K9玻璃磨削亚表面损伤深度预测模型及实验研究

基于压痕实验原理,建立了K9玻璃亚表面损伤深度预测模型。为获得预测模型中的未知参量,开展了K9玻璃磨削实验。利用激光扫描共聚焦显微镜检测工件磨削后的表面粗糙度值,利用扫描电镜检测磨削后的工件表面微观形貌和亚表面损伤层形貌,分析了工艺参数对表面粗糙度值和亚表面损伤深度的影响规律。考查了工艺参数对法向磨削力的影响规律,并根据实验数据,采用多元线性回归拟合法得到法向磨削力的经验公式,进而确定了亚表面损伤深度预测模型的参数。模型预测值与实验值具有较好的一致性,表明预测模型具有一定的可靠性。

准分子激光辐照K9玻璃的热力效应分析

基于传热学理论,利用有限元法对KrF准分子激光辐照K9玻璃样品中的热力效应进行了数值分析,并比较了脉冲数目和重频对损伤效果的影响。研究表明,较低的准分子激光能量就能够使K9玻璃在表面和体内产生热应力损伤,热应力损伤在光斑区域内主要由压缩热应力控制,在光斑边缘和材料内部则主要由拉伸热应力控制。在激光脉冲结束时刻,产生的温度和热应力最大,且热应力以热冲击波的形式在材料内传播,随时间变化而来回振荡,逐渐减弱。这种热应力的反复冲击会对材料产生持续的损伤增长效应,增加了材料的损伤时间,并使材料更容易断裂。脉冲数目和重复频率对损伤效果有着较大影响,在高重复频率下,损伤累积效应明显。

Experimental Investigation on Constrained Abrasive Fluid Polishing for Optical Glass

To find a cost effective,high-precision and environmental friendly way of polishing for optical glass,a series of experiments were focused on about constrained abrasive fluid polishing. Since abrasive particles can repeatedly impact the workpiece in a multidirectional way with high energy, the constrained abrasive fluid polishing method for optical glass has been proposed based on the abrasive fluid machining theory and elastic emission machining theory. A constrained abrasive fluid polishing system was designed and developed to polish K9 glass samples. Results show that K9 glass obtains a high accuracy with less fluid. Experiments indicate that,in a more effective,high-precision and environmental friendly way,constrained abrasive fluid polishing is possible to improve the quality of workpiece surface compared with free abrasive fluid polishing. In the process of removing materials of constrained abrasive fluid polishing,it gives priority to removing the materials of high spot and the high frequency error of smooth local zone can be modified. The abrasive particles can repeatedly impact the workpiece in a multidirectional way,and there are certain relationship among surface quality,material removal rate, and parameters such as speed,clearance, angle, time and particle size. In the process of constrained abrasive fluid polishing, it shows a high material removal rate,and it needn't to clamp workpieces. As a result,it could improve the processing efficiency significantly. The research on constrained abrasive fluid polishing has a practical significance and practical value in industrial production.

Ion Beam Polishing for K9 Glass

K9 glass is a common material of optics and micro system, with cheaper price and better processing function. With the development of the optical and micro system, the technique of manufacturing micron/nanometer dimensions microstructure and micro device on K9 glass has used in photoelectron, microwave and diffraction optics device et al The coarse surface of optics and microwave device can cause the light scattering and signal losing, and the function of device reduced. So the supersmooth surface plays an important role in optic and microwave device.

Investigation of the laser ultrasound propagation in K9 glass using optical interferometry

The propagating of laser-generated ultrasonic waves in K9 glass was investigated. Many methods have been developed to detect the laser ultrasound since laser ultrasonic waves can be used to measure material parameters or characterize materials properties. In order to reduce the measuring time, a Mach–Zehnder interferometer, a full field measuring tool,was preferred in this paper. The ultrasonic wave was produced on the K9 glass surface by a Q-switched Nd:YAG laser absorbed in a liquid layer. The interferograms were then taken at various delay times by a CCD camera after single pulse induced laser ultrasonic waves. Ultrasonic waves in the K9 glass can be observed from interferogram images. The results provide an understanding of laser ultrasound propagation in K9 glass in the lifetime.