Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/02—Details of features involved during the holographic process; Replication of holograms without interference recording
  • G03H1/0272—Substrate bearing the hologram
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
  • B01L3/50—Containers for the purpose of retaining a material to be analysed, e.g. test tubes
  • B01L3/502—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures
  • B01L3/5027—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip
  • B01L3/502761—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip specially adapted for handling suspended solids or molecules independently from the bulk fluid flow, e.g. for trapping or sorting beads, for physically stretching molecules
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
  • B01L3/50—Containers for the purpose of retaining a material to be analysed, e.g. test tubes
  • B01L3/508—Containers for the purpose of retaining a material to be analysed, e.g. test tubes rigid containers not provided for above
  • B01L3/5085—Containers for the purpose of retaining a material to be analysed, e.g. test tubes rigid containers not provided for above for multiple samples, e.g. microtitration plates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00274—Sequential or parallel reactions; Apparatus and devices for combinatorial chemistry or for making arrays; Chemical library technology
  • B01J2219/00277—Apparatus
  • B01J2219/00457—Dispensing or evacuation of the solid phase support
  • B01J2219/00459—Beads
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00274—Sequential or parallel reactions; Apparatus and devices for combinatorial chemistry or for making arrays; Chemical library technology
  • B01J2219/00277—Apparatus
  • B01J2219/00457—Dispensing or evacuation of the solid phase support
  • B01J2219/00459—Beads
  • B01J2219/00461—Beads and reaction vessel together
  • B01J2219/00463—Directed sorting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00274—Sequential or parallel reactions; Apparatus and devices for combinatorial chemistry or for making arrays; Chemical library technology
  • B01J2219/00277—Apparatus
  • B01J2219/00457—Dispensing or evacuation of the solid phase support
  • B01J2219/0047—Pins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00274—Sequential or parallel reactions; Apparatus and devices for combinatorial chemistry or for making arrays; Chemical library technology
  • B01J2219/00277—Apparatus
  • B01J2219/00497—Features relating to the solid phase supports
  • B01J2219/005—Beads
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00274—Sequential or parallel reactions; Apparatus and devices for combinatorial chemistry or for making arrays; Chemical library technology
  • B01J2219/00277—Apparatus
  • B01J2219/0054—Means for coding or tagging the apparatus or the reagents
  • B01J2219/00547—Bar codes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00274—Sequential or parallel reactions; Apparatus and devices for combinatorial chemistry or for making arrays; Chemical library technology
  • B01J2219/00277—Apparatus
  • B01J2219/0054—Means for coding or tagging the apparatus or the reagents
  • B01J2219/00572—Chemical means
  • B01J2219/00576—Chemical means fluorophore
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00274—Sequential or parallel reactions; Apparatus and devices for combinatorial chemistry or for making arrays; Chemical library technology
  • B01J2219/0068—Means for controlling the apparatus of the process
  • B01J2219/00702—Processes involving means for analysing and characterising the products
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L2200/00—Solutions for specific problems relating to chemical or physical laboratory apparatus
  • B01L2200/06—Fluid handling related problems
  • B01L2200/0636—Focussing flows, e.g. to laminate flows
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L2200/00—Solutions for specific problems relating to chemical or physical laboratory apparatus
  • B01L2200/06—Fluid handling related problems
  • B01L2200/0647—Handling flowable solids, e.g. microscopic beads, cells, particles
  • B01L2200/0668—Trapping microscopic beads
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L2300/00—Additional constructional details
  • B01L2300/06—Auxiliary integrated devices, integrated components
  • B01L2300/0627—Sensor or part of a sensor is integrated
  • B01L2300/0654—Lenses; Optical fibres
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L2400/00—Moving or stopping fluids
  • B01L2400/04—Moving fluids with specific forces or mechanical means
  • B01L2400/0403—Moving fluids with specific forces or mechanical means specific forces
  • B01L2400/0409—Moving fluids with specific forces or mechanical means specific forces centrifugal forces
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L2400/00—Moving or stopping fluids
  • B01L2400/04—Moving fluids with specific forces or mechanical means
  • B01L2400/0403—Moving fluids with specific forces or mechanical means specific forces
  • B01L2400/0457—Moving fluids with specific forces or mechanical means specific forces passive flow or gravitation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L2400/00—Moving or stopping fluids
  • B01L2400/04—Moving fluids with specific forces or mechanical means
  • B01L2400/0475—Moving fluids with specific forces or mechanical means specific mechanical means and fluid pressure
  • B01L2400/0487—Moving fluids with specific forces or mechanical means specific mechanical means and fluid pressure fluid pressure, pneumatics
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H2210/00—Object characteristics
  • G03H2210/50—Nature of the object
  • G03H2210/53—Coded object not directly interpretable, e.g. encrypted object, barcode
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H2230/00—Form or shape of the hologram when not registered to the substrate
  • G03H2230/10—Microhologram not registered to the substrate
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H2270/00—Substrate bearing the hologram
  • G03H2270/20—Shape
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H2270/00—Substrate bearing the hologram
  • G03H2270/20—Shape
  • G03H2270/24—Having particular size, e.g. microscopic

Definitions

• This invention relates to optical identification, and more particularly to optical elements used for identification or coding using diffraction gratings.
• an optical identification element comprises an optical substrate; at least a portion of the substrate having at least one diffraction grating disposed therein, the 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 the optical output signal being indicative of a code in the substrate.
• the present invention provides an optical element capable of having many optically readable codes.
• the element has a substrate containing an optically readable composite diffraction grating having one or more collocated index spacing or pitches ⁇ .
• the invention allows for a high number of uniquely identifiable codes (e.g., millions, billions, or more).
• the codes may be digital binary codes and thus are digitally readable or may be other numerical bases if desired.
• the element may be made of a glass material, such as silica or other glasses, or may be made of plastic, or any other material capable of having a diffraction grating disposed therein.
• the element may be cylindrical in shape or any other geometry, provided the design parameters are met.
• the elements may be very small “microbeads” (or microelements or microparticles or encoded particles) for small applications (about 1-1000 microns), or larger “macroelements” for larger applications (e.g., 1-lOOOmm or much larger).
• the elements may also be referred to as encoded particles or encoded threads.
• the element may be embedded within or part of a larger substrate or object.
• the code in the element is interrogated using free-space optics and can be made alignment insensitive.
