Zhai Xiaoyu, Meng Zhaopeng, Zhang Haoyun, Xu Xinyang, Qian Zhiwen, Xue Bin, Wu Hanzhong
Opt Express. 2019 Mar 4;27(5):6757-6769. doi: 10.1364/OE.27.006757.
In this paper, we theoretically and experimentally analyze the frequency-comb interferometry at 518 nm in the underwater environment, which we use to measure the underwater distance with high accuracy and precision. In the time domain, we analyze the principle of pulse cross correlation. The interferograms can be obtained in the vicinity of N∙lpp, where N is an integer and lpp is the pulse-to-pulse length. Due to the strong dispersion of water, the pulse can be broadened as the distance increases. The distance can be measured via the peak position of the interferograms. The experimental results show a difference within 100 μm at 8 m range, compared with the reference values. In the frequency domain, we analyze the principle of dispersive interferometry. The spectrograms can be observed near the location of N∙lpp, due to the low resolution of the optical spectrum analyzer. Because of the strong dispersion of water, the modulation frequency of the spectrogram is not constant. A balanced wavelength will exist with the widest fringe, at which the group optical path difference between the reference and measurement arm is equal to N∙lpp. The position of the widest fringe can be used to measure the distance. Compared with the reference values, the experimental results indicate a difference within 100 μm at 8 m range.
在本文中，我们对水下环境中518 nm的频率梳干涉测量法进行了理论和实验分析，该方法用于高精度和高精准度地测量水下距离。在时域中，我们分析了脉冲互相关原理。干涉图可在N∙lpp附近获得，其中N为整数，lpp为脉冲间长度。由于水的强色散，随着距离增加脉冲会变宽。距离可通过干涉图的峰值位置来测量。实验结果表明，在8 m范围内与参考值相比差异在100 μm以内。在频域中，我们分析了色散干涉测量原理。由于光谱分析仪分辨率较低，频谱图可在N∙lpp位置附近观察到。由于水的强色散，频谱图的调制频率并不恒定。会存在一个具有最宽条纹的平衡波长，此时参考臂和测量臂之间的群光程差等于N∙lpp。最宽条纹的位置可用于测量距离。与参考值相比，实验结果表明在8 m范围内差异在100 μm以内。
