Optical spectrophotometer having a multi-element light source

• US 5,257,086 A
• Filed: 06/09/1992
• Issued: 10/26/1993
• Est. Priority Date: 06/09/1992
• Status: Expired due to Fees

• Current Assignee: Plain Sight Systems Incorporated (Water Intelligence Plc)
• Original Assignee: D.O.M. Associates Int'l
• Inventors: Rys, Andrzej, Fateley, William G., Sobczynski, Radoslaw
• Primary Examiner(s): McGraw, Vincent P.
• Assistant Examiner(s): HANTIS, KAREN
• Application Number:
  US07/895,585
• Time in Patent Office: 504 Days
• Field of Search: 356/326, 356/328, 356/310, 356/329, 356/330--334, 356/302, 356/305, 356/73, 356/432, 250/553, 372/50, 372/53
• US Class Current: 356/328
• CPC Class Codes: G01J 2003/104 Monochromatic plural sources
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/2846 using modulation grid; Grid spectrometers
• CPC Class Codes: G01J 3/453 by correlation of the amplitudes

Abstract

A spectrophotometer includes an array of light emitting diodes configured for activation in successive Hadamard encodement patterns, a diffraction grating, an optical slit, a detector and electronic controls including a computer. In operation, the diffraction grating disperses and collimates radiation from the array and directs selected spectral components through the slit onto the detector whereupon the computer performs a Hadamard analysis on the detector signals.

Claims

1. A spectrophotometer apparatus comprising:

an electromagnetic radiation source array having a plurality of activatable radiation source elements configured for activation in a plurality of multiplexing encodement patterns, said elements having a solid state construction;

means including a detector for detecting radiation emissions from said elements, and for producing detector signals representative thereof;

structure defining an optical pathway for directing said emissions from said array to said detecting means; and

control means including

means coupled with said array for selectively activating said elements in order to produce a plurality of sequential multiplexing encodement patterns at a pattern rate of at least one patter per second, at least certain of said encodement patterns including simultaneous activation of a number of source elements and generation of a plurality of discrete emissions having different characterizing parameters, said pathway-defining structure including means for combining said different emissions and directing the combined emissions to said detector, and

means coupled with said detecting means for receiving and processing said detector signals, including detector signals representative of said combined emission, for storing a plurality of values respectively representative of said detector signals produced by said detector during said encodement patterns, and for performing a multiplex analysis of said values in correspondence with said encodement patterns in order to determine the individual intensities of emissions from each of said elements as received by said detecting means.

2. The apparatus as set forth in claim 1, said array including elements operable for emitting radiation in different spectral bands respectively.

3. The apparatus as set forth in claim 1, said radiation including visible light.

4. The apparatus as set forth in claim 1, said radiation including near infrared.

5. The apparatus as set forth in claim 1, said elements operable for emitting radiation in regions selected from the classifications consisting of visible, near infrared, infrared, and mid infrared.

6. The apparatus as set forth in claim 1, said elements including light emitting diodes.

7. The apparatus as set forth in claim 1, said multiplexing encodement patterns including Hadamard encodement patterns.

8. The apparatus as set forth in claim 1, said multiplexing encodement patterns including Fourier frequency oscillations.

9. The apparatus as set forth in claim 1, said elements being arranged in a configuration presenting four rows with twenty of said elements in each row.

10. The apparatus as set forth in claim 1, said control means including means for energizing said elements in an oscillating manner during activation thereof in order to produce corresponding oscillations in said signals for eliminating the effects of electronic noise on said signals.

11. The apparatus as set forth in claim 10, said oscillating manner being a square wave.

12. The apparatus as set forth in claim 11, said energizing means including means for oscillating the energization of said elements at least ten times for each pattern activation.

13. The apparatus as set forth in claim 1, said control means including a computer, a Hadamard pattern generator and an array driver operably configured for oscillating the energization of said elements in bursts within Hadamard pattern activations, said computer including means for digitally filtering said signals to reduce background noise therein.

14. The apparatus as set forth in claim 1, said detecting means including a detector selected from the group consisting of a photodiode, a photoresistor, and a phototransistor.

15. The apparatus as set forth in claim 1, said structure further including

means defining an output slit interposed in said pathway between said array and detector means, and

a diffraction grating placed in said pathway for receiving said radiation from said array and for directing a selected set of spectral components of the radiation from said elements through said output slit for impingement on said detector means.

16. The apparatus as set forth in claim 15 further including means for selectively changing the spacial relationship between said array, grating, slit and detector means for directing a different set of spectral components onto said detector means.

17. The apparatus as set forth in claim 16, said changing means including a mechanism coupled with said slit defining means for altering the spatial position thereof relative to said grating so that a different set of spectral components are directed through said slit onto said detector means.

18. The apparatus as set forth in claim 17, said mechanism including a stepper motor.

19. The apparatus as set forth in claim 1, said pattern rate including 5,000 patterns per second.

20. The apparatus as set forth in claim 1, said encodement patterns including Hadamard patterns, said multiplex analysis including a Hadamard analysis.

21. The apparatus as set forth in claim 1, said optical pathway including laser means for developing laser light.

22. The apparatus as set forth in claim 21, said laser means including

an organic laser dye cell interposed in said pathway,

a first semitransparent mirror positioned between said array and said dye cell, and

a second semitransparent mirror positioned in said pathway between said dye cell and said detector,

said dye cell and mirrors cooperatively making up a laser optically energized by radiation produced by said elements.

23. The apparatus as set forth in claim 22, said laser structure further including lenses respectively interposed between said elements and said first mirror for focusing the radiation emitted by said elements at respective focal points within said dye cell.

