阐述了参考光束型激光多普勒测速仪的基本原理, 从理论上分析了原理公式近似、高斯光束干涉、激光线宽、探测器孔径、有限渡越时间、信号处理算法、空气折射率变化及角度测量等诸多因素对激光多普勒测速仪测量结果造成的误差, 研究并给出了每一种影响因素所引起误差的理论公式, 在每一种影响因素中具体讨论了各种光学参数对测量误差的影响并对部分参数进行实验研究。理论分析和实验表明: 在实验中需要选择线宽较窄的激光器及孔径较小的光电探测器, 而在选择光束光斑半径和信号光中心光线的方向与粒子运动方向的夹角时, 既要考虑激光的质量和多普勒信号的强度, 同时也需要考虑原理公式近似、探测器孔径的尺寸、有限渡越时间及高斯光束干涉等多种因素对测量结果的影响。

Basic principles of reference-beam laser Doppler velocimeter (LDV) is expounded. The influences of error factors on LDV measurements are theoretically analyzed, such as principle formula approximation, Gauss-beam interference, laser linewidth, detector aperture, finite transition time, signal processing algorithm, change of air refractive index and angle measurement. The theoretical formula of measurement error caused by each error factor is presented, and the influence of optical parameters on each error is discussed. Theoretical analyses and experiments show that, narrow-band laser and small-aperture photoelectric detector are required to reduce measurement errors in experiments. When one chooses beam facular aperture and the angle of between light central beam and particle motion direction, he should consider the factors such as quality of laser, intensity of Doppler signal, principle formula approximation, detector aperture size, finite transition time and Gauss-beam interference need to be considered.