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In the high-power laser system, the mid-spatial frequency error of the surface of the high-power laser component will affect the normal operation of the high-power laser system. In order to improve the mid-spatial frequency error of the high-power laser component after magnetorheological finishing, the causes and influencing factors of the ribbon fluctuation in magnetorheological finishing are studied, and the influence of different ribbon fluctuation on the mid-spatial frequency error of the surface is studied. Firstly, the influence of different ribbon fluctuations on the mid-spatial frequency error of the machined surface is simulated by a computer. Secondly, the magnetic field in the circumferential direction of the polishing wheel, the fluctuation amount and frequency of the magnetorheological polishing ribbon are measured, and then the causes of the fluctuation of the magnetorheological polishing ribbon are analyzed. Moreover, through the principle of a single variable, the influence of process parameters on the fluctuation of magnetorheological polishing ribbon is explored. Finally, the fused silica component is scanned uniformly under the process parameters of magnetorheological polishing ribbon fluctuation of 40 μm, 80 μm, 150 μm, and 200 μm. The experimental results show that the greater the ribbon fluctuation, the greater the surface mid-spatial frequency error of the component, and the ribbon fluctuation is approximately linear with the RMS of the PSD2 in the mid-spatial frequency band on the surface of the component. Therefore, the fluctuation of the ribbon can be controlled by controlling the magnetorheological processing parameters, and the mid-spatial frequency band error on the surface of the high-power laser component can be significantly reduced by optimizing process parameters after magnetorheological finishing. [ABSTRACT FROM AUTHOR]

The scratches on an optical surface can worsen the performance of elements. The normal process method is removing scratches entirely. However, it is a tough and high-cost requirement of removing extremely deep scratches and maintaining all the other excellent indicators at the same time. As the alternative of removing, we propose the method of scratch morphology transformation to diminish the drawbacks induced by scratches. We measure the morphology of scratches, establish the transformation models and transform them to the needed shape. In engineering applications, transformation can solve scratch drawbacks or limitations in an efficient and effective way. Then, residual scratches become acceptable. The transformation can also be amalgamated into the error figuring processes. Typical scratch transforming examples are experimented and AFM measurement is conducted. We explore the rule of scratch morphology transformation by two typical fabrication means: magnetorheological finishing (MRF) and HF etching. This morphology transforming method is an economical alternative for current defect-free fabrication. That will significantly decrease fabrication time, cost and risk, while the optical quality maintain. [ABSTRACT FROM AUTHOR]

• A PSD (Power Spectral Density) analysis method based on the contour of removal function was proposed for AMRF technique. • A new polishing path called "non-equal-interval parallel raster path" customized for AMRF technique was proposed and applied to control mid-spatial-frequency ripple error. • Simulation and actual experiment verified the effects of analysis method and polishing path. With the continuous development of high-power laser systems, laser optics gradually changed towards large-aperture, high-quality. To adapt to the fabrication of large-aperture laser optics, a new-type array magnetorheological finishing (AMRF) technique was developed and had made initial progress. However, AMRF technique would introduce more obvious ripple structures (such as 1 mm−1 of spatial frequency) compared to original MRF technique while adopting conventional raster path, and the ripple structures might affect laser beam transmission. For the further application of AMRF technique, the formation mechanism of ripple structures was studied, and a method based on the contour of removal function was proposed to analyze the changes of spatial frequency and evaluate the effect of different polishing paths. According to the analysis method, non-equal-interval parallel raster path was chosen and applied into AMRF process, along with maintaining efficiency while controlling ripple structures. In general, this work could provide a valuable support for the AMRF process of large-aperture laser optics and had a certain significance for the high-power laser system. [ABSTRACT FROM AUTHOR]

• The development of new-type arrayed MRF equipment was conducted through theoretical analysis, simulation and experiment. • High removal efficiency of 2.03 × 107 μm3/min and stability better than 5 % were achieved. • Actual experiment verified the effects of arrayed MRF equipment. Along with the continuous development of optical systems, the fabrication of optics gradually moved towards large aperture and high quality. To meet the requirements of optical systems, advanced technologies represented by magnetorheological finishing (MRF) were applied in the processing of optics. According to the background of high-efficiency processing, this work focused on the design of arrayed magnetorheological equipment, including magnetic field theoretical analysis, magnetic field simulation, equipment construction, removal function preparation and stability test. Through the study, arrayed MR (magnetorheological) equipment was preliminarily built and the removal function was prepared. The volume removal rate of arrayed removal function was 2.03 μm3/min after detection, which was 1.35 times of electromagnetic equipment under the same process parameters, and the stability of the removal function was better than 5 %. The results of two-dimensional removal experiment also verified that arrayed MR equipment could significantly improve materials removal efficiency. Based on the experimental results in this work, it is believed that arrayed MR equipment have certain advantages in the improvement of processing efficiency and surface quality, and it could meet the requirement of optical processing at the present stage. The relevant design theories and methods could provide reference to the follow-up research. [ABSTRACT FROM AUTHOR]