Use of retinal nerve fiber layer birefringence as an addition to absorption in retinal scanning for biometric purposes

We built a device sensitive to the bireffingence of the retinal nerve fiber layer for biometric purposes. A circle of 20 degrees diameter on the retina was scanned around the optic disk with a spot of light from a 785 nm laser diode. The nonbirefringent blood vessels indenting or displacing the retinal nerve fiber layer were seen as "blips" in the measured bireftingence-derived signal. For comparison, the reflection-absorption signature of the blood vessel pattern in the scanned circle was also measured. The bireftingence-derived signal proved to add useful information to the reflectance-absorption signature for retinal biometric scanning. (c) 2008 Optical Society of America.