Optical System Design for Noncontact, Normal Incidence, THz Imaging of in vivo Human Cornea
Shijun Sung (University of California)
Shahab Dabironezare (TU Delft - Tera-Hertz Sensing)
Nuria Llombart (TU Delft - Tera-Hertz Sensing)
Skyler Selvin (University of California)
Neha Bajwa (University of California)
Somporn Chantra (University of California)
Bryan Nowroozi (University of California)
James Garritano (University of California)
Jacob Goell (University of California)
Alex Li (University of California)
Sophie X. Deng (TU Delft - OLD Complex Projects)
Elliott Brown (Wright State University)
Warren S. Grundfest (University of California)
Zachary D. Taylor (University of California)
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Abstract
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.