During the optical components figuring by ion beam, the temperature of the optical component will rise quickly because of the collision between the ions and the atoms of the optical component. In order to investigate the thermal effect of the ion beam figuring, the thermal deposition model is established based on the Sigmund theory of sputtering, and the thermal power density function of the surface heat source is obtained. Moreover, the thermal power density function is also modified based on the geometric relationship between surface of optical component and ion beam for establishing the incidence of the angle of ion beam to thermal power density. On this basis, the CAE (Computer Aided Engineering method was used to simulate the progress of the BK7 glass figuring by ion beam. And the modified thermal power density function is programed as heat flow load in the CAE model. The total power of thermal deposition under the different incidence angle of ion beam was obtained by Monte Carlo method. The result shows that the modified thermal power density function is close to the experimental result in other literatures. Meanwhile, the result shows the deposition energy and the maximum stress decrease with the increase of incidence angle.
The plunger hole machining using precision boring technology has the advantages of reducing cutting force, suppressing chatter and improving the surface quality of the workpiece. In this paper, a high-precision extended boring tool and indexing turntable device are designed, and the precision boring plunger hole process experiment is carried out. The influence of different process parameters on surface roughness was studied. Roughness prediction model is established by experimental data, and the accuracy of the prediction model is verified. Adopt particle swarm optimization, constraint conditions are established. The optimization model is obtained by substituting the constraint condition into the penalty function, and the optimization results of the machining parameters meet the design requirements of the surface roughness of the plunger hole.
Double-sided rapid polishing machine is a new type of polishing equipment which utilizes the principle of chemical mechanical polishing and the shape precision copying mechanism to remove materials from the upper and lower surfaces of optical elements. To analyze the principle of double-sided rapid polishing machine, a material removal model based on Preston equation was established, and the relationship between the parameters such as eccentricity, rotational speed ratio and swing stroke and the material removal uniformity was obtained, which provided a theoretical basis for the double-sided rapid polishing process. With 430mm×430mm×10mm large diameter optical element as the experimental object, the double-sided rapid polishing test was carried out, and the precision index of surface shape accuracy λ/2 was obtained, which realized the high efficiency and high precision machining of plate optical element.
It is a critical technology to improve the optical film uniformity during the film deposition process. The ion beam sputtering and polishing system was used to prepare the film on the surface of large-aperture optical elements. A calculation method for controlling the dwell time ratio I of the ion beam working at the center and edge of optical component was proposed. The dwell time ratio I was calculated by the film thickness data obtained from the center and edge, and the dwell time ratio I was revised step by step. Then it was input in the program as one of the sputtering process parameters. The experimental results show that, when I was revised to -26.6%, uniform film can be achieved on optical elements with a diameter of 300mm-600mm. Taking a Si film on the surface of fused silica as an example, the experiment was carried out for 6 hours. The film thickness is about 212 nm, and the film uniformity could reach up to 0.42%, which meets film thickness uniformity requirements by ion beam sputtering deposition method.
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