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Updated: Apr 20, 2026
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Uncovering Hidden Dynamics of Natural Photonic Structures Using Holographic Imaging
Published on: March 31, 2022
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Human infrared vision is triggered by two-photon chromophore isomerization
Grazyna Palczewska1, Frans Vinberg2, Patrycjusz Stremplewski3
1Department of Medical Devices, Polgenix, Inc., Cleveland, OH 44106;
Summary
Humans can see infrared light through a nonlinear optical process involving two-photon isomerization of visual pigments in the retina. This expands the known spectrum of human visual perception beyond visible light wavelengths.
Area of Science:
- Ophthalmology
- Biophysics
- Quantum Optics
Background:
- Human vision is typically limited to the 400-720 nm visible light spectrum.
- Photoreceptor cells in the retina utilize visual pigments for light detection.
- The eye's structure and pigment absorption spectra define current visual perception limits.
Purpose of the Study:
- To investigate the potential for human perception of infrared (IR) light.
- To determine the mechanism by which photoreceptors respond to near-IR wavelengths.
- To explore nonlinear optical processes in visual pigment activation.
Main Methods:
- Psychophysical experiments to assess human perception of IR laser emission.
- Biochemical assays using rhodopsin, cone pigments, and a chromophore model.
- Quantum mechanics modeling to validate proposed mechanisms.
- Measurement of photoreceptor sensitivity and laser power dependence.
Main Results:
- Humans can perceive near-infrared laser emission as visible light.
- Mammalian photoreceptors are activated by near-IR light, with sensitivity increasing above 900 nm.
- A quadratic dependence on laser power indicates a nonlinear optical process.
- Two-photon chromophore isomerization was biochemically demonstrated and computationally validated.
Conclusions:
- Human visual perception of near-infrared light is possible.
- This perception occurs via a two-photon isomerization mechanism of visual pigments.
- Near-IR light can activate photoreceptors through nonlinear optical processes, expanding known visual capabilities.
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