24. The apparatus as set forth in claim 21, said laser means including laser injector diodes.

25. The apparatus as set forth in claim 1, said optical pathway incorporating a concave, aberration corrected, holographic diffraction grating for collimating and dispersing radiation.

26. The apparatus as set forth in claim 1, said control means including a computer.

27. A spectrophotometer apparatus comprising:

an electromagnetic radiation source array having a plurality of activatable radiation source elements configured for activation in a plurality of Hadamard encodement patterns, said elements having a solid state construction;

structure defining an optical pathway for directing emissions from said array, said optical pathway having a concave diffraction grating for dispersing emissions from said array and having an optical slit;

a detector positioned for receiving emissions from said optical pathway and responsive thereto for producing detector signals representative thereof;

an electronically adjustable mechanism for selectively altering a wavelength defining angular relationship between said detector, said diffraction grating, and said array; and

control means including

a computer, an array driver, and a Hadamard pattern generator operable for energizing said elements in an oscillating burst manner during pattern activation thereof in order to produce corresponding oscillations in said signals, at least certain of said patterns including simultaneous activation of a number of source elements and generation of a plurality of different emissions having different characterizing parameters, said optical pathway serving to combine said different emissions and directing the combined emissions to said detector,

the computer being coupled with said detector and operable for receiving, filtering, and processing said detector signals, for storing a plurality of values respectively representative of said detector signals produced by said detector during said encodement patterns, and for producing a Hadamard analysis of said values in correspondence with said encodement patterns in order to determine the individual intensities of emissions from each of said elements as received by said detecting means.

28. A laser spectrophotometer comprising:

an electromagnetic radiation source array having a plurality of activatable radiation source elements configured for allowing activation in a plurality of multiplexing patterns, said elements having a solid state construction;

a detector for producing signals in response to electromagnetic radiation;

structure defining an optical pathway for directing radiation from said array to said detector, said optical pathway including

respective lenses for focusing electromagnetic radiation from said elements of said array,

a first semi-transparent mirror positioned to receive focused electromagnetic radiation from said lenses, said first semi-transparent mirror tending to allow passage therethrough of light from said array,

a laser amplifier cell for fluorescing light of a secondary wavelength category, said cell positioned to receive light passing through said first semi-transparent mirror, said first semi-transparent mirror tending to reflect light of the secondary wavelength category,

a diffraction grating for collimating fluoresced light from said cell by reflectively dispersing such light into various wavelength components,

a second semi-transparent mirror for reflecting collimated light, said second semi-transparent mirror tending to partially reflect light of the secondary wavelength category;

an electronically adjustable mechanism for selectively altering a wavelength defining angular relationship between said detector, said diffraction grating, and said array;

control means including

a computer, an array driver, and a Hadamard pattern generator operably configured for energizing said elements in an oscillating manner during pattern activation thereof in order to produce corresponding oscillations in said signals, and

said computer operably coupled with said detector for receiving, filtering, and processing said signals and for producing a multiplex analysis thereof,

said computer coupled with said mechanism in an operable manner for altering said angular relationship.

29. An electromagnetic radiation source array comprising:

a plurality of activatable radiation source elements, said elements having a solid state construction;

means for selectively activating ensembles of said elements simultaneously in a plurality of multiplexing encodement patterns, said activating means including electronic controls having a computer, a pattern generator and a driver for activating said elements in multiplexing encodement patterns at a rate of at least one pattern per second, said multiplexing encodement patterns selected from the group consisting of Hadamard and Fourier patterns.

30. A spectrophotometer apparatus comprising:

an electromagnetic radiation source array having a plurality of activatable radiation source elements configured for activation in a plurality of multiplexing encodement patterns, said elements having a solid state construction;

means including a detector for detecting a combination of emissions from said elements activated in said patterns to simultaneously impinge upon said detector, and for producing signals representative thereof representing a combined intensity of said combined radiations at said detector;

structure defining an optical pathway for directing said emissions from said array to said detecting means; and

control means including

means coupled with said array for selectively activating said elements in order to produce a plurality of sequential multiplexing encodement patterns at a pattern rate of at least one pattern per second, and

means coupled with said detecting means for receiving and processing said signals, and for producing a multiplex analysis thereof advantage from said detecting means by resolving said signals into respective discrete intensities corresponding to each activated element,

said optical pathway including laser means for developing laser light.

31. The apparatus as set forth in claim 30, said laser means including

an organic laser dye cell interposed in said pathway,

a first semitransparent mirror positioned between said array and said dye cell, and

a second semitransparent mirror positioned in said pathway between said dye cell and said detector,

said dye cell and mirrors cooperatively making up a laser optically energized by emissions produced by said elements.

32. The apparatus as set forth in claim 31, said laser structure further including lenses respectively interposed between said elements and said first mirror for focusing the radiation emitted by said elements at respective focal points within said dye cell.

33. The apparatus as set forth in claim 30, said laser means including laser injector diodes.

34. A method of spectrophotometric analysis comprising:

providing an array having a plurality of light emitting diodes having a solid state construction;

simultaneously activating selected ones of said diodes in successive multiplexing encodement patterns, each of said patterns including a plurality of different emissions having different characterizing parameters;

combining representative spectral emissions from the individual diodes, to produce combined emissions;

producing signals representative of an intensity of said combined emissions;

storing values representative of said signals; and

performing a multiplex analysis of said values in correspondence with said encodement patterns in order to resolve said values into respective intensity contributions from each of said activated diodes.