HK1037045B - Method and apparatus for reading and verifying holograms - Google Patents

Description

Method and apparatus for reading and verifying holograms

Technical Field

The present invention relates to holography, and more particularly to a hologram reader/verifier.

Background

Prior art hologram readers rely on the use of holograms having a particular format or particular characteristics. Fig. 1a and 1b illustrate examples of prior art hologram readers. In the hologram reader of FIG. 1a, the holographic barcode is illuminated by a laser beam 520 generated by a laser 525. The speckle pattern 505 is then reconstructed on a set of photodetectors 500 dedicated to detecting speckle at specific locations.

In the hologram reader of FIG. 1b, a hologram 510 containing an unfocused image record is illuminated by a laser beam 520 generated by a laser 525. The laser beam 520 at its reference (or varying reference) angle tends to reconstruct an image 555 on a grounded glass screen 550, viewable by a human eye viewer 560.

Another type of prior art hologram reader (not shown) does not actually read the hologram, but rather compares a wavefront recorded in the hologram with a reference wavefront. However, another type of prior art hologram reader (not shown) simply compares a single 2-dimensional view of the hologram with the stored 2-dimensional reference image.

U.S. patent No.4,641,017 to Lopata, entitled anti-counterfeit credit card system.

U.S. patent No.5,331,443 to Stanisci, entitled laser inscription verification hologram and associated method.

U.S. patent No.4,761,543 to Hayden et al, entitled holographic security device and system.

U.S. pa ten No.4,108,367 to Hannan, entitled indicia and reader for a marketing machine.

U.S. patent No.5,712,731 to Drinkwater et al, entitled security device for security documents, such as checks and credit cards.

U.S. patent No.5,306,899 to Marom, et al, entitled authenticity verification system for an article with holographic image display using holographic recording.

U.S. patent No.4,131,337 to muraw, et al, entitled comparison reader for holographic identification cards.

U.S. pa tent No.3,905,019 to Aoki, et al, entitled pattern recognition optics.

U.S. patent No.5,666,417 to Liang, et al, entitled fluorescence authenticity validation reader utilizing coaxial devices.

U.S. patent No.5,465,243 to Boardman, et al, entitled optical recorder and reader of data on a photosensitive medium.

U.S. patent No. re 035,117 to Rando, et al, entitled scanner with specimen confirmation.

The prior art hologram readers described above and in the above-listed patents read holograms only if the hologram is specifically designed for the reader.

Disclosure of Invention

Therefore, there is a need for a hologram reader capable of reading all kinds of holograms, which does not require a hologram to be specifically designed for the reader, and which is capable of reading variable information from the hologram.

In accordance with the principles of the present invention, a diffractive object is illuminated with spatially correlated light, a light pattern diffracted by at least a portion of the diffractive object is detected, and then a particular representation of the detected pattern is compared to a representation of a predetermined reference pattern, whereby information can be extracted from the diffractive object and the diffractive object verified.

According to an aspect of the present invention, there is provided an apparatus for extracting information from a diffraction object, comprising: means for illuminating the diffractive object with spatially dependent light; means for detecting at least a portion of the pattern diffracted by the object; means for convolving the detected portion of the pattern with a template pattern to produce a deformed version of the pattern; means for identifying and locating peaks in the deformed version; means for representing the position of the peak in the morphed pattern as a vector; and means for comparing the vector with a set of reference vectors in a database to classify the vector and thereby classify the diffraction pattern from the diffraction object.

In one aspect of the present invention, there is provided a scanner for extracting detailed structural information from a diffraction image, comprising: a laser source for generating a laser beam; focusing optics for directing a laser beam from the laser source to a spot; means for positioning the diffraction image such that the spot illuminates an area on the diffraction image; means for detecting a light pattern diffracted from the region; and means for comparing the light pattern to a reference pattern.

Drawings

FIG. 1a is a schematic diagram of a prior art hologram reader.

FIG. 1b is a schematic diagram of another prior art hologram reader.

FIG. 2a is a schematic representation of the diffraction pattern exhibited by a typical rainbow hologram illuminated at a point with a perpendicular beam.

Figure 2b is a schematic representation of the diffraction pattern exhibited by a typical composite hologram comprising both diffraction grating elements and rainbow hologram elements.

