Near infrared ink security feature
First Claim
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1. A security feature for authentication of an article comprising:
- a marking on the article, the marking comprising a dye having a substantially narrow absorption band and a maximum absorption wavelength of electromagnetic radiation in the near infrared range;
a first illumination source for emitting an electromagnetic signal having a wavelength substantially identical to the maximum absorption wavelength of the dye;
a second illumination source for emitting an electromagnetic signal having a wavelength less than the wavelength of the first illumination source;
a third illumination source for emitting an electromagnetic signal having a wavelength greater than the wavelength of the first illumination source; and
a detector configured to receive a signal comprising at least one electromagnetic radiation signal emitted by the first, second or third illumination source and reflected by the article, wherein the detector further comprises a differentiator for outputting a differential signal, which is the difference between a first reflective signal and a second reflective signal;
wherein the first reflective signal comprises electromagnetic radiation emitted by the first, second and third illumination sources and the second reflective signal comprises electromagnetic radiation emitted by the second and third illumination sources.
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Abstract
Systems and methods of providing a covert security marking for items such as documents, packaging, credit cards, and other valuable goods to combat the steady increase in forgery, counterfeiting, and other fraudulent activities is presented. A spectrally narrow, near infrared ink system serves as the basis of a covert security feature for items of value. Alternatively, or in combination, metal oxides having a substantially narrow absorption band and a maximum absorption wavelength of electromagnetic radiation in the near infrared range are also utilized.
23 Citations
16 Claims
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1. A security feature for authentication of an article comprising:
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a marking on the article, the marking comprising a dye having a substantially narrow absorption band and a maximum absorption wavelength of electromagnetic radiation in the near infrared range; a first illumination source for emitting an electromagnetic signal having a wavelength substantially identical to the maximum absorption wavelength of the dye; a second illumination source for emitting an electromagnetic signal having a wavelength less than the wavelength of the first illumination source; a third illumination source for emitting an electromagnetic signal having a wavelength greater than the wavelength of the first illumination source; and a detector configured to receive a signal comprising at least one electromagnetic radiation signal emitted by the first, second or third illumination source and reflected by the article, wherein the detector further comprises a differentiator for outputting a differential signal, which is the difference between a first reflective signal and a second reflective signal; wherein the first reflective signal comprises electromagnetic radiation emitted by the first, second and third illumination sources and the second reflective signal comprises electromagnetic radiation emitted by the second and third illumination sources.
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2. A method of authenticating an article comprising:
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marking the article with a dye having a substantially narrow absorption band and a maximum absorption wavelength of electromagnetic radiation in the near infrared range; illuminating the article with at least one of a first, second and third illumination sources, the first illumination source for emitting an electromagnetic signal having a wavelength substantially identical to the maximum absorption wavelength of the dye, the second illumination source for emitting an electromagnetic signal having a wavelength less than the wavelength of the first illumination source, the third illumination source for emitting an electromagnetic signal having a wavelength greater than the wavelength of the first illumination source; detecting a first reflective signal comprising an electromagnetic radiation signal emitted by the first, second and third illumination source and reflected by the article; detecting a second reflective signal comprising an electromagnetic radiation signal emitted by the second and third illumination source and reflected by the article; and differentiating the first and second reflective signals to generate a differential signal. - View Dependent Claims (3, 4, 5, 6, 7, 8)
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9. A security feature for authentication of an article comprising:
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a marking on the article, the marking comprising a metal oxide having a substantially narrow absorption band and a maximum absorption wavelength of electromagnetic radiation in the near infrared range; a first illumination source for emitting an electromagnetic signal having a wavelength substantially identical to the maximum absorption wavelength of the metal oxide; a second illumination source for emitting an electromagnetic signal having a wavelength less than the wavelength of the first illumination source; a third illumination source for emitting an electromagnetic signal having a wavelength greater than the wavelength of the first illumination source; and a detector configured to receive a signal comprising at least one electromagnetic radiation signal emitted by the first, second or third illumination source and reflected by the article, wherein the detector further comprises a differentiator for outputting a differential signal, which is the difference between a first reflective signal and a second reflective signal; wherein the first reflective signal comprises electromagnetic radiation emitted by the first, second and third illumination sources and the second reflective signal comprises electromagnetic radiation emitted by the second and third illumination sources.
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10. A method of authenticating an article comprising:
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marking the article with a metal oxide having a substantially narrow absorption band and a maximum absorption wavelength of electromagnetic radiation in the near infrared range; illuminating the article with at least one of a first, second and third illumination sources, the first illumination source for emitting an electromagnetic signal having a wavelength substantially identical to the maximum absorption wavelength of the metal oxide, the second illumination source for emitting an electromagnetic signal having a wavelength less than the wavelength of the first illumination source, the third illumination source for emitting an electromagnetic signal having a wavelength greater than the wavelength of the first illumination source; detecting a first reflective signal comprising an electromagnetic radiation signal emitted by the first, second and third illumination source and reflected by the article; detecting a second reflective signal comprising an electromagnetic radiation signal emitted by the second and third illumination source and reflected by the article; and differentiating the first and second reflective signals to generate a differential signal. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification