Described over 100 years ago, the Gouy phase anomaly refers to the additional $\pi$ phase shift that is accumulated as a wave passes through focus. It is potentially useful in analyzing any type of phase-sensitive imaging; in light microscopy, digital holographic microscopy (DHM) provides phase information in the encoded hologram. One limitation of DHM is the weak contrast generated by many biological cells, especially unpigmented bacteria. We demonstrate here that the Gouy phase anomaly may be detected directly in the phase image using the z-derivative of the phase, allowing for precise localization of unlabeled, micrometer-sized bacteria. The use of dyes that increase phase contrast does not improve detectability. This approach is less computationally intensive than other procedures such as deconvolution and is relatively insensitive to reconstruction parameters. The software is implemented in an open-source FIJI plug-in.

中文翻译：

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使用古伊相位异常在数字全息显微镜 4D 图像中定位和跟踪细菌

100 多年前描述的 Gouy 相异常是指额外的$\pi$当波通过焦点时累积的相移。它可用于分析任何类型的相敏成像；在光学显微镜中，数字全息显微镜 (DHM) 提供编码全息图中的相位信息。DHM 的一个限制是许多生物细胞，尤其是无色素细菌产生的弱对比度。我们在这里证明，可以使用相位的 z 导数直接在相位图像中检测 Gouy 相位异常，从而可以精确定位未标记的微米级细菌。使用增加相衬的染料不会提高可检测性。这种方法比其他程序（如反卷积）的计算强度较低，并且对重建参数相对不敏感。该软件是在开源斐济插件中实现的。