Abstract:
A portable token and systems and methods for identification and authentication of the same are disclosed. The portable token may be utilized for a variety of purposes and uses a thin section of rock as a unique identifying element, which is extremely resistant to forgery or duplication. Identification and authorization of tokens is achieved by a system that uses optical examination of the microstructure and the refractive properties of crystalline minerals within the identifying element, by transmitted polarized light techniques. Comparison between stored reference data and acquired examination data is the basis for verifying authenticity. The naturally-occurring three-dimensional orientations of the optical axes of mineral crystals contribute to the identification information by their effects.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to systems and methods for identifying and authenticating portable tokens, typically used to control access, by a person, to an entity, a benefit or a process. Another area of use is in the association of a token with one or more entities as an indicator of valid registration or allowance. The technical fields of transmitted-light optics, data-storage and handling, petrology, polarizing microscopes and crystallography are relevant to the invention. 
     2. Description of the Related Art 
     Identifying and authenticating tangible articles, particularly high-value items, as being genuine is an important function that has a long history as prior art. The art of photography and, more recently, electro-optical image recording, has enabled comparisons between an original and a suspect object, as exemplified in U.S. Pat. No. 5,521,984, where a reflected light microscope is used to make an image of very fine detail of subjects such as paintings, sculptures, stamps, gemstones, or of an important document. Forgery of an original work, or of an anti-counterfeiting device that is associated with goods of generally similar appearance, is a driving force for the art of authentication systems. 
     Though biometric and fingerprint identification systems may supersede many token-based access-control systems, an agreement without a document or a physical device has little weight in law: documents and devices are likely to persist as bonds of valid registration, allowance or entitlement. 
     The rates of ‘false-accepts’ and ‘false-rejects’ are important to the utility of any authentication system and closely related to the value of the entity or situation being controlled or to the security level required. A high ‘false-reject’ rate will lose consumer-confidence in the system, affecting both parties. A high-security facility or a passport-control may generally tolerate higher ‘false-rejects,’ to the inconvenience of some person, with no ‘false-accepts.’ Similarly, for very high value items both rates should be close to zero. The examination and comparison processes can be precise and accurate, as exemplified in the U.S. Pat. No. 5,521,984 previously referred to, leaving overall security weakness in identification in the domain of the data-handling and storing processes employed. 
     The field of anti-counterfeiting devices for mid-price consumer goods and credit-cards has led to many inventions for two-dimensional devices for that market, including stamped transmission holograms and various improved diffractive optical devices. The utility of reflection holograms has some difficulties in cost and suitable materials: all holograms have limitations in scaling the subject matter. Some of these devices may be optically duplicated, however, and most have master dies that could be duplicated or misappropriated. In many cases these devices are read, the data is ‘digested’ and then compared to accompanying data. Abrasion-wear or flexing damage can cause problems with reading the authentic device and lead to higher ‘false-rejects.’ False-rejects&#39; often require intervention by a human-being. 
     Some methods for device and document authentication use reflected coherent light as a method of obtaining a characteristic signature of the subject, as exemplified in U.S. Pat. No. 7,812,935. Generally, methods using speckle, complex diffractions or refraction have to contend with minor changes, unconnected with any fraud, causing large alterations in presented properties when read. The minor changes could occur at all points in the subject, e.g. thermal expansion, stress-fracturing, scratches or color-fading; this creates difficulties in establishing identity without using multiple application of statistical percentiles to develop pass criteria, or may require data-digests to be made from encoding schemes held within the reading device. 
     The use of a third dimension, usually depth, in a security device is exemplified in U.S. Pat. No. 4,825,801, where glitter and dye-balls in a hardened resin, as a seal, practically defies successful duplication. This latter example&#39;s high-security application permits adequate time for the examination process. Subsequently, various multiple objects have been set in ‘hardenable’ liquids: by example, U.S. Pat. No. 7,353,994. Qualitatively these seem to be strong devices; quantifying the spatial features in them however, in a reading device, can be problematic. 
