Reflection-mode terahertz (THz) imaging of corneal tissue water content (CTWC) is a proposed method for early accurate detection and study of corneal diseases. Despite promising results from ex vivo and in vivo cornea studies, interpretation of the reflectivity data is confounded by the contact between corneal tissue and dielectric windows used to flatten the imaging field. Herein, we present an optical design for noncontact THz imaging of cornea. A beam-scanning methodology performs angular normal incidence sweeps of a focused beam over the corneal surface while keeping the source, detector, and patient stationary. A quasi-optical analysis method is developed to analyze the theoretical resolution and imaging field intensity profile. These results are compared to the electric field distribution computed with a physical optics analysis code. Imaging experiments validate the optical theories behind the design and suggest that quasi-optical methods are sufficient for designing of THz corneal imaging systems. Successful imaging operations support the feasibility of noncontact in vivo imaging. We believe that this optical system design will enable the first, clinically relevant, in vivo exploration of CTWC using THz technology.

中文翻译：

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人体角膜非接触、正常入射、太赫兹成像的光学系统设计

角膜组织含水量 (CTWC) 的反射模式太赫兹 (THz) 成像是一种用于早期准确检测和研究角膜疾病的建议方法。尽管体外和体内角膜研究取得了有希望的结果，但角膜组织和用于展平成像场的介电窗之间的接触混淆了反射率数据的解释。在此，我们提出了一种用于角膜非接触式太赫兹成像的光学设计。光束扫描方法在角膜表面上执行聚焦光束的角法向入射扫描，同时保持源、检测器和患者静止。开发了一种准光学分析方法来分析理论分辨率和成像场强分布。将这些结果与使用物理光学分析代码计算的电场分布进行比较。成像实验验证了设计背后的光学理论，并表明准光学方法足以设计太赫兹角膜成像系统。成功的成像操作支持非接触式体内成像的可行性。我们相信，这种光学系统设计将使使用太赫兹技术对 CTWC 进行首次临床相关的体内探索成为可能。