Diffraction grating-based optical identification element

• US 20040233485A1
• Filed: 09/12/2003
• Published: 11/25/2004
• Est. Priority Date: 08/20/2002
• Status: Active Grant

• Current Assignee: Illumina Incorporated
• Original Assignee: Illumina Incorporated
• Inventors: Putnam, Martin A., Moon, John A.
• Granted Patent: US 7,106,513 B2
• Time in Patent Office: Days
• US Class Current: 359/2
• CPC Class Codes: B01J 2219/005 Beads
• CPC Class Codes: B01J 2219/0056 Raised or sunken areas
• CPC Class Codes: G06K 19/06009 with optically detectable marking G06K19/063, G06K19/08 take precedence
• CPC Class Codes: G06K 2019/06234 miniature-code
• CPC Class Codes: G06K 2019/0629 Holographic, diffractive or retroreflective recording
• CPC Class Codes: G06K 7/1094 the record carrier being at least partially of the hologram type
• CPC Class Codes: G07D 7/0032 using holograms
• CPC Class Codes: G07D 7/004 using digital security elements, e.g. information coded on a magnetic thread or strip

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 colocated 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.

Claims

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.

2. The apparatus of claim 1 wherein said substrate is made of a glass material.

3. The apparatus of claim 1 wherein said code comprises a plurality of bits.

4. The apparatus of claim 1 wherein the number of pitches is indicative of the number of said bits in said code.

5. The apparatus of claim 1 wherein said substrate has a length that is less than about 500 microns.

6. The apparatus of claim 1 wherein said substrate has a cylindrical shape.

7. The apparatus of claim 1 wherein said grating is a blazed grating.

8. The apparatus of claim 1 wherein said code comprises a plurality of bits, each bit having a plurality of states.

9. The apparatus of claim 1 wherein said substrate has a reflective coating disposed thereon.

10. The apparatus of claim 1 wherein said substrate is has a magnetic or electric charge polarization.

11. The apparatus of claim 1 wherein said substrate has a grating region where said grating and a non-grating region where said grating is not located;

and wherein said substrate has a plurality of grating regions.

12. The apparatus of claim 1 wherein said substrate has geometry having holes therein.

13. The apparatus of claim 1 wherein said substrate is has a geometry having protruding sections.

14. The apparatus of claim 1 wherein at least a portion of said substrate is has an end cross sectional geometry selected from the group:

circular, square, rectangular, elliptical, clam-shell, D-shaped, and polygon.

15. The apparatus of claim 1 wherein at least a portion of said substrate is has a side view geometry selected from the group:

circular, square, rectangular, elliptical, clam-shell, D-shaped, and polygon.

16. The apparatus of claim 1 wherein at least a portion of said substrate is has a 3-D shape selected from the group:

sphere, a cube, a pyramid.

17. The apparatus of claim 1 wherein said code comprises at least a predetermined number of bits, said number being:

3, 5, 7, 9, 10, 12, 14, 16, 18, 20, 24, 28, 30, 40, 50, or 100.

18. A microparticle 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 in said substrate.

19. A method of reading a code in an optical identification element, comprising:

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.