Fluorescence authentication reader with coaxial optics

• US 5,574,790 A
• Filed: 12/18/1995
• Issued: 11/12/1996
• Est. Priority Date: 09/27/1993
• Status: Expired due to Term

• Current Assignee: Angstrom Technologies, Inc.
• Original Assignee: Angstrom Technologies, Inc.
• Inventors: Wray, Donald L., Ryan, William J., Silverglate, David, Liang, Louis H., Marinello, Daniel A.
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US08/575,729
• Time in Patent Office: 330 Days
• Field of Search: 380/23, 380/54, 380/59, 250/271, 250/556, 156/643, 235/491, 235/492, 283/88, 283/91, 283/92, 106/21, 382/7, 378/44, 340/825.34
• US Class Current: 283/89
• CPC Class Codes: G02B 6/3839 for a plurality of light guides
• CPC Class Codes: G02B 6/3861 Adhesive bonding adhesives in general C09J
• CPC Class Codes: G06K 7/12 using a selected wavelength, e.g. to sense red marks and ignore blue marks
• CPC Class Codes: G07D 7/0043 using barcodes
• CPC Class Codes: G07D 7/04 Testing magnetic properties of the materials thereof, e.g. by detection of magnetic imprint G07D7/01 takes precedence
• CPC Class Codes: G07D 7/1205 Testing spectral properties
• CPC Class Codes: G07D 7/121 Apparatus characterised by sensor details

Abstract

A multiple-reader system for authentication of articles uses a first reader (400) which employs predetermined modulated illuminating light (20) and a multiplicity of discriminating variables, such as wavelengths (110), amplitudes (120), and time delays (140) relative to the modulated illuminating light (20) to characterize fluorescent light (70) detected from fluorescent indicia on the articles. The fluorescent indicia may also incorporate spatial distributions such as bar codes as discriminating features. Additional readers (410 and 420), which may be readers of fluorescent marks and/or readers of other indicia, are synchronized with the fluorescence reader by timing signals. The discriminating features may be re-programmed by the user of the authentication system. Thus the discriminating features define a user-determined and programmable encryption of the articles'"'"' authentic identity. The outputs provided by individual readers (400, 410 and 420) are combined by a computer (85) programmed to produce the authentication result. The fluorescence authentication reader includes integration and synchronization of multiple readers of various types, an improved coaxial optics subsystem (450), and electronic circuitry with improved time-base stability, which cooperate in enhancing signal/noise ratio. The resultant stable triggering of the authentication output of the individual fluorescence reader, combined with time synchronization of the individual fluorescence reader with other readers, provides a reliable integrated multi-reader authentication system.

Claims

1. An authentication system for discriminating among articles marked with one or more fluorescent substances which emit fluorescent light in response to electromagnetic radiation, comprising:

a) a source of electromagnetic radiation in at least one of the ultraviolet, visible, and infrared spectral ranges;

b) means for modulating said electromagnetic radiation at a frequency of more than about 25 kHz;

c) means for synchronously detecting said fluorescent light at said modulation frequency to produce an analog signal;

d) first optical means for transmitting said electromagnetic radiation from said source toward said articles;

e) second optical means for transmitting said fluorescent light toward said means for synchronously detecting said fluorescent light, wherein said first and second optical means are adapted to be substantially coaxial;

f) conversion means to convert said analog signal to a first digital signal;

g) comparison means comparing said first digital signal with a predetermined second digital signal to within a predetermined tolerance; and

h) output means indicating a positive authentication result if said first and second digital signals agree to within said tolerance, and otherwise indicating a negative authentication result.

2. An authentication system as recited in claim 1, wherein said comparison means comprises a computer operable by a predetermined program to control said output means according to said authentication results.

3. An authentication system as recited in claim 2, further comprising at least one additional detector having an output, said output of said at least one additional detector being responsive to indicia selected from the list consisting of:

a) magnetic indicia,

b) holographic indicia,

c) visible characters, and

d) visible bar codes.

