Modification of a polished surface of oxygen-free copper under the action of single pulse of focused high-power UV radiation of an Nd:YAG laser has been studied. It is established, that at a subthreshold energy density (E ∼ 0.6 J/cm²) the metal surface in the irradiated region exhibited irreversible uplift in the absence of significant traces of material ablation. With an increase in the laser energy density, the ablation process develops that leads to leveling of the surface uplift phenomenon.

Cleaning and preparation of metal surfaces is one of the main stages of technological process. These operations ensure high resource of final products for many areas of science, technology and industry. Problems due to surface contamination often arise in operation of high-power infrared gas lasers which have 100 percent resonator mirrors made of copper having higher reflectivity in the infrared range. For example, reflectivity of clean copper mirror surface at a wave length l = 10.6 μm can reach R = 0.990.002 [1]. Being operated, the copper mirror degrades under exposure and due to chemical contact with laser medium. As a consequence, the reflectivity can lower down to 0.96, which means the radiation leaks increase from 0.01 to 0.04 (4 times). No-touch surface cleaning methods enable partial recovery of reflectivity, and additional effect of laser cleaning improves mirror quality as compared with the fresh-polished mirrors (R = 0.985). This method can be applied to cleaning of comparatively expensive components made of non-ferrous metals and having polished surface or complex geometry (inner cavities), which can be damaged during cleaning or tolerate no efficient cleaning with any other methods. This work was carried out in Tver State University with the support of Ministry of Education and Science of the Russian Federation in the framework of accomplishment of Federal Targeted program “Investigation and Engineering in High-Priority Lines of Development of Science and Technology in Russia for 2014–2020” agreement 14.577.21.0004.

The effect of nanosecond UV laser pulses on copper and low-alloy copper samples has been studied. Traces of high-temperature deformation have been found at the energy density of 0.1–1 J/cm ² in the below-threshold regime without obvious traces of melting. They manifest themselves as the results of slipping and cracking along grain boundaries, as well as traces of crystallographic slip inside grains. The surface of the metal in the irradiated zone exhibits an uplift. The damage increases with the number of pulses. The height of the resulting uplift can reach 1 μm, and even more in some cases. The results obtained are similar to the electroplastic and magnetoplastic effects. By analogy, we propose to call the detected effect opticoplastic.

The optical properties of pure and doped germanium single crystals of natural isotopic composition and isotopically pure ⁷⁰Ge and ⁷⁴Ge single crystals have been investigated. The influence of dopants and the presence of residual oxygen in germanium on the position and shape of phonon absorption peaks and on the attenuation coefficients for these peaks in the spectral range of 520–1000 cm⁻¹ is experimentally revealed. The decrease in the frequency of peaks in phonon absorption bands with an increase in the mass number of germanium isotopes is analyzed.