Sub-nanometer precision optical components are widely used in optical systems. As the key equipment of sub-nanometer precision calculation, the dynamic performance of ion beam figuring equipment is very important. However, most studies have focused on optimizing ion beam figuring processes; However, the research on the dynamic performance of machine tools with sub-nanometer precision is not sufficient and comprehensive. At present, most of the research is limited to the analysis of plane machining, that is, only the dynamic performance of the scanning axis is analyzed. As the surface shape changes from plane to surface, the accuracy requirement is from nanometer to sub-nanometer, so the influence of the scanning axis cannot be simply considered. The dynamic performance of the target distance axis of three-axis ion beam figuring equipment under different surface shape characteristics and removal function characteristics of the sub-nanometer machining process was analyzed theoretically and simulated. The results of this study can promote the application of three-axis ion beam figuring equipment in the manufacture of complex surfaces and high-precision optical components.
In order to solve the problem that the extra removal layer and the motion characteristics of the machine tool are difficult to meet the processing requirements of ion beam figuring, an ion beam figuring method based on new controllable ion source is proposed. By changing the working parameters of the ion optical system, the timing and duration of ion beam extraction are controlled in real time. The influence law of the machine tool motion acceleration in the process is analyzed theoretically, and then a new ion beam figuring method is proposed for the lack of dynamic performance. By adjusting the working parameters of the ion source developed by ourselves, the pulse duty ratio is continuously adjustable from 0 to 100% , and the pulse frequency is continuously adjustable from 1 to 1000 Hz. The sample is Φ100 mm monocrystalline silicon plane mirror. Firstly, the long-time stability of the new ion source was verified by line- scanning experiments, and then the error of 14.5 mm wavelength was etched with the axis of motion at a constant speed. The results show that the technology can make up for the lack of motion acceleration and avoid the extra removal layer, and have a wide range of potential applications in high precision quality adjustment, special surface treatment and so on. It is expected to promote the progress of ultra-precision machining technology.
Ion beam figuring has the advantages of non-contact, high certainty, and removal function’s long-term stability. It is the primary processing method of ultra-high precision optical elements such as lithography objective lens. In general, the IBF process does not require high motion precision of the moving mechanism. However, when the shape of the optical components changes from a plane to a curved surface and the RMS value of the surface accuracy is better than 0.3nm, the influence of the motion accuracy cannot be ignored. The paper focuses on the influence mechanism of IBF equipment’s motion accuracy on the shape of removal function, removal rate, and other essential parameters under the three-axis figuring mode of curved surface elements. We have discussed the sub-nanometer precision generation requirements of curved elements for removal function positioning accuracy and motion accuracy of polishing equipment. The feasibility of ion beam triaxial machining for the sub-nanometer precision generation of curved optical elements is demonstrated by analysis and calculation. The results show that under the condition of ensuring the micron motion accuracy, the three-axis ion beam figuring equipment can also process the curved surface’s surface to the ultra-high precision that the RMS value is better than 0.3nm. Still, it is difficult to achieve the machining goal only by improving the motion precision of the machine tool’s motion axis, so it is necessary to control the components’ initial profile error.
In aerospace and high power laser devices, fused quartz material is in large demand because of its strong adaptability.The fused quartz optical mirror blank was processed by ultra-precision grinding, magnetorheological machining (MRF) and small smooth polishing (SP).Ultra-precision grinding machine was used for rough pre-polishing to obtain high precision surface shape, and then MRF was used for ultra-precision polishing to further improve the surface shape.The medium and high frequency errors generated by MRF processing were controlled by using smooth polishing.The experiments of ultra-precision machining of fused quartz mirror were carried out by using the combined process, and the rapid convergence of deterministic machining and full frequency error was realized.The combined process can not only improve the processing efficiency of optical mirror, but also reduce the processing cost and realize short process processing.
Jet polishing plays an important role in ultra-precision machining. In this paper, the effects of slotted and slotless nozzles on micro jet machining are investigated. The pressure distribution and magnitude of the two nozzles on the workpiece were first calculated by finite element simulation software. Then a set of comparative tests were conducted on two single crystals of silicon. The results showed that the pressure distribution of the slotless nozzle was more uniform compared to the slotted nozzle, and the pressure value of the slotless nozzle on the surface of the workpiece was greater. In addition, the slotless nozzle is more capable of improving the surface roughness of the workpiece in the same time.
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