The optical frequency comb serves as a powerful tool for distance measurement by integrating numerous stable optical modes into interferometric measurements, enabling unprecedented absolute measurement precision. Nonetheless, due to the periodicity of its pulse train, the comb suffers from measurement dead zones and ambiguities, thereby impeding its practical applications. Here, we present a linear group delay spectral interferometer for achieving precise full-range distance measurements. By employing a carefully designed linear group delay (LGD) device for phase modulation of the comb modes, interference can occur and be easily measured at any position. Our approach effectively eliminates the dead zones and ambiguities in comb-based ranging, without the need for cumbersome auxiliary scanning reference devices or reliance on complex high-repetition-rate combs or high-resolution spectrometers. We conducted length metrology experiments using a mode-locked comb referenced to a rubidium clock, achieving a large nonambiguity range up to 0.3 m, covering the entire measurement period. The maximum deviation compared to a laser interferometer was less than 1.5 μm, and the minimum Allan deviation during long-term measurements reached 5.47 nm at a 500 s averaging time. The approach ensures high accuracy while maintaining a simple structure, without relying on complex external devices, thereby propelling the practical implementation of comb-based length metrology.

现代测量技术中，频率调制连续波激光雷达结合了传统雷达和激光干涉测量的优点，凭借其非接触性、测量范围大、分辨率高和抗干扰能力强等特性，在大尺寸空间精密测量、微小测量以及生物计量等领域发挥着至关重要的作用。但实际应用中，激光光源的频率调制不能呈现出完全线性，使得频率调制连续波激光雷达技术的测量精度严重下降。所以，如何抑制激光的调频非线性带来的影响成为频率调制连续波激光雷达测量领域的一项研究热点。本文介绍了频率调制连续波激光雷达的工作原理，根据频率调制非线性校正方案的不同，针对性地介绍和分析了四种应用较为广泛和部分特殊的非线性校正方法，并进行了总结和展望。

绝对距离测量的精度对于航空航天科技、精密装备加工、卫星编队、行星空间定位等领域具有重要意义。近年来，基于可调谐激光器的扫频干涉（FSI）测距技术以其突破2π模糊度、无测量死区、不接触且不依赖导轨等优点成为国际研究热点。文中在阐述FSI测距原理的基础上，简要分析了测距系统中部分器件的类型与性能，如可调谐激光器、探测器等，以及影响测距系统不确定度的因素，包括非线性扫频、多普勒频移、色散失配等方面，着重介绍了国内外对影响不确定度因素的相应补偿方法，并对补偿后的测量结果进行对比与总结。

在基于视觉图像的位姿测量中，非线性位姿测量算法的全局收敛存在不确定性，测量结果取决于初值的选取，不能保证位姿测量的鲁棒性。线性位姿测量算法对图像处理的要求比较高，如果定位特征点图像坐标提取不够精确，会导致位姿测量精度降低。在自然光条件下，相机采集定位特征点图像，图像中高亮度区域的存在对定位特征点提取精度产生影响，进而使有效定位特征点数量减少，影响位姿测量精度。针对上述问题，文中提出了一种基于最佳偏振角的线性位姿测量方法：在相机镜头前加装线偏振片，根据Stokes矢量建立偏振片最佳偏振角度求解模型，在使用最佳偏振角度的前提下采集定位特征点图像，提取图像坐标；建立线性位姿求解模型，计算被测物体位姿。实验结果表明，该方法能够有效减少图像中的高亮度区域，改善成像质量，提高线性位姿测量精度，在−60°~+60°的测量范围内，角度测量误差小于±0.16°，在0~20 mm的测量范围内，位移测量误差小于±0.05 mm。

随着大尺寸工件和设备的制造加工以及装配的精度要求提高，对工件加工装配过程进行测量的测量系统精度要求也有所提高。多边法激光跟踪三维坐标测量系统只利用距离测量数据解算空间点坐标，能够避免激光跟踪仪角度测量带来的误差。文中提出了一种通过在跟踪仪测头挂载夹具进行球心拟合来获取跟踪仪测量原点的方式进行系统自标定，并辅以移站的方式，可使用两台激光跟踪仪构建四站多边法激光跟踪三维坐标测量系统。另外，文中还尝试了三站系统的构建。实验证明，四站系统将对标称长度1000.943 mm位于约20 m处的标准尺长度测量误差由最大110 μm减小至28 μm，三站系统将对标称长度969.045 mm位于约7.5 m处的标准尺长度的测量误差由最大67 μm减小至21 μm，相较于单台跟踪仪提高了精度，相较于传统多边系统降低了测站数量和成本，能够在工业现场实现高精度三维坐标测量。

Laser-based light detection and ranging (lidar) plays a significant role in both scientific and industrial areas. However, it is difficult for existing lidars to achieve high speed, high precision, and long distance simultaneously. Here, we demonstrate a high-performance lidar based on a chip-scaled soliton microcomb (SMC) that can realize all three specialties simultaneously. Aided by the excellent properties of ultrahigh repetition rate and the smooth envelope of the SMC, traditional optical frequency comb (OFC)-based dispersive interferometry is heavily improved and the measuring dead zone induced by the mismatch between the repetition rate of the OFC and resolution of the optical spectrum analyzer is totally eliminated. Combined with an auxiliary dual-frequency phase-modulated laser range finder, the none-dead-zone measurable range ambiguity is extended up to 1500 m. The proposed SMC lidar is experimentally implemented in both indoor and outdoor environment. In the outdoor baseline field, real-time, high-speed (up to 35 kHz) measurement of a long distance of ～1179m is achieved with a minimum Allan deviation of 5.6 μm at an average time of 0.2 ms (27 nm at an average time of 1.8 s after high-pass filtering). The present SMC lidar approaches a compact, fast, high-precision, and none-dead zone long-distance ranging system, aimed at emerging applications of frontier basic scientific research and advances in industrial manufacturing.