Method for adjusting spectral measurements to produce a standard Raman spectrum

• US 6,281,971 B1
• Filed: 09/08/2000
• Issued: 08/28/2001
• Est. Priority Date: 05/18/1999
• Status: Active Grant

• Current Assignee: Bruker Optics, Inc. (Bruker Corporation)
• Original Assignee: New Chromex, Inc.
• Inventors: Zhao, Jun, Allen, Fritz Schreyer
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US09/658,708
• Time in Patent Office: 354 Days
• Field of Search: 356/301
• US Class Current: 356/301
• CPC Class Codes: G01J 2003/2866 Markers; Calibrating of scan
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/027 Control of working procedures of a spectrometer; Failure detection; Bandwidth calculation
• CPC Class Codes: G01J 3/0297 Constructional arrangements for removing other types of optical noise or for performing calibration
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01J 3/4412 Scattering spectrometry particle sizing by light scattering G01N15/0205; optical velocimetry of particles G01P5/20, G01P5/26
• CPC Class Codes: G01N 21/65 Raman scattering

Abstract

A method for producing a standard Raman spectrum of a sample. A source of incident radiation is provided. Means provide an incident beam and a monitor beam from the incident radiation. The incident beam is directed to the sample and a Raman beam is generated from the sample. Spectral data may be collected directly from the monitor beam and the Raman beam simultaneously. The occurrence of a frequency shift in the incident radiation is determined. One spectral measurement is made after the occurrence of the frequency shift, or a first spectral measurement is made before and a second spectral measurement is made after the frequency shift. One or more arithmetic calculations are applied to the single spectral measurement, or the second spectral measurement is subtracted from the first spectral measurement. One or more integral transforms are applied to the resulting spectral measurement data to produce the standard Raman spectrum.

Claims

1. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample, comprising the steps of:

selecting an apparatus for measuring and applying instrumentation correction to one or more beams of radiation, including an incident beam and a Raman beam;

quantifying one or more frequency shifts in the incident beam and Raman beam;

obtaining spectral data from the one or more beams of radiation; and

applying one or more spectral data modifications to the spectral data to determine the standard Raman spectrum of a sample.

2. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample as recited in claim 1, wherein the selecting step includes the step of choosing a semiconductor laser as a source of the incident beam.

3. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample as recited in claim 1, wherein the quantifying step includes the substep of inducing one or more frequency shifts in the incident beam.

4. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample as recited in claim 1, wherein the quantifying step includes the substep of determining one or more frequency shifts in the incident beam.

5. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample as recited in claim 1, wherein the quantifying step includes the substep of measuring the one or more frequency shifts.

6. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample as recited in claim 1, wherein the obtaining step includes the substeps of:

collecting spectral data from the incident beam and Raman beam substantially simultaneously;

displaying data about the one or more frequency shifts on one or more graphs; and

displaying the one or more graphs on a computer monitor.

7. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample as recited in claim 1, wherein the obtaining step includes the substep of directing the spectral data to a detector.

8. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample as recited in claim 1, wherein the obtaining step includes the substeps of:

obtaining first spectral data from the incident beam;

obtaining first spectral data from the Raman beam;

confirming occurrence of a frequency shift in the incident beam and Raman beam;

obtaining second spectral data from the incident beam; and

obtaining second spectral data from the Raman Beam.

9. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample as recited in claim 1, wherein the applying step includes the substep of scaling.

10. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample as recited in claim 8, wherein the applying step includes the substeps of:

subtracting the second spectral data from the incident beam from the first spectral data from the incident beam to provide a first result; and

subtracting second spectral data from the Raman beam from the first spectral data from the Raman beam to provide a second result.

11. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample as recited in claim 10, wherein applying step includes the substep of applying one or more integral transforms to the first result and second result to produce the standard Raman spectrum of the sample.