     The prior art of creating unique arrangements in a relatively thin security device also includes U.S. Pat. No. 7,793,837, wherein a captive brittle layer in a consumer-card, such as a credit card, is intentionally shattered and the pattern of shards examined for authenticity. 
     BRIEF SUMMARY OF THE INVENTION 
     It is a primary object of the invention to provide a portable-token identification and authentication system, which is more reliable and more often correct at determining identity and authenticity of the portable token than prior systems and methods of the art. 
     Another object of the invention is to provide a portable token that, once fabricated, cannot be duplicated by any person, including the original manufacturer, or by using his data, equipment, materials or knowledge: forgery of any of these portable tokens that the systems and methods could determine as being authentic is considered to be near impossible by any practical means. 
     A further object of the invention is to provide a portable token with a security element that is resistant to color-fading, heat, cold, abrasion, shock and other physical effects that it may encounter in normal handling. Conversely, another object is to be more able to disclose interference with the token than prior systems and methods: forgery attempts principally. 
     The invention uses a thin planar section of naturally-occurring rock of the Earth&#39;s crust as an element subject to identification, being contained within an essentially transparent and portable token. The planar rock section is sufficiently thin to transmit light through the majority of the rock-forming minerals within. Image-forming optics are used with polarized light to form and record luminance, color and chromaticity image-data of the detailed assemblage of rock-forming minerals presented. These image data are then used as a basis for identifying and authenticating the token. Additionally, the invention uses the naturally-occurring three-dimensional orientations of the optical axes of mineral crystals, principally by their effects, to obtain further defining information for use in identifying and authenticating the token. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The drawings of this specification show 4 figures. 
         FIG. 1  depicts a cross-sectional view of an embodiment of a portable token. The cross-section is taken through the assembly shown in  FIG. 2 . 
         FIG. 2  depicts a plan view of an embodiment of a portable token, according to the invention. 
         FIG. 3  depicts an embodiment of the invention in a schematic form: a system to identify and authenticate a portable token. The figure shows a portable token in an apparatus that performs optical examination of the token by transmitted light and shows paths of data through functional sub-systems. In this figure the data-paths for both reference-images and examination-images are shown; in this embodiment a photographic-plate camera is used. 
         FIG. 4  depicts a second embodiment of the invention in a schematic form: a system to identify and authenticate a portable token. The figure shows a portable token in an apparatus that performs optical examination of the token by transmitted light and shows paths of data through functional sub-systems. In this figure the data-paths for both reference-images and examination-images are shown; in this embodiment an electro-optical type of camera is used and sub-systems that perform functions such as image-analysis are shown. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  depicts the cross-section of a portable token according to one embodiment of the invention; portable token  20  includes a transparent planar substrate layer  21 , an adhesive that is essentially transparent to light rays  22 , a planar section of naturally-occurring rock of the Earth&#39;s crust, of less than 250 micrometers in its least dimension, being in part or in whole transmissive of light rays in its least dimension  23 , a transparent planar covering-plate layer  24  and markings  25 , where the substrate layer  21  and covering-plate layer  24  are made of any of the class of materials that are transparent crystalline ceramics or partly-crystalline glass-ceramics, tending to confer strength, abrasion resistance and high optical clarity. The components of portable-token  20  are physically joined together by the optically clear adhesive  22 , the planar section of rock  23  being within the adhesive component  22 . The portable token thus described is, by choice of materials, substantially transparent to wavelengths of light between 250 and 800 nanometers, scratch-resistant, rigid, dimensionally stable and durable. In various embodiments, the portable token may be made physically strong, or it may be made more frangible to suit an application such as a security-seal element. 
