预放大数字全息显微系统的特性分析

Characteristic analysis of digital holographic microscopy with pre-magnification

为了提高预放大数字全息显微系统的成像质量,采用理论分析与实验验证相结合的方法,分别对采用平面及球面参考光记录的预放大数字全息显微系统进行了研究和比较。结果表明:在通常的实验条件下,系统的横向分辨力主要取决于显微物镜的成像分辨力;记录距离较小时,两种系统的横向分辨力均随着记录距离的增大略有降低;但当记录距离较大时,球面参考光预放大数字全息系统的横向分辨力降低得更为明显,即平面参考光预放大数字全息显微系统较为优越;在记录距离为0的情况下,即像面数字全息成像情况下,两种系统的再现像均具有最高的分辨力,在利用普通工业用传感器条件下,横向分辨力远超过了2.19μm,且像质较好。因此,尽可能减小全息图的记录距离,或者采用像面数字全息系统,可以有效提高数字全息系统的成像分辨力。

In order to improve the imaging quality of pre-magnification digital holography, the imaging systems of pre-magnification digital holography with the plane wave and spherical wave respectively as the reference light are studied and compared theoretically and experimentally. The results show that, the lateral resolution of the two systems mainly depends on the resolution of microscopic lens in general experimental conditions. When the recording distance is short, the lateral resolution of both systems will be slightly lower with the recording distance increasing; and when the recording distance is comparatively large, the resolution of the system with spherical wave as the reference light is worse, scilicet, the system of plane wave is relatively superior. As the recording distance of the hologram is zero, which is named as digital image-plane holography, the resolution of reconstructed image is best. When an ordinary industrial sensor is adopted, the lateral resolution far exceeds 2.19 μm, and the image quality is fairly good. Reducing the recording distance of digital hologram as much as possible, or employing the digital image-plane holography, can improve the imaging resolution of digital holography.