【作者】 徐荣青；

【导师】 陆建； 倪晓武；

【作者基本信息】 南京理工大学 ， 测试计量技术及仪器， 2004， 博士

【摘要】 本文主要从实验上全面研究了高功率激光与物质相互作用存在的力学效应、超声效应、空泡效应、等离子发射光谱以及等离子冲击波。 首先提出了一种由负轴棱镜和球面透镜组成的光学系统，该系统可产生光斑尺寸可变的无衍射光束，指出若用该系统作为激光加工的聚焦系统，在无衍射范围内对工件位置误差的敏感度为零，对工件表面的平整度适应性强，并可通过更换普通的球面透镜来适应不同加工要求，同时指出该系统在测量方面潜在的应用价值。 采用光学阴影同步照相法研究了激光烧蚀靶材过程中烧蚀物的空间形状及其发展过程，首次提出光场力概念，结果表明：烧蚀物离开靶材表面时的速率分布由蒸发机制决定，在作用激光作用时间内烧蚀物的传输行为由扩散机制和光场力机制共同决定，激光作用结束后，烧蚀物的传输行为由扩散机制单独决定。 研制了基于光探针技术的测量等离子体发射光谱的装置，并用该装置研究了激发态Al原子的特征谱线的飞行谱，计算了激发态Al原子的飞行速度。 研制了基于表面形变效应光偏转的激光超声测试仪，用其测量了Lamb波、表面波及纵波。 研制了基于折射率效应光偏转的等离子冲击波测试仪，首次用光偏转法测量了透明固体中的冲击波。 首次研制了基于胡克定律的光纤瞬态力学传感器，用其研究了不同激光能量下水下打靶过程中靶的力学效应，结果表明：靶依次受到三个瞬态脉冲压力；空泡射流的产生及射流冲击力的大小，由泡能和无量纲参数共同决定。实验研究了气液环境中激光打孔的效率，得到了水中激光打孔效率远高于空气中打孔效率的重要结论，并分析了原因。 根据考虑空泡能量耗散的球形空泡动力学模型，数值计算了激光泡的脉动过程，在此基础上，基于气液两相面折射率变化引起光偏转原理，设计并研制了测量激光泡一维几何线度的实验装置，用其研究了不同激光能量下靶材表面激光泡各次脉动的最大泡半径及最小径向距离，并对数值计算与实验结果进行了分析。 本文的研究结果对激光的应用及相关检测技术的发展有一定的促进作用。更多还原

【Abstract】 The mechanical effect, the ultrasonic effect, laser-generated bubble dynamics, the plasma emission spectrum and the laser-induced plasma shock wave during the high-power laser and matter interaction are systemically investigated by experiments.A novel optical system including a negative axial prism and a lens system is first designed to generate a non-diffraction beam with changeable spot size. The system acts as the focusing system to laser processing. It is proposed that the system has naught sensitivity to the position error of work in the range of non-diffraction, high adaptability to the smoothness of work and can satisfy various processing requirements by replacing the general spherical lens. The potential applications of the system are also proposed.The spatial shape and the transportation of ablated material during the process of laser ablates target material is studied by the mean of synchrostep shadowgraph. Light field force is first proposed. As a result, the speed distribution of ablated materials when they leaving target material surface is determined by the mechanism of ablation. The transportation behavior of ablated materials during the action of working laser is controlled by diffusion mechanism and light field force mechanism. The transportation behavior is determined by diffusion mechanism only after the action of laser.Based on the optical probe method, a system is designed to detect the plasma emission spectrum. The characteristic spectral line flight spectrum of Al atoms in excited state is investigated by experiment and the flight velocity is calculated.By the beam deflection technique based on surface shape change effect, a laser ultrasonic detector is developed. Lamb wave, surface wave and longitudinal wave aredetected.An instrument based on the beam deflection principle by refractive index effect is designed to detect the laser-induced plasma shock wave and the shock wave in transparent solid is first measured by beam deflection technique.Based on Hooke Law, a fiber transient mechanical sensor is first proposed. And the mechanical effect of target during the action of laser with various energy working on the target under water is investigated. The result shows that three transient pulse forces stress the target in turn. The generation and the impact force of cavitation liquid-jet depend on the bubble energy and non-dimension parameters. The efficiency of laserslotting in air and water is also investigated by experiment. The experimental results show that the efficiency in water is much higher than that in air. The reasons have been analyzed.According to the spherical cavitation bubble dynamic model considering the bubble energy dissipation, the impulsive motion of laser-generated bubble is calculated numerically. Then based on beam deflection by the variation of refractive index on the boundary surface between air and water, a system is designed to measure laser-generated bubble linear dimension geometric size. The maximum radius and the minimum radial distance of the bubbles near the target surface induced by laser with different pulse energy are investigated by this system. Furthermore, the results from numerical calculation and experiment have been matched.These research results will develop laser applications and corresponding detection techniques.更多还原