FIG. 3 is a schematic diagram of an embodiment of a hologram reader according to the present invention.

FIG. 4 is a schematic representation of a typical fluorescent quantum dot including a core and an organic molecular cap.

Fig. 5 is a schematic representation of two exemplary labels containing a hologram, fluorescent material, and encrypted data printed directly on the label in a string.

FIG. 6 is a schematic diagram of a credit card verifier (credit card verifier) including the hologram reader, magnetic stripe reader and electronic subsystem of FIG. 3.

Detailed Description

FIG. 7 is a schematic illustration of the type of pattern formed according to the following operations: i.e. half of the diffraction pattern of a single point composite hologram is recorded in an image, the half of the diffraction pattern of the next single point along a line in the hologram, slightly offset from the first one, is recorded on the same medium, and this is done for a series of points along a line throughout the hologram, a schematic representation of the type of pattern formed. Which is a stacked +1 order diffraction pattern.

FIG. 8 is a flow chart of a system for using a hologram reader and label printer to detect and track counterfeit products.

FIG. 2a illustrates a detailed description of the invention in which an illumination beam (not shown) that is incident at an angle corresponding to the angle of a reference beam (not shown) used to make the hologram 300, perpendicular to the surface of the hologram 300, will result in the generation of a first order diffracted beam that forms a straight line segment, rather than an arc. Within the first-order arc as shown in FIG. 2a, is a "spot" of light 310, which is associated with a feature of the image, visible through an illuminated point on the hologram 300. To read a rainbow hologram, the spots 310 need only be identified and tracked when the illumination spot moves to all salient points on the hologram 300. For example, salient points on a hologram may be defined as those points on a line parallel to the edge of the card or label on which the hologram is located through the hologram 300, and which are at a predetermined distance from the edge.

Fig. 2b illustrates a diffraction pattern 320 resulting from a combined rainbow hologram and diffraction grating image. The small spots 350, 360, 370 on the pattern correspond to areas containing diffraction gratings, while the lines and arcs 315 correspond to areas containing rainbow hologram elements or "2D" hologram elements. If the line or arc 315 contains a spot 310, the corresponding hologram component is typically a 3D hologram. If the line or arc contains only a substantially featureless or uniform light distribution, the corresponding hologram component is a "2D" hologram.

Since standard image processing techniques can be used to identify the size, shape and location of each spot 310, it is helpful to take advantage of the characteristics specific to holograms in order to simplify the feature detection and identification tasks.

Unless the holograms are luminescent, they produce a diffraction pattern that is approximately radially symmetric, as shown by the spots 360 in FIG. 2 b. If, however, the hologram is luminescent, the positions of the +1 and-1 orders are symmetrical, but the brightness of one is substantially higher than the brightness of the other, as shown by the spot 370 in fig. 2 b.

Certain features of the hologram are important to a hologram reader that is capable of distinguishing between different holograms. These features include spot position, spot asymmetry, spot size, spot shape, spot velocity, spot profile, and stray light, each of which will be discussed below.

The position of a spot is usually defined as the position of its brightness peak. Further, the spot position may be defined as the center of the intensity distribution. Radial coordinates are suitable because the entire pattern has a large degree of radial symmetry.

Spot asymmetry can be defined as the ratio of the respective spot intensities in the +1 and-1 orders. Each spot pair will have its own asymmetry.

The spot size may be defined as the maximum width of the area covered by one spot. Coverage may be defined as having an intensity greater than some critical level determined by the peak intensity of the spot and the background brightness.

In the diffraction patterns of most holograms in commercial use today, the spots are either point-like or line-like. The linear spots appear on the arc shown in fig. 2, while the spot-like spots appear anywhere in the diffraction pattern. The hologram diffraction pattern shown in figure 2b has both spots. Other spot shapes are possible and the image processing software should be able to detect the presence of very shapes.

The spots in the diffraction pattern move and change in a piecewise continuous manner as the hologram is read by an illumination spot passing through the hologram. Spot velocity is the velocity at which the position, asymmetry, size and shape of the spot in the diffraction pattern changes relative to the change in position of the illuminated spot on the hologram.

