Apparatus and method for detecting blood flow

摘要

A method and apparatus for detecting blood flow in or at a subject's fingertip (20) or other body part, in which Doppler-shifted measuring beam radiation (18) is reflected by the red blood cells and re-enters the laser cavity of the laser diode (10), so as to effect changes in operation thereof, such changes being representative of the blood flow. The apparatus may be incorporated in a fingerprint sensor as a “liveness” detector.