Patent ID: 6507391
Filing Date: 2003-01-14
Classification: G01N,G02B,G06T

Abstract:
A velocity measurement system for determining an indication of a velocity of an object passing through a field of view, comprising:(a) an optical element disposed to direct light traveling from an object passing through the field of view along a collection path; (b) at least one optical grating of substantially uniform pitch disposed in the collection path, said at least one optical grating modulating the light traveling along the collection path to produce modulated light having a modulation frequency proportional to a velocity of an object passing through the field of view; (c) at least one light sensitive detector on which the modulated light is incident, said at least one light sensitive detector producing an electrical signal responsive to the modulated light; (d) means for processing the electrical signal in the time domain to determine the indication of the velocity.