     In one embodiment of the invention, the planar section of naturally-occurring rock is fashioned from igneous, metamorphic or sedimentary rock and is made to a thickness of thirty micrometers in its least dimension by the known prior art of manufacturing mineralogical ‘thin-sections.’ The term ‘planar rock section’ shall also be used to refer to item  23  in the Figures. In this same embodiment, the rock shall be selected as being unweathered intact rock that has the preferred properties of: a low proportion of opaque minerals; a substantial proportion of optically anisotropic minerals; and variety in mineral types. A metamorphic schist would typify these preferences for a source of rock, though most crustal rocks suffice. With regard to that same embodiment, the thickness of the planar rock section is sufficient to permit the use of a practicable radiant flux from light source  30  and a practicable sensitivity of the image recording device  38 , while also preserving certain physical attributes of the planar rock section  23 . 
       FIG. 2  depicts a plan view of a portable token  20  according to one embodiment of the present invention, wherein the planar rock section  23  is surrounded by the adhesive  22 , to seal it from the external environment. In this particular embodiment of the invention, markings  25  are present on or within the portable token; the markings depicted in  FIG. 2  are only an example, the markings may be spatial references, alphanumeric symbols, graphical compositions, or encrypted data. A typical example of markings  25  would be a human-readable reference number for the portable token. In other embodiments of the invention, the portable token may have: a shape differing from the rectangular embodiment of  FIG. 1  and  FIG. 2 ; perforations; wave-retarding plates included; polarizing filters included; or colored transparent layers included. 
     An embodiment of the invention, in the form of a system for identifying and authenticating a portable token is depicted in  FIG. 3 , in which functional components, functional arrangements, functional blocks of the system and data-paths are shown. With reference to  FIG. 3 : a source of linear-polarized light is created by the combination of a light source  30 , a means of directing light rays, shown as a condenser-lens assembly  31  and a linear-polarizing plate  32 . The light source  30  may be monochromatic or polychromatic light, produced by known arts of light-sources. According with the known art of microscopy, the linear-polarizer  32  may also be below or within the condenser-lens assembly  31 , and a variable aperture may be present in the condenser-lens assembly  31 . Another embodiment of the invention may, by using a particular light source, be without a condenser-lens assembly  31 . The linear-polarizer  32  may be rotated freely through 360 degrees, about an axis corresponding to the optical axis of the condenser lens, or the path of directed light rays, thus rotating its axis of polarization. 
     In  FIG. 3 , a portable token  20  is placed upon a supporting-stage  33 ; the latter may be translated in three axes, thus enabling translation of the portable token  20  in concert. Linear-polarized light is directed toward the planar rock section  23  in portable token  20 . Notwithstanding the presence of any opaque minerals in it, light rays will be transmitted by planar rock section  23 , in the direction of a means of generating an image. In  FIG. 3 , image-forming optics-part A,  34 , and image-forming optics-part B,  35 , comprise a means of generating an image, by known arts of microscope optics. In one embodiment of the invention, the combination of items  34  and  35  provides a magnification ratio of  30 , at which a large amount of detail may be apparent in item  23 , for practical use. In  FIG. 3  a particular embodiment of the invention is shown, wherein a wave-retarding plate  36  and a linear polarizing plate  37  are interposed between items  34  and  35 : in another embodiment of the invention the wave-retarding plate  36  may be absent, and in another embodiment of the invention the linear polarizing plate  37  may be absent. It is a practical point of configuration that items  36  and  37  be placed between the objective-lens assembly of item  34  and the ocular assembly of item  35 , known to the prior art of polarizing microscopes: the items  36  and  37  may be positioned, in their depicted sequence, elsewhere in the light-path between the portable token  20  and the camera  38  to the same effect. An image formed by the components  34  and  35 , from that light transmitted by portable token  20 , is then recorded by a camera  38 . In the embodiment of the invention shown in  FIG. 3  the camera  38  is a photographic plate camera, from which photographic data is passed through data-paths  39  and  40 , as recorded image data. In another embodiment of the invention, the translation of the portable token  20  in order to obtain different views of it by the camera  38  may be achieved by translating components  30 ,  31 ,  32 ,  34 ,  35 ,  36 ,  37  and  38  in concert while components  33  and  20  remain stationary, or by other combinations of relative translation. 
