Direct finger reading

Claim 2

Method of direct reading of a finger object, characterized by the steps of illuminating the finger object (F) with a substantially coherent, substantially collimated light beam (16) having an interrogating zone in the form of a slit, the light rays in the interrogating zone defining an interrogating light beam in the form of a plane, said plane being substantially perpendicular to the surface of the finger (F) being interrogated, and scanning the interrogating light rays that define said plane across said finger (F).

Claim 3

Method according to claim 1, characterized in that said plane is substantially parallel to a predetermined axis, said predetermined axis being approximately coincident with the axis of the finger (F) to be interrogated.

Claim 4

Method according to claim 2, characterized in that said plane intersects said predetermined axis.

Claim 5

Method according to claim 2, characterized in that said step of scanning is along a direction substantially perpendicular to said plane.

Claim 6

Method according to claim 1, characterized in that said step of illuminating and scanning provides a reflected light beam (22) having a modulated zone, the light rays in said modulated zone defining a light beam in the form of a second plane, said second plane being substantially perpendicular to the surface of the finger (F) being interrogated and being substantially co-planar with said plane of said interrogating light beam (16).

Claim 7

Method according to claim 5, characterized by the step of focusing the image carried by a reflected modulated light beam (22) onto a linear array (12) of photoelectric transducers downstream from the finger (F) being interrogated.

Claim 8

Method according to claim 5, characterized in that said step of focusing provides a resolution of said transducers at least as fine as 0.04 mm of finger surface per pixel.

Claim 9

Method according to claim 1, characterized by the step of supporting said finger (F) in a substantially predetermined position and orientation with a support (38) that leaves a predetermined portion of said finger (F) uncovered to permit the direct interrogation of said portion by said interrogating light beam (16).

Claim 10

Method according to claim 1, characterized in that the interrogating light rays are incident on the finger surface being interrogated at a predetermined off-normal angle within said normal plane.

Claim 11

Optical finger image processing apparatus for carrying out the method according to claims 1 to 9, characterized by finger support means (38) adapted to support a finger (F) thereon such that a forward portion of any finger supported thereon will extend beyond a forward edge of said support means (38), means (14) to generate a coherent, substantially collimated light beam (16) positioned such that it can interrogate a portion of a finger (F) extending beyond said edge of said support means (38) to provide a reflected light beam (22) containing fingerprint information, and photo-electric transducer means (12) optically downstream from said finger support means (38) and positioned to receive the fingerprint image carried by said modulated light beam (22), said interrogating light beam (16) having an interrogating zone in the form of a slit, light rays in said interrogating zone defining the interrogating portion of said light beam (16) in the form of a plane, said plane being substantially perpendicular to the surface of the finger (F) being interrogated, said reflected light beam (22) including a modulated zone representing the reflection from said interrogating beam (16), said modulated zone being in the form of a plane, the plane of said modulated zone and the plane of said interrogating zone being substantially coplanar.

Claim 12

Apparatus according to claim 10, characterized in that the image provided at said transducer means (12) has a resolution at least as fine as 0.04 mm of finger surface per pixel.

Claim 13

Apparatus according to claim 10, characterized by an imaging lens means (24, 26) positioned in said reflected light beam (22), said imaging lens means (24, 26) capable of augmenting depth of focus to thereby produce a focused fingerprint image at said array (12).

Claim 14

Apparatus according to claim 10, characterized by cylindrical lens means (18, 20) positioned in the path of said coherent substantially collimated light beam (16) to shape said light beam (16) into said plane format.

Claim 15

Apparatus according to claim 12, characterized by cylindrical lens means (18, 20) positioned in the path of said coherent substantially collimated light beam (16) to shape said light beam (16) into said plane format.

Claim 16

Apparatus according to claim 12, characterized in that the image provided at said transducer means (12) has a resolution at least as fine as 0.04 mm of finger surface per pixel.

Claim 17

Apparatus according to claim 13, characterized in that the image provided at said transducer means (12) has a resolution at least as fine as 0.04 mm of finger surface per pixel.

Claim 18

Apparatus according to claim 14, characterized in that the image provided at said transducer means (12) has a resolution at least as fine as 0.04 mm of finger surface per pixel.

Claim 19

Apparatus according to claim 12, characterized in that said imaging lens means (24, 26) comprises first and second imaging lenses positioned in the path of said reflected light beam (22), said portion of said finger (F) extending beyond said edge of said support (38) being positioned generally at the front focal plane of said first imaging lens (24), said transducer means (12) being positioned at the back focal plane of said second imaging lens(26).

Claim 20

Apparatus according to claim 10, characterized by a fingertip positioner (36) spaced a predetermined distance from said edge of said finger support (38) to aid in supporting said finger (F).