In a rainbow hologram, the arc (as shown in fig. 2a and 2 b) is defined by the limit at which the spot boundary moves in response to changes in the position of the illumination spot. The spots never move outside the boundaries of the arc. The arc itself corresponds to the size and shape of the H-1 hologram used to make the rainbow hologram, or the size and shape of an aperture through which H-1 light is emitted to form an H-2 hologram. The position, curvature and orientation of the arc then provides information about the physical device used to make the hologram.

In most holograms, there is stray light in the diffraction pattern. This light constitutes a blurred, symmetrical pattern when illuminated with a normal incident light beam, but it has no obvious relation to the visible image. Typically these stray diffraction components originate from scattered light in the hologram recording device, which scattered light is recorded as a hologram along with the target light. One common holography technique is to illuminate a hologram with laser light and to view the image through it for the recording device in the hologram.

All the information recorded in the hologram can be extracted by illuminating the diffraction pattern produced by each point of the hologram (as shown, for example, in figures 2a and 2 b). Typically holograms used for document security are made in batches from a single original master hologram, the diffraction pattern being the same for all holograms. However, new low cost hologram recording materials and inexpensive lasers have been developed and have begun to be used practically for making a large number of disposable holograms, each containing unique information. In order to read the information in such holograms it is necessary to either design the hologram to be easy to read (as in the prior art) or to design a reader, for example a reader according to a preferred embodiment of the invention, which is capable of reading all the diffraction patterns produced by the dots of the hologram.

FIG. 3 shows a hologram reader according to an embodiment of the present invention. The hologram reader comprises a laser diode 600, focusing optics 630, preferably with aberration correction, a first beam splitter 605, a color selection filter 662, an image sensor 620, a time gate line array sensor 625, spectral shaping devices 615, 635, and a second beam splitter 605. The laser diode 600, preferably having the shortest available wavelength, generates a beam 650 whose shape is determined by the focusing optics 630 to form a converging spherical wave. The converging spherical wave converges to a small spot on a hologram 690 that is hot stamped onto the credit card 680. A suitable laser diode 600 that can be used as the light source for the hologram reader is a green dual frequency diode. However, blue laser diodes or UV laser diodes may be desirable because they are commercially available at a reasonable price.

The hologram 690 on the credit card 680 may be transparent, in which case the embossed surface of the hologram 690 is preferably coated with a high refractive index material (not shown) to make the hologram 690 fairly bright. Suitable high refractive index materials include titanium oxide or zinc sulfide. If the hologram 690 is transparent, the surface of the credit card 680 underneath the hologram may have features detectable through the hologram, such as a pattern of fluorescent ink, colored ink, fibers, magnetic ink, or optically variable ink.

In operation, laser beam 650 diffracts from hologram 690, forming a pattern on the image sensor 620. The image sensor 620 does not sense all of the images in the hologram. Instead, the image sensor 620 senses only the pattern of diffracted light from one illuminated spot on the hologram 690. The color selection filter 662 ensures that the image sensor 620 only receives light of the same color as the illumination laser beam 650, thereby receiving primarily diffracted, scattered, and reflected light. If the illumination laser beam 650 is directed at the appropriate angle to the hologram 690, it corresponds to the angle between the reference and object beams (not shown) used to make the hologram 690. Only the forward diffraction orders will fall on the image sensor 620 placed directly above the hologram. In addition, the illumination laser beam 650 may be directed vertically toward the hologram 690, as shown in FIG. 3, so that the image sensor 620 can receive both positive and negative diffraction orders when placed directly above the hologram 690.

Illumination of the fluorescent ink printed on the credit card 680 substrate will result in the emission of fluorescence. This fluorescence passes through the spectral shaping device 615, 635 to the second beam splitter 605, which directs the fluorescence to the time gate line array sensor 625, where the fluorescence spectrum is shaped at the time gate line array sensor 625L. A stop 692 prevents direct reflections of the illumination laser beam 650 (zero order diffracted beam) from striking the line array sensor 625.

Fluorescence from different substances has two main distinguishing features: emission spectrum and time characteristics. For example, many organic dyes have very short fluorescence lifetimes, such that if they are illuminated with picosecond pulses of activating light, they emit short bursts of fluorescence that are shorter than nanoseconds. Other fluorescent substances emit fluorescence after activation in hundreds of nanoseconds. Many materials are fluorescent to some extent, but most have only a short fluorescence lifetime; it is therefore desirable to use fluorescent inks with long fluorescence lifetimes to allow easier elimination of background fluorescence in time-gated methods.

