【作者】 吴学锋；

【导师】 王泽敏；

【作者基本信息】 华中科技大学 ， 光学工程， 2011， 硕士

【摘要】 激光淬火处理技术广泛应用于工业加工领域,但高斯光束的能量分布模式无法获得均匀的淬硬层深而阻碍了该技术的发展。光束整形器能通过改善光束的质量提高激光淬火质量,因而成为研究的热点,但很少被直接应用于激光淬火的工程实验之中。结合实验室的设备条件,本文主要设计并加工了用于高功率光纤器淬火系统的光束整形器,将激光束能量分布由近似高斯分布转变成近似平顶分布,从而提高了激光淬火的质量。具体研究内容包括:(1)以几何光学和能量守恒定律等为依据,选用偶次非球面透镜作为整形元件,并确定了光束整形系统的初始数据(如镜片厚度、镜片间距、镜片直径等);(2)运用ZEMAX光学设计软件对光束整形系统进行了模拟分析,再根据相应的评价函数对系统进行优化,使整形后的光束能量分布尽量均匀,找出最优的方案。(3)将加工好的整形系统用于激光淬火实验,验证整形镜的整形效果。实验结果表明:在系统工作面上的光斑除中心黑斑边缘有一亮环外,其余部分的能量密度较为均匀;在不考虑中心黑斑的情况下,光斑在工作面前后随工作距离的变化趋势与理论模拟一致。整形后激光束的工作距离较理论模拟值减小了90mm,而整形后的光斑在材料表面作用后得到的直径较理论值增加了1mm。最后,通过光纤激光淬火实验验证了整形镜的整形效果,基本达到设计的要求,获得的淬硬层深基本相同。更多还原

【Abstract】 Laser quenching is widely used in industrial processing areas. The lasers with energy distribution of gaussian are often used during quenching processes, which retards the further development of this technology for not obtainting uniform deepth hardened layer. The quality of laser quenching can be improved by using the shaped laser beam in therory. However, a few research results are used in laser quenching experiments for potential applications.In this thesis, a laser beam shaper used in high-power fiber laser quenching system was designed and assembled based on our laboratory conditions. The main aim is to change the distribution of the fiber laser beam from gaussian to approximately flat-top. The main studies include: (1) the even aspheric lens was selected as the lens of beam shaping system based on the geometric optics and energy conservation law. In addition, the initial data (including the thickness of the lens, distance and diameter) were determined. (2) The ZEMAX optical design software was used to simulate the beam shaper. Then the system was optimized according to the merit function to make the energy density of the laser beam homogenize. (3) The assembled shaper was used in the fiber laser quenching experiments to verify the effect of shaping.The results show that the energy distribution of the spot is basically uniform except for a bright ring near the center black spot. When the center black spot is not considered and the laser spot locates near the working distance, the change of the spot size with the working distance is consistent with that of the simulation results. In experiment, the working distance is reduced by a value of 90 mm in comparison with the theoretical value. But the real spot size has increased 1 mm than the theoretical value. Finally, the laser quenching experiments based on the designed shaper can obtaint hardened layer with uniform depth, which demonstrates that the designed shaper has met the design requirements for high-power fiber laser quenching system.更多还原