分析了可用于绝对距离测量的波长扫描法布里－珀罗干涉仪腔内多光束干涉对输出信号的影响， 及由此产生的相位测量误差。研究表明， 通过选择合适的腔端面反射率和参考腔长度可以减小相位测量误差。优化选择的腔面反射率为０．１０～０．１５， 参考腔长为０．９５ ｍ ｍ ， 在１ ｍ ｍ 范围内系统可达到０．０５ μｍ 的测距精度。 The effect of multi-beam interference in the wavelength-scan Fabry-Perot interferometer on the output signal, which can be used for absolute distance measurement, and the resulting phase measurement error are analyzed. Research shows that the phase measurement error can be reduced by selecting the appropriate cavity end reflectance and reference cavity length. The optimized surface reflectance is 0.10 ~ 0.15, the reference cavity length is 0.95 m m, and the system can reach the precision of 0.05 μm within 1 m m range.