A PRISM FINGERPRINT SENSOR USING A HOLOGRAPHIC OPTICAL ELEMENT

摘要

A fingerprint sensor (17) also includes a right angle 45 degree prism (12) with a hypotenuse surface A, a right angle sensor surface B and a right angle transmission surface C. A holographic phase grating (14) is optically coupled to the right angle sensor surface B of the prism (12). The holographic phase grating (14) is oriented such that its diffracting fringe planes (16) diffract planar waveform light totally internally reflecting from the interior surface (18) of the grating (14) to propagate normally back through the right angle transmission surface B of the prism (12).