Research on High-Contrast Portable Fundus Camera

Objetive: To address the inherent limitations of conventional portable non-mydriatic fundus cameras, including the mutual constraints between illumination and imaging optical paths, severe interference from corneal stray light, and the difficulty of achieving simultaneous clear imaging of different retinal regions, this paper proposes a novel fundus optical system design. Method: The proposed system adopts a four-point rectangular illumination layout combined with regionally adjustable illumination intensity. At a pupil diameter of 3.2 mm, the corneal stray light is reduced by 91.56% compared with traditional approaches, enabling high-contrast synchronous imaging of both the optic disc and macular regions. Furthermore, a separated illumination and imaging optical path architecture is employed. By integrating a wire-grid polarizer with a stacked liquid-crystal polarization scheme, stray light caused by optical surface reflections is effectively suppressed. Result: Within a compact system envelope of 230.4 mm × 90 mm, the proposed fundus camera simultaneously achieves a wide field of view of 53°, a refractive error compensation range of ±20 D, and a retinal spatial resolution of 6 μm. Conclusion: The proposed system enables the acquisition of high-contrast retinal images with clearly resolved details of both the optic disc and macula in a single-shot capture, demonstrating its suitability for portable non-mydriatic fundus imaging applications.