An efficient method for rapid, non-contact scanning of human cornea is presented. The optics utilize two, 101.6-mm diameter off-axis parabolic mirrors fed by a goniometrically scanned, planar mirror. An evaluation system at 650 GHz was built and demonstrated ~ 1.5 mm beam radius on target and ~ 30 ^o x 30 ^o field of view. The system was inspired by confocal laser scanning principles and represents a system design where image acquisition time is limited by SNR, not mechanical translation.

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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.@en