In the embodiment shown in FIG. 3, the line array sensor 625 is time gated and the laser diode 600 is pulsed. If the fluorescence lifetime of the fluorophore printed on the substrate of the credit card 680 is longer than the typical fluorescence lifetime of common materials, selective detection of only fluorescence received after the activation pulse at greater than 100 nanoseconds can effectively exclude background fluorescence.

One example of a suitable fluorescent material is the use of quantum dots 210, as shown in FIG. 4. The quantum dots 210 are preferably made of CdSe and are encapsulated with ZnSe as the capping 200. Such ZnSe capped CdSe quantum dots are known to have fluorescence lifetimes on the order of 100 nanoseconds. In addition, the line array sensor 625 only needs to have a response time on the order of tens or hundreds of nanoseconds, and the laser diode 600 can be modulated at a rate of one to tens of megahertz. The fluorescence lifetime can then be measured as a function of the phase difference between the illumination modulation and the fluorescence signal. In any case, the line array sensor 625 detects the fluorescence spectrum of any ink or other fluorescent substance beneath the hologram 690 at the illuminated spot.

An example of a label 400, 410 formed from a hologram 450 having fluorescent material 430 underneath it is shown in figure 5. In both cases, the hologram 450 is applied as a translucent hot stamping foil applied over a substrate 460 which may be formed of white paper. The phosphor material 430 is preferably printed directly on the substrate 460. The hologram 450 has a spot in which encrypted information is printed directly on the substrate 460 in the form of a string 470. The labels 400, 410 preferably have an adhesive backing (not shown) and a release protective silicone paper pad (not shown).

The fluorescent substance 430 may be a fluorescent ink containing a fluorophore. Preferably, a patterned phosphor 430 having a characteristic fluorescence spectrum is used on the substrate 460. One suitable fluorescent substance 430 is a fluorescent ink containing a fluorophore, such as the above-described ZnSe capped CdSe quantum dots 420. The quantum dots 420 are preferably sized such that the fluorescence spectrum is relatively narrow. Special organic dyes, such as rhodamine 6G, which has a characteristic peak fluorescence wavelength, may also be used. The fluorescent substance 430 is described in more detail in a co-pending patent application entitled "quantum dot security device and method", filed concurrently with the present application and incorporated herein by reference.

The credit card 120 of fig. 5 is representative of all types of labels, indicia, documents, identification cards, authenticity labels, bank notes, seals, and other items on which holograms, diffractive images, security labels, or other security devices are typically placed. The holograms 690, 450, 140 shown in fig. 3, 5, and 6, respectively, are representative of all kinds of diffractive images, including point-based holograms, 2D3D holograms, stereograms, kinegrams, motion patterns, bragg holograms, embossed holograms, holograms embossed on color film, holographic hot stamping foils, pixel patterns, electron beam diffraction patterns, and binary optical patterns. As used herein, the term "substrate" means any surface or substance upon which a hologram is placed or in close proximity thereto, including any ink, fiber, embossing, chemical treatment, magnetic properties, or other properties or characteristics of the surface or substance.

Returning to FIG. 3, the image sensor 620, in addition to sensing the light pattern diffracted by the hologram 690 or 450, also senses light scattered from the substrate of the card 680 or 460 due to the fibers, texture, or other characteristics of the substrate material. Light diffracted by the holograms 690, 450 generally produces a much higher contrast pattern than light uniformly scattered by, for example, a white substrate. However, holograms typically produce a unique diffraction pattern that can be subtracted from the sensed pattern. The change in the average intensity of light received by the image sensor 620, subtracted by the diffraction pattern, corresponds to the amount of change in the light diffusely scattered from the substrate by the printed pattern or other light-induced pattern on the substrate. Thus, the hologram reader shown in fig. 3 can read the hologram, the fluorescent pattern, and the light scattering or light absorbing pattern as long as the patterns are clear in the wavelength range of light emitted from the laser diode 600. Although the laser diode 600 may be used as the illumination source for the hologram reader of fig. 3, it should be understood that other light sources may be used, such as any precisely collimated (spatially coherent) white light source. In such cases, the diffraction pattern, speckle, and scattered light are all discernable by the image sensor 620.

