Radiant energy – Luminophor irradiation
Reexamination Certificate
1999-09-01
2001-06-12
Hannaher, Constantine (Department: 2878)
Radiant energy
Luminophor irradiation
C250S459100, C235S454000, C235S491000, C359S352000
Reexamination Certificate
active
06246061
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates, in general, to the authentication of media More specifically, the present invention provides methods for authenticating papers and other media, a process for producing counterfeit-resistive items, counterfeit-resistive items, and an apparatus for authenticating documents and other media.
(2) Description of Related Art
The issues of authentication and counterfeit deterrence can be important in many contexts. Bills of currency, stock and bond certificates, credit cards, passports, bills of lading, as well as many other legal documents (e.g., deeds, wills, etc.) all must be reliably authentic to be useful. Authentication and avoidance of counterfeiting can also be important in many less obvious contexts. For example, improved verification/counterfeiting prevention mechanisms would be very useful in, for example, verifying the contents of shipping containers, quickly identifying individuals with particular health or criminal histories, etc.
A wide variety of attempts have been made to limit the likelihood of counterfeiting. For example, some have tried to assure the authenticity of items by putting coded or uncoded markings thereon (e.g., an artist's signature on his or her painting). Unfortunately, as soon as the code is broken—e.g., a counterfeiter learns to duplicate a signature, this method becomes worthless for authentication purposes. In the context of paper products (e.g., currency), counterfeiting-prevention methods have also used two-dimensional authentication mechanisms—e.g., watermarks or special threads incorporated within the paper used to make the currency. These mechanisms are clearly helpful, but they can also be overcome. For example, counterfeiters routinely bleach a one dollar bill (in such a way that the colored threads which mark the special currency paper are not damaged) and then imprint the markings of a one-hundred dollar bill thereon.
Other authentication methods have utilized mechanisms which provide three dimensions of data. For example, the holograms provided on many credit cards provide more variables (i.e., relative to two-dimensional threads or watermarks) which may be precalibrated, and thereafter, used to verify the authenticity of an item. Nevertheless, since holograms have a pre-set, or deterministic, pattern they may also be duplicated, and counterfeit products made. Authentication mechanisms which utilize deterministic patterns are inherently vulnerable to counterfeiting since the counterfeiter, in essence, has a “fixed” target to shoot at. This is the reason that military codes are frequently changed. At the other end of the spectrum, a random authentication mechanism would provide an incessantly “moving” and nonrepeating target which would be practically impossible to duplicate.
Finally, although existing authentication mechanisms provide adequate protection against counterfeiting in some context, increasingly valuable documents require increasingly reliable levels of authentication. Furthermore, current counterfeiters have access to extremely powerful tools—e.g., color photocopying equipment, reverse engineering of semiconductor chips, etc. These factors have combined to provoke strong demand for new methods and mechanisms for authenticating items, especially methods and mechanisms which are less vulnerable to counterfeiting.
SUMMARY OF THE INVENTION
The present invention soles the above-noted problems and overcomes the suboptimizations inherent in the prior art by providing an authentication mechanism utilizing fluorescent dichroic indicators. Fibers or other tubular elements function very well as the indicators. Fluorescent dichroic fibers can provide an extremely reliable means of authentication for a wide variety of products. For example, fluorescent, dichroic fibers may be incorporated into paper used to print currency or laminated into plastic products such as credit cards. Alternatively, fibers may be incorporated into an aerosol dispenser—e.g., for use in verifiably marking container&
Fluorescent dichroic fibers provide authentication mechanisms that are exceptionally difficult to counterfeit. Importantly, the fibers are distributed throughout the media in a random fashion during the production process. Thus the fiber related signature is a random variable rather than a deterministic one. The signature of every item will be different making it more difficult to reverse engineer. For example, two dimensional images (e.g. in the x-y plane) of papers incorporating the inventive fluorescent dichroic fibers provide increased security over the prior art “blue” threads used in currency. A comparison of a white light image and a fluorescence image showing the two dimensional distribution of florescent dichroic fibers provides unique information. Fibers lying at or near the surface of the paper are easily observed by the white light image but are quickly masked below the surface. In a fluorescence image, fibers that lie below the surface are also readily observable. A comparison of the two images provides a signature. Furthermore, processing of the paper (calendaring) further alters this image comparison. The pressing process reduces the fluorescence from the surface fibers while not perturbing the subsurface fibers thus depth information is available by comparing the two images. Hence, even when not utilized in the most preferred mode, the inventive method provides improved authentication relative to previously available methods.
Furthermore, since fluorescent dichroic fibers are used in the invention, the fibers' emission characteristics will also vary depending upon the angular orientation of the fibers within the media relative to a polarized excitation source For example, at a given wavelength, the intensity of electromagnetic energy emitted by the fibers may vary by up to a factor of five depending upon whether the fibers within the media are vertically or horizontally oriented relative to the direction of a linearly polarized excitation source and a parallel polarization analyzer. Hence, the dichroic nature of the fibers provides a fourth variable for each point along the fiber (i.e., x, y, z and dichroism/emission behavior). This makes it exceedingly more difficult to duplicate/counterfeit the media containing the fibers of the invention.
Furthermore, since dichroic fibers are used in the invention, each fluorescent dichroic fiber, through its emission spectrum, can provide data on the fiber's local environment For example, consider the use of the present invention in paper media or in an aerosol application. The local environment of the fluorescent, dichroic fibers cause photon scattering (e.g., the orientation and number density of the paper fibers) and absorption (e.g., varying thickness of the dried carrier vehicle in an aerosol application). This local environment is indirectly observed through the measurement of the fluorescent dichroic fiber's apparent fluorescent anisotropy. The apparent fluorescent anisotropy provides the fourth data dimension. This fourth data dimension has random values because the process of incorporating the inventive fibers into the media is a random process. This preferred mode of utilization of the inventive method provides the greatest improvement to the authentication and makes it extremely difficult to duplicate/counterfeit the media containing the fibers of the invention.
In addition to increased security relative to prior art methods, the invention provides an authentication mechanism of varying levels of imperviousness to counterfeiting. Depending upon the security/authentication requirements of the particular application, and hence the permissible level of expense, the user may employ the inventive method in any of several modes of operation. For example, at the first level (i.e., the lowest authentication/lowest cost), an item having fluorescent dichroic fibers incorporated therewith may merely be checked to see that the fluorescent fibers are present in the item. Even this level of authe
Klatt Leon N.
Ramsey J. Michael
Gagliarol Albert
Hannaher Constantine
Hardaway/Mann IP Group
O'Toole J. Herbert
UT-Battelle LLC
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