飞秒激光时空同步聚焦特性及其微纳加工应用研究

发布时间：2018-05-04 14:29

本文选题：飞秒激光 + 时空同步聚焦　；参考：《北京理工大学》2015年硕士论文

【摘要】：飞秒激光是一种应用广泛的超快激光,飞秒激光具有极短的持续时间和极高的峰值功率,这使得其在微纳加工中具有诸多独特的优势;时空同步聚焦则是一种全新的宽频激光光场聚焦方式,时空同步聚焦提供了新的聚焦维度和可控维度,这使得其在光斑尺寸形状及动态控制等方面具有突出优势。近年来,越来越多的研究学者将飞秒激光与时空同步聚焦结合并应用于加工领域,这一技术解决了诸多原来单使用飞秒激光加工所具有的诸多问题。例如,避免了长焦距聚焦下飞秒激光加工引起的自聚焦效应;解决了飞秒激光直写加工微通道截面不圆的问题并实现了具有可变深宽比截面的微通道加工;提高了多光点三维快速成型加工时激光传播方向精度等。飞秒激光时空同步聚焦加工技术的独特性质使得其在微通道加工、三维快速成型加工、生物及高散射材料加工、加工过程的高速动态控制等领域具有巨大的应用前景。然而,飞秒激光时空同步聚焦加工技术是一种非常新的技术,对其特性及加工应用的研究才刚刚开始,尚存在诸多未解决的科学问题。本文对飞秒激光时空同步聚焦的聚焦光斑静态及动态特性进行了理论研究,并且通过实验研究了其聚焦特性在微纳加工中的应用。论文主要研究内容如下:1.通过引入频率这一光场整形维度,拓展了原空间整形及聚焦的计算算法,研究并实现了通用的空间域和时域超快激光光场整形及聚焦算法。通过理论计算分析了多种振幅整形、相位整形及偏振整形的空间聚焦特性。2.理论研究了时空同步聚焦的光斑的静态特性和动态特性。静态上,相比于空间聚焦,时空同步聚焦的光斑的瑞利长度更短,同时时空同步聚焦的焦平面存在一定的倾斜现象;动态上,时空同步聚焦的聚焦光斑可以随时间快速位移或变形。根据时空同步聚焦光斑的动态特性,提出了一种控制超快光斑动态演化的方法。并将时空同步聚焦技术与其它技术相结合实现了多种形状光斑的快速移动、光斑间歇式移动、多点同步移动等。这为微纳加工提供了全新的控制维度,并为微纳加工中超快过程的动态控制提供了基础。3.实验研究了时空同步聚焦光斑的静态特性和动态特性对加工的影响。静态上,观测了时空同步聚焦的空气电离状态,并将其与传统空间聚焦作对比,并将这种聚焦方法应用于微通道加工。动态上,研究了时空同步聚焦所引起的光斑快速平移现象对加工区域及加工微结构的影响。
[Abstract]:Femtosecond laser is a widely used ultra-fast laser. Femtosecond laser has a very short duration and a very high peak power, which makes it have many unique advantages in micro-nano machining. Spatio-temporal synchronous focusing is a new mode of wide-band laser field focusing. Spatio-temporal synchronous focusing provides a new dimension of focus and controllable dimension, which makes it have outstanding advantages in the aspects of spot size and dynamic control. In recent years, more and more researchers combine femtosecond laser with spatio-temporal synchronous focusing and apply it to the field of processing. This technique solves many problems of single femtosecond laser processing. For example, the self-focusing effect caused by femtosecond laser processing under long focal length focusing is avoided, and the problem of non-circular microchannel section in femtosecond laser direct-writing processing is solved and the micro-channel machining with variable aspect ratio section is realized. The accuracy of laser propagation direction is improved during the three-dimensional rapid prototyping of multi-light spot. The unique properties of femtosecond laser space-time focusing technology make it have a great application prospect in the fields of micro-channel processing, three-dimensional rapid prototyping, biological and high-scattering materials processing, high-speed dynamic control of processing process, and so on. However, the femtosecond laser spatio-temporal focusing technology is a very new technology. The research on its characteristics and processing applications has just begun, and there are still many unsolved scientific problems. In this paper, the static and dynamic characteristics of the focusing spot of femtosecond laser focusing in time and space are studied theoretically, and the application of the focusing characteristic in micro / nano machining is studied by experiments. The main contents of this paper are as follows: 1: 1. By introducing frequency as the dimension of optical field shaping, the calculation algorithm of original space shaping and focusing is extended, and the general algorithms of spatial and time domain ultra-fast laser field shaping and focusing are studied and implemented. The spatial focusing characteristics of amplitude shaping, phase shaping and polarization shaping are analyzed by theoretical calculation. The static and dynamic characteristics of spatiotemporal synchronous focusing spot are studied theoretically. In the static state, the Rayleigh length of the spot is shorter than that of the spatial focusing, and the focal plane of the spatio-temporal synchronous focusing is inclined to a certain extent. Spatio-temporal focusing spot can shift or deform rapidly with time. According to the dynamic characteristics of space-time synchronous focusing spot, a method to control the dynamic evolution of ultra-fast spot is proposed. The spatio-temporal synchronous focusing technology is combined with other technologies to realize the fast movement of various shapes of light spots, the intermittent movement of light spots, and the synchronous movement of multiple points. This provides a new control dimension for micro / nano machining and provides a basis for dynamic control of ultra fast process in micro / nano machining. The effects of static and dynamic characteristics of spatiotemporal synchronous focusing spot on machining are studied experimentally. In static state, the air ionization state of spatio-temporal synchronous focusing is observed and compared with that of traditional spatial focusing, and this focusing method is applied to microchannel processing. Dynamically, the effect of the fast translation of spot caused by spatio-temporal synchronous focusing on the processing area and microstructure was studied.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN249

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