Conference Agenda

Although human vision is traditionally confined to the visible spectrum, recent research has revealed that pulsed near-infrared (NIR) light can be perceived as visible due to two-photon absorption (TPA) in the photoreceptors. This nonlinear optical process enables infrared photons to effectively stimulating the visual pigments in a manner similar to conventional visible-light absorption. This expands our understanding of retinal physiology and opens new possibilities for both fundamental and applied vision research. In this presentation, I will discuss our recent investigations into TPA-mediated vision, including its impact on visual acuity and color perception. Our experimental studies demonstrate that visual resolution under TPA conditions is comparable to that of normal visible-light vision, achieved by scanning a pulsed NIR beam across the retina to form letter stimuli. Furthermore, our psychophysical experiments reveal that perceived hues shift predictably with increasing NIR wavelength (880 to 1100 nm) and radiant power (10 to 30 µW), transitioning from reddish-purple to blue, green, and yellow-green. These findings provide novel insights into the intensity-dependent interplay between single-photon (1P) and two-photon (2P) absorption processes in human vision. Beyond its fundamental implications, TPA vision presents exciting clinical and technological opportunities. It offers a potential method for retinal diagnostics that circumvents ocular opacities. Additionally, the development of TPA-based RGB displays could revolutionize display technologies. This presentation will provide an overview of our key findings, the methodologies employed, and the broader impact of TPA vision research and applications.

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