Direct discrimination of structured light by humans

Area of Science:

• Optics and Photonics
• Human Vision
• Biophysics

Background:

• Optical spin-orbit states involve polarization-coupled spatial modes.
• The human eye's macula contains radially symmetric dichroic elements.
• Previous research has not explored direct human perception of these optical states.

Purpose of the Study:

• To predict and experimentally verify an entoptic phenomenon for perceiving optical spin-orbit states.
• To investigate the direct perception and discrimination of light states by humans.
• To explore potential applications in characterizing the macula and retina signaling.

Main Methods:

• A psychophysical study was conducted using participants' retinas.
• Optical states with superpositions of circular polarization and orbital angular momentum (OAM) were used.
• Participants viewed distinct profiles induced by light-matter interaction.

Main Results:

• Humans can perceive and discriminate optical spin-orbit states.
• The number of observed azimuthal fringes correlates with the beam's polarization profile.
• Participants achieved 77.6% accuracy in discriminating between OAM states.

Conclusions:

• Direct perception of optical spin-orbit states is achievable through the human visual system.
• This phenomenon enables robust characterization of the macula and retina.
• The findings support experiments using human detectors with nonseparable optical states.