Study on evaluation of RB-SiC aspherical mirror high frequency surface quality fabricated with fixed abrasive technology

Abstract

The issue of the letter is focused on the RB-SiC aspherical mirror high frequency surface quality which is fabricated with the different type fixed abrasive pellets. The two-dimensional (2D) surface roughness of the mirror is simulated and experimented. The errors between the simulation and the experiment are 5.97%, 3.19%, 3.59%, 37.37% using W1.5, W3.5, W5, W7 pellets respectively. The error emerging reason is analyzed in detail after the comparison. Also the fractal theory is applied on the analysis of the optical mirror surface fabricated with the fixed abrasive technology. The analysis result shows that the good surface quality of the RB-SiC mirror can be obtained quickly with being polished with the fixed abrasive technology. So the fixed abrasive technology is very suitable for the fast optical surfacing, especially can obtain good surface roughness fast in the stage of grinding mirror which is not suitable for being tested with interferometer. OCIS codes: 220.0220, 220.4000, 220.4610, 220.5450. doi: 10.3788/COL201210.S22201. Generally, the surface error, the ripple and the surface roughness should be tested quantificationally when a SiC mirror is finished. The mirror surface quality is evaluated through the parameters tested. The surface error which is also called low frequency error is studied for decades [1 3] . So the surface error is not in the letter’s extension, it is focused on the high frequency error of the SiC mirror fabricated with the fixed abrasive technology, which is studied through several different methods. The existence of the high frequency error on the mirror will increase the scattering energy, decreasing the effective energy entering the camera, then the image quality will be decreased. So we should understand exactly what factor and which stage leads to the increase of the high frequency error on the mirror in the fabrication. In the most situation, the study is only focused on the method of testing the high frequency error, but the theoretical study on the high frequency error is seldom. The starting point of the letter is simulating the microcosmic formation the high frequency error in the fabrication process. And also the mirror surface fabricated with pellets is analyzed and evaluated using the fractal theory for the first time. Because of the complexity of simulating the fabrication process of SiC mirror with diamond abrasive actually, the following important assumption is made: the final mirror surface is formed by the indentation into the SiC mirror with the still diamond particles. In the fabrication of the SiC material, the size and depth of the indentation formed by the diamond particles are totally different. So we are on the assumption that the position distribution of the indentations is uniform, the size of the indentations are in Gaussian distribution, the depth is � [4]