ANNULAR LIGHT SOURCE DEVICE FOR FUNDUS CAMERAS

A device has a light guide portion and a light collector portion. The light guide portion is cup shaped. The wall of the cup has a cross section defined by sections of two ellipses disposed in a predefined manner with each other. The light collector portion is also cup-shaped, inverted with reference to the light guide portion, by a section of an ellipse and straight lines defined with reference to the light guide portion. The device radiates an annular illumination at the rim of the cup through total internal reflection of light from an LED, collected by the light collector portion. The device is made of a clear, colourless, substantially transparent material by injection moulding, one example being Polycarbonate. An annular light source system and a fundus camera using such a system are also disclosed.