     The following is a descriptive note on the recorded image data obtained by a particular embodiment of the invention where white polychromatic light is emitted from item  30  and items  36  and  37  are absent, without limitation as to what is obtained therefrom. The recorded image data will typically show: irregular dark areas due to opaque minerals; a complex irregular pattern of lines due to mineral-grain boundaries; fractures; internal cleavage-planes; micro-voids; banding; assemblages of mineral-grains; gross crystal forms; and a range of luminances of individual mineral-grains. In this example, various anisotropic mineral-grains may show color, arising from the different absorption spectra of the ordinary and extraordinary rays in that mineral, in combination; any color in isotropic mineral-grains would arise from a sole absorption spectrum. The recorded image data may thus be described as maps of luminance or chromaticity, or as a combination of luminance and chromaticity representing color. If the polarization axis of item  32  is rotated, then the color and luminance of a particular anisotropic mineral-grain may be seen to change, providing that it is not being viewed in a direction parallel to an optic axis, of which there may be two; this color-change effect is pleochroism and may be used, qualitatively or Quantitatively, to further the identification of the token. In another embodiment of the invention, where the linear polarizing plate  37  is included and its polarization axis is aligned to be orthogonal to that of plate  32 , transparent anisotropic mineral-grains may show luminance-variations under their relative rotation to the pair of polarizing plates and variations of color may be evident; these effects arise from velocity and phase differences between their ordinary and extraordinary rays leading to constructive or destructive interference at different wavelengths when re-combined by polarizing plate  37 . Thus, using various embodiments of the invention, changing attributes for any particular point on a two-dimensional image, or map, may be observed between maps recorded under different relative rotations of the portable token  20  and the polarization axes of polarizing plates  32  and  37 : these changes can be used qualitatively or quantitatively in identifying and authenticating the portable token. 
     In an embodiment of the invention depicted in  FIG. 3 , the system uses the principle of making a set of reference image data, typically under the control of a trusted entity, and then comparing subsequent image data from a portable-token subject to inquiry to that reference image data: substantial sameness is the basis for identifying and authenticating a portable token as being the original item. Referring to  FIG. 3 , image data from camera  38  is passed through data-path  39  when recorded as reference image data; image data from camera  38  is passed through data-path  40  when recorded as image data to be subject to inquiry. Reference image repository  51  is a storage of reference image data, which may be retrieved; examination image repository  41  is a storage of image data to be subject to inquiry, which may also be retrieved. A comparison process  70  retrieves recorded image data from reference image repository  51  and examination image repository  41 . The comparison process  70  seeks a substantial sameness between members of the reference image data set and the members of the examination image data set, it may use various means to search, index, align, scale or register images, or any other action required. The comparison process  70  passes data to an authentication decision subsystem  75 , which may also pass data back to item  70 . The authentication decision subsystem  75  decides whether or not to declare the portable token  20  as authentic based, in the least, upon the data received from the comparison process  70 . The authentication decision subsystem  75  may pass data back to the comparison process  70 , for example, in the form of requests relating to comparison efforts. Data from the authentication decision subsystem  75  is passed to an indicator  80 ; the latter provides a binary logic indication indicative of a declaration by the decision subsystem  75 . The indicator  80  may include: switches, binary state-transitions, or any other means of indication. 
