Abstract
Although the high-speed polishing technology has been widely applied to obtain an ultra-smooth surface in the field of spherical optical manufacture, it is still mainly used in small-size or easily polished lenses. In the infrared optical system, large-size silicon lenses are often used to increase the luminous flux. As is known, the material is hard-polished, it is time-consuming to reduce the surface roughness by iterative polishing and it is difficult to avoid the form accuracy getting worse. To produce an ultra-smooth surface efficiently without destroying the figure, a scientific understanding of material removal in the high-speed polishing process is necessary, which would lead to the process being more deterministic. In this paper, a mathematical model of material removal is developed based on the classic Preston equation. The predicted results of the proposed model show good agreement with the experimental data. Further, a method to achieve uniform polishing can be addressed with a systematic analysis of the key factors affecting material removal and their contribution to spatial non-uniform removal. Finally, the experimental results indicate that the surface roughness of hard-polished spherical optics can be improved efficiently using the uniform polishing method without the surface figure being destroyed.
Highlights
It is universally recognized that the accuracy of a spherical optical lens is easy to measure and spherical polishing machines are inexpensive compared with aspherical polishing machines
It is meaningful to develop a scientific understanding of the relationship between processing parameters and the distribution of material removal through an effective mathematical model
This paper presents a mathematical model of material removal characteristics in high-speed polishing for spherical optical manufacture
Summary
It is universally recognized that the accuracy of a spherical optical lens is easy to measure and spherical polishing machines are inexpensive compared with aspherical polishing machines. The molecular-level effects are described macroscopically by the Preston coefficient k0 which is often regarded as an invariant constant in a process [5] We show that the key issue of the calculation of the material removal rate is establishing an effective mathematical model of pressure and relative velocity distribution on the workpiece surface. Different from the sub-aperture type, the polishing tool is larger than the workpiece (see Figure 1b,c) and material removal distribution is obtained by controlling a series of processing parameters (rotation speed, load pressure and so on). A mathematical model of material removal is developed for the high-speed polishing of spherical optical elements based on the classic Preston equation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have