Apparatus for producing a high contrast visible image from an object

• US 3,906,520 A
• Filed: 08/03/1973
• Issued: 09/16/1975
• Est. Priority Date: 08/03/1973
• Status: Expired due to Term

• Current Assignee: Brian G. Phillips
• Original Assignee: Brian G. Phillips
• Inventors: Phillips, Brian G.
• Primary Examiner(s): Wibert, Ronald L.
• Assistant Examiner(s): Evans, F. L.
• Application Number:
  US05/385,627
• Time in Patent Office: 774 Days
• Field of Search: 350/96B 356/71 340/146.3E 354/62
• US Class Current: 396/15
• CPC Class Codes: A61B 5/1172 using fingerprinting
• CPC Class Codes: G02B 6/06 the relative position of the fibres being the same at both ends, e.g. for transporting images
• CPC Class Codes: G03B 15/00 Special procedures for taking photographs; Apparatus therefor
• CPC Class Codes: G06V 40/1312 direct reading, e.g. contactless acquisition
• CPC Class Codes: G06V 40/63 by static guides

Abstract

A fibre-optic imaging block for producing a high contrast, visible image of an object. A common light entry/exit face of the block is illuminated with light which is totally internally reflected interior of the individual block fibres toward an opposing partially cylindrical angular objective surface. When the object is placed on the objective surface of the block, a high contrast visible image is produced over the entire imaging angle defined by the sector angle of the objective surface. A complementary correction slug eliminates compound distortions introduced by the objective surface configuration. In an alternate embodiment of the imaging block, field distortions are eliminated by forming the individual fibre ends tangent to the objective surface, and a special correction slug is provided for optionally eliminating inclined plane and line curvature distortions. A finger printing system employs the imaging block in combination with a flash lamp and means for viewing the finger print image before recording on film.

Claims

1. An optical imaging device for producing a high contrast image from an object having ridges and valleys, said device comprising:

a fibre optics block comprising a plurality of substantially parallel individual fibres, said block having a planar light input/image output face and an objective surface for surface contact with said ridges of said object, said objective surface being inclined at an angle theta with respect to said planar face, where theta is an angle <

90*, said fibres extending in a direction substantially normal to said planar face.

2. The device of claim 1, wherein said objective surface is concave.

3. The device of claim 2, wherein said concave surface is cylindrical.

4. The device of claim 3, wherein said concave cylindrical surface is inclined at an angle theta lying in the range from about 35* to about 45*.

5. The device of claim 3, wherein the axis of each said fibre lying in a common plane normal to the projection of the axis of said cylindrical surface onto said planar face is substantially normal to the curve formed by the intersection of said plane with said cylindrical surface.

6. An optical imaging system for producing a distortion compensated high contrast image from an object having ridges and valleys, said system comprising:

a fibre optics imaging block comprising a plurality of substantially parallel individual fibres, said block having a planar light input/image output face and an objective surface for receiving said object, said objective surface being inclined at an angle theta with respect to said planar face, where theta is an angle <

90*;

means for illuminating said planar face;

means for projecting the image emerging from said face onto a focal plane; and

a correction device for removing distortions from said projected image, said device comprising a fibre optics block having a plurality of substantially parallel individual fibres, a substantially planar image input face positioned substantially coplanarly with said focal plane, and an output face inclined at an angle gamma with said image input face, said fibres of said correction device fibre optics block extending in a direction substantially normal to said planar image input face.

7. The system of claim 6, wherein said angle gamma equals said angle theta .

8. The system of claim 6, wherein said planar face of said imaging block is inclined at an angle theta 2 with respect to a plane substantially normal to said imaging block fibres;

and said angles are selected so that cos theta cos theta 2 cos gamma .

9. The system of claim 6, wherein said objective surface of said imaging block is concave, and said output face of said correction device is curved with substantially identical curvature to said objective surface.

10. The system of claim 9, wherein said objective surface of said imaging block is cylindrically concave and said output face of said correction device is cylindrically convex.

11. The system of claim 6, wherein said objective surface of said imaging block is cylindrically concave and the axis of each said fibre lying in a common plane normal to the projection of the axis of said cylindrically concave surface onto said planar light input/image output face is substantially normal to the curve formed by the intersection of said plane with said surface, and wherein said individual fibres of said correction device are arranged in planes parallel to the axis of said cylindrically concave objective surface, adjacent ones of said planes being progressively displaced in a first direction with increasing distance along a second direction from a central reference To, said first and second directions being substantially normal to said correction device fibres.

12. A system for generating a high contrast image of a finger print, said system comprising:

an imaging block, comprising a plurality of substantially parallel individual fibres, said block having a planar light input/image output face and an objective surface adapted to be contacted by the ridges of said finger print, said objective surface being inclined at an angle theta with respect to said planar face, where theta is an angle <

90*, said fibres extending in a direction substantially normal to said planar face;

flash lamp means for illuminating said planar face; and

means for projecting the resultant image from said face onto a focal plane.

13. The system of claim 12, wherein said objective surface is concave.

14. The system of claim 13, wherein said concave surface is cylindrical.

15. The system of claim 14, wherein said concave cylindrical surface is inclined at an angle theta lying in the range of from about 35* to about 45*.

16. The system of claim 14 wherein the axis of each said fibre lying in a common plane normal to the projection of the axis of said cylindrical surface onto said planar face is substantially normal to the curve formed by the intersection of said plane with said cylindrical surface.

17. The system of claim 12 further including means for recording said projected image.

18. The system of claim 12, wherein said projecting means includes a focusing lens and a shutter.

19. The system of claim 18, wherein said projecting means further includes a light filter interposed in the path of said projective image.

20. The system of claim 12, further including viewing means for inspecting the image before recording.

21. The system of claim 20, wherein said viewing means includes a mirror and an objective lens.