A no-moving-parts sensor for the detection of eye fixation using polarised light and retinal birefringence information

Abstract

Polarised near-infra-red light is reflected from the foveal area in a detectable bow-tie pattern of polarisation states, offering the opportunity for eye tracking. A coaxial optical transducer was developed, consisting of a laser diode, a polariser, a filter, and a photodetector. Several such transducers may be used to interrogate different spots on the retina, thus eliminating the requirement for scanning systems with moving parts. To test the signal quality obtainable, using just one transducer, a test subject was asked to fixate successively on twelve targets located on a circle around the transducer, to simulate the retina’s being interrogated by twelve sensors placed on a 3⁰ diameter circle surrounding the projection of the fovea. The resulting signal is close to the “ideal” sine wave that would have been recorded from a propeller-type birefringence pattern from a human fovea. The transducer can be used in the detection of fixation for medical and other purposes. It does not require calibration, strict restrictions on head position, or head-mounted appliances.

Keywords:

• Eye fixation
• eye tracking
• retinal scanning
• retinal birefringence sensor

Disclosure statement

The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Funding

This work was partially supported by an Individual Biomedical Research Award from The Hartwell Foundation granted to Boris Gramatikov.