近距离数字全息术记录和再现问题

Recording and Reconstruction of Near-Distance Digital Holography

讨论了记录距离小于菲涅耳衍射要求的近距离数字全息记录和再现问题。对全息记录与再现中高次相位的补偿问题进行了分析,证明了在CCD的参量和记录距离给定后,只要记录时使物体的大小、球面参考光波的位置和距离满足一定的条件,即使在记录距离小于菲涅耳衍射要求的最小距离情况下,也可将高次相位的影响补偿到足够小,使得近距离数字全息的数字再现仍可用快速傅里叶变换算法计算。推导出了满足高次相位补偿的条件和满足补偿条件时的数值再现计算公式。实验结果与理论分析的结论相吻合,并给出了一种修正实际记录的参考光和计算机模拟的理想参考光之间偏差的方法。

Some issues in recording and reconstruction of near distance digital holography are discussed where the recording distance is shorter than the Fresnel diffraction distance. The compensation of the higher-order phase in recording and reconstruction of in a hologram is analyzed. It is indicated that when the size of CCD and recording distance are determined, and some conditions of the object size and position of the spherical reference light are satisfied, the effect of higher-order phase can be compensated to small enough, even if the recording distance is shorter than the Fresnel diffraction distance. The higher-order phase compensation condition and numerical reconstruction equation are derived. Under the compensation condition, the fast Fourier transform algorithm can be used in numerical reconstruction. Experimental results are accordant with analysis conclusions. A correction method of difference between actual reference wave-front with the spherical reference wave-front in reconstructing is introduced.