数字全息成像系统的景深和焦深分析

根据全息理论,分析了数字全息成像系统的景深和焦深.针对数字全息不同的记录光路结构,分别给出了焦深的近似表达式.结果表明：数字全息系统的景深和焦深不仅与记录波长以及记录时的数值孔径有关,还与记录时参考光波的偏置情况有关；在记录距离和CCD参量一定的条件下,离轴无透镜傅里叶变换全息对称偏置下的焦深比非对称偏置下的稍小；显微成像情况下离轴无透镜傅里叶变换全息系统的焦深大于同轴菲涅耳数字全息系统的焦深,计算机模拟表明了结果的正确性.

Analysis of Depth of View and Focus of Digital Holographic Imaging System

Based on the Fresnel diffraction theory, the depth of view (DOV) and the depth of focus (DOF) of the digital holographic system are analyzed. The approximate expressions of the DOF of the different holographic recording configurations are deduced. The results show that the DOV and DOF of the digital holographic imaging system are related to the optical wavelength and the numerical aperture of the CCD camera and to the offset of the reference light wave. With both the same recording distance and parameter of CCD, the DOF of the off-axis Fresnel holographic system is found larger than that of the in-line Fresnel digital holographic system. The DOF of off-axis lensless Fourier digital holographic system with symmetrical offset of reference wave is slightly smaller than that of the system without symmetrical offset. Moreover, in digital holographic microscopy, the DOF of off-axis lensless Fourier digital holographic system is larger than that of in-line Fresnel digital holographic system. The computer simulation results confirm the validity of the theoretical analysis.