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.
Monocrystalline silicon reflectors are widely used in infrared high energy laser systems. In order to ensure the system to achieve high precision and high stability of beam transmission, the reflector needs to have a good laser load capacity for high power density laser under long time irradiation. However, the evaluation of reflector laser load capacity is influenced by multiple factors, which is difficult to be decoupled one by one, and the multiple index systems are not perfect. In this paper, multi-modal characterization methods such as reflectivity, fluorescence detection and surface roughness detection are proposed to establish the influence model of multiple influencing factors on the laser load capacity of monocrystalline silicon reflector. Through quantitative analysis of these defects with specific types and different properties, the surface cleanliness and integrity of the monocrystalline silicon reflector were analyzed from different angles, and the influence trend of each influencing factor on the laser load capacity of the element was obtained. In this paper, a relatively completed characterization system of monocrystalline silicon and the influence model of the laser load capacity of the monocrystalline silicon reflector have been established effectively. The influencing factors of the laser load capacity on the surface of the monocrystalline silicon reflector are evaluated effectively, which lays a foundation for the efficient acquisition of the monocrystalline silicon reflector with high load capacity.
The rapid development of high-power optical system and free electron laser put higher request forward the reflectivity performance of monocrystalline silicon optical materials. In this paper, the surface characteristics of monocrystalline silicon elements before and after ion beam figuring are tested. Firstly, the photothermal absorption was measured at the infrared band of 1064 nm, which shows that the absorption amplitude of the processed region is higher than the other. Then, the power spectral density function(PSD) was used to compare the surface roughness in different frequency bands. And surface reflectivity of the processed infrared band is improved by 5% measured by spectrophotometer. The experimental results show that after ion beam figuring, the hydrolyzed layer of monocrystalline silicon optical element is exposed, and the absolute reflectivity and photothermal absorption performance are improved, which can improve the performance of optical element in high power laser system.
For avoiding the defect of introducing contamination for doped phosphate glass in conventional polishing technology, this paper proposes the machining method of Ion Beam Figuring(IBF). Material removal mechanism is also presented from a microscopic view. Surface roughness was analyzed by changing the incidence angle of normally and 20°. The results show that both surface roughness RMS are increased a little, and the PSD(power spectral density) of surface roughness RMS is shown, too.
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