The components, modules and combinations of components in the optical and electronic subsystems of the reader can be replaced with other equivalent components, modules and combinations of components can be replaced for the purpose of sensing the pattern of scattered light from the illuminated spot on the hologram and/or the amount of light scattered from each point on or under the hologram and/or the amount, time or spectrum of fluorescence emitted from the hologram or its substrate.

A wavelength selective filter (not shown) may be inserted in the optical path from the hologram 690 to the image sensor 620 and/or in the optical path from the hologram 690 to the time gate line array sensor 625. The wavelength selective filter limits the detected light to a desired wavelength range. For example, since the scattered and diffracted light is at the same wavelength as the laser diode 650, it may be desirable to insert a filter between the sensor 620 and the beam splitter 610 that transmits the wavelength of the laser diode 650, while reflecting or absorbing other wavelengths. Similarly, a filter can be inserted between sensor 625 and beamsplitter 605 that reflects or absorbs light at the wavelength of the laser diode 650, while transmitting light in the fluorescence bandwidth of the fluorophore.

In addition, beam splitter 610 may be a polarizing beam splitter, and a quarter wavelength 608 may be inserted between beam splitter 610 and hologram 690 such that the laser light reaches the beam splitter almost 100% of the way it travels to hologram 690 and is reflected almost 100% of the way to the image sensor 620. In this case, the beam splitter 610 may be a wavelength selective polarization beam splitter, such that most of the fluorescence is directed to the line array detector 625, as shown in FIG. 6.

The hologram reader shown in fig. 3 may be combined with readers using other technologies. For example, a reader/verifier using multiple technologies as shown in FIG. 6 may be used to detect counterfeit credit cards. In addition to including an optical read head 110, which may be the hologram reader of FIG. 3, the reader/verifier of FIG. 6 may also include a conventional magnetic stripe reader 130. The optical read head 110 reads the hologram 140 on the credit card 120 and the magnetic stripe reader 130 reads information recorded on a conventional magnetic stripe (not shown) on the credit card 120 as the credit card 120 slides through the slot 150. The reader/verifier also includes an electronics subsystem 100. The electronics subsystem preferably includes a microprocessor (not shown), a Field Programmable Gate Array (FPGA) (not shown), and a Read Only Memory (ROM) (not shown) to store software for execution by the microprocessor. The electronics subsystem 100 also preferably includes means for communicating with external systems, such as a computer (not shown) or a telephone network (not shown).

The FPGA in the electronics subsystem 100 is used to perform image processing. Another implementation uses an Artificial Neural Network (ANN). In fact, any image processing device capable of identifying the salient features of the diffraction pattern can be used to distinguish between different holograms and counterfeit diffraction patterns, as well as effective holograms or other diffractive anti-counterfeit designs, known as DOVIDs, holograms, stereograms, motion patterns, point-based holograms, motion patterns, pixel patterns, and the like.

One suitable FPGA that may be used for the electronics subsystem is the model 6216FPGA available from Xilinx. The FPGA can be programmed to perform almost any desired signal processing function. For example. The FPGA may be programmed by downloading a settings file to the FPGA. The profile determines the pattern of interconnections between logic gates on the FPGA. In the case of the Xilinx 6216FPGA, which has 128 pins for output and input, there are approximately 35,000 logic gates on the FPGA. All logic gates may operate in parallel, synchronously or asynchronously. The setup files for the FPGA design may also be provided by commercially available design tools. However, in some cases, the best approach is to design the profile using improved calculations. Such improved calculation methods are within the level of individuals or groups having ordinary skill in the fields of genetic algorithms or genetic programming, FPGA architecture and design methods, chip-level electronics, and image processing mathematics. Additionally, an improved design tool for FPGA setup files is available from New Light Industries, Ltd, Spokane, WA99224 under the trade name "FPGA-Generator".

In a preferred embodiment of the present invention, an improved technique is used to design FPGA-based algorithms in the electronic subsystem for feature recognition and extraction. In one version, the following steps are performed:

1. a target function is defined by visually identifying features in a set of diffraction patterns to produce an image of the feature marks.

2. An experimental function is defined by assigning a matrix as a template for convolution.

3. A batch of templates was randomly generated and each member of each batch was used to generate a set of convoluted images of the experimental images.