• the gratings are embedded inside (including on or near the surface) of the substrate and may be permanent non-removable codes that can operate in harsh environments (chemical, temperature, nuclear, electromagnetic, etc.).
• the code is not affected by spot imperfections, scratches, cracks or breaks in the substrate.
• the codes are spatially invariant. Thus, splitting or slicing an element axially produces more elements with the same code. Accordingly, when a bead is axially split-up, the code is not lost, but instead replicated in each piece.
• FIG. 1 is a side view of an optical identification element, in accordance with the present invention.
• Fig. 2 is a side view of whole and partitioned optical identification element, in accordance with the present invention.
• Fig. 3 is a side view of an optical identification element, in accordance with the present invention.
• FIG. 4 and 5 are perspective views of an optical identification element, in accordance with the present invention.
• Fig. 6 is a side view of an optical identification element showing one optical reading embodiment, in accordance with the present invention.
• Fig. 7 is an image on a CCD camera of Fig. 6, in accordance with the present invention.
• Fig. 8 is a graph showing an digital representation of bits in a code derived from the image of Fig. 7, in accordance with the present invention.
• FIG. 9 illustrations (a)-(c) show images of digital codes on a CCD camera, in accordance with the present invention.
• Fig. 10 illustrations (a)-(d) show graphs of different refractive index pitches and a summation graph, in accordance with the present invention.
• Fig. 11 is a side view of an optical identification element and optics associated therewith, in accordance with the present invention. 025559
• Figs. 12-15 are side and end views of an optical identification element and optics associated therewith, in accordance with the present invention.
• Fig. 16 is an end view of a beam for an optical identification element, in accordance with the present invention.
• Fig. 17 is a side view of an alternative embodiment of an optical identification element, in accordance with the present invention.
• Fig. 18 is a graph of a plurality of bits within a Bragg envelope of an optical identification element, in accordance with the present invention.
• Fig. 19 shows an alternative optical schematic for reading a code in an optical identification element, in accordance with the present invention.
• Figs. 20-22 are a graphs of a plurality of bits and a Bragg envelope of an optical identification element, in accordance with the present invention.
• Figs. 23-24 are side views of a thin grating for an optical identification element, in accordance with the present invention.
• Fig. 25 is a perspective view azimuthal multiplexing of a thin grating for an optical identification element, in accordance with the present invention.
• Fig. 26 is side view of a blazed grating for an optical identification element, in accordance with the present invention.
• Fig. 27 is a graph of a plurality of states for each bit in a code for an optical identification element, in accordance with the present invention.
• Fig. 28 is a perspective view of a grooved plate for use with an optical identification element, in accordance with the present invention.
• Fig. 29 is a perspective view of a tube for use with an optical identification element, in accordance with the present invention.
• Fig. 30 is a side view an optical identification element having a reflective coating thereon, in accordance with the present invention.
• Figs. 31 and 32 are side views or a groove plate having a reflective coating thereon, in accordance with the present invention.
• Fig. 33-38 are alternative embodiments for an optical identification element, in accordance with the present invention.
• Fig. 39 is a view an optical identification element having a plurality of grating located rotationally around an optical identification element, in accordance with the present invention.
• Fig. 40 is a view an optical identification element having a plurality of gratings disposed on a spherical optical identification element, in accordance with the present invention.
• Fig. 41 illustrations (a)-(e) show various geometries of an optical identification element that may have holes therein, in accordance with the present invention.
• Fig. 42 illustrations (a)-(c) show various geometries of an optical identification element that may have teeth therein, in accordance with the present invention.
• Fig. 43 illustrations (a)-(c) show various geometries of an optical identification element, in accordance with the present invention.
• Fig. 44 is a perspective view of an optical identification element having a grating that is smaller than the substrate, in accordance with the present invention.
• Fig. 45 is a side view of an optical identification element where light is incident on an end face, in accordance with the present invention.
• Fig. 46 is an illustration of input light and output light passing through two mediums, in accordance with the present invention.
• Figs. 47-48 are a side view of an optical identification element where light is incident on an end face, in accordance with the present invention.
• Figs. 49-51 are side views of an optical identification element having a blazed grating, in accordance with the present invention.
• Fig. 52 is a perspective view of a plate with holes for use with an optical identification element, in accordance with the present invention.
• Fig. 53 is a perspective view of a grooved plate for use with an optical identification element, in accordance with the present invention.
• Fig. 54 is a perspective view of a disc shaped optical identification element, in accordance with the present invention.
• Fig. 55 is a side view of Fig. 54, in accordance with the present invention.
• Fig. 56 illustrations (a)-(b) are graphs of reflection and transmission wavelength spectrum for an optical identification element, in accordance with the present invention.
• Fig. 57 illustrations (a)-(b) are side views of an optical identification element polarized along an electric or magnetic field, in accordance with the present invention.
• Fig. 58 is a side view of an optical identification element having a coating, in accordance with the present invention.
• an optical identification element 8 comprises a known optical substrate 10, having an optical diffraction grating 12 disposed (or written, impressed, embedded, imprinted, etched, grown, deposited or otherwise formed) in the volume of or on a surface of a substrate 10.
• the grating 12 is a periodic or aperiodic variation in the effective refractive index and/or effective optical abso ⁇ tion of at least a portion of the substrate 10.
• the substrate 10 has an inner region 20 where the grating 12 is located.
• the inner region may be photosensitive to allow the writing or impressing of the grating 12.
• the substrate 10 has an outer region 18 which does not have the grating 12 therein.
• the grating 12 is a combination of one or more individual spatial periodic sinusoidal variations in the refractive index that are collocated along the length of the grating region 20 of the substrate 10, each having a spatial period (or pitch) A.
• the grating 12 (or a combination of gratings) represents a unique optically readable code, made up of bits. In one embodiment, a bit corresponds to a unique pitch A within the grating 12.
• the grating 12 may also referred to herein as a composite or collocated grating. Also, the grating 12 may be referred to as a "hologram", as the grating 12 transforms, translates, or filters an input optical signal to a predetermined desired optical output pattern or signal.
• the substrate 10 comprises silica glass (SiO 2 ) having the appropriate chemical composition to allow the grating 12 to be disposed therein or thereon. Other materials for the optical substrate 10 may be used if desired.
• the substrate 10 may be made of any glass, e.g., silica, phosphate glass, borosilicate glass or other glasses, or made of glass and plastic, or solely plastic.
• the optical substrate 10 made of a glass material is desirable. If a flexible substrate is needed, a plastic, rubber or polymer-based substrate may be used.
