Influence of radiation force of a high-energy laser beam on the second harmonic generation (SHG) efficiency through stress within a mounted potassium dihydrogen phosphate (KDP) crystal is studied, as well as an active method of improving the SHG efficiency by controlling the stress is proposed. At first, the model for studying the influence of the radiation force on the SHG efficiency is established, where the radiation force is theoretically analyzed, the stress caused by the radiation force is theoretically analyzed and numerically calculated using the finite-element method, and the influence of the stress on the SHG efficiency is theoretically analyzed. Then, a method of improving the SHG efficiency by controlling the stress through adjusting the structural parameters of the mounting set of the KDP crystal is examined. It demonstrates that the radiation force causes stress within the KDP crystal and further militates against the SHG efficiency; however, the SHG efficiency could be improved by controlling the stress through adjusting the structural parameters of the mounting set of the KDP crystal.
Operating posture of complicated opto-mechanical structures critically matter gravity-induced distortion of the structure, and further affect optical performance. With the aim to solve this problem, determination of operating postures of a supporting system of a KDP crystal is studied. A concept of key stiffness component is firstly proposed in this paper, as far as the authors are concerned, taking advantage of which gravity-induced distortion of the supporting system is analyzed, as well as the rotation of the KDP crystal that is cased by the distortion of the supporting system. Furthermore, effects of operating postures of the supporting system on the distortion of the supporting system and the rotation of the KDP crystal are investigated. It is demonstrated that key stiffness component is of great insignificance to distortion of the supporting system, and it could function as a guidance in determination of operating posture of the supporting system.
With the aim to decrease the gravitational distortion and stress for the large aperture optics, a novel mounting configuration was proposed, analyzed and optimized. The effects of the design factors of external load, supporting surface topography and supporting width were studied by using the Finite Element Method (FEM), the changing trends of the distortion and stress with these varying factors were obtained, respectively. More over, orthogonal tests of the influence of these factors were carried out, consequently, the regression analysis of the test results were processed, and the mathematical models for comprehensively considering the coupling effects of these factors were received. Further more, the optimization of the mounting configuration, based on the mathematical models and additionally considered the engineering specifications, was performed, and the optimal configuration was figured out. The numerical results showed the feasibility of the mounting configuration in the aspects of decreasing the gravitational distortion and stress.
Large-aperture optical element is widely used in optical engineering and reasonable mounting results in higher
performance. In order to reduce the gravitational sag induced by its own weight, three types of mounting configurations
were proposed and simulated by finite element method, and the effects of axial loads and non-uniformity and asymmetry
were analyzed in the same time. The results showed that full periphery mounting configuration was the optimal
mounting configuration and the optimal axial load was 0.085MPa with the corresponding maximum distortion was
2.32μm, and the effects of non-uniformity and asymmetry on distortion were small.