Processing system for remote chemical identification

• US 6,885,965 B2
• Filed: 05/22/2003
• Issued: 04/26/2005
• Est. Priority Date: 05/22/2002
• Status: Expired due to Fees

• Current Assignee: TSB Ventures, LLC
• Original Assignee: First Responder Systems and Technology Inc.
• Inventors: Butler, Matthew, Plummer, Grant
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): LE, JOHN H
• Application Number:
  US10/444,045
• Publication Number:
  US 20040111232A1
• Time in Patent Office: 705 Days
• Field of Search: 702/22, 702/23, 702/27, 702/28, 702/99, 702/130, 356/51, 356/451, 356/311, 250/338.5, 250/339, 250/341, 600/316, 607/88, 374/131
• US Class Current: 702/130
• CPC Class Codes: G01J 3/0264 Electrical interface; User interface
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/453 by correlation of the amplitudes
• CPC Class Codes: G01N 2021/1793 Remote sensing
• CPC Class Codes: G01N 21/3518 Devices using gas filter correlation techniques; Devices using gas pressure modulation techniques
• CPC Class Codes: G01N 2201/1211 for temperature
• CPC Class Codes: G01N 2201/129 Using chemometrical methods

Abstract

A fourth embodiment of the present invention is a method of generating a temperature compensated absorbance spectrum. The method includes the steps of: a. providing a sample spectrum and an estimated temperature of a backdrop object; b. from a set of known temperature spectra related to a known background temperature, selecting at least two known temperature spectra representing a background temperature above and below the estimated temperature; c. comparing the sample spectrum to the known temperature spectra in order to determine a sample background spectrum; and d. calculating an absorbance spectrum from the sample spectrum and the background spectrum.

Claims

1. A method of generating a background spectrum for use in spectral analysis, said method comprising the steps of:

a. providing a sample spectrum and an estimated temperature of a background object;

b. from a set of known temperature spectra related to a known background temperature, selecting at least two known temperature spectra representing a background temperature above and below said estimated temperature;

c. comparing said sample spectrum to said known temperature spectra in order to determine a sample background spectra.

2. The method of claim 1, wherein said step of comparing said sample spectra to said known temperature spectra further comprises the step of using classical least squares analysis.

3. The method of claim 1, wherein said estimated temperature is determined by a method comprising the steps of:

a. providing a predetermined relationship between a parabolic center frequency and a backdrop temperature, wherein said parabolic center frequency is that of a single beam spectrum of a reference backdrop at a known temperature;

b. providing a sample spectra recorded against a backdrop of an unknown temperature;

c. determining a best fit parabolic curve of said sample spectra;

d. determining a sample parabolic center frequency of said best fit parabolic curve;

e. comparing said sample parabolic center frequency to said predetermine relationship of center frequency and backdrop temperature;

f. estimating a temperature of said backdrop based upon said comparison.

4. The method of claim 3, wherein said step of determining a best fit parabolic curve further comprises the step of using classical least squares analysis.

5. The method of claim 4, wherein said step of using classical least squares analysis further comprises the step of using a weight iterative classical least squares analysis.

6. The method of claim 5, wherein weight iterations are continued until a fractional change in a sum of squared errors is less than a predetermined fraction.

7. A method of generating a temperature compensated absorbance spectrum, said method comprising the steps of:

a. providing a sample spectrum and an estimated temperature of a backdrop object;

b. from a set of known temperature spectra related to a known background temperature, selecting at least two known temperature spectra representing a background temperature above and below said estimated temperature;

c. comparing said sample spectrum to said known temperature spectra in order to determine a sample background spectrum;

d. calculating an absorbance spectrum from said sample spectrum and said background spectrum.

8. The method of claim 7, further comprising the step of comparing said absorbance spectrum to at least one chemical reference spectrum in order to identify a chemical represented in said absorbance spectrum.

9. The method of claim 8, wherein said step of comparing further includes using the spectra for CO2 and H2O in order to identify said chemical.

10. A method of identifying a chemical represented in an absorbance spectrum, said method comprising the steps of:

a. providing a sample absorbance spectrum;

b. comparing said absorbance spectrum to the analytical frequency range for CO2 and H2O and a plurality of chemical reference spectra in order to identify a chemical represented in said absorbance spectrum; and

c. wherein said plurality of chemical reference spectra comprise a primary set of chemical reference spectra and said primary set of chemical reference spectra is formed from a plurality of chemical spectra identification methods.

11. The method of claim 10, further providing a chemical database associating predefined characteristics and properties with a plurality of chemical compounds, wherein at least one chemical reference spectra is identified by said database for inclusion in said primary set.

12. The method of claim 10, further providing a chemical/location database associating at least one chemical compound with an assigned map location of said compound, wherein at least one chemical reference spectra is identified by said chemical/location database for inclusion in said primary set.

13. The method of claim 12, wherein a user location is provided by a global positioning system.

14. The method of claim 13, wherein said assigned map location in said database is in a street address format.

15. The method of claim 13, wherein said user location is provided in a longitude/latitude format and compared to said database.

16. The method of claim 15, further identifying all compounds in said database which are within a predetermined radius of said user location.

17. The method of claim 10, further providing a container database associating predetermined container shapes with a set of compounds and a user interface, wherein said user interface displays container shapes for selection by a user and selection of a container shape identifies at least one chemical reference spectrum for inclusion in said primary set.

18. The method of claim 10, further providing a placard database associating a predetermined placard with a set of compounds and a user interface, wherein said user interface displays placard information for selection by a user and selection of a placard identifies at least one chemical reference spectrum for inclusion in said primary set.

19. A method of identifying a chemical represented in an absorbance spectrum, said method comprising the steps of:

a. providing a sample absorbance spectrum;

b. comparing said absorbance spectrum to the analytical frequency range for CO2 and H2O and a plurality of chemical reference spectra in order to identify a chemical represented in said absorbance spectrum; and

c. wherein said plurality of chemical reference spectra comprise a primary set of chemical reference spectra and said comparison of said primary set of chemical reference spectra to said absorbance spectrum includes the steps of;

i. making a comparison of said primary set of chemical reference spectra to said absorbance spectrum;

ii. determining whether there are undetermined results for any of said reference spectra in said comparison;

iii. if undetermined results do exist in said comparison, then removing said reference spectra having undetermined results in said primary set;

iv. making another comparison of said primary set of chemical reference spectra to said absorbance spectrum;

v. repeating steps b-d until no undetermined results exist.

20. The method of claim 19, wherein after step (v), further taking a new reference spectrum from a secondary set of chemical reference spectra and adding said new reference spectrum to said primary set.

21. The method of claim 20, wherein steps (ii)-(iv) are repeated until no undetermined results exist in said primary step.

22. The method of claim 21, wherein said step of moving a new reference spectrum from said secondary set to said primary set is repeated until said secondary set is empty.

23. The method of claim 21, wherein said comparisons comprise a classical least squares analysis.

24. The method of claim 23, wherein all negative scaling factor values associated with a reference spectrum form a residual set.