• the optical substrate 10 may be any material capable of having the grating 12 disposed in the grating region 20 and that allows light to pass through it to allow the code to be optically read.
• the optical substrate 10 with the grating 12 has a length L and an outer diameter Dl, and the inner region 20 diameter D.
• the length L can range from very small (about 1-1000 microns or smaller) to large (about 1.0 - 1000 mm or greater).
• the outer dimension Dl can range from small (less than 1000 microns) to large (1.0 - 1000 mm and greater). Other dimensions and lengths for the substrate 10 and the grating 12 may be used.
• the grating 12 may have a length Lg of about the length L of the substrate 10.
• the length Lg of the grating 12 may be shorter than the total length L of the substrate 10, as shown in Fig. 11.
• the 20 of the grating 12 may be less than any corresponding dimension of the substrate 10.
• the grating 12 may be embedded within or part of a much larger substrate 12.
• the element 8, or the grating 12 other dimensions/coordinates for size may be used, e.g., polar or vector dimensions.
• the element 8 may be embedded or formed in or on a larger object for identification of the object.
• the substrate 10 may have end-view cross-sectional shapes other than circular, such as square, rectangular, elliptical, clam-shell, D-shaped, or other shapes, and may have side-view sectional shapes other than rectangular, such as circular, square, elliptical, clam-shell, D-shaped, or other shapes.
• 3D geometries other than a cylinder may be used, such as a sphere, a cube, a pyramid, a bar, a slab, a plate, a brick, or a disc shape, or any other 3D shape.
• the substrate 10 may have a geometry that is a combination of one or more of the foregoing shapes.
• the dimensions, geometries, materials, and material properties of the substrate 10 are selected such that the desired optical and material properties are met for a given application.
• the resolution and range for the optical codes are scalable by controlling these parameters (discussed more hereinafter).
• the substrate 10 may be coated with a polymer material or other material that may be dissimilar to the material of the substrate 10, provided that the coating on at least a portion of the substrate, allows sufficient light to pass transversely through the substrate for adequate optical detection of the code using side illumination.
• the grating 12 is axially spatially invariant.
• the substrate 10 with the grating 12 may be axially subdivided or cut into many separate smaller substrates 30-36 and each substrate 30- 36 will contain the same code as the longer substrate 21 had before it was cut.
• the limit on the size of the smaller substrates 30-36 is based on design and performance factors discussed hereinafter.
• the outer region 18 is made of pure silica (SiO 2 ) and has a refractive index n2 of about 1.458 (at a wavelength of about 1553 nm), and the inner grating region 20 of the substrate 10 has dopants, such as germanium and/or boron, to provide a refractive index nl of about 1.453, which is less than that of outer region 18 by about 0.005.
• dopants such as germanium and/or boron
• the grating region 20 may have an index of refraction that is larger than that of the outer region 18 or grating region 20 may have the same index of refraction as the outer region 18 if desired.
• one pu ⁇ ose of the outer region 18 (or region without the grating 12) of the substrate 10 is to provide mechanical or structural support for the inner grating region 20.
• the entire substrate 10 may comprise the grating 12, if desired.
• the support portion may be completely or partially beneath, above, or along one or more sides of the grating region 20, such as in a planar geometry (Fig. 4), or a D- shaped geometry (Fig.
• the non-grating portion 18 of the substrate 10 may be used for other pmposes as well, such as optical lensing effects or other effects (discussed hereinafter).
• the end faces of the substrate 10 need not be pe ⁇ endicular to the sides or parallel to each other. However, for applications where the elements 8 are stacked end-to-end, the packing density may be optimized if the end faces are pe ⁇ endicular to the sides.
• an incident light 24 of a wavelength ⁇ e.g., 532 nm from a known frequency doubled Nd:YAG laser or 632nm from a known Helium-Neon laser, is incident on the grating 12 in the substrate 10.
• a wavelength ⁇ e.g., 532 nm from a known frequency doubled Nd:YAG laser or 632nm from a known Helium-Neon laser.
• ⁇ is within the optical transmission range of the substrate (discussed more hereinafter).
• a portion of the input light 24 passes straight through the grating 12 as indicated by dashed lines 25.
• the remainder of the light 24 is reflected by the grating
• reflected light 27 each having the same wavelength ⁇ as the input wavelength ⁇ and each having a different angle indicative of the pitches (Al- ⁇ n) existing in the grating 12.
• the grating 12 is a combination of one or more individual sinusoidal spatial periods or pitches A of the refractive index variation along the substrate, each collocated at substantially the same location on the substrate 10 (discussed more hereinafter).
• the resultant combination of these individual pitches is the grating 12 comprising spatial periods ( ⁇ l- ⁇ n) each representing a bit in the code.
• the code is determined by which spatial periods ( ⁇ l- ⁇ n) exist (or do not exist) in a given composite grating 12.
• the code may also be determined by additional parameters as well, as discussed hereinafter.
• the reflected light 26-36 passes through a lens 37, which provides focused light beams 46-56 which are imaged onto a CCD camera 60.
• a lens 37 which provides focused light beams 46-56 which are imaged onto a CCD camera 60.
• other imaging optics may be used to provide the desired characteristics of the optical image/signal onto the camera 60 (e.g., spots, lines, circles, ovals, etc.), depending on the shape of the substrate and input optical signals.
• CCD camera other devices may be used to read/capture the output light.
• the image on the CCD camera 60 is a series of illuminated stripes indicating ones and zeros of a digital pattern or code of the grating 12 in the element 8.
• lines 68 on a graph 70 are indicative of a digitized version of the image of Fig. 7 as indicated in spatial periods ( ⁇ l- ⁇ n).
• Each of the individual spatial periods ( ⁇ l- ⁇ n) in the grating 12 is slightly different, thus producing an array of N unique diffraction conditions (or diffraction angles) discussed more hereinafter.
• the element 8 is illuminated from the side, in the region of the grating 12, at the appropriate angle (discussed hereinafter), with a single input wavelength ⁇ (monochromatic) source, the diffracted (or reflected) beams 26-36 are generated.
• the digital code may be generated by selectively creating individual index variations (or individual gratings) with the desired spatial periods ⁇ l- ⁇ n.
