The work is aimed at the investigation of the influence of nonlinear active ions concentration profiles in Yb:YAG laser elements on temperature distribution and wavefront distortions during amplification using sub-kilowatt level diode pumping. A mathematical model is presented for the theoretical study of the amplification process in crystals with cubic crystal system. A detailed comparison of Yb:YAG active elements with the same thickness and absorbed pumping power, but with various concentration profiles of Yb³⁺, ions is carried out. It is shown that the use of active elements with an increasing dopant concentration in the pump beam direction allows one to optimize the temperature profile inside the active element and, thus, reduce the thermal-induced wavefront distortions of the amplified radiation. Modeling is carried out for the experimentally grown crystal with linear concentration gradient profile. It is shown that the linear doping profile with a gradient of 0.65 at.%/mm allows increasing the small-signal gain up to 10% and decreasing the thermal-induced wavefront distortions by ~15%.

The mathematical model of a speckle-suppression method based on two Barker code-type diffractive optical elements (DOEs) moving in orthogonal directions is developed. The analytic formulae for speckle suppression efficiency are obtained. The model indicates that the one pair of DOEs can be used for laser beams of different colors. The speckle contrast is not dependent on the distance from the viewer to the screen until the distance decreases below the distance where the spatial resolution of the eye on the screen is less than the length of the image of the DOE structure period on the screen. The analysis of the simulated results demonstrates that the method can decrease the speckle contrast to less than 5%, which is below human eye sensitivity, with an optical efficiency greater than 90%.

Although microprisms have become an important medical means of strabismus treatment, related research concerning the design, fabrication, and testing of microprismatic glasses for preventing eyestrain has rarely been reported. In this study, the structure of microprismatic glasses for preventing eyestrain related to using electronic monitors, including computers and mobile phones, is introduced. A designing theory of anti-fatigue glasses with microprisms is developed. The fabrication technique and the process are described, and the performances of the fabricated microprisms are characterized. Finally, a compact testing system for the measurement of prismatic diopter is designed and constructed. This measuring system can be used not only for Fresnel microprisms, but also for other types of prisms. The measured results agree with our calculations. Although this study is focused on optimizing the objective prismatic diopter for anti-fatigue microprismatic glasses, 2.0–3.0 prismatic diopters (Δ) for each eye in the anti-fatigue glasses are suggested according to our experience on strabismus treatments. The clinical research for patients using the developed anti-fatigue glasses will be fully implemented in our further research to confirm the optimal subjective prismatic value.

Analysis of the spatial distribution of the color centers formed in wide-gap LiF and MgF2crystals in a laser beam channel has shown that these centers are formed in numerous longitudinal filaments...