     In an embodiment of the invention depicted in  FIG. 4 , image data from an electronic-imaging camera  38  is passed through data-path  39  when recorded as reference image data and through data-path  40  when recorded as image data to be subject to inquiry. Reference image repository  51  is a storage of reference image data, which may be retrieved; examination image repository  41  is a storage of image data to be subject to inquiry, which may also be retrieved. A photo-printer  44  is connected to examination image repository  41  and a photo-printer  54  is connected to reference image repository  51 , both serve to make physical prints from digital image data. An image analysis subsystem  55  receives two-dimensional image data from the reference image repository  51  and measures and derives attributes and characteristics from a set of images pertaining to a particular token, it may use a computer processor and memory to do this. Image analysis subsystem  55  passes data of measurements, attributes and characteristics into reference-characteristic data repository  57 . Similarly, an image analysis subsystem  45  receives two-dimensional image data from the examined image repository  41  and measures and derives attributes and characteristics from a set of images pertaining to a particular token subject to inquiry, it may use a computer processor and memory to do this. Image analysis subsystem  45  passes data of measurements, attributes and characteristics into examined-characteristic data repository  47 . A comparison process  70  retrieves recorded image data as prints from photo-printer  54 , for reference images, and from photo-printer  44 , for examination images. The comparison process  70  seeks a substantial sameness between members of the reference image data set and the members of the examination image data set. Comparison process  70  also retrieves data of measurements, attributes and characteristics from reference-characteristic data repository  57  and examined-characteristic data repository  47 , and seeks a substantial sameness between those data pertaining to a particular token. 
     In the particular embodiment depicted in  FIG. 4 , an imaging-control subsystem  72  is shown. Imaging-control subsystem  72  may receive commands from the comparison process  70  and may transmit commands to components  30 ,  31 ,  32 ,  33 ,  34 ,  35 ,  36 ,  37  and  38 , with objects including: varying the brightness of item  30 ; varying the polarization-axis of item  32 ; varying the polarization-axis of item  37 ; achieving a relative translation of the planar rock section  23 , to attain a different viewing area or focal point at the planar rock section  23 ; varying the focal points of the image-forming optics  34  and  35 . The imaging-control subsystem  72  may, then, be used to direct and control the apparatus that acquires images of a portable token. 
     In other embodiments of the invention, data in data-paths or storage or repositories may be encrypted as a security measure; data also may be passed bi-directionally through the data-paths between functional sub-units of the system. 
     In other embodiments of the invention, the comparison process  70  may use a computer processor, a computer-readable memory and a processor instruction set to carry out its functions. 
     In other embodiments of the invention, image analysis subsystems  45  and  55  may use a computer processor, a computer-readable memory and a processor instruction set to carry out their functions or to store measured or calculated attributes. 
     In a particular embodiment of the invention, a wave-retarding plate  36  may be included which may, for example, improve measurements of color by presenting a higher ‘order’ of interference-colors having more saturated chromaticities. 
     In a particular embodiment of the invention, certain identifying attributes of one or more mineral grains may be derived to further the verification of identity. In such an embodiment, and using an illustrative example: the color exhibited by a particular mineral grain may change with changes in the angular value between the polarization-axis of the linear-polarized light source and a predetermined axis that is orthogonal to the least dimension of the planar rock section; by noting how this color, or luminance alone, changes with the angle a characteristic can be measured. Such colors may be matched to those in a color space and to a luminance scale: C.I.E.xyY could be used as an absolute color space in such an embodiment, one in which there are coordinates describing chromaticity and luminance. Coordinates from matching the color at each angular value can be put into sets, which may define vector-paths in the color space or luminance scale. Such coordinate sets or vector-paths protect against forgery of an, otherwise, two-dimensional image. When a set of vector-paths is made for a number of suitable mineral grains, they are correlated. 
     One or more features from any embodiment may be combined with one or more features of any other embodiment without departing from the scope of the disclosure. In this specification a recitation of ‘a’, ‘an’ or ‘the’ is intended to mean ‘one or more,’ unless specifically otherwise indicated. 
     The above description is provided to illustrate the main principles of the invention, by examples of various embodiments, and is not to be construed as restrictive. Variations or other embodiments within the scope of the disclosure of the invention may be apparent to those skilled in the art upon review of the foregoing disclosure. Thus, the scope of the disclosure of the invention shall be defined only by the full scope of the claims set forth below.