A mode of laser heat treatment of the brass surface prior to conducting of diffusion bonding is proposed. We used the frequency-pulse radiation of a nanosecond ultraviolet laser at a pulse energy density W = 0.15 - 0.52 J/cm2. The metal sample was moved relative to a stationary laser beam along a raster trajectory (“snake”) so that adjacent spots were overlapped with an overlap ratio of ⩾ 99 %. The impact of radiation on brass was carried out in a subthreshold mode excluding crater formation. The process took place while the metal remained in a condensed state. A regular rough structure with a height of individual uplifts of the order of 1 micron was formed on the surface of the brass. article is devoted to creation of aerosolized detergent compositions, needful for use during operation of high-precision metal mirrors, as a rule, in field conditions. The created detergent compositions with inhibitory properties allow, simultaneously with carrying out the process of physicochemical cleaning of optical surface from technological impurities, to ensure its protection from the influence of adverse climatic factors during storage, transportation, installation and exploitation of the element with the possibility of its alignment. The high climatic resilience of the protective films investigated in this article, which are formed during the cleaning of the optical surface, is shown. In this case, the optical characteristics of the processed elements after climatic tests do not get worse.

The laser pre-treatment of Cu-Zr alloy surface for diffusion welding, which is used in the aerospace industry for joining dissimilar materials, has been investigated. The effect of a nanosecond UV laser pulse on the surface of Cu-Zr alloy samples was studied. It was found that at a pulse energy density E ∼ 0.2-1 J/cm2 pre-ablative microscopic effects of mainly thermal nature were observed in the metal, also there were uplifts of material in the irradiated zone. The surface profile of the sample in the irradiated zone corresponds to the energy distribution of the laser beam. Significant deformations occurred in the crystal structure of the surface layer, and an irreversible configuration of the metal surface was created. At E ≥ 1 J/cm2 an optical breakdown with the formation of a plasma torch and with the appearance of a classical laser crater was observed. The arising erosion of the surface prevented registration of this effect. Microanalysis showed that the concentration of zirconium in the surface layer of the metal after exposure decreased.

The polished surface of monocrystalline silicon was exposed to radiation of nanosecond ultraviolet laser (lambda = 355 nm, pulse duration - 10 ns, pulse energy - up to 8 mJ, pulse repetition rate - up to 100 Hz). Then the samples were examined by scanning electron microscopy and multibeam optical profilometry. The optical damage threshold accompanied by the appearance of a plasma torch near the surface and crater formation was 1.2 J/cm(2). Microbreakdown centers on processing defects were observed at an energy density more than 0.2 J/cm(2). In the range 0.2 - 1.2 J/cm(2) traces of surface lifting were observed.

Abstract The effect of UV laser pulses of nanosecond duration on surface of Cu-Cr-Zr alloy samples was investigated. Noticeable changes in the morphology of the surface layer after irradiation were found at pre-threshold values of the energy density of ∼ 0.2 – 0.8 J/cm2. Changes are traces of thermoplastic deformation resulting from influence of a concentrated energy flow and appears in irregular elevation of the irradiated surface area of the sample by up to 1 μm and in some cases – more. A developed metal surface, deformation of the crystal structure of the surface layer can support the diffusion process during diffusion welding. For energy densities of the order of 1 J/cm2 or more, optical breakdown with the formation of a crater on the metal surface occurred. The mechanical impulse of a laser plasma when exposed to a metal surface prevents the thermomechanical expansion of the material, and the effect of raising the surface of the samples was not observed.

Методами оптической профилометрии и сканирующей электронной микроскопии исследовано воздействие излучения наносекундного ультрафиолетового лазера (λ - 355 нм, длительность импульса 10 нс, энергия в импульсе - до 8 мДж, частота следования импульсов до 100 Гц) на монокристалл кремния. При плотности энергии ≥ 1,2 Дж/см наблюдалось образование плазменного факела и кратера. При плотности энергии ≥ 0,2 Дж/см, возникают очаги микропробоя на дефектах обработки и зафиксированы следы неконтролируемого поднятия поверхности. Облучение сканирующим пучком лазера при плотности энергии 0, 2 Дж/см образует микрократеры на поверхности размером несколько мкм. С увеличением плотности энергии размер микропробоев увеличивался, и при плотности энергии ≥ 0,7 Дж/смвоздействие сканирующим лучом образует сплошную зону повреждений. The effect of radiation of a nanosecond ultraviolet laser (λ = 355 nm, pulse duration 10 ns, pulse energy up to 8 mJ, pulse repetition rate - up to 100 Hz) on a silicon single crystal has been investigated by methods of the optical profilometry and scanning electron microscopy. At an energy density of ≥ 1,2 J/cm, formation of the plasma torch and crater was observed. At an energy density of ≥ 0,2 J/cm, pockets of microbreakdown appeared on processing defects, and traces of uncontrolled surface uplift were recorded. Irradiation with a scanning laser beam at an energy density of 0,2 J/cm forms microcraters on a surface with a size of several microns. With an increase in the energy density, the size of the microbreakdowns increased, and at an energy density ≥ 0,7 J/cm, the impact of the scanning beam forms a continuous damage zone.