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

The article presents the results of a study of the influence of the main technical parameters of a ribbon electron flow on the microrelief of the surface of optical glass. A mathematical apparatus has been developed that allows the processing of probe characteristics obtained by sensing the energy parameters of a paraxial electron flow. The dependence of the influence of the main technical parameters (shape, size and distribution of current density) of a low-energy electronic stream of ribbon form on the microrelief of the surface of an optical glass of the crown variety has been established. This made it possible to evaluate the interaction of the electron flow with the surface of the optical glass. It was also found that the useful current of the electron flow is about 30% of the total emission current of the cathode of the electron gun. It is shown that the following factors can influence the accuracy of determining the technical parameters of a ribbon electron flow by sounding: a decrease in the diameter of the probes under the influence of the electron flow and heating of the probes during measurement. The total error of the probe method for determining the current density of the electron flow does not exceed 8%. Using atomic force microscopy, it was established that after processing the surfaces of optical glass of the crown variety with a low-energy electron-beam of a ribbon-shaped shape, provided that the rational shape, size and distribution of current density both in the working space and on the treated surface are reduced by irregularities from 40-75 nm to 3.5-5 nm. However, it was noted that the surface of the glass after electron flow treatment has a more uniform structure and is free from microdefects, in contrast to surfaces without electron flow processing

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 results of experimental studies of the geometry of gradient structures formed in optical glass by the method of electron-beam modification of its surface are presented. The expediency of using the atomic force microscopy method for determining the geometrical parameters of microlayers formed in the surfaces of optical materials by the method of their electron-beam modification is substantiated. A new method for determining the basic geometric parameters (thickness of the gradient layer, topology of the interface “gradient layer – the basis of the material”, surface microrelief, etc.) gradient structures, based on the method of atomic force microscopy is proposed. The proposed method is based on the principle of the complex application of various operating modes of an atomic-force microscope (the results of the instrument operation are considered, both in contact and in non-contact modes) in one measurement cycle. According to the proposed method, the dependencies between the change in the refractive index and the modes of electron-beam modification of the optical glass surface, as well as the dependence between the electron-beam effect modes and the geometric parameters of the gradient structure on the glass (thickness of the gradient structure, surface microrelief and interface between the layers and the base material ). The possibility of predicting the development of hidden microdefects at the interface “gradient layer – the basis of the material” is shown. Proved high reliability and adequacy of the proposed method by comparing the results obtained with the results of determining the geometric parameters obtained by other alternative methods.

The results of microprocessing by the ribbon-shaped electron beam of the elements of optical measuring instruments (the material of such elements – K8 glass) with the initial nanorelief of surfaces 15-22 nm after industrial grinding and polishing are presented. Based on the results of studies using a computerized complex control system based on an atomic force microscope, it was established that after electron-beam microprocessing, the nanorelief of optical elements of measuring instruments decreased to 1.5-2.2 nm, satisfying to the requirements put forward to their surfaces.

The results of microprocessing by the ribbon-shaped electron beam of the elements of optical measuring instruments (the material of such elements – K8 glass) with the initial nanorelief of surfaces 15-22 nm after industrial grinding and polishing are presented. Based on the results of studies using a computerized complex control system based on an atomic force microscope, it was established that after electron-beam microprocessing, the nanorelief of optical elements of measuring instruments decreased to 1.5-2.2 nm, satisfying to the requirements put forward to their surfaces.

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 to improve the properties of the surface layers of the elements of optical glass (K8, K108, 6 8 2 K208, BK10, TF110) after their processing by mobile electron beam with density of heat exposure F = 7·10 …8·10 W/m and n -3 -2 displacement speed V = 5·10 …5·10 m / s (a reduction of residual microroughness height at the surface from 4 … 6 nm (unprocessed elements) to 0.5 … 1 nm (processed elements), the occurrence of melted layers of thickness up to 250 … 300 microns with a modified structure, which is close to the quartz glass) are presented. It was found that the improvement of these properties increases the resistance of elements to external-heat: an increase in 1.3 … 1.7 times of the critical value of external heat fluxes and the time of their exposure, the excess 5 7 of which leads to the destruction of elements and damage to the test instrument turndown external pressure 10 …10 Pa; increasing the maximum permissible values of thermal stress in the elements from 20 … 40 MPa to 90…100 MPa heating temperatures 300 … 1200 K;an increase of the probability of failure-free operation in the 2 … 2.5 times by increasing the speed of the external heating from 100 K / s to 400 K / s.

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.

The results of experimental studies to improve the properties of the surface layers of the elements of optical glass (K8, K108, K208, BK10, TF110) after their processing by mobile electron beam with density of heat exposure Fn = 7·10⁶…8·10⁸ W/m² and displacement speed V = 5·10^-3…5·10^-2 m/s (a reduction of residual microroughness height at the surface from 4 … 6 nm (unprocessed elements) to 0.5 … 1 nm (processed elements), the occurrence of melted layers of thickness up to 250 … 300 microns with a modified

structure, which is close to the quartz glass) are presented. It was found that the improvement of these properties increases the resistance of elements to external-heat: an increase in 1.3 … 1.7 times of the critical value of external heat fluxes and the time of their exposure, the excess of which leads to the destruction of elements and damage to the test instrument turndown external pressure 10⁵…10⁷ Pa; increasing the maximum permissible values of thermal stress in the elements from 20 … 40 MPa to 90…100 MPa heating temperatures 300 … 1200 K; an increase of the probability of failure-free operation in the 2 … 2.5 times by increasing the speed of the external heating from 100 K / s to 400 K / s.

In the article are presented the results of researches of action of electronic ray on optical elements. The analysis of surfaces of elements before and after a beam-processing the method of atomic-force microscopy shows that in first case the height of microburries makes 50…60 nm, and in second case goes down to the level of 0,5…1 nm. Influence of parameters of electronic ray is set on the height of microburries: the increase of closeness of thermal influence of ray in 6 times results in diminishing of height of microburries in 3…4 time, diminishing of rate of movement of ray in 5 times results in diminishing of height of microburries in 5…6 times. It is shown that by optimization of the modes of beam-processing of elements it is possible substantially to improve (to 50…60%) properties of its superficial layers and basic operating descriptions of devices. Thus probability of destruction of elements and death devices in the conditions of intensive external thermal influences, devices can undergo that at their storage, portage and application, diminishes in 1,5…2 time.