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中国物理学会期刊

基于四波混频的调频连续波测距振动抑制方法

CSTR: 32037.14.aps.75.20251416

Vibration suppression method for frequency-modulated continuous wave ranging based on four wave mixing

CSTR: 32037.14.aps.75.20251416
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  • 调频连续波测距技术在工业制造领域应用广泛, 尤其被广泛用于大型高端装备尺寸测量与系统装配等. 但测量现场由于存在微小振动, 振动产生的多普勒频移导致拍频信号展宽, 无法实现准确测量, 从而影响测距系统的测量精度. 本文采用一种基于四波混频效应的振动抑制方法, 单频激光器发出的单频激光和可调谐激光器出射的调频光经过高非线性光纤, 产生四波混频效应形成转换光, 调频光与转换光形成了完全同步的对称扫频光源, 可以抑制振动引起的多普勒频移. 基于马赫-曾德干涉测量原理构建了一套四波混频效应的调频连续波测量系统, 利用该系统对6.9 m处静态目标进行测量, 测距峰峰值由抑制前的199.8 μm降低到16 μm, 提升12.4倍; 在6—7.2 m范围内的测距精度比对实验结果高于9.4 μm. 实验结果表明, 基于四波混频效应的振动抑制方法能够有效提高调频连续波测距的测量精度, 对解决工业测量现场振动干扰导致的测距精度遇到的应用问题具有重要意义.

     

    Frequency-modulated continuous wave ranging technology is widely used in industrial manufacturing. Because the on-site working environments are complex, the measured target may have slight vibration. The Doppler frequency shift caused by vibration leads to the broadening of the beat frequency signal generated by the superposition of the reference light wave and the measuring light wave in the continuous wave ranging system, which reduces the measurement accuracy of the ranging system. In this paper, we analyze the measurement principle of frequency modulation continuous wave ranging technology and the influence of target vibration on the range measurement accuracy. The analysis results indicate that the target vibration displacement can amplify the measurement error by dozens to hundreds of times. To address the above measurement error caused by tiny vibration displacement, in this paper we propose a vibration suppression method for the frequency modulation continuous wave ranging based on the four-wave mixing effect. Firstly, the generation principle of four-wave mixing is introduced. The single-frequency laser is used as the pump light, and the tunable laser is used as the signal light. These two lights are simultaneously incident into the highly nonlinear fiber. The converted light is generated by the third-order parametric process of the nonlinear medium of the fiber. The converted light and the signal light from the tunable laser form a symmetrical light source with scanning directions that are completely opposite. When the superimposed upper and lower scanning lights are filtered by high-pass filtering, the influence of vibration on the measurement signal is suppressed. Secondly, an experimental system of the four-wave mixing frequency modulation continuous wave is built, and the single-point measurement stability is verified. Based on the Mach-Zehnder interferometric measurement principle, a four-wave mixing effect frequency modulation continuous wave range measurement system is constructed. The static target at 6.9 m away is measured by this constructed ranging system. The distance of peak-to-bottom range is reduced from 199.8 μm before vibration suppression to 16μm, which represents an improvement of more than 12 times. A ranging accuracy comparison experiment is also carried out in a range of 6–7.2 m, and the ranging accuracy is lower than 9.4 μm. Experimental results demonstrate that the vibration suppression method utilizing the four-wave mixing effect can effectively improve the measurement accuracy of frequency modulation continuous wave ranging, which holds significant importance in industrial applications.

     

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