Magnetorheological Finishing (MRF) is widely regarded as an effective means of processing aspheric optical components. We developed a MRF polishing machine based on a robot arm. Compared to the traditional MRF polishing machines, our new generation machines are more flexible, cost-effective and efficient. The basic components of were introduced and the calculating angle was transformed. We processed a flat SiC mirror and the final accuracy is 0.012λ.
Ion beam figuring(IBF) is commonly used during the process of fine optical fabrication. According to sputtering theory, material removal rate varies with the ion inject angle and the surface curvature. During the process of figuring high gradient aspherical surface, the removal function of ion beam figuring should be calibrated strictly to guarantee the accuracy of the figuring results. In this paper, we describe the influence of ion density distribution and surface curvature on material removal rate. Since the removal function varies from point to point within the ion bombed region for high gradient surface, rectification matrix was proposed to fix the disparity between the practical removal function and flat removal function. Experiments were implemented with high gradient aspherical surface to prove the rectification matrix can fit the variety of the material removal rate effectively.
Ion beam figuring technology is ultra-high precision optical processing method. This paper introduces the independent FSGJ800-IBF five axis ion beam figuring equipment. According to the requirement of ion beam motion system dynamic performance of complex optical surface ion beam figuring, the design and control scheme of 3-RPS+XY mobile platform based on hybrid mechanism form five axis motion system was finished. Firstly, the radio frequency (RF) ion beam source was use in this machine. The Ion Beam Figuring System with Five-Axis Hybrid Mechanism was introduced especially the 3-RPS parallel mechanism. The process of polishing complex optical curved surface by ion beam is analyzed. The most close to the spherical surface processing strategy based on the experiments of high gradient lens was done. The aperture of the lens is 44mm and the R/# is 0.705, after a round of ion beam polishing, surface error of optical components RMS from the initial 0.019 lambda (lambda =632.8nm) converges to 0.006 lambda. The experiments verified the availability of the Five-Axis Hybrid Mechanism for high precision complex optical surface error correction.
Ion beam figuring (IBF) is an advanced and deterministic method for optical mirror surface processing. The removal function of IBF varies with the different incident angles of ion beam. Therefore, for the curved surface especially the highly steep one, the Ion Beam Source (IBS) should be equipped with 5-axis machining capability to remove the material along the normal direction of the mirror surface, so as to ensure the stability of the removal function. Based on the 3-RPS parallel mechanism and two dimensional displacement platform, a new type of 5-axis hybrid machine tool for IBF is presented. With the hybrid machine tool, the figuring process of a highly steep fused silica spherical mirror is introduced. The R/# of the mirror is 0.96 and the aperture is 104mm. The figuring result shows that, PV value of the mirror surface error is converged from 121.1nm to32.3nm, and RMS value 23.6nm to 3.4nm.