• FIG. 9 illustrations (a)-(c), for the grating 12 in a cylindrical substrate 10 having a sample spectral 17 bit code (i.e., 17 different pitches ⁇ 1- ⁇ 17), the corresponding image on the CCD (Charge Coupled Device) camera 60 is shown for a digital pattern of 7 bits turned on (10110010001001001); 9 bits turned on of (11000101010100111); all 17 bits turned on of (11111111111111).
• Fig. 9 Charge Coupled Device
• the length of the substrate 10 was 450 microns
• the outer diameter Dl was 65 microns
• the inner diameter D was 14 microns
• ⁇ n for the grating 12 was about 10 "4
• nl in portion 20 was about 1.458 (at a wavelength of about 1550 nm)
• n2 in portion 18 was about 1.453
• the average pitch spacing ⁇ for the grating 12 was about 0.542 microns
• the spacing between pitches ⁇ was about
• the pitch ⁇ of an individual grating is the axial spatial period of the sinusoidal variation in the refractive index nl in the region 20 of the substrate 10 along the axial length of the grating 12 as indicated by a curve 90 on a graph 91.
• a sample composite grating 12 comprises three individual gratings that are co-located on the substrate 10, each individual grating having slightly different pitches, ⁇ l, ⁇ 2, ⁇ 3, respectively, and the difference (or spacing) ⁇ between each pitch A being about 3.0 % of the period of an adjacent pitch ⁇ as indicated by a series of curves 92 on a graph 94.
• illustration (c) three individual gratings, each having slightly different pitches, ⁇ l, ⁇ 2, ⁇ 3, respectively, are shown, the difference ⁇ between each pitch ⁇ being about 0.3% of the pitch A of the adjacent pitch as shown by a series of curves 95 on a graph 97.
• the individual gratings in Fig. 9, illustrations (b) and (c) are shown to all start at 0 for illustration pmposes; however, it should be understood that, the separate gratings need not all start in phase with each other. Referring to Fig.
• the overlapping of the individual sinusoidal refractive index variation pitches ⁇ l- ⁇ n in the grating region 20 of the substrate 10 produces a combined resultant refractive index variation in the composite grating 12 shown as a curve 96 on a graph 98 representing the combination of the three pitches shown in Fig. 9, illustration (b).
• the resultant refractive index variation in the grating region 20 of the substrate 10 may not be sinusoidal and is a combination of the individual pitches ⁇ (or index variation).
• the light must be efficiently reflected (or diffracted or scattered) off the grating 12.
• the input angle ⁇ i and the output angle ⁇ o are defined as outside the cylinder substrate 10.
• Eq. 1 applies to light incident on outer surfaces of the substrate 10 which are parallel to the longitudinal axis of the grating (or the k ⁇ vector), or where a line 203 normal to the outer surface is pe ⁇ endicular to the the k ⁇ vector. Because the angles ⁇ i, ⁇ o are defined outside the substrate 10 and because the effective refractive index of the substrate 10 is substantially a common value, the value of n in Eq. 1 cancels out of this equation.
• ⁇ o sin '( ⁇ / ⁇ - sin( ⁇ i)) Eq. 2
• ⁇ i 0.532 microns (or 532 run)
• a grating spacing ⁇ 0.532 microns (or 532 nm)
• the output angle of reflection ⁇ o will be at 43.47 degrees
• the second condition for reading the output light is that the reflection angle ⁇ 0 of the output light must lie within an acceptable region of a "Bragg envelope" 200 to provide an acceptable level of output light.
• the Bragg envelope defines the reflection (or diffraction or scatter) efficiency of incident light.
• ⁇ B half-width
• the output light path angle ⁇ 0 should be at the center of the Bragg envelope.
• the equation governing the reflection or scattering efficiency (or normalized reflection intensity) profile for the Bragg envelope is approximately:
• the reflection efficiency I (Eqs. 3 & 4) is maximized, which is at the center or peak of the Bragg envelope.
• the efficiency decreases for other input and output angles (i.e., ⁇ i ⁇ ⁇ 0 ), as defined by Eqs. 3 & 4.
• the angle ⁇ i of the input light 24 should be set so that the angle ⁇ o of the reflected output light equals the input angle ⁇ i.
• the width of the sin(x)/x function increases and, the coefficient to or amplitude of the sine 2 (or (sin(x)/x) 2 function (and thus the efficiency level across the Bragg envelope) also increases, and vice versa.
• the half-width of the Bragg envelope as well as the efficiency level across the Bragg envelope both decrease.
• ⁇ n should be made as large as possible to maximize the brightness, which allows D to be made smaller.
• ⁇ is a reflection efficiency factor which is the value for x in the sine (x) function where the value of sinc 2 (x) has decreased to a predetermined value from the maximum amplitude as indicated by points 204,206 on the curve 2Q0.
• ⁇ R ⁇ /( ⁇ w) Eq. 6
• ⁇ is the wavelength of the light
• w is the beam half-width (HW) at the focal point (or "beam waist") measured at the point of 1/e 2 of the peak beam intensity (for a Gaussian beam).
• HW beam half-width
• the beam half- width w is determined at the point of incidence on the element 8. As the beam width w decreases, the divergence angle increases (and vice versa). Also, as the wavelength ⁇ of light increases, the beam divergence angle ⁇ R also increases.
• the beam width 2w should be less than the outer dimensions of the substrate 10 by a predetermined beam width factor ⁇ , e.g., about 50% to 80% for each dimension.
• ⁇ e.g., about 50% to 80% for each dimension.
• the beam should be shorter than the longitudinal length L in the axial dimension (side view) and narrower than the diameter of the cylinder in the cross-sectional dimension (end view). Accordingly, for a cylinder substrate 10, the input beam 24 may have a non-circular cross-section.
• the beam 24 half-width w will have a half-width dimension w ⁇ along one dimension (e.g., the length) of the grating 12 and a half-width dimension w2 along the other dimension (e.g., the cross-sectional diameter) of the grating 12.
• Other spot sizes may be used if desired, depending on the amount of end scatter that can be tolerated by the application (discussed more hereinafter).
• the factor ⁇ has a value of 0.5.
• the half- width wl of the incident beam along the grating length L may be about 100-150 microns to avoid end scatter effects.
• the other half-width w2 of the incident beam 24 may be about 15 microns.
• Other spot dimensions may be used if desired, depending on the amount of end scatter that can be tolerated by the application.
