This invention relates to the use of holographic optical elements in the design and application of biometric scanning instruments used typically for capturing biometric information such as fingerprints and handprints to provide enhanced operational features. Holographic optical elements may be used in place of conventional fingerprint scanning elements, such as platens and prisms, to provide the opportunity for fingerprint scanning manufacturers to reduce product development cycle times, reduce product cost, size, and weight, and provide optical design flexibility not afforded by common glass and plastic refractive optical elements.
The holographic elements may be used to create an active platen. The active platen may be illuminated to project graphical displays on the platen such as time stamps, instructions to users, or feedback on print quality.
Further embodiments, features, and advantages of the present invention, as well as the structure and operation of the various embodiments of the present invention, are described in detail below with reference to the accompanying drawings.
The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.
The present invention will be described with reference to the accompanying drawings. The drawing in which an element first appears is typically indicated by the leftmost digit(s) in the corresponding reference number.
Holography is a method of producing an image by means of optical wave-front reconstruction. In this method, a holographic element is used to reconstruct in detail the wave field emitted by the object to be imaged. To make a holographic image, two optical beams may be used, one of which illuminates the object to be imaged. The other beam, often called a reference beam, is reflected onto an image-capturing screen or plate. Often, the output from a coherent light source (such as a laser) is separated into two beams for the illumination and reference beam purposes. Alternatively, the reference beam may be used to illuminate the object.
The image-capturing screen, or detector, is exposed simultaneously to the reference beam and the reflected light from the object. The resulting interference pattern recorded by the detector constitutes the reconstructed image, called the hologram. A hologram is a special ‘photograph’ of an object that retains information about the phase of waves coming from the actual object. The hologram is illuminated with a monochromatic optical beam (usually a laser beam). Part of the resulting diffracted wave field is a precise, three-dimensional copy of the original wave reflected by the object.
Holographic material is used in biometric scanners, such as live print scanners, to capture biometric data and to provide additional operational features. Embodiments of the present invention describes multiple applications of holographic optical elements for providing several novel operational features including, but not limited to, display, annunciation and control of biometric fingerprint and handprint scanning instruments. These operational features with holographic material can also be utilized in other types of instruments where control, display or operator inputs are required.
While specific configurations and arrangements are discussed, it should be understood that this is done for illustrative purposes only. A person skilled in the pertinent art will recognize that other configurations and arrangements can be used without departing from the spirit and scope of the present invention. It will be apparent to a person skilled in the pertinent art that this invention can also be employed in a variety of other applications.
Holographic material 606 may be configured to act as one or more optical components, such as a lens and/or mirror, at various angles of input light. In this way, holographic material 606 can shape and direct incident reference beams to capture desired images including print images as described herein. When holographic material 606 is illuminated by reference beam 602, a high contrast fingerprint image may be obtained. Reference beam 602 may be produced by, for example, source 616. Typically, the fingerprint image will be due to frustrated total internal reflection (“TIR”) caused by reference beam 602 at the platen surface 604 of the holographic material 606 in the presence of fingerprint ridges or valleys.
In a bright-field illumination embodiment, when a finger, for example, is placed in contact with platen surface 604, the TIR within holographic material 606 is broken by ridges of the finger. Thus, light from reference beam 602 will reflect from areas of platen surface 604 under valleys of the finger, while light absorbed by ridges of the finger will not be reflected. The contrast between the ridges and valleys of the finger form an image 610 that can be viewed by a detector, such as detector 608. In this embodiment, ridges may appear relatively dark while valleys and background areas may appear relatively bright in the captured print image. Further, holographic material 606 can optionally act to focus image 610 onto a detector 608. Additional optical elements or optical systems (not shown) can also be added as a further option if additional beam shaping, focusing, magnifying, or directing of image 610 onto detector 608 is desired.
Alternatively, in a dark-field illumination embodiment light from holographic material 606 on platen 604 may not be directly imaged by detector 608. In a dark-field illumination embodiment, the finger is directly illuminated, and light entering the print ridges is diffused and reflected back into holographic material 606 in the areas where the print ridges contact platen surface 604 and break TIR. The light reflected from the ridges is focused at image 610, thereby producing a representative print image. The valleys and background areas may appear relatively dark while ridges may appear relatively bright in the captured print image. Like the bright-field arrangement, holographic material 606 can optionally act to focus image 610 onto detector 608 to capture image 610 in a dark-field arrangement.
Additional optical elements or optical systems (not shown) can also be added as a further option if additional beam shaping, focusing, magnifying, or directing of image 610 onto detector 608 is desired.
Reference beam 602 causes holographic platen 606 to transmit image 610 to detector 608. Other reference beams, such as reference beam 614 from source 618, may illuminate holographic material 606 to provide holographic material 606 with additional features.
Certain areas of a holographic platen in a live print scanner can be specially illuminated to actively display a user guide on the holographic platen. For example, the user guide may indicate where a user is to place his or her finger or hand.
Similarly, as shown in
Beam source 108 may be controlled by a controller (not shown). In one embodiment, beam source 108 may produce a single illumination beam to illuminate holographic material 100. In another embodiment, beam source 108 may be an array of discrete illumination elements which turn on or off in response to the controller, and which can be used to dynamically change text or graphics on holographic material 100. In yet another embodiment, beam source 108 may be configured to produce an illumination beam which causes holographic material 100 to display predetermined text or graphics, the activation of which is controlled by the controller. In still another embodiment, beam source 108 may pass through an aperture, such as a filter, LCD, or the like, which contains a pattern to be displayed on holographic material 100.
According to a further embodiment, certain areas of a holographic platen in a live print scanner can be specially illuminated to provide a quality feedback indication to a user in a live scan. For instance, such a quality feedback indication can indicate whether a captured print is of acceptable or not acceptable quality. In an example shown in
According to further embodiments, certain areas of a holographic platen in a live print scanner can be specially illuminated to provide control or other information to a user in a live scan. In one example,
In another example,
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
This application claims benefit to U.S. Provisional Pat. Appl. No. 60/603,282, filed Aug. 23, 2004, the disclosure of which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | |
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60603282 | Aug 2004 | US |