基于双折射原理的飞秒激光脉冲分束技术研究及应用

发布时间：2018-10-25 20:03

【摘要】：脉冲数字全息术将全息成像与飞秒激光相结合,通过记录物场的强度和相位信息来探测超快瞬态过程。在记录超快现象时,需要将单个脉冲分割成具有飞秒至皮秒量级时间的角度相同的物光子脉冲序列和具有同样时间延迟的角度不同的参考光子脉冲序列,两脉冲序列在CCD感光面上叠加产生干涉,得到一系列全息图并同时记录在一幅CCD图像中。其中,物光子脉冲序列通过物光分束系统得到,该系统需将一个激光脉冲分成在同一传播方向上相邻脉冲时间间隔相等、能量相等、无啁啾或者低啁啾的子脉冲序列。同理,参考光分束系统的作用是使得到的子脉冲序列脉冲间隔与物光子脉冲序列相等,子脉冲能量相等且与物光子脉冲能量相等,并且子脉冲序列传播方向不同,与物光子脉冲传播方向有一定的夹角。分束子脉冲的脉冲宽度、脉冲间隔、脉冲能量及子脉冲的数量与超快探测的精度相关,因此,超短脉冲分束技术在脉冲数字全息系统中具有关键作用。超短脉冲分束技术的另一个应用方向是飞秒激光微加工。传统的微加工技术主要采用单点扫描的方式,由于采用该方式加工一个微结构耗时较长,成为飞秒激光微加工技术进一步发展的主要障碍。因此,并行加工方式的提出对提高加工效率具有非常重要的研究意义。实现并行加工首先需要解决的是超短脉冲的空间分束问题。将双折射晶体用于实现超短脉冲空间分束,较其它方法精度更高。本文主要研究超短脉冲分束技术及其应用,课题来源于国家自然科学基金科学仪器基础研究项目(61227010)。本文的主要研究内容如下所述。首先介绍了超短脉冲数字全息术与飞秒激光并行加工技术,及其国内外研究现状,并对光在晶体中的双折射现象进行了探讨。其次,针对超短脉冲分束技术在脉冲数字全息应用中的重要作用,提出了基于双折射原理的共线传输的超短脉冲分束方法;并在研究双折射原理及常见双折射晶体的特性的基础上,设计了脉冲数字全息光路中的物光分束系统。最后,提出基于双折射原理的空间分布的并行传输的超短脉冲分束方法,分析了该方法在飞秒激光并行加工和脉冲数字全息系统中的应用。
[Abstract]:Pulse digital holography combines holographic imaging with femtosecond laser to detect ultrafast transient process by recording the intensity and phase information of object field. In recording ultrafast phenomena, it is necessary to divide a single pulse into a sequence of object photons of the same order of magnitude from femtosecond to picosecond and a sequence of reference photons at different angles with the same time delay. A series of holograms are obtained and recorded simultaneously in a CCD image by interference of two pulse sequences superimposed on the CCD photosensitive surface. Among them, the object photon pulse sequence is obtained by the object light beam splitting system. The system needs to divide a laser pulse into sub-pulse sequences with equal time interval, equal energy and no chirp or low chirp in the same direction of propagation. In the same way, the function of the reference beam splitting system is to make the pulse interval of the obtained sub-pulse sequence equal to that of the object photon pulse sequence, the energy of the sub-pulse is equal to that of the object photon pulse, and the propagation direction of the sub-pulse sequence is different. It has a certain angle with the propagation direction of the object photon pulse. The pulse width, pulse interval, pulse energy and the number of sub-pulses are related to the accuracy of ultra-fast detection. Therefore, ultrashort pulse splitting plays a key role in the pulse digital holography system. Another application of ultrashort pulse splitting is femtosecond laser micromachining. The traditional micromachining technology mainly adopts the single point scanning method. Because it takes a long time to process a microstructure, it becomes the main obstacle to the further development of femtosecond laser micromachining technology. Therefore, it is of great significance to improve the efficiency of parallel machining. The space beam splitting problem of ultrashort pulse is the first problem to be solved to realize parallel processing. The application of birefringent crystal to ultrashort pulse spatial beam splitting is more accurate than other methods. In this paper, ultrashort pulse beam splitting technology and its application are mainly studied. The subject comes from the basic research project of scientific instruments of the National Natural Science Foundation (61227010). The main contents of this paper are as follows. This paper first introduces the technology of ultrashort pulse digital holography and femtosecond laser parallel processing, and its research status at home and abroad, and discusses the phenomenon of birefringence of light in crystal. Secondly, aiming at the important role of ultrashort pulse beam splitting technology in the application of pulse digital holography, a collinear transmission method of ultrashort pulse beam splitting based on birefringence principle is proposed. On the basis of studying the principle of birefringence and the characteristics of common birefringence crystals, the optical beam splitting system in pulse digital holographic optical path is designed. Finally, a spatially distributed ultrashort pulse beam splitting method based on birefringence principle is proposed, and its application in femtosecond laser parallel processing and pulse digital holography system is analyzed.
【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN26;TN249

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