针对传统波长位移检测准确度受波长扫描步长限制而无法提升的问题，本文提出一种基于互谱相关原理的粗位移计测与精细位移相结合的计测方法.粗位移计测技术采用相关检测原理，可实现宽动态测量范围;精细位移计测技术采用互谱检测原理，可实现高准确度测量;两者的结合实现了动态范围和检测准确度的同步提升.该方法实现了对光纤光栅的波长位移量的直接计测，而无需对光纤光栅中心波长绝对数值进行标定，减小了系统误差影响;同时采用平滑滤波法进行数据处理，消除了检测系统中的随机干扰.系统仿真结果表明，该方法解决了波长扫描步长对检测准确度的限制问题，波长位移计测准确度提升了三个数量级.采用新方法进行了0~60 g范围内光纤光栅纵向荷载测量实验，测得纵向荷载灵敏度为13.2 pm/g，表明该方法对实测数据具有较好的适用性.

In order to improve the accuracy of wavelength shift measurement which is limited by the scanning wavelength step in the traditional measurement, a method which combinates a coarse measurement and a fine one was present based on the crossspectrum detection and crosscorrelation technology. The coarse wavelength shift measurement which is based on the principle of crosscorrelation detection has achieved a wide range of measurement, and the fine wavelength shift mesurement which is based on the principle of crossspectrum detection has achieved a highprecision measurement. Both the range and the precision are improved with the combination of the coarse and the fine measrurement. The smoothing tecnlogy is applied for data processing, which has eliminated the influence of random noise in the detection system. The fiber grating wavelength shift is measured directly to reduce the system error which has avoided the measurement of the absolute values of FBG center wavelength. Simulation results show that the method breaks the limit of the scanning wavelength step, and the measurement accuracy is improved about three orders. FBG longitudinal load measuring experiment with the load range of 0~60 g was carried out and the new method was applied to process the experiment data, the results show that the FBG longitudinal load sensitivy is 13.2 pm/g, the new method has a better applicability.