4. An authentication system as recited in claim 1, wherein said first and second optical means each comprises at least one light guide.

5. An authentication system as recited in claim 1, wherein said first and second optical means each comprises at least one lens.

6. An authentication system as recited in claim 2, further comprising a reader adapted to read indicia, said reader having a reader output, and wherein said computer is adapted to receive said first digital signal and said reader output and to produce an authentication result depending on whether or not said digital signal and said reader output agree with predetermined codes.

7. An authentication system as recited in claim 2, further comprising a magnetic stripe reader having a digital output, wherein said magnetic stripe reader digital output is connected to said computer to provide information used by said predetermined program to produce said digital outputs indicating authentication or lack of authentication.

8. An authentication system as recited in claim 3, wherein said output of said at least one additional detector is connected to said computer to provide information used by said predetermined program to produce said digital outputs indicating authentication or lack of authentication.

9. An authentication system as recited in claim 4, wherein said first optical means comprises a single light guide and said second optical means comprises a plurality of light guides disposed around said first optical means.

10. An authentication system as recited in claim 4, wherein said second optical means comprises a single light guide and said first optical means comprises a plurality of light guides disposed around said first optical means.

11. An authentication system as recited in claim 5, wherein said first optical means comprises a single lens and said second optical means comprises a plurality of lenses disposed around said first optical means.

12. An authentication system as recited in claim 5, wherein said second optical means comprises a single lens and said first optical means comprises a plurality of lenses disposed around said first optical means.

13. An authentication system as recited in claim 5, wherein said first optical means comprises a single lens and said second optical means comprises an annular lens disposed around said first optical means.

14. An authentication system as recited in claim 5, wherein said second optical means comprises a single lens and said first optical means comprises an annular lens disposed around said first optical means.

22. An authentication system as recited in claim 13, wherein said first and second optical means are integrated into a single coaxial optical element.

23. An authentication system as recited in claim 14, wherein said first and second optical means are integrated into a single coaxial optical element.

26. An authentication system as recited in claim 1, wherein said means for modulating said electromagnetic radiation comprises

a) a crystal-controlled oscillator adapted to be operated at a frequency of more than about 25 kHz,

b) a photodetector adapted to be responsive to said electromagnetic radiation, said photodetector having a feedback output, and

c) an inverter energizing said source of electromagnetic radiation, said inverter being controlled both by said crystal-controlled oscillator and by said feedback output of said photodetector.

27. An authentication system as recited in claim 1, wherein said means for synchronously detecting said fluorescent light includes an electrical bandpass filter passing said frequency.

28. An authentication system as recited in claim 1, wherein said comparison means includes means responsive to a timing signal to time at least said authentication results.

29. An authentication system as recited in claim 2, wherein said computer further comprises an input responsive to a timing signal to time at least said authentication results.

30. An authentication system as recited in claim 6, wherein said reader is further adapted to be have a synchronizing output, and wherein said computer is adapted to receive said synchronizing output to control the timing of at least said authentication result.

31. An authentication system as recited in claim 1, wherein said computer is further adapted to be responsive to a timing signal to control timing of at least said digital output means.

32. An authentication system as recited in claim 26, wherein said means for synchronously detecting said fluorescent light further comprises a lock-in amplifier controlled by said crystal-controlled oscillator.

33. An authentication system as recited in claim 27, wherein said electrical bandpass filter has a bandwidth of plus and minus about 2 kHz around said frequency.

