# Fabrication of Smart Materials Using Laser Processing: Analysis and Prospects
## 7 Computer-Generated Diffractive Optical Elements for Laser-Processed Smart Materials  
Computer-generated DOEs hold significant promise for the manufacturing and modification of laser-processed materials [49]. They enable the precise shaping of material structures, leading to improvements in their physical and mechanical properties by laser modification [198; 199; 200]. DOEs are structures that introduce specific phase shifts into the incoming wave to create the desired phase profile of the outgoing beam [201]. They offer such advantages as high efficiency, precision, compact size, and flexibility, with two primary types: beam splitters and beam shapers. Beam splitters divide the laser beam into multiple beams, while beam shapers transform input beams into uniform spots of specific shapes. Figure 16 presents various diffractive structures demonstrating their capacity to redirect and divide incident radiation. Laser processing for smart materials often requires the accurate irradiation of specific surface areas with adjustable intensity. For example, in laser hardening of steels, it is necessary to achieve uniform martensitic transformation and avoid uneven superheating laser hardening of steels, it is necessary to achieve uniform martensitic transformation and avoid overheating non-uniformities. However, the use of laser beams with limited sizes provided by standard laser equipment typically requires the creation of multiple tracks, leading to issues with the uniformity of hardening. Various optical systems for shaping of laser beams have limited intensity adjustment capabilities, which hinder adaptation to the geometric features of processed objects and the required thermal cycles for the chosen material. The use of free-form DOEs allows for the dynamic adaptation of the laser beam, ensuring, when required, the relative uniformity of the hardened profile [202]. Such an approach  
Figure 16: Illustration of diffractive structures. The upper panel shows phase delay maps for each structure, and the lower panel outlines intensity distribution in the focal plane. Symmetrical distributions are visualized in two halves, with the left corresponding to amplitude distribution and the right to intensity distribution. Structure (**a**) functions as a shifted lens, directing radiation away from the optical axis, with increased aberrations observed in the zoomed-in focal spot as the shift from the optical axis increases. Structure (**b**) combines a binary phase grating with a converging lens, creating two spots alongside the optical axis. Structure (**c**) pairs a sinusoidal phase grating with a converging lens, while structure (**d**) is a Dammann grating, forming a 3 \(\times\) 2—point matrix joined with a converging lens [201]. includes solving the inverse heat conduction problem to achieve desired thermal effects in materials. The benefits of this approach are evident, particularly in enhancing temperature field parameters during laser heat treatment, including ensuring uniform temperature distribution. In the experimental phase of the study, chromium-nickel-molybdenum steel samples were processed using a CO\({}_{2}\) laser. The laser processing was carried out with varying the laser power between 800 and 1000 W, with a processing speed of 10-13 mm/s. The modified laser optical system was equipped with a DOE as the beam-focusing mirror. The laser beam was precisely focused to shape an approximately rectangular laser spot with a specified power density distribution. Additionally, the importance of integrating optical system components for real-time adjustments to the laser beam's shape and intensity has been emphasized. A technique for laser local annealing of sheet aluminum and titanium alloys was formulated [203], expanding the potential for shaping these materials and improving the accuracy of structural component production. Titanium alloys, critical for durability in power and aerospace industries, encounter challenges in cold shaping due to high deformation resistance, hardening, and susceptibility to cracking.