基于He-Ne激光回馈的纳条纹技术

发布时间：2018-05-17 16:14

本文选题：溯源性 + 分辨率标定　；参考：《北京化工大学》2015年硕士论文

【摘要】：激光回馈现象的物理内涵极其丰富,亟待人们对它进行探索和发现,基于此现象制作的激光回馈测量系统普遍具有灵敏度高、自准直的优点。与传统双光路干涉仪相比,回馈干涉仪只需要一条光路即可完成信号探测和放大,因此它还具有结构简单紧凑、价格便宜等优势。目前,人们对激光回馈现象的研究更多地停留在弱回馈水平下,对强回馈水平下的研究少有涉猎,因为当处于强回馈水平时,激光器对外界信号的灵敏度很高,对干扰的抵抗能力较弱,信号检测和处理的难度很大。针对上述优势和不足,本文对He-Ne激光器在较强回馈水平下的高阶回馈现象及其在位移测量领域的应用做了较为系统的研究,提出了一种具有纳米量级测量分辨率、可溯源至光波长的单重高阶回馈位移测量系统及其标定方法。另外,为了提高系统的稳定度,研制了针对回馈激光器的特殊稳频方法。首先,我们对单频激光高阶回馈现象作了系统的研究,得到了激光在非准直外腔下的高阶回馈曲线。并运用软件光线追迹和强弱回馈相互标定的方法,同时得到了外腔镜在特定角度下所对应的激光回馈阶次,成功获得了系统具有纳米量级的位移测量分辨率。在此基础上,发现了在非准直外腔回馈下,激光腔内的偏振跳变现象。为了利用这一现象进行位移判向,我们分别运用腔镜加力和外腔旋转波片的方式,成功控制了偏振跳变点在回馈条纹一个周期中的位置,并通过设定光强阈值的方法实现了位移判向。其次,我们通过在半外腔He-Ne激光器谐振腔内加入石英晶体,并调整其角度的方法,在非准直外腔强回馈条件下,获得了高密度、类余弦、相位差为90度的双频高阶回馈位移测量曲线。系统位移测量分辨率同样能达到纳米量级,而且所得到的双频纳米条纹可用于进一步的位移判向和电路条纹细分处理,最终获得了亚纳米量级的测量分辨率。再次,针对He-Ne激光高阶回馈系统的特点,提出了结合激光管外电阻丝热稳频和外腔镜调制稳频的方法,成功解决了激光器在较强回馈水平时的稳频难题,提高了系统的抗干扰能力和测量准确度。最后,为了解决非准直凹面回馈外腔镜上不同阶次回馈光点相互混合,无法获得准确的位移测量分辨率和幅值均匀的回馈条纹等问题,设计和搭建了基于Fabry-Perot回馈外腔的高阶位移测量系统。并在这一系统中,首次获得了幅值均匀、分辨率确定的单重高阶弱回馈纳米条纹。然后,我们运用传统一阶回馈半波长条纹与该纳米条纹相互标定,通过微调F-P回馈镜角度,获得了与理论值相符合的两种回馈条纹个数之比。该方法能帮助我们有效地减小因为光线传播过程中离轴所造成的Abbe误差,保证系统位移测量的溯源性。经过标定,得到系统位移测量分辨率为0.55nm,其中可溯源的光学分辨率为10.9nm。该系统具有用作纳米位移计量标准的潜力。
[Abstract]:The physical connotation of laser feedback phenomenon is extremely rich, it is urgent for people to explore and discover it. The laser feedback measurement system based on this phenomenon generally has the advantages of high sensitivity and self-collimation. Compared with the traditional dual optical path interferometer, the feedback interferometer needs only one optical path to detect and amplify the signal, so it also has the advantages of simple and compact structure, low price and so on. At present, the study of laser feedback is more focused on the weak feedback level, but less on the strong feedback level, because when the laser is at the strong feedback level, the laser is highly sensitive to the external signal. The ability to resist interference is weak, and it is very difficult to detect and process signals. In view of the above advantages and disadvantages, the high-order feedback phenomenon of He-Ne laser and its application in displacement measurement are systematically studied in this paper, and a kind of nanoscale measurement resolution is proposed. A single high order feedback displacement measurement system and its calibration method traceable to the wavelength of light. In addition, in order to improve the stability of the system, a special frequency stabilization method for feedback lasers is developed. Firstly, we systematically study the high-order feedback phenomenon of single-frequency laser, and obtain the high-order feedback curve of laser in non-collimated external cavity. By using the method of software ray tracing and strong or weak feedback mutual calibration, the laser feedback order corresponding to the external mirror at a specific angle is obtained, and the displacement measurement resolution of the system with nanometer magnitude is obtained successfully. On this basis, the phenomenon of polarization jump in the laser cavity is found under the non-collimation external cavity feedback. In order to make use of this phenomenon, we successfully control the position of polarization jump point in a period of feedback fringes by using the method of endoscope force and external cavity rotating wave plate, respectively. The method of setting the threshold of light intensity is used to determine the direction of displacement. Secondly, by adding quartz crystal into the resonator of semi-external cavity He-Ne laser and adjusting its angle, we obtain the high density and similar cosine under the condition of non-collimation external cavity strong feedback. A high order feedback displacement measurement curve with a phase difference of 90 degrees. The resolution of system displacement measurement can also reach nanometer order, and the obtained dual-frequency nanometer fringes can be used for further displacement direction determination and circuit fringes subdivision, and finally sub-nanoscale resolution can be obtained. Thirdly, according to the characteristics of He-Ne laser high-order feedback system, a method combining thermal frequency stabilization with external mirror modulation is proposed, which successfully solves the problem of laser frequency stabilization at strong feedback level. The anti-interference ability and measurement accuracy of the system are improved. Finally, in order to solve the problem that different order feedback light points are mixed with each other on the non-collimated concave feedback mirror, it is impossible to obtain accurate displacement measurement resolution and uniform amplitude feedback fringes, etc. A high order displacement measurement system based on Fabry-Perot feedback cavity is designed and built. In this system, the single-order high-order weak feedback nanoscale stripes with uniform amplitude and definite resolution are obtained for the first time. Then, we calibrate each other with the traditional first-order feedback half-wavelength fringe and the nanoscale fringe. By fine-tuning the angle of the F-P feedback mirror, we obtain the ratio of the number of the two feedback fringes in accordance with the theoretical values. This method can effectively reduce the Abbe error caused by off-axis in the process of ray propagation and ensure the traceability of the system displacement measurement. After calibration, the system displacement measurement resolution is 0.55 nm, and the traceable optical resolution is 10.9 nm. The system has the potential to be used as a nanometer displacement measurement standard.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN24

【共引文献】