15. An authentication system for discriminating among articles marked with one or more fluorescent substances which emit fluorescent light in response to electromagnetic radiation, comprising:

a) a source of electromagnetic radiation in at least one of the ultraviolet, visible, and infrared spectral ranges;

b) a driver circuit adapted to energize said source at a predetermined frequency, said driver circuit further comprising at least one crystal, and said predetermined frequency being determined by said at least one crystal;

c) first optical means for transmitting said electromagnetic radiation from said source toward said articles;

d) second optical means for transmitting said fluorescent light toward at least one detector capable of producing a first analog signal responsive to said fluorescent light, said first and second optical means being adapted to be substantially coaxial;

e) wavelength-selective means disposed to allow selected portions of said spectral ranges to illuminate said detector;

f) amplifier means adapted to synchronously detect said first analog signal at said predetermined frequency;

g) an electrical bandpass filter adapted to pass said predetermined frequency and to remove selected other frequencies from said first analog signal to produce a second analog signal;

h) an analog-to-digital converter converting said second analog signal to a digital signal,

i) a computer operating under a predetermined program and comparing said digital signal to one or more predetermined digital signals, said computer being adapted to discriminate between said marked articles and other articles not so marked, and

j) digital output means responsive to said computer to indicate authentication or lack of authentication of said articles to be discriminated.

16. An authentication system as recited in claim 15, wherein said first and second optical means each comprises at least one light guide.

17. An authentication system as recited in claim 15, wherein said first and second optical means each comprises at least one lens.

18. An authentication system as recited in claim 16, wherein said first optical means comprises a single light guide and said second optical means comprises a plurality of light guides disposed around said first optical means.

19. An authentication system as recited in claim 16, wherein said second optical means comprises a single light guide and said first optical means comprises a plurality of light guides disposed around said first optical means.

20. An authentication system as recited in claim 17, wherein said first optical means comprises a single lens and said second optical means comprises a plurality of lenses disposed around said first optical means.

21. An authentication system as recited in claim 17, wherein said second optical means comprises a single lens and said first optical means comprises a plurality of lenses disposed around said first optical means.

24. An authentication system as recited in claim 20, wherein said first and second optical means are integrated into a single coaxial optical element.

25. An authentication system as recited in claim 21, wherein said first and second optical means are integrated into a single coaxial optical element.

34. An authentication system, comprising

a) a first reader adapted to read first indicia printed with a substance that emits fluorescent light when illuminated with ultraviolet light, said first reader having a first output, and said first reader comprising:

i) a source of electromagnetic radiation in at least one of the ultraviolet, visible, and infrared spectral ranges;

ii) a crystal-controlled oscillator adapted to be operated at a predetermined frequency of more than about 25 kHz;

iii) a first photodetector adapted to be responsive to said electromagnetic radiation, said first photodetector having a feedback output;

iv) an inverter adapted to energize said source of electromagnetic radiation with a square-wave waveform having a 50% duty cycle, said inverter being controlled both by said crystal-controlled oscillator and by said feedback output of said first photodetector;

v) first optical means for transmitting said electromagnetic radiation from said source toward said first indicia;

vi) second optical means for transmitting said fluorescent light toward at least one second photodetector capable of producing a first analog signal responsive to said fluorescent light, said first and second optical means being adapted to be substantially coaxial;

vii) at least one wavelength-selective means disposed to allow selected portions of said spectral ranges to illuminate said second photodetector;

viii) amplifier means adapted to synchronously detect said first analog signal at said predetermined frequency;

ix) an electrical bandpass filter adapted to pass said predetermined frequency and to remove selected other frequencies from said first analog signal to produce a second analog signal;

x) an analog-to-digital converter converting said second analog signal to a first digital signal,

xi) comparison means comparing said first digital signal with a predetermined second digital signal to within a predetermined tolerance to discriminate between said first indicia and other indicia; and

xii) digital output means responsive to said comparison means to provide said first output;

(b) at least a second reader adapted to read second indicia, said second reader having a second output, at least one of said first and second readers being adapted to provide a synchronizing signal; and

(c) a computer responsive to said synchronizing signal and adapted by being programmed to receive said first and second outputs respectively from said first and second readers, to decode said first and second indicia, and to produce an authentication result depending on whether or not said first and second indicia agree with predetermined indicia codes.