System for identifying known materials within a mixture of unknowns

• US 5,926,773 A
• Filed: 10/27/1997
• Issued: 07/20/1999
• Est. Priority Date: 11/04/1994
• Status: Expired due to Term

• Current Assignee: Sandia Corporation (Martin Marietta Corporation)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Wagner, John S.
• Primary Examiner(s): Cosimano, Edward R.
• Application Number:
  US08/958,099
• Time in Patent Office: 631 Days
• Field of Search: 250/339.05, 250/339.11, 250/339.12, 250/373, 356/317, 356/318, 356/320, 364/497, 364/498, 395/13, 395/20, 395/21, 395/23, 422/82.05, 436/171, 702/22, 702/23, 702/25, 702/27
• US Class Current: 702/22
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01N 21/25 Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
• CPC Class Codes: G01N 21/3577 for analysing liquids, e.g. polluted water
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 33/0034 comprising neural networks or related mathematical techniques

Abstract

One or both of two methods and systems are used to determine concentration of a known material in an unknown mixture on the basis of the measured interaction of electromagnetic waves upon the mixture. One technique is to utilize a multivariate analysis patch technique to develop a library of optimized patches of spectral signatures of known materials containing only those pixels most descriptive of the known materials by an evolutionary algorithm. Identity and concentration of the known materials within the unknown mixture is then determined by minimizing the residuals between the measurements from the library of optimized patches and the measurements from the same pixels from the unknown mixture. Another technique is to train a neural network by the genetic algorithm to determine the identity and concentration of known materials in the unknown mixture. The two techniques may be combined into an expert system providing cross checks for accuracy.

Claims

1. A system for identifying the amount of at least one known constituent contained within an unknown mixture comprising:

(a) a reference electromagnetic wave excitation source for irradiating a purest available sample of at least one constituent at a first set of wavelengths;

(b) means for recording at least one parameter as a measurement of the response of the sample of the at least one constituent to the excitation source at a second set of wavelengths to form an n-dimensional array consisting of a multiplicity of elements, where n≧

2;

(c) means for creating an optimized patch subset in the array by an evolutionary algorithm, the optimized patch subset containing only those array elements which indicate the presence of the pure sample of the at least one constituent;

(d) means for irradiating the unknown mixture at the first set of wavelengths;

(f) means for recording the at least one parameter as a measurement of the response of the unknown mixture to the excitation source at the second set of wavelengths to form the n-dimensional array of step (b); and

(g) means for determining the amount of the at least one known constituent in the unknown mixture by minimizing a function of the residuals between measurements of the at least parameter associated with the elements in the optimized patch subset for the sample of the at least one constituent and the measurements of the at least one parameter associated with the elements in a patch subset from the unknown mixture which corresponds with the optimized patch set.

2. A system for identifying the amount of at least one known constituent contained within an unknown mixture comprising:

(a) a reference electromagnetic wave excitation source for irradiating a purest available sample of at least one constituent at a first set of wavelengths;

(b) means for recording at least one parameter as a measurement of the response of the sample of the at least one constituent to the excitation source at a second set of wavelengths to form an n-dimensional array consisting of a multiplicity of elements, where n≧

2;

(c) means for creating a patch subset in the array, the patch subset containing those array elements which indicate the presence of the sample of the at least one constituent;

(d) means for irradiating the unknown mixture at the first set of wavelengths;

(e) means for recording the at least one parameter as a measurement of the response of the unknown mixture to the excitation source at the second set of wavelengths to form an n-dimensional array of the type recited in step (b); and

(f) means for determining the amount of the at least one known constituent in the unknown mixture by minimizing a function of the residuals between measurements of the at least parameter associated with the elements in the patch subset for the sample of the at least one constituent and the measurements of the at least one parameter associated with the elements in a patch subset in the n-dimensional array from the unknown mixture which corresponds with the patch set for the at least one known constituent.

3. The system of claim 2 wherein the excitation source is a flash lamp equipped with a plurality of filters to provide the first set of wavelengths.

4. The system of claim 2 wherein the excitation source is a laser tuned to the first set of wavelengths.

5. The system of claim 2 wherein the means for determining of the amount of the at least one known constituent comprises multivariate analysis means.

6. The system of claim 2 wherein the at least one known constituent is at least one chemical.

7. The system of claim 2 wherein the at least one parameter is the magnitude of the each of the second set of wavelengths.

8. The system of claim 7 wherein the magnitude measured is of uv fluorescence.

9. The system of claim 2 wherein the at least one known constituent is at least one biologic material.

10. The system of claim 9 wherein the at least one biologic material is at least one material selected from the group consisting of viruses, bacteria, DNA, RNA, and abnormal cells including cancer cells.

11. The system of claim 2 wherein the element is a pixel representing one of the second set of wavelengths.

12. The system of claim 11 wherein the pixel is associated with other pixels to form a two dimensional array.

13. The system of claim 12 wherein the patch subset for the at least one known constituent includes only those associated pixels which contain information indicative of the at least one known constituent.

14. A system for identifying the amount of at least one known constituent contained within an unknown mixture comprising:

(a) means to store an n-dimensional array, where n≧

2, consisting of a multiplicity of elements with the array including a patch subset that contains those elements of the array that indicate the presence at least one known constituent wherein the stored array is the product of a separate system comprising;

(1) a reference electromagnetic wave excitation source for irradiating a purest available sample of the at least one constituent at a first set of wavelengths;

(2) means for recording at least one parameter as a measurement of the response of the sample of the at least one constituent to the excitation source at a second set of wavelengths to form the n-dimensional array;

(3) means for creating the patch subset in the array;

(b) means for irradiating the unknown mixture at the first set of wavelengths;

(c) means for recording the at least one parameter as a measurement of the response of the unknown mixture to the excitation source at the second set of wavelengths to form an n-dimensional array of the type recited in step (a); and

(d) means for determining the amount of the at least one known constituent in the unknown mixture by minimizing a function of the residuals between measurements of the at least parameter associated with the elements in the patch subset for the sample of the at least one constituent and the measurements of the at least one parameter associated with the elements in a patch subset in the n-dimensional array from the unknown mixture which corresponds with the patch set for the at least one known constituent.