4. The convolved image produced by each member of each batch of templates is compared with the signature images of the target set to produce an adaptation value for each member such that the adaptation value represents the degree of correlation between the produced convolved image and the signature image.

5. The templates may be recombined and/or adaptively mutated using standard genetic algorithm techniques to develop an optimized template.

The precise selection of recombination and mutation factors, as well as other GA parameters, such as recombination rate, mutation rate and size, overall size, superior taste of senior, etc., can all affect the rate of evolution. Currently, there is no optimal choice for all problematic, known, factors and GA parameters.

In operation, the reader/verifier of FIG. 6 detects counterfeit credit cards 120 by reading the hologram 140. In particular, as the credit card 120 slides through the slot 150, a series of dots along the hologram 140 are illuminated in the manner described above with reference to FIG. 3. The diffraction patterns from the spots are formed on the image sensor 620 where they are converted to a video signal. The video signal is analyzed by the electronics subsystem 100 to extract eigenvectors corresponding to the values of the significant features of the diffraction pattern in the hologram 140. The feature vector is then compared to a database of feature vectors from valid and invalid holograms, and the holograms 140 are sorted by their similarity to the vectors in the database. Data identifying valid hologram feature vectors may also be stored on the magnetic stripe and read by the magnetic stripe reader 130 for comparison with the feature vectors of the hologram 140.

The electronics subsystem 100 may also build a representation of the scattered and fluorescence information extracted from the credit card 120 to determine if the credit card 120 is valid. The optical readhead 110 used in the hologram reader of fig. 6 is thus able to sense the diffraction, fluorescence, light scattering and light absorption properties of a point on the credit card 120. The reader/verifier may also sense differences between those characteristics from point to point if the image sensor and/or line array sensor or associated electronics are properly designed.

One preferred method of creating a representation of the diffraction information in hologram 140 is to detect an intensity peak in the diffraction pattern and generate a list of the location, sharpness and relative brightness of the peak. If a series of diffraction patterns are observed across a series of regions of the article, the diffraction characteristics of the entire article are preferably represented as a tabulated list or a compiled ordered list.

A simple way to express this diffraction information is to halve the diffraction pattern and save only the position and intensity data obtained from this part. Then, by stacking the data, a representative image of a complete set of diffraction patterns is constructed from a certain line along the hologram, as shown in FIG. 7. Then a set of spots 820, 830, 840 leaves a track on the composite image, and any spots 800, 850, 860 from the diffraction grating component also leave a track on the composite image. This representative image may then be tested by convolving it with one or more representative images of the reference image(s) obtained by similar methods, which may correspond to valid and counterfeit holograms. The trajectories in fig. 7 resulting from spot and spot motion are essentially independent of the particular choice of hologram point as the sample, as long as the dimensions are substantially unchanged.

As mentioned above, one advantage of the hologram reader shown in fig. 3 is that it can read virtually any kind of hologram. Thus, there are many techniques available for recording holograms that can be used on the hologram reader of FIG. 3. Each such hologram has its own unique characteristics. Some features or parameters are helpful in classifying different kinds of holograms and diffraction patterns, including:

1. a recording medium;

2. reference and target beam angles and positions;

3. the size, shape, spacing, position, grating angle of the dots, and grating period in the dot-based hologram;

4. rainbow (Benton), classical, 2D3D, stereogram, or point-based hologram;

5. transmission or reflection;

6. a reflectivity-enhancing layer;

7. recording the color selectivity and Bragg grating structure of the medium;

8. recording and reconstructing the color characteristics of the geometry;

9. encoding a reference beam or a target beam; and

10. the characteristics and features of a substrate having a hologram laminated or hot stamped thereon.

The hologram reader of fig. 3 may be integrated into an integrated anti-counterfeiting/security system, as shown in fig. 8. The anti-counterfeiting/security comprises one or more sites 700 for manufacturing anti-counterfeiting/security labels carrying detectable random data covered by transparent holograms on a substrate, one or more production points 710, 715 for producing a product, one or more hologram readers at each production point, a label printer at each production point, one or more intermediate distribution points 730, 720 with hologram readers, one or more distribution points 750, 760 with hologram readers, and a computer network of hierarchy nodes 740, 750, 720.

