Abstract We demonstrate dual-comb time-of-flight absolute distance measurement with a free-running dual-wavelength dual-comb mode-locked Er-fiber laser. An anodized aluminum plate with 1.6- μ m RMS roughness that locates at a distance of ∼ 3.46 m serves as a scattering target. The echo has been collected non-coaxially with a 5-inch aperture telescope. The target time-of-flight is acquired by linear optical sampling, which relies on interference between the two combs with spectral overlap. We find that the wavelength of the overlapped spectra determines the fringe density of the interferograms, thus the accuracy of time-of-flight extraction algorithm. The ranging precision is ∼ 10 μ m when the collected optical power is ∼ 1/5000 of that emitted from the launcher. By using Kalman filtering, an improved ranging precision of 225.7 nm has been obtained. The measurement has been conducted at a fixed update rate of 20 Hz, mainly limited by the real-time-based computer data processing speed. Additional measurements of fixed height steps assembled by standard gauge blocks and surface profiling applications have been demonstrated to verify the accuracy of the ranging system. The presented technique is promising for future dual-comb based high precision lidar and remote sensing applications.

中文翻译：

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单自激锁模光纤激光器对非合作目标的双梳绝对距离测量

摘要 我们展示了使用自由运行的双波长双梳锁模 Er 光纤激光器进行双梳飞行时间绝对距离测量。位于约 3.46 m 距离处的具有 1.6-μm RMS 粗糙度的阳极氧化铝板用作散射目标。回波是用 5 英寸孔径望远镜以非同轴方式收集的。目标飞行时间是通过线性光学采样获得的，它依赖于光谱重叠的两个梳子之间的干涉。我们发现重叠光谱的波长决定了干涉图的条纹密度，从而决定了飞行时间提取算法的准确性。当收集到的光功率约为发射器发射光功率的 1/5000 时，测距精度约为 10 μm。通过使用卡尔曼滤波，测距精度提高了 225.7 nm。测量是在 20 Hz 的固定更新率下进行的，主要受基于实时的计算机数据处理速度的限制。由标准量块和表面轮廓应用程序组装的固定高度台阶的附加测量已被证明可以验证测距系统的准确性。所提出的技术有望用于未来基于双梳的高精度激光雷达和遥感应用。