Optical finger print detector e.g. for access control

摘要

The detector has an image shot part (4), a source of illumination (3) and an optical block (2) with a limited angle of view. The optical block carries the light from the source to the surface (6) where the finger is placed. The image shot part has a processing unit (5) which is coupled to the light source to synchronise illumination with the taking of the views. The finger surface is alternately illuminated and not illuminated, allowing the image under ambient light to be taken and subtracted from the illuminated image to remove the effects of ambient light.