【摘要】 针对激光频率扫描干涉(FSI)测距系统中激光器输出光频率非线性对测量精度的影响,提出了一种基于非平稳信号阶次跟踪的方法。从频域的角度分析了FSI测距系统中影响测量精度的主要因素。通过检测法布里-珀罗标准具的透射信号,实现对光频率的快速间接测量。利用最小二乘的方法对光频率进行线性拟合,实现对光频率变化率的修正。通过多项式拟合的方法确定光频率的时间-频率数学表达式,构造等频率的间隔点对其逆向插值,获得对应的时间序列。对采样的干涉信号在时间序列处正向插值,重构等频率间隔采样的干涉信号,对重构的干涉信号进行频谱分析,最终得到非平稳干涉信号的干涉频率。结果表明,在不限制待测距离的条件下,利用阶次跟踪的方法,可以有效抑制激光器输出光频率非线性的影响,FSI测距系统的测量精度得到显著提高。在1000 mm的测量范围内,测量结果的空间分辨率提高了36倍以上。更多还原

【Abstract】 A new method based on order tracking technique for reducing the effect of nonlinear optical frequency swept in frequency sweeping interferometer(FSI) is presented. The main factors affecting the measuring accuracy of the FSI system are discussed in frequency domain. This method utilizes the optical resonant characteristic of a Fabry-Perot etalon to measure the instantaneous optical frequency of a laser rapidly. Carries on the data linear fitting to the optical frequency on the least-square method and make the slope of the linear equation as the correction rate of optical frequency. The time series of equidistant optical frequency grid can be obtained with polynomial fit and interpolation of optical frequency. The interference signal can be resampled according to time series of equidistant optical frequency grid, and then reconstructed by using data interpolation. The frequency value of non-stationary interference signal is achieved after spectral analysis of reconstructed interference signal. The results indicate that this method dramatically reduces the effects of the nonlinear sweep without limit the range of the measured distance, and demonstrates spatial resolution enhancement of more than 36 times in the range of1000 mm.更多还原