## 5 Conclusions  
The presented analysis proves the necessity of improving the processes of laser-matter interaction related to thermochemical transformations of matter in the field of powerful light wave, and optical systems for controlling the irradiance, and wavefront spatial distributions. The application of new techniques of periodical pulsed laser irradiation significantly supplements the concepts of fundamental processes occurring in matter--primarily in condensed media--under the action of intense light flows. The high spatial coherence of the laser beam makes it possible to achieve good focusing which, in turn, allows for chemical reactions, including the heterogeneous oxidation of metals, to be carried out locally, with a high spatial resolution. The absorption mechanisms of the laser beam are distinguished between metals and semiconductors, i.e., oxides formed by a thermochemical reaction. In the case of semiconductors, the light absorption process is more complex than in metals. When analysing the thermal effects of laser irradiation on semiconductors, the following mechanisms of light absorption are distinguished: intrinsic or interband absorption, intraband absorption or absorption by free carriers, impurity absorption, and lattice or residual absorption. Depending on the degree of roughness, the enhancement of laser beam absorption can be due to the various mechanisms. When the roughness is smaller than the wavelength, the light absorption can be due to the anti-reflective effect of sub-wavelength surface textures. In the cases where the roughness is larger than the wavelength, the enhancement may be due a multiple reflection at the air-metal interface. During the processes of interaction of laser radiation with metals in an oxidising environment, leading to the formation of semiconductor layers on the metal surface, there is a significant change in the absorptivity of metallic materials, depending on the thickness of the oxide film. These processes significantly change the heating dynamics, making it necessary to take into consideration the change in the absorption capacity of the surface, which introduces a significant non-linearity in the time dependence of the temperature. The enhancement of laser beam shaping systems using computer optics elements offers the possibility of efficient control of chemical processes by achieving the desired redistribution of power density. One of the main aims of computer optics is to extend the range of optical system components by means of computational tools and control systems; thus, optical elements with broader functionality can be created. The high monochromaticity and long coherence length of the laser beam make it possible to use diffractive freeform optics for beam shaping. By applying an iterative approach to solve the inverse diffraction problem under sharp focusing conditions, it is possible to obtain a complex distribution at the entrance of the focusing system, creating a desired intensity distribution in the focal region. Through the flexibility of computer design and the capabilities of modern precision technology, a unique optical tool for the necessary wavefront control and predetermined laser beam shaping is obtained. The features of laser thermochemical processes of formation of quasi- one-dimensional nanostructured metal oxides are presented. The main task of controlling such processes is to prevent thermochemical instability, i.e., the emergence of positive feedback in the system and avalanche-like acceleration of the oxidation reaction after a certain time. The absorbed energy has the meaning of the transfer coefficient or the feedback coefficient. This makes it possible to control the behaviour of the system by changing the energy or power of the laser beam as well as their density distribution.