Theory and experiment analysis of factors affecting THG efficiency for the TIL prototype laser facility

Proceedings of the Institution of Mechanical Engineers, Part J:

et al. 2017

The performance of potassium dihydrogen phosphate optics in inertial confinement fusion devices is highly affected by its surface topography. This paper theoretically investigates the relationship between the air-induced vibration of aerostatic bearing and high-frequency ripples (amplitudes of around 12 nm, spatial periods in the range of 8–30 mm) on machined surface of potassium dihydrogen phosphate optics. A simulation model, which combines transient computational fluid dynamic analysis and transient dynamic analysis, is proposed to simulate the vibration of tool tip. The three-dimensional flow status of air film is studied based on large eddy simulation method, and air vortex shedding phenomenon is observed, which results in the dynamical change of air film force. The simulated vibration amplitudes of tool tip is 8 nm, and its spatial periods are in the range of 10–24 mm, which agree well with the measured data.

Section: Introductionmentioning

confidence: 99%

Influence of air-induced vibration of aerostatic bearing on the machined surface quality in ultra-precision flycutting

Gao

Proceedings of the Institution of Mechanical Engineers, Part J:

et al. 2017

“…More and more attentions have been paid to this issue recently. 10,11 An et al 12 found some waviness errors on the machined surface of KDP along the feeding direction. The amplitude of these waviness errors is less than 0.1 mm and the wavelengths are about 100 nm.…”

Section: Introductionmentioning

confidence: 99%

The influence of oil source pressure fluctuation on the waviness error of potassium dihydrogen phosphate in ultra-precision machining

Gao

Proceedings of the Institution of Mechanical Engineers, Part B:

et al. 2017

The performance of potassium dihydrogen phosphate optical components is very sensitive to the waviness error. The time-varying oil source pressure leads to dynamic change in the eccentricity of hydrostatic slide; waviness errors can be induced on the finished surface of potassium dihydrogen phosphate consequently. The relationship between unsteady oil source pressure and the waviness errors of potassium dihydrogen phosphate is studied in this article. A mathematical model is built to calculate the displacement of hydrostatic slide induced by unsteady oil supply pressure. Moreover, a comprehensive fluid–structure interaction model is built to consider the influence of structural deformation of slide on the pressure distribution of oil film. Experiments are carried out to verify the proposed model. The calculated results agree well with the experimental results, and it is found that the calculated results show better accuracy when fluid–structure interaction is considered, which validates the reliability of this model.

“…These waviness errors cause the distortion and initiate the changes of the incident angle and refractive index of the laser, inducing the phase mismatch and ultimately reducing the frequency conversion efficiency, which attracts the attention of the researchers. [12][13][14] Figure 1(a) shows the three-dimensional (3D) morphology on the machined surface, Figure 1(b) shows the power spectral density (PSD) analysis of the morphology. It can be noted that the waviness is distributed mainly along the feeding direction and presented at regular periods.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the influence of constant pressure oil source fluctuations on ultra-precision machining

Proceedings of the Institution of Mechanical Engineers, Part B:

Liang

Sun

et al. 2014

The waviness errors on the machined surfaces have significant impact on the performance of optical components. Midspatial frequency errors (amplitude near 10 nm, wavelength about 1 mm) are found on the machined surfaces along feeding direction, and the oil pressure fluctuations of the hydrostatic slide are confirmed to be the main source which produces such waviness errors. In this article, the influence of oil pressure fluctuations on the machined surface is studied quantitatively for the first time, and the corresponding experiments are carried out. Besides, the three-dimensional surface profile simulations of workpieces considering the oil pressure fluctuations are achieved. The simulation results have been verified by the experiments on an ultra-precision flycutting machine.