高精度无合作目标自适应FMCW激光绝对测距方法与关键技术研究

Manufacturing of major equipment and large-scale science instrument maintenance put forward increasingly more high requirements for large-scale precision measurement. Laser ranging as an important method of large-scale precision measurement is therefore extremely important. Frequency modulated continuous wave (FMCW) laser ranging is a large-scale absolute distance measuring technology, with the characteristics of large measuring range, high measuring resolution and non- cooperative. However, the resolution and precision are limited, because of the performance deficiency of the tunable laser, such as limited mode hop free continuous modulation range, non-linearity modulation，broad line width. In order to satisfy the requirements of the large-scale precision measurement in major equipment manufacturing, in this project, a new method is proposed to improve the measurement accuracy of the FMCW laser range. The research includes: 1. The method of sampling the interference signal at equal optical frequency intervals is proposed, and the measuring error due to the nonlinearity of optical frequency modulation is eliminated. 2. The method of equivalent laser modulation range extending is proposed. Using this method, we can reduce the modulation range of the tunable laser without decreasing the resolution. 3. The influence of material, color, texture and roughness of diffuse surface to intensity, polarization, phase and noise of the modulated laser is studied. And adaptive ranging system is designed. Using this system, high precision non-cooperative target absolute distance measurement is realized.

重大装备与大型科学仪器的制造维护对大尺度精密测量提出了越来越高的要求，激光测距作为大尺度精密测量的重要手段，具有非常重要的研究意义。调频连续波激光测距是一种大尺寸激光绝对测距技术，具有量程大、测量分辨力高、可实现无合作目标测距等优点。但是可调谐激光器的无跳模连续调制范围有限、光频调制线性度差以及线宽较宽等不足限制了FMCW激光测距的分辨力、精度以及量程。为了满足重大装备制造对大尺度精密测量的要求，本课题探索提高FMCW激光测距测量精度的新思路，研究内容主要包括：1.研究等光频间隔直接采样法，抑制由于激光调制线性度差导致的测量精度下降。2.研究激光器调制范围等效扩展的技术方法，突破激光调制范围对测距分辨力的限制。3.研究漫反射表面材质、颜色、纹理以及粗糙度等对调制信号光强、偏振态、相位以及噪声的影响，设计自适应测距系统，实现对远距离漫反射目标的高精度无合作目标绝对测距。

本研究工作目的在于提出一种调频连续波激光测距方法和系统，具有组成简单、测量精度高、测量范围大的优点，更适合于实际工业测量。.本报告提出了一种调频连续波激光测距系统及方法，可以有效抑制激光器调制非线性对调频连续波激光测距测量精度的限制，实现高精度的激光绝对距离测量。本研究首先采用了等光频间隔重采样的方法，详细分析了等光频间隔重采样的原理，设计了双干涉光路系统，实现了对测量干涉信号的等光频间隔重采样，消除了激光器调制非线性对测距分辨率的影响；其次采用了利用F-P标准具作为基准，对双干涉调频连续波激光测距系统的辅助干涉系统进行实时校正，以消除由于光纤的弯折、色散、以及外界温度和振动的影响都会导致测量精度的下降，从而进一步提高测距精度。通过与激光干涉仪的测量结果比对的实验证明了，该系统的测量不确定度达到了±20μm（95%置信区间）。另外还对漫反射目标对调频连续波激光的影响做了研究分析，实现了对漫反射目标的直接探测。.通过本项目的研究，将调频连续波激光测距引入大尺度精密测量领域，实现大量程、高精度的激光绝对距离测量，可以广泛应用于大型飞机、海洋船舶以及大型设备的加工制造与检测等工业精密测量领域。另外，调频连续波激光测距还可以扩展到更多的其应用领域，如构成大空间坐标测量、漫反射表面特性信息远距离获取、卫星编队飞行、空间技术应用等。