【作者】 王楠；

【导师】 李涛；

【作者基本信息】 山东大学 ， 工程硕士（电子与通信工程）（专业学位）， 2022， 硕士

【摘要】 目前,飞秒激光在医疗美容、军事武器、汽车制造、手机制造和激光加工等领域有着广泛的应用。尤其在激光精细加工领域,飞秒激光扮演着重要的角色。脉冲宽度是飞秒激光的一个非常重要的参数,影响着飞秒精细加工的质量。利用色散元件对激光脉冲进行展宽和压缩成为现在飞秒激光研究的热点之一。现在市场上的脉宽调控产品基本上都是单一的脉宽展宽器或是脉宽压缩器,都无法对激光器的输出脉宽进行监测的同时又进行调控。本论文将脉宽展宽和脉宽压缩整合在一个系统之内,利用正色散啁啾镜实现脉宽展宽,利用电动位移台的移动改变负色散透射光栅对的间距进行脉宽压缩,同时使用高精度的自相关仪监测系统的脉宽。搭配使用开发的一套控制软件,系统能够实现激光脉宽的在线监测与调控。本论文主要研究内容如下:1.系统主要由脉宽展宽模块、脉宽压缩模块和脉宽探测模块三部分组成。介绍了目前常见的几种脉冲展宽器和脉冲压缩器以及现有的脉宽监测方法,介绍了常用的色散补偿器件的优缺点。确定了使用正色散啁啾镜进行脉宽展宽的方案和使用透射型光栅对进行脉宽压缩的方案。最后确定了整个系统的光路图以及主要光学元件的选型。2.针对系统中使用的光学镜片,具体包括光栅对、中空屋脊棱镜反射镜、D形反射镜和分光镜,确定了它们所用的夹具。对啁啾镜设计了专门的夹具使得光路更加紧凑,对位移台设计了位移台转接台以方便位移台位置的改变。针对光束中心高度不匹配的问题还设计了一种爬高镜,降低成本的同时提高了实用性。设计了整个系统的底板和外壳,最后进行了工程装配。设计了一个功率控制模块,通过一个电动位移台改变一片连续可变中性密度滤光片的位置,将自相关仪的输入功率控制在允许的合适范围之内。3.分析了整个系统软件的控制思路,并使用Visual Studio 2019选择C#语言进行软件编写。设计了软件界面,主要分为脉宽显示和脉宽控制两个区域,实现了脉宽的稳定监测与控制。4.介绍了系统中用到的线性位移台以及自相关仪两个仪器的主要参数,按照光路图进行了系统光路的搭建,完成了整个系统样机的组装。运行系统软件进行脉宽控制,对监测到的数据进行了分析,得到系统的脉宽探测精度以及脉宽控制精度。还分析了系统中可能遇到的故障以及对应的解决办法。更多还原

【Abstract】 Femtosecond lasers have a wide range of applications in multiple fields such as medical aesthetics,military weapons,automotive manufacturing,cell phone manufacturing and laser processing.Especially in the field of laser fine processing,femtosecond laser plays an important role.Pulse width is a very important parameter of femtosecond laser,which affects the quality of femtosecond fine processing.The use of dispersive elements to broaden and compress the laser pulse has become one of the hot spots in femtosecond laser research.Nowadays,the pulse width control products on the market are basically single pulse width stretcher or pulse width compressor,which cannot monitor and control the output pulse width of the laser at the same time.This thesis integrates pulse width spreading and pulse width compression in one system,using positive dispersion chirped mirrors to achieve pulse width spreading,using the movement of the motorized displacement stage to change the spacing of negative dispersion transmission grating pairs for pulse width compression.and using a high precision autocorrelator to monitor the pulse width of the system.With the use of a set of control software developed,the system can realize online monitoring and regulation of laser pulse width.The main research content of this thesis is as follows:1.The system mainly consists of three parts:pulse width spreading module,pulse width compression module and pulse width detection module.Several common pulse stretchers and pulse compressors and existing pulse width monitoring methods are introduced,and the advantages and disadvantages of commonly used dispersion compensation devices are introduced.The scheme of using positive dispersion chirp mirrors for pulse width broadening and the scheme of using transmission grating pair for pulse width compression are determined.Finally,the optical path diagram of the whole system and the selection of the main optical components are determined.2.For the optics used in the system,specifically grating pairs,hollow roof prism mirrors,D-shaped mirrors and beamsplitters,the fixtures used for them are determined.A special fixture was designed for the chirp mirrors to make the optical path more compact,and a displacement stage adapter was designed for the displacement stage to facilitate the change of the displacement stage position.A height-climbing mirror was designed for the mismatch of beam center height to reduce the cost and improve the practicality.The base plate and housing of the whole system were designed,and finally the engineering assembly was carried out.A power control module was designed to control the input power of the autocorrelator within a suitable range allowed by changing the position of a continuously variable neutral density filter through a motorized displacement stage.3.The control idea of the whole system software was analyzed,and the software was written in C#language selected using Visual Studio 2019.The software interface was designed,mainly divided into two areas of pulse width display and pulse width control,which realized the stable monitoring and control of pulse width.4.Introduced the main parameters of the two instruments used in the system,the linear displacement stage and the autocorrelator,built the system optical path according to the optical path diagram,and completed the assembly of the whole system prototype.The system software was run for pulse width control,and the monitored data were analyzed to obtain the pulse width detection accuracy and pulse width control accuracy of the system.The faults that may be encountered in the system and the corresponding solutions are also analyzed.更多还原