• the number of bits N which is equal to the number of different grating pitches A (and hence the number of codes), that can be accurately read (or resolved) using side-illumination and side-reading of the grating 12 in the substrate 10 is determined by numerous factors, including: the beam width w incident on the substrate (and the corresponding substrate length L and grating length Lg), the thickness or diameter D of the grating 12, the wavelength ⁇ of incident light, the beam divergence angle ⁇ R, and the width of the Bragg envelope ⁇ B. Note that in Fig. 11 both the Bragg envelope ⁇ B and the beam divergence ⁇ R are defined as half angles from a central line.
• the number of bits N increases. Also, as the length of the grating Lg gets shorter (and thus the beam width gets smaller), the number of bits N decreases, as the divergence angle ⁇ R increases for each bit or pitch A. Accordingly, the number of bits N is limited to the number of bits that can fit within the Bragg envelope (2 ⁇ B).
• the lens 37 (i.e., in the "near field"), if the lens 37 is placed in the near field it will separate out the individual beams and provide separately resolved beams having a desired spot size to provide an effective far field effect shown by Eq. 5.
• the beams may be optically detected in the far field without the lens 37, or with other imaging optics as desired.
• the 10 affects how much power is scattered off the ends of the substrate 10.
• the intensity fringes outside the HW point on the incident beam 24 may reflect off the front or rear faces of the substrate 10 toward the output beam. Therefore, the smaller the outer diameter Dl of the substrate, the smaller the amount of unwanted beam scatter.
• edges of the substrate may be bowed (see Fig. 17) or angled or otherwise have a geometry that minimizes such scatter or the ends may be coated with a material that minimizes scatter.
• the lens 37 collimates the reflected light 290 which appears as a line 295. If the bottom of the substrate 10 was flat as indicated by a line 296 instead of curved (convex), the reflected light beam would not be spread out in this dimension, but would substantially retain the shape of the incident light (accounting for beam divergence), as indicated by dashed lines 297. In that case, the output light would be spots or circles instead of lines.
• the lens 37 focuses the reflected light 290 to a point or spot having a diameter of about 30 microns (full width, at the 1/e 2 intensity point) for a 65 micron diameter substrate.
• the lens 37 focuses the reflected light onto different spots 293 along a line 292.
• the bits may be read/detected by providing a plurality of wavelengths and reading the wavelength spectrum of the reflected output light signal. In this case, there would be one bit per wavelength, and thus, the code is contained in the wavelength information of the reflected output signal.
• each bit (or ⁇ ) is defined by whether its corresponding wavelength falls within the Bragg envelope, not by its angular position within the
• the Bragg envelope As a result, it is not limited by the number of angles that can fit in the Bragg envelope for a given composite grating 12, as in the embodiment discussed hereinbefore.
• the only limitation in the number of bits N is the maximum number of grating pitches A that can be superimposed and optically distinguished in wavelength space for the output beam.
• the reflection wavelength spectrum ( ⁇ l- ⁇ n) of the reflected output beam 310 will exhibit a series of reflection peaks 695, each appearing at the same output Bragg angle ⁇ o.
• One way to measure the bits in wavelength space is to have the input light angle ⁇ i equal to the output light angle ⁇ o, which is kept at a constant value, and to provide an input wavelength ⁇ that satisfies the diffraction condition (Eq. 1) for each grating pitch ⁇ . This will maximize the optical power of the output signal for each pitch ⁇ detected in the grating 12.
• the transmission wavelength spectrum of the transmitted output beam 330 (which is transmitted straight through the grating 12) , will exhibit a series of notches (or dark spots) 696. Therefore, instead of detecting the reflected output light 310, the transmitted light 330 may be detected at the detector/reader 308. Alternatively, the detector/reader 308 may read the both the transmitted light 25 and the reflected light 310. It should be understood that the optical signal levels for the reflection peaks 695 and transmission notches 696 will depend on the "strength" of the grating 12, i.e., the magnitude of the index variation n in the grating 12.
• the grating 12 thickness D may be made large to make the width of the Bragg envelope 200 narrow, and thus the reflection efficiency large, so it is comparable to or slightly smaller than the angular width of the output beam corresponding to one of the bits 340.
• the bits may be detected by continuously scanning the input wavelength.
• a known optical source 300 provides the input light signal 24 of a coherent scanned wavelength input light shown as a graph 304.
• the source 300 provides a sync signal on a line 306 to a known reader 308.
• the sync signal may be a timed pulse or a voltage ramped signal, which is indicative of the wavelength being provided as the input light 24 to the substrate 10 at any given time.
• the reader 308 may be a photodiode, CCD camera, or other optical detection device that detects when an optical signal is present and provides an output signal on a line 309 indicative of the code in the substrate 10 or of the wavelengths present in the output light, which is directly related to the code, as discussed herein.
• the grating 12 reflects the input light 24 and provides an output light signal 310 to the reader 308.
• the wavelength of the input signal is set such that the reflected output light 310 will be substantially in the center 314 of the Bragg envelope 312 for the individual grating pitch (or bit) being read.
• the source 300 may provide a continuous broadband wavelength input signal such as that shown as a graph 316.
• the reflected output beam 310 signal is provided to a narrow band scanning filter 318 which scans across the desired range of wavelengths and provides a filtered output optical signal 320 to the reader 308.
• the filter 318 provides a sync signal on a line 322 to the reader, which is indicative of which wavelengths are being provided on the output signal 320 to the reader and may be similar to the sync signal discussed hereinbefore on the line 306 from the source 300. In this case, the source 300 does not need to provide a sync signal because the input optical signal 24 is continuous.
• the scanning filter instead of having the scanning filter being located in the path of the output beam 310, the scanning filter may be located in the path of the input beam 24 as indicated by the dashed box 324, which provides the sync signal on a line 323.
• the reader 308 may be a known optical spectrometer (such as a known spectrum analyzer), capable of measuring the wavelength of the output light.
• bit readout with two different input wavelengths, e.g., ⁇ l, ⁇ 2.
• the rightmost bit 342 falls outside the Bragg envelope 200 when ⁇ l is the source, but falls within the Bragg envelope 200 for ⁇ 2.
• the effective position of the bit 342 shifts based on input wavelength as indicated by a line 344.
• each readout wavelength is associated with a predetermined number of bits within the Bragg envelope. Bits (or grating pitches ⁇ ) written for different wavelengths do not show up unless the correct wavelength is used.
