NIST, Boulder, Colorado 80305, USA.
Opt Lett. 2013 Jun 15;38(12):2026-8. doi: 10.1364/OL.38.002026.
We demonstrate a comb-calibrated frequency-modulated continuous-wave laser detection and ranging (FMCW ladar) system for absolute distance measurements. The FMCW ladar uses a compact external cavity laser that is swept quasi-sinusoidally over 1 THz at a 1 kHz rate. The system simultaneously records the heterodyne FMCW ladar signal and the instantaneous laser frequency at sweep rates up to 3400 THz/s, as measured against a free-running frequency comb (femtosecond fiber laser). Demodulation of the ladar signal against the instantaneous laser frequency yields the range to the target with 1 ms update rates, bandwidth-limited 130 μm resolution and a ~100 nm accuracy that is directly linked to the counted repetition rate of the comb. The precision is <100 nm at the 1 ms update rate and reaches ~6 nm for a 100 ms average.
我们展示了一种梳状校准的调频连续波激光检测和测距（FMCW ladar）系统，用于绝对距离测量。FMCW ladar 采用紧凑的外腔激光器，以 1 kHz 的速率在 1 THz 范围内进行准正弦扫描。该系统以 3400 THz/s 的速率同时记录外差 FMCW ladar 信号和瞬时激光频率，这是通过与自由运行的频率梳（飞秒光纤激光器）进行测量得出的。通过将 ladar 信号与瞬时激光频率进行解调，可以以 1 ms 的更新速率测量到目标的距离，带宽限制为 130 μm 的分辨率，精度约为 100 nm，这与梳的计数重复率直接相关。在 1 ms 的更新速率下，精度小于 100nm，在 100ms 的平均时间内达到约 6nm。