The random data (plus the location of the fluorescent dots 420 under the hologram 450 in the labels 400, 410 shown in fig. 5) is read at the label manufacturing site 700 and stored in a database. Each hologram printer of the manufacturing site 700 is associated with an encryption engine. The encryption engine combines the representation of the random data corresponding to the dots 420 on the label 400, 410 with the private key information securely maintained within the encryption engine and the variable information generated within the encryption engine to produce an encrypted string 470 (see fig. 5) which is then printed on the label 400, 410 by the label printer.

The printed labels are placed on products that will be distributed by intermediate and final distribution links. These tags can be read at the distribution point by a hologram reader associated with the decryption engine. The hologram reader reads random data from a substrate beneath the hologram, using the random data as a public key to decrypt a string printed on the label without having to determine a private key securely held in an encryption engine. If the tag is counterfeit or made illegally, the string either cannot be encrypted or the random data will not be contained in the tag manufacturer database.

The term "string" refers to any encoded information, including bar codes, optically readable alphanumeric characters, encoded magnetic strips, magnetically readable alphanumeric characters, optically readable bit strings, icons, and the like.

Information about the special tags passing through each distribution point, as well as validity and invalidity, may be collected over a network of computer nodes; and analyzed at one or more points. A central computer node may download information to various distribution points to alert them to some counterfeit threat, or to upgrade their decryption engine and/or download an upgraded version of the encryption engine to the label printer.

The anti-counterfeiting/security system shown in fig. 8 is capable of detecting counterfeit products at any point in the production and distribution process and collecting and analyzing the product process. If counterfeiting is detected, the time and geometric pattern of its appearance can be used to help track its source and distribution channels. The system provides the ability to detect factory overruns of labels or products, control label production quantities, and the like.

It is to be understood that even though various embodiments and advantages of the present invention have been set forth in the foregoing description, the foregoing disclosure is illustrative only, and changes may be made in detail, while remaining within the broad principles of the present invention. For example, many of the components described above may use digital or analog circuitry, or a combination of both, as appropriate, or may be implemented by software executed on suitable processing circuitry. Accordingly, the invention is not to be restricted except in light of the attached claims.

Claims (9)

1. An apparatus for extracting information from a diffractive object, comprising:

means for illuminating the diffractive object with spatially dependent light;

means for detecting at least a portion of the pattern diffracted by the object;

means for convolving the detected portion of the pattern with a template pattern to produce a deformed version of the pattern;

means for identifying and locating peaks in the deformed version;

means for representing the position of the peak in the morphed pattern as a vector; and

means for comparing the vector with a set of reference vectors in a database to classify the vector and thereby classify the diffraction pattern from the diffraction object.

2. A method of designing a template for a deformed pattern by convolution, comprising:

providing a set of experimental patterns and corresponding target patterns;

providing an initial set of test templates as an initial population in a genetic algorithm;

defining an adaptation value as a degree of correspondence between a convolution result of the test template and the experimental pattern and a corresponding target pattern; and

a genetic algorithm with adapted values and populations is used to develop a template that, when convolved with each experimental pattern, produces a convolved pattern that approximates the target pattern.

3. A scanner for extracting detailed structural information from a diffraction image, comprising:

a laser source for generating a laser beam;

focusing optics for directing a laser beam from the laser source to a spot;

means for positioning the diffraction image such that the spot illuminates an area on the diffraction image;

means for detecting a light pattern diffracted from the region; and

means for comparing the light pattern to a reference pattern.

4. A scanner according to claim 3 wherein the spot is less than 1mm in diameter.

5. A scanner for extracting detailed structural information from a diffraction image, comprising:

a laser source for generating a laser beam;

focusing optics for directing a laser beam from the laser source to a spot;

means for positioning the diffraction image such that the spot illuminates an area on the diffraction image;

means for moving the image relative to the spot so that the spot illuminates a series of areas on the image;

means for detecting a series of light patterns diffracted from the series of regions, respectively; and

means for comparing the series of light patterns to a reference series of patterns.

6. A scanner according to claim 5 wherein the spot is less than 1mm in diameter.

7. A scanner according to claim 5 wherein the reference series of patterns is represented in the form of a set of parametric curves.

8. A scanner according to claim 5 wherein the reference series of patterns is represented in the form of a two dimensional array of values.

9. The scanner of claim 8, wherein the two-dimensional array of values comprises numbers, scales, vectors, or strings.