• the Bragg envelope 400 is set so that about 3 bits (or pitches ⁇ ) 402 fit within the Bragg envelope 400 for a given input wavelength ⁇ l, as indicated by a solid line 404, so that a second set of 3 bits (or pitches ⁇ ) 402 fit within the Bragg envelope 400 for second input wavelength ⁇ 2, as indicated by a dashed line 406, and so that a third set of 3 bits (or pitches ⁇ ) 402 fit within the Bragg envelope 400 for a third input wavelength ⁇ 3 as indicated by a dashed line 408.
• each of the sets of bits may not lie on top of each other in the Bragg envelope as shown in Fig. 22.
• the bits (or grating pitches A) can be read using one wavelength and many angles, many wavelengths and one angle, or many wavelengths and many angles.
• the grating 12 may have a thickness or depth D which is comparable or smaller than the incident beam wavelength ⁇ .
• This is known as a "thin” diffraction grating (or the full angle Bragg envelope is 180 degrees).
• the half-angle Bragg envelope ⁇ B is substantially 90 degrees; however, ⁇ n must be made large enough to provide sufficient reflection efficiency, per Eqs. 3 and 4.
• D* ⁇ n » ⁇ /2 which corresponds to a ⁇ phase shift between adjacent minimum and maximum refractive index values of the grating 12.
• phase shift between adjacent minimum and maximum refractive index values of the grating 12 should approach a ⁇ phase shift; however, other phase shifts may be used.
• the grating 12 is illuminated with the input light 24 oriented on a line 705 orthogonal to the longitudinal grating vector 705.
• the +/-l st order beams corresponds to output beams 700,702, respectively.
• the +/-2 nd order beams corresponds to output beams 704,706, respectively.
• the 0 th order (undefracted) beam corresponds to beam 708 and passes straight through the substrate.
• the output beams 700-708 project spectral spots or peaks 710- 718, respectively, along a common plane, shown from the side by a line 709, which is parallel to the upper surface of the substrate 10.
• one can use only the +/-l st order (m +/-1) output beams for the code, in which case there would be only 2 peaks to detect, 712, 714.
• an individual peak may be used instead of using a pair of output peaks for a given order.
• the +/-l st order beams corresponds to output beams 720,722, respectively.
• the +/-2 nd order beams corresponds to output beams 724,726, respectively.
• the 0 th order (un-defracted) beam corresponds to beam 718 and passes straight through the substrate.
• the output beams 720-726 corresponding to the second pitch ⁇ 2 project spectral spots or peaks 730-736, respectively, which are at a different location than the point 710-716, but along the same common plane, shown from the side by the line 709.
• each different pitch corresponds to a different elevation or output angle which corresponds to a predetermined set of spectral peaks. Accordingly, the presence or absence of a particular peak or set of spectral peaks defines the code.
• the readout angles may no longer be symmetric, leading to possible difficulties in readout.
• the angular sensitivity to the alignment of the longitudinal axis of the substrate 10 to the input angle ⁇ i of incident radiation is reduced or eliminated.
• the input light can be oriented along substantially any angle ⁇ i with respect to the grating 12 without causing output signal degradation, due the large Bragg angle envelope.
• the grating 12 can be oriented at any rotational (or azimuthal) angle without causing output signal degradation.
• the bits can also be multiplexed in an azimuthal (or rotational) angle ⁇ a of the substrate.
• a plurality of gratings 750,752,754,756 each having the same pitch ⁇ are disposed in a surface 701 of the substrate 10 and located in the plane of the substrate surface 701. The input light 24 is incident on all the gratings 750,752,754,756 simultaneously.
• Each of the gratings provides output beams oriented based on the grating orientation.
• the grating 750 provides the output beams 764,762
• the grating 752 provides the output beams 766,768
• the grating 754 provides the output beams 770,772
• the grating 756 provides the output beams 774,776.
• Each of the output beams provides spectral peaks or spots (similar to that discussed hereinbefore), which are located in a plane 760 that is parallel to the substrate surface plane 701.
• a single grating pitch ⁇ can produce many bits depending on the number of gratings that can be placed at different rotational (or azimuthal) angles on the surface of the substrate 10 and the number of output beam spectral peaks that can be spatially and optically resolved/detected.
• Each bit may be viewed as the presence or absence of a pair of peaks located at a predetermined location in space in the plane 760.
• the azimuthal multiplexing can be combined with the elevation (or output angle) multiplexing discussed hereinbefore to provide two levels of multiplexing. Accordingly, for a thin grating, the number of bits can be multiplexed based on the number of grating pitches ⁇ and/or geometrically by the orientation of the grating pitches.
• the edges of the substrate 10 no longer scatter light from the incident angle into the "code angular space", as discussed hereinbefore.
• a continuous broadband wavelength source may be used as the optical source if desired.
• the pitches ⁇ in the grating 12 may be created at a angle ⁇ g.
• the pitches when the input light 24 is incident normal to the surface 792, will produce a reflected output beam 790 having an angle ⁇ o determined by Eq. 1 as adjusted for the blaze angle ⁇ g. This can provide another level of multiplexing bits in the code.
• an additional level of multiplexing may be provided by having the optical code use other numerical bases, if intensity levels of each bit are used to indicate code information. This could be achieved by having a corresponding magnitude (or strength) of the refractive index change ( ⁇ n) for each grating pitch ⁇ .
• intensity levels of each bit are used to indicate code information. This could be achieved by having a corresponding magnitude (or strength) of the refractive index change ( ⁇ n) for each grating pitch ⁇ .
• four intensity ranges are shown for each bit number or pitch ⁇ , providing for a Base-4 code (where each bit corresponds to 0,1,2, or 3). The lowest intensity level, corresponding to a 0, would exist when this pitch ⁇ is not present in the grating.
• the next intensity level 450 would occur when a first low level ⁇ nl exists in the grating that provides an output signal within the intensity range corresponding to a 1.
• the next intensity level 452 would occur when a second higher level ⁇ n2 exists in the grating 12 that provides an output signal within the intensity range corresponding to a 2.
• the next intensity level 452, would occur when a third higher level ⁇ n3 exists in the grating 12 that provides an output signal within the intensity range corresponding to a 3.
• an additional level of multiplexing may be provided Referring to Figs. 33-37, alternatively, two or more substrates 10,250, each having at least one grating therein, may be attached together to form the element 8, e.g., by an adhesive, fusing or other attachment techniques. In that case, the gratings 12,252 may have the same or different codes.
• the substrate 10 may have more than one region 20 having codes.
• the length L of the element 8 may be shorter than its diameter D, such as a plug or puck or wafer or disc.
