam, within which there is improvement in the properties of the surface layers of the optical elements, which leads to the increase of the basic technical-operational characteristics of devices based on (reliability, lifetime) in the conditions of use of devices with the influence of external-heat are established.

The optimal parameters of the ranges of the electron beam are found (heat density, velocity, displacement), within which there is improvement of the physical and mechanical properties of surface layers of optical elements: there is no formation of negative defects on their surfaces which become atomically smooth (residual microscopic ridges do not exceed 0.5… 1.5 nm); the microhardness of the surface increases, hardened layers are formed with compressive stresses. This leads to the reduction of the light scattering coefficient of surface layers of elements and increase of their coefficient of infrared radiation transmittance and, ultimately, to the improvement of metrological characteristics and reliability of devices under intensive external thermal action.