提出一种基于系统标定的相衬显微数字全息方法。对相衬显微数字全息原理进行了理论分析,表明用两个分别位于记录面和像面的数字相位掩模,在不影响重建像放大倍率的情况下,可以消除由显微物镜引入的相位弯曲。给出了相位掩模的数学模型,并提出通过系统标定来构建所需相位掩模的方法。其基本思路是,通过预先拍摄成像物镜加入前后的两幅参考数字全息图,结合滤波还原和最小二乘拟合等数字处理方法,提取全息记录系统的参数,用于构建数字相位掩模。利用该技术对最大宽度不超过0.09 mm的小水珠进行了不同放大倍率的相衬显微成像实验,验证了该技术的有效性和方便性。

A phase-contrast imaging technology with digital holographic microscope based on system calibration is present. After a theoretical analysis of the phase-contrast microscopy,results show that the phase curvature introduced by the microscope objectives can be compensated by introducing two digital phase masks located on recording plane and imaging plane respectively. Without affecting the sice of the reconstructed image,the mathematic models of the two phase masks are defined,which can be constructed by the proposed system calibration method. The calibration process includes pre-recording two reference holograms,inserting the imaging microscope objective,filtering and square fitting etc digital processing to compute the recording system parameters,constructing the required digital phase masks by the calibrated system parameters. Finally,a demonstration experiment is carried out. In the experiment a small water bead with size of no more than 0.09 mm is phase-contrast imaged with different magnification ratios. The experiment shows that the proposed method is credible and convenient.