• the substrate 10 may have a plurality of the gratings 12 having the same codes written therein at numerous different angular or rotational positions of the substrate 10.
• the gratings 550,552 have a common central (or pivot or rotational) point where the two axes 551,553 intersect.
• the angle ⁇ i of the incident light 24 is aligned properly with the grating 550 and is not aligned with the grating 552, such that output light 555 is reflected off the grating 550 and light 557 passes through the grating 550 as discussed herein.
• the angle ⁇ i of incident light 24 is aligned properly with the grating 552 and not aligned with the grating 550 such that output light 555 is reflected off the grating 552 and light 557 passes through the grating 552 as discussed herein.
• the bead When multiple gratings are located in this rotational orientation, the bead may be rotated as indicated by a line 559 and there may be many angular positions that will provide correct (or optimal) incident input angles ⁇ i to the grating. While this example shows a circular cross-section, this technique may be used with any shape cross-section.
• the substrate 10 may have an outer coating 799, such as a polymer or other material that may be dissimilar to the material of the substrate 10, provided that the coating 799 on at least a portion of the substrate, allows sufficient light to pass through the substrate for adequate optical detection of the code.
• the coating 799 may be on any one or more sides of the substrate 10.
• the coating 799 may be a solid, liquid, gas or powder, a chemical polymer, metal, or other material, or they may be coated with a material that allows the beads to float, sink, glow, reflect light, repel or absorb a fluid (liquid and/or gas) or material, align, have a predetermined electrical or magnetic polarization, moment or field, or have other properties.
• the substrate 10 may be made of a material that is less dense than certain fluid (liquids and/or gas) solutions, thereby allowing the elements 8 to float or be buoyant or partially buoyant.
• the substrate may be made of a porous material, such as controlled pore glass (CPG) or other porous materials, which may also reduce the density of the element 8 and may make the element 8 buoyant or partially-buoyant in certain fluids.
• CPG controlled pore glass
• the substrate 10 may be made of a material that dissolves in the presence of certain chemicals or over time.
• the substrate may have a spherical geometry.
• the substrate 10 may have multiple gratings 554, 556 located in different three- dimensional planes.
• input light 24 is incident on the gratings 554,556 and the gratings 554,556 provide reflected output light 560,562 as discussed hereinbefore.
• the substrate 10 may have one or more holes located within the substrate 10.
• holes 560 may be located at various points along all or a portion of the length of the substrate 10. The holes need not pass all the way through the substrate 10. Any number, size and spacing for the holes 560 may be used if desired.
• holes 572 may be located very close together to form a honeycomb-like area of all or a portion of the cross-section.
• one (or more) inner hole 566 may be located in the center of the substrate 10 or anywhere inside of where the grating region(s) 20 are located.
• the inner hole 566 may be coated with a reflective coating 573 to reflect light to facilitate reading of one or more of the gratings 12 and/or to reflect light diffracted off one or more of the gratings 12.
• the incident light 24 may reflect off the grating 12 in the region 20 and then reflect off the surface 573 to provide output light 577.
• the incident light 24 may reflect off the surface 573, then reflect off the grating 12 and provide the output light 575.
• the grating region 20 may run axially or circumferentially 571 around the substrate 10.
• the holes 579 may be located circumferentially around the grating region 20 or transversely across the substrate 10.
• the grating 12 may be located circumferentially (and running up- down) around the outside of the substrate 10, and there may be holes 574 inside the substrate 10.
• the grating 12 may be located circumferentially (and running circumferentially) around the outside of the substrate 10.
• any of the holes described herein for the element 8 or substrate 10 may be filled with a solid, liquid, gas or powder, a chemical polymer, metal, or other material, or they may be coated with a material that allows the beads to float, sink, glow, reflect light, repel or absorb a fluid or material, align, have a predetermined electrical or magnetic polarization, moment or field, or have other properties, or may be similar to or the same as the coating 799 (Fig. 58) or the reflective coating 514 of Fig. 30, discussed hereinbefore.
• the substrate 10 may have one or more protruding portions or teeth 570, 578,580 extending radially and/or circumferentially from the substrate 10.
• the teeth 570, 578,580 may have any other desired shape.
• the grating region 20 may have end cross-sectional shapes other than circular and may have side cross-sectional shapes other than rectangular, such as any of the geometries described herein for the substrate 10.
• the grating region 20 may have a oval cross-sectional shape as shown by dashed lines 581, which may be oriented in a desired direction, consistent with the teachings herein. Any other geometries for the substrate 10 or the grating region 20 may be used if desired, as described herein. In the case of an oval shaped grating region 20 may provide high diffraction efficiency, when light is incident on the long side of the oval.
• the elements 8 may be placed in a tray or plate 207 with grooves 205 to allow the elements 10 to be aligned in a predetermined direction for illumination and reading/detection as discussed herein.
• the grooves 205 may have holes 210 that provide suction to keep the elements 8 in position.
• the groove plate may be illuminated from the top, side or the bottom of the plate.
• the beads may be aligned in a tube 502 that has a diameter that is only slightly larger than the substrate 10, e.g., about 1-
• the incident light 24 may pass through the tube 502 as indicated by the light 500 or be reflected back due to a reflective coating on the tube 500 or the substrate as shown by return light 504.
• Other techniques can be used for alignment if desired.
• at least a portion of a side of the substrate 10 may be coated with a reflective coating 514 to allow incident light 510 to be reflected back to the same side from which the incident light came, as indicated by reflected light 512.
• the surfaces inside the V-grooves 205 may be made of or coated with a reflective material that reflects the incident light.
• a light beam is incident onto the substrate and diffracted by the grating 12.
• the diffracted beam may be reflected by a surface 520 of the V-groove 205 and read from the same direction as the incident beam 24.
• the incident light beam 24 may be diffracted by the grating 12 and pass through the upper surface 529 of the v-groove and reflected off two surfaces 526, 528 which are made or coated with a reflective coating to redirect the output beam upward as a output light beam 530 which may be detected as discussed hereinbefore. Referring to Fig.
• the substrate 10 can be electrically and/or magnetically polarized, by a dopant or coating, which may be used to ease handling and/or alignment or orientation of the substrate 10 and/or the grating 12, or used for other pmposes.
• the bead may be coated with conductive material, e.g., metal coating on the inside of a holy substrate, or metallic dopant inside the substrate. In these cases, such materials can cause the substrate 10 to align in an electric or magnetic field.
