1.
    发明专利
    未知

    公开(公告)号:NO880371L

    公开(公告)日:1988-08-01

    申请号:NO880371

    申请日:1988-01-28

    Abstract: The technique for optically scanning a finger to produce a fingerprint image involves positioning the finger surface to be optically scanned so that it is exposed and, in particular, is not pressed against a platen. A slit light beam along the length of the forward part of the finger is circumferentially rotated (38) about an axis (x-x) about the nominal center of the finger. A reflected slit light beam carries modulation information which is focused on a linear array of photo-electric transducers (12) to provide the fingerprint image. The interrogating light is coherent, substantially collimated, light. The plane of the interrogating slit light beam and the plane of the reflected modulated slit light beam are coplanar thereby establishing an illumination plane (42). The illumination plane is parallel to the axis of the finger and is rotated about that axis during the interrogating scan. The illumination plane is slightly offset (d) from that rotational axis and the incident light (16) in the illumination plane impinges on the finger surface at a slight off-normal axis. This offset and off-normal incidence creates two dimensional shadowing. The finger surface being interrogated is positioned slightly off of the object plane for the downstream focusing optics thereby creating a constructive destructive interference effect at the image plane defined by the transducers.

    2.
    发明专利
    未知

    公开(公告)号:FI880364A0

    公开(公告)日:1988-01-27

    申请号:FI880364

    申请日:1988-01-27

    Abstract: The technique for optically scanning a finger to produce a fingerprint image involves positioning the finger surface to be optically scanned so that it is exposed and, in particular, is not pressed against a platen. A slit light beam along the length of the forward part of the finger is circumferentially rotated (38) about an axis (x-x) about the nominal center of the finger. A reflected slit light beam carries modulation information which is focused on a linear array of photo-electric transducers (12) to provide the fingerprint image. The interrogating light is coherent, substantially collimated, light. The plane of the interrogating slit light beam and the plane of the reflected modulated slit light beam are coplanar thereby establishing an illumination plane (42). The illumination plane is parallel to the axis of the finger and is rotated about that axis during the interrogating scan. The illumination plane is slightly offset (d) from that rotational axis and the incident light (16) in the illumination plane impinges on the finger surface at a slight off-normal axis. This offset and off-normal incidence creates two dimensional shadowing. The finger surface being interrogated is positioned slightly off of the object plane for the downstream focusing optics thereby creating a constructive destructive interference effect at the image plane defined by the transducers.

    Liquid platen fingerprint image enhancement

    公开(公告)号:AU4132697A

    公开(公告)日:1998-03-06

    申请号:AU4132697

    申请日:1997-08-12

    Abstract: A fingerprint enhancement system has a platen with a liquid contacting and finger-touching surface. Two collimated interrogating light beams lie below and are opposite sides of the finger-touching surface. The horizontal extensions of the light beams assume an angle of approximately forty-five degrees with the finger longitudinal axis. Side surfaces of the platen are oriented normal to the incident colliminated light beams prior to interrogation. The light beam modulated by the fingerprint passes to a reflecting mirror, imaging means and a scanner below the platen. A polarizing filter lies between the platen and reflecting mirror. A second polarizing filter lies above the platen. A contrast enhancement circuit increases the modulation of the scanned fingerprint signal and automatically adjusts the level of the modulated signal without saturation. Circuit filtering eliminates spurious input signals. Finger position sensing by a light emitting diode and photo transistor is also provided.

    4.
    发明专利
    未知

    公开(公告)号:FI880364A

    公开(公告)日:1988-07-30

    申请号:FI880364

    申请日:1988-01-27

    Abstract: The technique for optically scanning a finger to produce a fingerprint image involves positioning the finger surface to be optically scanned so that it is exposed and, in particular, is not pressed against a platen. A slit light beam along the length of the forward part of the finger is circumferentially rotated (38) about an axis (x-x) about the nominal center of the finger. A reflected slit light beam carries modulation information which is focused on a linear array of photo-electric transducers (12) to provide the fingerprint image. The interrogating light is coherent, substantially collimated, light. The plane of the interrogating slit light beam and the plane of the reflected modulated slit light beam are coplanar thereby establishing an illumination plane (42). The illumination plane is parallel to the axis of the finger and is rotated about that axis during the interrogating scan. The illumination plane is slightly offset (d) from that rotational axis and the incident light (16) in the illumination plane impinges on the finger surface at a slight off-normal axis. This offset and off-normal incidence creates two dimensional shadowing. The finger surface being interrogated is positioned slightly off of the object plane for the downstream focusing optics thereby creating a constructive destructive interference effect at the image plane defined by the transducers.

