Study On Magnetorheological High Efficiency And Low Defect Polishing Process Of Single Crystal Silicon Mirror

The single crystal silicon mirrors are mainly used in high-power laser systems,and the improvement in manufacturing level is the key to improving the overall performance of high-power laser systems.At present,the processing of single crystal silicon mirrors mainly has problems such as low de-damage efficiency,uncontrollable defect removal,and even introduction of scratches and long processing cycles.In order to achieve high-efficiency and low-defect manufacturing level of single crystal silicon components,magnetorheological polishing is applied to the processing technology of single crystal silicon,but the surface of the single crystal silicon mirror after magnetorheological polishing has a "tail" defect.In this paper,the high-efficiency and low-defect manufacturing of single crystal silicon mirrors is taken as the research goal.The process parameters experiment is conducted to find the optimal processing parameters.The influencing factors and suppression methods of magneto-rheological polishing of single-crystal silicon "tail" defects are studied.The combined process realizes high efficiency and low defect processing of single crystal silicon.This paper mainly researches from the following aspects:1.the experiment of process parameters is conducted,and the neural network optimization genetic algorithm is used to optimize the process parameters experiment.The final optimized parameters are: polishing wheel speed 280/rpm,flow rate 81.8 L/min,magnetic field strength 6A,and depth coefficient 0.2.2.Study the influencing factors and inhibition methods of MRF polishing single crystal silicon "tail" defects.Combined with the simulation analysis of the fluid flow velocity in the polishing zone,the mechanism analysis and the process experiment of the magnetorheological polishing material removal,the main factors affecting the defect of the "tail" are: process parameters,scanning speed,and single removal depth.A polishing experiment is conducted to analyze the relationship between these three factors and the defect of the "tail".Finally,the corresponding optimization parameters are obtained: the scanning speed is 1000mm/min,and the single removal depth is within 360 nm.3.Introduce immersion polishing to perform surface defect control and surface roughness recovery on the surface after magnetorheological polishing.The experimental results show that a better surface quality can be achieved after immersion polishing at 100 nm.4.Combine magnetorheological polishing with immersion polishing to form a combined process for the trimming stage of single crystal silicon mirrors.Through the processing examples of plane mirror and aspherical mirror,it is verified that the combined process can realize the high efficiency and low defect manufacturing of single crystal silicon mirror.