• the substrate can be doped with an element or compound that fluoresces or glows under appropriate ilfumination, e.g., a rare earth dopant, such as Erbium, or other rare earth dopant or fluorescent or luminescent molecule.
• a rare earth dopant such as Erbium
• fluorescent or luminescent molecule such fluorescence or luminescence may aid in locating and/or aligning substrates.
• the input light 24 may be incident on the substrate 10 on an end face 600 of the substrate 10.
• the input light 24 will be incident on the grating 12 having a more significant component of the light (as compared to side illumination discussed hereinbefore) along the longitudinal grating axis 207 of the grating (along the grating vector k ⁇ ), as shown by a line 602.
• the light 602 reflects off the grating 12 as indicated by a line 604 and exits the substrate as output light 608.
• the code information is readable only in the spectral wavelength of the reflected beam, similar to that discussed hereinbefore for wavelength based code reading with Fig. 19.
• the input signal in this case may be a scanned wavelength source or a broadband wavelength source.
• the code information may be obtained in reflection from the reflected beam 614 or in transmission by the transmitted beam 616 that passes through the grating 12.
• nj n sin ⁇ in n oUt sin ⁇ out Eq. 13 where n ⁇ n is the refractive index of the first (input) medium, and n oUt is the refractive index of the second (output) medium, and ⁇ in and ⁇ out are measured from a line 620 normal to an incident surface 622.
• the grating region 20 of the substrate 10 will act as a known optical waveguide for certain wavelengths.
• the grating region 20 acts as a "core” along which light is guided and the outer region 18 acts as a "cladding” which helps confine or guide the light.
• such a waveguide will have a known “numerical aperture” ( ⁇ na) that will allow light that is within the aperture ⁇ na to be directed or guided along the grating axis 207 and reflected axially off the grating 12 and returned and guided along the waveguide.
• the grating 12 will reflect light having the appropriate wavelengths equal to the pitches ⁇ present in the grating 12 back along the region 20 (or core) of the waveguide, and pass the remaining wavelengths of light as the light 632.
• having the grating region 20 act as an optical waveguide for wavelengths reflected by the grating 12 allows incident light that is not aligned exactly with the grating axis 207 to be guided along and aligned with the grating 12 axis 207 for optimal grating reflection.
• any standard waveguide may be used, e.g., a standard telecommunication single mode optical fiber (125 micron diameter or 80 micron diameter fiber with about a 8-10 micron diameter), or a larger diameter waveguide (greater than 0.5 mm diameter), such as is describe in U.S. Patent Application, Serial No. 09/455,868, filed December 6, 1999, entitled “Large Diameter Waveguide, Grating”.
• any type of optical waveguide may be used for the optical substrate 10, such as, a multi-mode, birefringent, polarization maintaining, polarizing, multi-core, multi-cladding, or microsturctured optical waveguide, or a flat or planar waveguide (where the waveguide is rectangular shaped), or other waveguides.
• a multi-mode, birefringent, polarization maintaining, polarizing, multi-core, multi-cladding, or microsturctured optical waveguide or a flat or planar waveguide (where the waveguide is rectangular shaped), or other waveguides.
• the substrate 10 does not behave as a waveguide for the incident or reflected light and the incident light 24 will be diffracted (or reflected) as indicated by lines 642, and the codes detected as discussed hereinbefore for the end-incidence condition discussed hereinbefore with Fig. 45, and the remaining light 640 passes straight through.
• the input light 24 is coupled out of the substrate 10 at a known angle as shown by a line 650.
• the input light 24 may be incident from the side and, if the grating 12 has the appropriate blaze angle, the reflected light will exit from the end face 652 as indicated by a line 654.
• the grating 12 may have a plurality of different pitch angles 660,662, which reflect the input light 24 to different output angles as indicated by lines 664, 666. This provides another level of multiplexing (spatially) additional codes, if desired.
• the incident light 670 is reflected off the grating and exits through the end as a light 672 and the remaining light passes through the grating and the plate 674 as a line 678.
• incident light 670 may be reflected out the side of the plate (or any other desired angle), as indicated by a line 680.
• input light may be incident from the side of the plate 674 and reflected out the top of the plate 474 as indicated by a line 684.
• the light 672 may be a plurality of separate light beams or a single light beam that illuminates the entire tray 674 if desired.
• the v-groove plate discussed hereinbefore with Fig. 28 may be used for the end illumination readout condition.
• the grating 12 may have a blaze angle such that light incident along the axial grating axis will be reflected upward, downward, or at a predetermined angle for code detection.
• the input light may be incident on the grating in a downward, upward, or at a predetermined angle and the grating 12 may reflect light along the axial grating axis for code detection.
• the substrate 10 may have a plurality of gratings
• the grating 12 may be impressed in the substrate 10 by any technique for writing, impressed, embedded, imprinted, or otherwise forming a diffraction grating in the volume of or on a surface of a substrate 10. Examples of some known techniques are described in US Patent No. 4,725,110 and 4,807,950, entitled “Method for Impressing Gratings Within Fiber Optics", to Glenn et al; and US Patent No. 5,388,173, entitled “Method and Apparatus for Forming Aperiodic Gratings in Optical Fibers", to Glenn, respectively, and US Patent 5,367,588, entitled "Method of
• the grating 12 may be partially or totally created by etching or otherwise altering the outer surface geometry of the substrate to create a corrugated or varying surface geometry of the substrate, such as is described in US Patent 3,891,302, entitled “Method of Filtering Modes in Optical Waveguides", to Dabby et al, which is inco ⁇ orated herein by reference to the extent necessary to understand the present invention, provided the resultant optical refractive profile for the desired code is created.
• the grating 12 may be made by depositing dielectric layers onto the substrate, similar to the way a known thin film filter is created, so as to create the desired resultant optical refractive profile for the desired code.
• microbead is used herein as a label and does not restrict any embodiment or application of the present invention to certain dimensions, materials and/or geometries.
• the dimensions and/or geometries for any of the embodiments described herein are merely for illustrative pu ⁇ oses and, as such, any other dimensions and/or geometries may be used if desired, depending on the application, size, performance, manufacturing requirements, or other factors, in view of the teachings herein.
• any of the features, characteristics, alternatives or modifications described regarding a particular embodiment herein may also be applied, used, or inco ⁇ orated with any other embodiment described herein.
• the drawings herein are not drawn to scale.

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