    5.
    发明专利
    未知

    公开(公告)号:DK47288D0

    公开(公告)日:1988-01-29

    申请号:DK47288

    申请日:1988-01-29

    Abstract: The technique for optically scanning a finger to produce a fingerprint image involves positioning the finger surface to be optically scanned so that it is exposed and, in particular, is not pressed against a platen. A slit light beam along the length of the forward part of the finger is circumferentially rotated (38) about an axis (x-x) about the nominal center of the finger. A reflected slit light beam carries modulation information which is focused on a linear array of photo-electric transducers (12) to provide the fingerprint image. The interrogating light is coherent, substantially collimated, light. The plane of the interrogating slit light beam and the plane of the reflected modulated slit light beam are coplanar thereby establishing an illumination plane (42). The illumination plane is parallel to the axis of the finger and is rotated about that axis during the interrogating scan. The illumination plane is slightly offset (d) from that rotational axis and the incident light (16) in the illumination plane impinges on the finger surface at a slight off-normal axis. This offset and off-normal incidence creates two dimensional shadowing. The finger surface being interrogated is positioned slightly off of the object plane for the downstream focusing optics thereby creating a constructive destructive interference effect at the image plane defined by the transducers.

    7.
    发明专利
    未知

    公开(公告)号:DK47288A

    公开(公告)日:1988-07-30

    申请号:DK47288

    申请日:1988-01-29

    Abstract: The technique for optically scanning a finger to produce a fingerprint image involves positioning the finger surface to be optically scanned so that it is exposed and, in particular, is not pressed against a platen. A slit light beam along the length of the forward part of the finger is circumferentially rotated (38) about an axis (x-x) about the nominal center of the finger. A reflected slit light beam carries modulation information which is focused on a linear array of photo-electric transducers (12) to provide the fingerprint image. The interrogating light is coherent, substantially collimated, light. The plane of the interrogating slit light beam and the plane of the reflected modulated slit light beam are coplanar thereby establishing an illumination plane (42). The illumination plane is parallel to the axis of the finger and is rotated about that axis during the interrogating scan. The illumination plane is slightly offset (d) from that rotational axis and the incident light (16) in the illumination plane impinges on the finger surface at a slight off-normal axis. This offset and off-normal incidence creates two dimensional shadowing. The finger surface being interrogated is positioned slightly off of the object plane for the downstream focusing optics thereby creating a constructive destructive interference effect at the image plane defined by the transducers.

    8.
    发明专利
    未知

    公开(公告)号:NO880371D0

    公开(公告)日:1988-01-28

    申请号:NO880371

    申请日:1988-01-28

    Abstract: The technique for optically scanning a finger to produce a fingerprint image involves positioning the finger surface to be optically scanned so that it is exposed and, in particular, is not pressed against a platen. A slit light beam along the length of the forward part of the finger is circumferentially rotated (38) about an axis (x-x) about the nominal center of the finger. A reflected slit light beam carries modulation information which is focused on a linear array of photo-electric transducers (12) to provide the fingerprint image. The interrogating light is coherent, substantially collimated, light. The plane of the interrogating slit light beam and the plane of the reflected modulated slit light beam are coplanar thereby establishing an illumination plane (42). The illumination plane is parallel to the axis of the finger and is rotated about that axis during the interrogating scan. The illumination plane is slightly offset (d) from that rotational axis and the incident light (16) in the illumination plane impinges on the finger surface at a slight off-normal axis. This offset and off-normal incidence creates two dimensional shadowing. The finger surface being interrogated is positioned slightly off of the object plane for the downstream focusing optics thereby creating a constructive destructive interference effect at the image plane defined by the transducers.

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