Retinal scan is a part of bio-metrics,the field of science and engineering which develops ways to uniquely identify individual persons. Retina scan requires that the person removes their glasses,place their eye close to the scanner ,stare at a specific point and remain still, and focus on a specified location for approximately 10-15 sec while the scan is completed.A retinal scan involves the use of a low intensity coherent light sources (infrared light). which is projected onto the retina to illuminate the blood vessels which are then photographed and analysed. A coupler is used to read the blood vessel patterns. T he blood filled capillaries absorb more of the infrared light then the surrounding tissues.Because of this their is a variation in the intensity of the reflection. The scanner measures this reflection at 320 points along the beam path.It then assigns an intensity grade between zero and 4;095. Then, the resulting numbers are compressed into an 80-byte computer code, and stored in a data base.This is how , person's retina is scanned with the help of an eye scanner.