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The high-power laser system imposes stringent demands on the complete spatial frequency range, particularly the mid-spatial frequency errors of its optical elements. The presence of mid-spatial frequency errors significantly compromises the optical performance of the system. To mitigate the mid-spatial frequency waviness error in high-power laser elements following magnetorheological polishing, this study utilized a proprietary rotatable magnetorheological polishing apparatus. The aim was to simulate the impact magnetorheological polishing on the surface's mid-spatial frequency waviness errors in the absence of rotation, as well as to evaluate the effectiveness of random rotation angles in suppressing the surface's mid-spatial frequency waviness errors. Ultimately, the fused quartz element was simulated and modified. The simulation results demonstrate that utilizing the rotatable magnetorheological polishing equipment with a rotating magnetorheological polishing head effectively suppresses the low-spatial frequency surface accuracy, resulting in reduced mid-spatial frequency waviness on the processed element's surface. The RMS of surface errors decreases from 11.142 nm to 0.765 nm, eliminating noticeable mid-spatial frequency waviness errors and completely eradicating the characteristic peak in the Power Spectral Density (PSD) curve. Consequently, the surface accuracy of the element is significantly enhanced. Therefore, by adjusting the rotational angle of the magnetorheological polishing head, it is possible to effectively suppress mid-spatial frequency waviness errors on the element's surface and achieve deterministic shaping, thereby meeting the manufacturing requirements for high-power laser elements.
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