Optical identification element using separate or partially overlapped diffraction gratings
First Claim
1. An optical identification element, comprising:
- an optical substrate;
at least a portion of said substrate having at least one diffraction grating disposed therein, said grating having at least one refractive index pitch superimposed at a common location;
the grating providing an output optical signal when illuminated by an incident light signal; and
said optical output signal being indicative of a code.
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Accused Products
Abstract
An optical identification element 8 includes an optical substrate 10 having at least one diffraction grating 12 disposed therein. The grating 12 has a one or more of collocated pitches A which represent a unique identification N bit digital code that is detected when illuminated by incident light 24. The incident light 24 may be directed transversely onto the side or onto an end of the substrate 10 with a narrow band (single wavelength) or multiple wavelength source, in which case the code is represented by a spatial distribution of light or a wavelength spectrum, respectively. The element 8 can provide a large number of unique codes, e.g., greater than 67 million codes, and can withstand harsh environments. The element 8 can be used in any application that requires sorting, tagging, tracking or identification, and can be made on a micron scale “microbeads” if desired, or larger “macro-elements” for larger applications. The code may be digital binary or may be other numerical bases.
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Citations
19 Claims
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1. An optical identification element, comprising:
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an optical substrate;
at least a portion of said substrate having at least one diffraction grating disposed therein, said grating having at least one refractive index pitch superimposed at a common location;
the grating providing an output optical signal when illuminated by an incident light signal; and
said optical output signal being indicative of a code. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A microparticle comprising:
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an optical substrate;
at least a portion of said substrate having at least one diffraction grating disposed therein, said grating having at least one refractive index pitch superimposed at a common location;
the grating providing an output optical signal when illuminated by an incident light signal; and
said optical output signal being indicative of a code in said substrate.
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19. A method of reading a code in an optical identification element, comprising:
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obtaining an optical substrate at least a portion of which having a diffraction grating with one or more refractive index pitches superimposed at a common location; and
illuminating said substrate with incident light, said substrate providing an output light signal;
reading said output light signal and detecting a code therefrom.
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Specification