Lin Yunyi, Dong Liang, Chen Haige, Huang Sujuan
Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, Shanghai University, Shanghai 200072, China.
Department of Urology, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200072, China.
Biomed Opt Express. 2017 Dec 4;9(1):1-13. doi: 10.1364/BOE.9.000001. eCollection 2018 Jan 1.
Off-axis digital holography (DH) has great potential in histopathology for its high efficiency and precision. Phase distribution, usually extracted by the angular spectrum (AS) algorithm from a digital hologram, reflects important structural information of biological tissues. However, the complex structure of tissues introduces spectrum aliasing of the hologram, making the AS algorithm hard to realize and accurate phase analysis difficult to conduct. Here, we present a hybrid reconstruction algorithm, combining Fresnel reconstruction in spatial domain with the AS algorithm in frequency domain, to solve aliasing by spatial filtering. Through simulation, we demonstrate the feasibility and superiority of the hybrid algorithm and verified the precision (10 rad) of the hybrid algorithm with spectrum aliasing. We extract phase distributions from normal urothelial and bladder cancer tissues by the hybrid algorithm and make quantitative analysis through histogram and standard deviation. The result shows the hybrid algorithm in off-axis DH has great advantage for the high-precision phase extraction of tissues and supplies significant information for cancer diagnosis.
离轴数字全息术（DH）因其高效性和精确性在组织病理学中具有巨大潜力。相位分布通常通过角谱（AS）算法从数字全息图中提取，它反映了生物组织的重要结构信息。然而，组织的复杂结构会引入全息图的频谱混叠，使得AS算法难以实现，精确的相位分析也难以进行。在此，我们提出一种混合重建算法，将空间域中的菲涅耳重建与频域中的AS算法相结合，通过空间滤波来解决混叠问题。通过模拟，我们证明了混合算法的可行性和优越性，并验证了存在频谱混叠时混合算法的精度（10弧度）。我们通过混合算法从正常尿路上皮组织和膀胱癌组织中提取相位分布，并通过直方图和标准差进行定量分析。结果表明，离轴DH中的混合算法在组织高精度相位提取方面具有很大优势，为癌症诊断提供了重要信息。
