【作者】 范琦； 赵建林； 张延； 曹王军；

【Author】 Fan Qi Zhao Jianlin Zhang Yancao Wang Jun (Institute of Optical Information science and Technology, School of Science, Northwestern Polytechnical University, Xi’an 710072, China)

【机构】 西北工业大学理学院光信息科学与技术研究所；

【摘要】 在数字全息显微术中,当物体与CCD相当近时,菲涅耳近似条件将不再成立,对数字全息图必须用卷积法再现。由于用卷积法所得再现像平面上的采样间隔与CCD的像元尺寸相同,因此,如果再现像的横向分辨率高于CCD的横向分辨率,采样定理将不满足,混淆现象就会出现。本文提出一种提高卷积法再现数字全息图的显示分辨率的新方法。通过给卷积再现法中两次傅里叶变换间的频谱面补足够的零,来减小再现像平面上的采样间隔,从而使再现像的显示分辨率得到提高。实验结果与理论分析一致。更多还原

【Abstract】 In digital holography microscopy,the Fresnel approximation is no longer valid, when the object is placed near to the CCD. The convolution approach has to be applied. On the other hand, the sampling spacing in image plane calculated by this approach is equal to the pixel size of the CCD. If the lateral resolution in the reconstructed image is higher than that in the CCD, Nyquist sampling criteria can be violated and aliasing errors can be introduced. In this paper, a new method is proposed to solve the problem by investigating convolution reconstruction of digital holograms. The method is that improving the displayed resolution of the reconstructed image meets the need of the high lateral resolution in the reconstructed image. The displayed resolution of the reconstructed image can be improved by appending enough zeros to the angular spectrum between the two FFT’s in convolution reconstruction of digital holograms. Experimental results show a good agreement with theoretical analysis.更多还原