基于数字相位原理的光栅干涉位移传感技术研究

发布时间：2018-08-03 18:54

【摘要】：随着精密与超精密加工技术迅速发展,对位移测量的精度提出了更高的要求。目前微米级精度位移测量技术已远远不能满足需求,因此纳米级位移测量技术得到了迅猛发展,已成为测试计量行业中的研究热点。基于衍射光栅的衍射干涉式位移传感测量技术有着测量精度高、抗干扰能力强和制造成本廉价等优点,在当前的超精密测试计量技术领域得到了普遍的运用。国外在该领域的研究起步比较早,相关技术比较成熟,而国内的技术水平相比于国外有着较大的差距。本文就基于数字相位原理的光栅干涉位移传感技术进行研究。采用数学方法,对光栅衍射现象、光学多普勒现象、相干光的干涉现象和光电转换的实现进行了求解。在测量系统的光路设计方面,重点采用了一种双层光路结构,有效地减小了测量系统的空间,提高了其实用性。在信号调理电路方面,根据光电转换输出信号的特征,分别采用差分放大、低通滤波等多个基本电路完成了信号调理电路的设计。采用多级放大的方式有效地降低噪声干扰,提高电路的信噪比。同时,在PCB电路制作中也采用了一些抗干扰措施来减小不确定噪声的影响。研究过程中发现,光电转换器的安装角度误差、条纹宽度的测量以及电路的延迟作用会使输出的两路信号处于非正交的状态,导致信号的细分计算误差较大。为减少信号的非正交性产生的细分计算误差,本文根据数字相关原理,提出了一种基于数字相位差测量的细分计算方法。对经典数字相关法测量相位差的原理和误差来源进行了详细讨论,提出一种以经典数字相关理论为基础的相位差计算方法,打破了经典计算理论中需要对被测信号进行整周期采样的限制条件,实现了相位差的高精度测量。将相位差的测量结果引入细分计算表达式中,得到最后的细分计算结果。此外,还运用软件的方法实现了信号整周期数计算和运动方向辨别的,有效地简化了信号处理电路。利用实验室现有条件,搭建了光栅干涉位移传感系统实验平台,并对该系统的光路结构、信号调理电路和信号采集系统等模块进行独立调试和系统联调,获得了包含有位移信号的干涉条纹,并经光电转换后得到了双路输出电信号,再经数据采集系统和计算机处理后得到位移值。实验的结果显示,系统的分辨率可达到5nm,且具有良好的重复性和线性度。
[Abstract]:With the rapid development of precision and ultra-precision machining technology, the accuracy of displacement measurement is required higher. At present, the precision displacement measurement technology of micron scale is far from meeting the demand, so the nanometer displacement measurement technology has been developed rapidly, and has become the research hotspot in the field of measurement and measurement. The diffraction interferometric displacement sensing technology based on diffraction grating has many advantages such as high measurement precision, strong anti-interference ability and low cost of manufacture, so it has been widely used in the field of ultra-precision measurement and measurement. The foreign research in this field started early, the related technology is relatively mature, but the domestic technical level has a big gap compared with the foreign countries. In this paper, the grating interferometric displacement sensing technology based on digital phase principle is studied. The diffraction phenomenon of grating, optical Doppler phenomenon, interference phenomenon of coherent light and the realization of photoelectric conversion are solved by mathematical method. In the aspect of optical circuit design of measurement system, a two-layer optical circuit structure is adopted, which effectively reduces the space of measurement system and improves its practicability. In the aspect of signal conditioning circuit, according to the characteristics of photoelectric conversion output signal, the signal conditioning circuit is designed by using several basic circuits, such as differential amplifier, low pass filter and so on. Multistage amplification is used to effectively reduce noise interference and improve the signal-to-noise ratio of the circuit. At the same time, some anti-interference measures are adopted in PCB circuit to reduce the influence of uncertain noise. During the research, it is found that the angle error of the photoelectric converter, the measurement of the width of the stripe and the delay of the circuit will make the two output signals in a non-orthogonal state, resulting in a large error in the subdivision calculation of the signal. In order to reduce the subdivision error caused by non-orthogonality of signal, a subdivision calculation method based on digital phase difference measurement is proposed according to the principle of digital correlation. The principle and error source of phase difference measurement by classical digital correlation method are discussed in detail. A phase difference calculation method based on classical digital correlation theory is proposed. It breaks the limit condition of the classical calculation theory, which requires the whole period sampling of the measured signal, and realizes the high precision measurement of the phase difference. The measurement results of phase difference are introduced into the expression of subdivision calculation, and the final subdivision results are obtained. In addition, the method of software is used to calculate the whole period number of signal and distinguish the direction of motion, which simplifies the signal processing circuit effectively. The experimental platform of grating interferometric displacement sensing system is built by using the existing conditions in the laboratory. The optical circuit, signal conditioning circuit and signal acquisition system of the system are debugged independently and the system is combined. The interference fringes with displacement signals are obtained. After photoelectric conversion, two output electrical signals are obtained, and the displacement values are obtained by data acquisition system and computer processing. The experimental results show that the resolution of the system can reach 5 nm, and the system has good repeatability and linearity.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH822;TN25

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