The polarization sense in human vision

Area of Science:

• Vision Science
• Biophysics
• Optics

Background:

• Animals exhibit differential sensitivity to polarized light orientation.
• The Haidinger's brushes phenomenon, observed since 1844, involves blue-yellow brushes seen when viewing the sky through a polarizer.
• Existing models fail to fully explain the mechanism behind human polarization sensitivity.

Purpose of the Study:

• To propose and validate a novel mechanism for human polarization sensitivity.
• To explain the formation of Haidinger's brushes based on optical principles and retinal geometry.
• To investigate the dynamic properties and inter-eye differences in polarization perception.

Main Methods:

• Applied Fresnel's laws to oblique rays interacting with the cylindrical geometry of foveal blue cones.
• Constructed an artificial eye model to simulate and photograph entoptic phenomena.
• Conducted in vivo and in vitro tests using stationary and dynamic stimuli.

Main Results:

• The proposed model, incorporating cylindrical blue cone geometry and Fresnel's laws, explains extrinsic dichroism and polarization sensitivity.
• Artificial eye models and simulations successfully reproduced entoptic blue-dark brushes.
• Dynamic stimuli revealed a rapid creation and erasing time (approx. 0.1s) for the entoptic image, in addition to a 3s fading time.
• A more regular and symmetrical polarization pattern was observed in the dominant eye.

Conclusions:

• The cylindrical geometry and distribution of foveal blue cones induce extrinsic dichroism, explaining human sensitivity to polarized light.
• The study validates a biophysical model for Haidinger's brushes and polarization vision.
• Polarization sense may offer unexplored information, with potential applications in various fields.