数字同轴和数字离轴全息系统分析

Analysis of digital in-line and digital off-axis holography

利用最高空间频率分析法,通过逐点分析记录在 CCD 上的空间频率信息,研究了物体可允许记录的最大横向尺寸、最小记录距离、全息图的信息量、空间分辨力、再现像的横向分辨力、轴向分辨力及散斑大小,并得到了数学表达式。理论分析和实验结果表明,数字同轴全息系统放宽了对 CCD 分辨力的要求,有较高的分辨力,较低的散斑噪声、灵活、简单的系统结构及较高的 CCD 空间带宽利用率,在增强系统性能方面要优于数字离轴全息系统。这一研究为数字全息系统的设计和操作提供了一定的理论和实验指导。

The spatial frequency information recorded on CCD is analyzed point-by-point by way of highest spatial frequency analysis. Such spatial frequency information refers to the maximum lateral size of object be recorded, the minimal recording distance, information content of hologram, the spatial resolution of digital holography, the lateral and axial resolution of the reconstructed image and the speckle size and their mathematical expressions are presented. Theoretical analysis and experimental results show that, in digital coaxial holography system, the coaxial configuration can relax spatial resolution requirement on CCD sensors while keeping advantages of high resolution to the reconstructed image, low speckle noise and simple, flexible system setup and efficient utilization of CCD space-bandwidth. In the field of system performance, the digital coaxial holography system is more superior to the digital off-axis holography system. The study provides some theoretical and experimental guidance for the design and operation of a digital holography system.