【作者】 姜玉峰；

【导师】 雷訇；

【作者基本信息】 北京工业大学 ， 光学工程， 2010， 硕士

【摘要】 激光冲击强化是一种新型的材料表面处理技术,与传统的表面强化技术相比,具有非接触、无热影响区和强化效果显著等明显的技术优势,能够大幅度增强金属材料的耐久性,防止表面出现裂纹,从而提高使用寿命和降低维护修理成本。冲击强化激光器通常是由一个振荡器和一个或多个放大器组成。本论文主要针对振荡器和主放大器之间的预放大器和应用于主放大器的受激布里渊散射(SBS)相位共轭镜进行研究。预放大器要将毫焦量级的单频激光放大到百毫焦量级,采用四通放大结构。为与主放大器工作物质钕玻璃的峰值增益相匹配,采用Nd:YLF作为预放大器的工作物质。本文对多通放大进行了能流模拟,还对四通放大光路,Nd:YLF晶体和偏振元件的特性进行了分析,设计了单频激光和泵浦电脉冲的时间匹配关系。进行了双通放大实验,得到了40mJ的输出,实现20倍增益。还进行了四通放大的初步实验研究。应用于主放大器的SBS相位共轭镜要在较高的能量负载条件下实现较高的能力反射率和保真度。采用双池结构,散射介质为高击穿阈值的FC-72液体。建立一维瞬态SBS理论模型,通过时间上的差分和空间上的差商实现离散化处理。对SBS过程进行了数值模拟,讨论了Stokes光和泵浦光的能量配比、注入强度、注入时间差以及放大池长对输出波形和能量反射率的影响,为大能量短脉冲激光系统中的双池SBS相位共轭镜的实验分析和结构设计提供了理论依据。更多还原

【Abstract】 Laser Shock is a new surface treatment technology. Comparing with traditional surface treatment technique, Laser Shock has many obvious technical advantages such as non-contact, no heat affected zone and a significant strengthening effect, can greatly enhance the durability of metallic materials and prevent surface cracks, thereby enhancing the service life and lower maintenance repair costs. Shock processing laser is formed by an oscillator and one or more amplifiers.The research focuses on pre-amplifier which between the oscillator and main amplifier, and stimulated Brillouin scattering (SBS) phase conjugation mirror of main amplifier.The magnitude of the single frequency laser will be amplified from mJ to 100mJ by the pre-amplifier. Using Nd:YLF as work material of pre-amplifier in order to match the gain peak of Nd:glass used in main amplifier. The energy flow of multi-pass amplification has been simulated, the optical path of four-pass amplifier,the characters of Nd:YLF crystal and Polarization components have been analyzed. The synchronization of single frequency seed laser and electrical pump pulses. In the double-pass amplification experiment, the output energy is 40mJ, with a gain of 20. There is also some preliminary work of four-pass amplification.The SBS phase conjugate mirror applied in the main amplifier needs to achieve high reflectivity and fidelity in a high energy load conditions. Dual-cell structure and high breakdown threshold scattering medium FC-72 liquid are selected. SBS process was simulated numerically based on a one-dimensional transient model. Use an implicit finite differencing in time and a down-winding or backward differencing scheme in space. Under different parameters in amplified cell, theoretical simulate the impact of output energy and Waveform. Providing reference for structural design and experiment of dual-cell SBS phase conjugation mirror in laser system with lager energy and shot pulse.更多还原