为了研究参考光波面形状对于测量透镜焦距值的影响, 采用数字全息的方法进行了理论分析和实验验证。通过在两种色光下进行实验, 分别测量出参考光为平面波和球面波时的焦距值, 并与标称值和理论计算值进行了比较。结果表明, 当参考光为平面波时, 测量到的透镜焦距值与标称值和理论计算值相对误差在5%以上; 而当参考光为球面波时, 与两者的相对误差均在2%以下, 因此当参考光为球面波时所测量的焦距值精度更高; 通过计算得出这两种参考光所测量的焦距值都在理论焦深范围内, 故利用测量焦距值对全息图进行重构时所获得的再现像与用标称值和理论计算值所得到的再现像质量相当。这一结果对测量透镜焦距值和数字全息图重建方面有一定的帮助。

In order to study influence of the surface shape of reference wave on lens focal length, digital holography method was used for theoretical analysis and experimental verification. Focal length was measured respectively with planar reference wave and spherical reference wave at different wavelengths. And then, the measured values were compared with the nominal values and the theoretical calculation values. The results show that the relative errors are above 5% between the measured value, the nominal value and the theoretical calculation value with planar reference wave. The relative errors are blow 2% with spherical reference wave. Therefore, the precision of focal length measured by spherical reference wave is higher. After calculation, focal lengths measured by two different reference lights are within the range of theoretical depth of focal. Therefore, the reconstructed image obtained by the measured value is equivalent to the reconstructed image obtained by the nominal value and the theoretical value. So the spherical reference wave has higher precision to the measurement results. Both kinds of reference wave are within the scope of the theoretical depth of focus. So the quality of the reconstructed images which are calculated with measured values, the nominal values and the theoretical calculating values is about the same. The study provides guidance for measurement of lens focal length and wavefront reconstruction of digital holography.