数字全息显微术中重建物场波前的相位校正

数字全息显微术克服了传统光学显微术无法直接提取样品相位信息的缺点,可以对活体细胞组织等相位型生物样品进行定量测量和有效观察。但在数字全息显微成像过程中,像场弯曲会对再现像相位分布的测量和观察产生影响。提出一种采用相位相减来校正数字全息再现像像场弯曲的方法。通过在样品加入前后两次拍摄全息图,并对数值重建像分别进行去包裹运算再令其相减,即可实现对像场弯曲的有效校正,对蝉翼和大蒜表皮细胞等相位型物体进行测量,并采用数值校正和相位相减两种方法对像场弯曲进行校正。与现有的数值校正方法相比,利用相位相减获得样品三维相位信息的方法更为简单、可靠,是校正像数字全息再现场弯曲的有效方法。

Phase Correction of Wavefront Reconstruction in Digital Holographic Microscopy

Compared with traditional optical microscopy,digital holographic microscopy can be used to measure phase information of samples.Therefore it allows quantitative detection and effective observation of transparent biological samples such as living cells.But the field curvature caused by the microscopic imaging in the hologram recording process will affect phase distribution of the reconstructed image.In order to correct the field curvature,a phase-subtraction method is presented.Recording two holograms before and after inserting the sample,unwrapping the numerical reconstructed images of the two holograms solely and subtracting them each other,the corrected phase distribution of the sample image will be obtained.As examples,some cicada wing and epidermal cells of garlic are measured by using digital holographic microscopy and the field curvature is corrected by numerical-correction method and phase-subtraction method,respectively.It is shown that the phase-subtraction method is more credible and convenient to get three-dimensional phase information and more effective to correct the field curvature than current numerical-correction method in digital holographic microscopy.