Patent ID: 6111671
Filing Date: 2000-08-29
Classification: G06K

Abstract:
An optical apparatus suited for recording fingerprint hologram matched filters comprising in combination:a. a scanner for generating a flat, dimensionally undistorted, high contrast, fingerprint light image;b. a recording, intensity sensitive, spatial light modulator (RSLM) having planar write and read faces receiving the flat, dimensionally undistorted, high contrast fingerprint light image from the scanner on its write face,c. a common source of coherent light providing a collimated, coherent light, object beam and a collimated, coherent light, reference beam wherein:(i) the object beam is directed to the planar read face of the recording spatial light modulator (RSLM) for transforming the received, flat, high contrast fingerprint image received by the planar `write` face of the spatial light modulator (RSLM) into a planar coherent light fingerprint image; and(ii) the reference beam is directed to a hologram plane located an optical path length (MF) from the read face of the spatial light modulator (RSLM) determined for assuring phase correlation with an interrogating, coherent light object beam image of a fingerprint read from a read face of a verifying spatial light modulator (VSLM) of a verification optical fingerprint apparatus,d. means for optically directing the planar, coherent light fingerprint image from the spatial light modulator to a Fourier transform focus creating a coherent light, phase distribution image of the fingerprint in a focal plane;e. a lens optically expanding the coherent light, phase distribution image of the fingerprint in the focal plane;f. an optical element blocking a central region of the expanded, coherent light, phase distribution image of the fingerprint eliminating a central region from the phase distribution image;g. means for optically directing the expanded and blocked coherent light, phase distribution image of the fingerprint to the hologram plane; andh. an optically sensitive material located in the hologram plane for recording a hologram of the reference beam and the expanded and blocked coherent light, phase distribution image of the fingerprint, whereby, the hologram once developed is suitable as a match filter for any verification optical fingerprint apparatus presenting an interrogating, coherent light object beam of a comparison fingerprint, optical path length (MF) from a read face of a verifying spatial light modulator (VSLM).