12. A method for adjusting a spectral measurement to produce a standard Raman spectrum of a sample, comprising the steps of:

selecting an apparatus for measuring and applying instrumentation correction to one or more beams of radiation, including an incident beam and a Raman beam;

obtaining a spectral measurement set from the incident beam and Raman beam;

shifting the spectral measurement set frequency axis to obtain one or more shifted spectral data sets; and

applying one or more spectral data modifications to the spectral measurement set and one or more shifted spectral data sets to determine the standard Raman spectrum of a sample.

13. A method for adjusting a spectral measurement to produce a standard Raman spectrum of a sample as recited in claim 12, wherein the selecting step includes the substep of choosing a laser as a source of the incident beam.

14. A method for adjusting a spectral measurement to produce a standard Raman spectrum of a sample as recited in claim 12, wherein the obtaining step includes the substeps of:

collecting spectral data from the incident beam and Raman beam substantially simultaneously;

displaying data about the one or more frequency shifts on one or more graphs; and

displaying the one or more graphs on a computer monitor.

15. A method for adjusting a spectral measurement to produce a standard Raman spectrum of a sample as recited in claim 12, wherein the shifting step may include the substeps of:

mathematically altering the spectral measurement set; and

altering the frequency axis of the apparatus.

16. A method for adjusting a spectral measurement to produce a standard Raman spectrum of a sample as recited in claim 15, wherein the shifting step may include the substep of performing a subsequent measurement to produce a second frequency shifted result.

17. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample as recited in claim 12, wherein the applying step includes the substeps of subtracting the spectral measurement set from the one or more shifted spectral data sets to produce a set of spectral differences.

18. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample as recited in claim 17, wherein the applying step includes the substep of flattening the set of spectral differences.

19. A method for adjusting spectral measurements to produce a standard Raman spectrum of a sample as recited in claim 18, wherein the applying step includes the substep of applying one or more integral transforms to the set of spectral differences to produce the standard Raman spectrum of the sample.

20. A method for producing a standard Raman spectrum of a sample, comprising the steps of:

selecting a source of incident radiation;

locating in the path of incident radiation means for providing an incident beam;

including one or more devices in the path of the incident beam for directing the incident beam at a sample;

installing adjacent the one or more devices means for generating a Raman beam from the sample;

providing means for substantially simultaneous collection of spectral data from the incident beam and Raman beam;

collecting one or more spectral measurements from one or more frequency shifts in the incident beam and one or more frequency shifts in the Raman beam;

obtaining first spectral data from the incident beam and from the Raman beam;

confirming occurrence of a frequency shift in the incident beam and Raman beam;

obtaining second spectral data from the incident beam and from the Raman Beam; and

applying one or more spectral data modifications to the one or more spectral measurements to produce the standard Raman spectrum of the sample.

21. A method for producing a standard Raman spectrum of a sample as recited in claim 20, wherein the selecting step includes the substep of selecting a substantially monochromatic source of light.

22. A method for producing a standard Raman spectrum of a sample as recited in claim 20, wherein the locating step includes the substep of inducing one or more frequency shifts in the incident beam.

23. A method for producing a standard Raman spectrum of a sample as recited in claim 22, wherein the locating step includes the substep of identifying one or more frequency shifts in the incident beam.

24. A method for producing a standard Raman spectrum of a sample as recited in claim 20, wherein the collecting step includes the substeps of:

displaying data about the one or more frequency shifts on one or more graphs; and

displaying the one or more graphs on a computer.

25. A method for producing a standard Raman spectrum of a sample as recited in claim 20, wherein the applying step may include the substep of scaling.

26. A method for producing a standard Raman spectrum of a sample as recited in claim 25, wherein the applying step includes the substeps of:

subtracting the second spectral data from the incident beam from the first spectral data from the incident beam to provide a first result; and

subtracting second spectral data from the Raman beam from the first spectral data from the Raman beam to provide a second result.

27. A method for producing a standard Raman spectrum of a sample as recited in claim 26, wherein the applying step includes the substep of applying one or more integral transforms to the first result and second result to produce the standard Raman spectrum of the sample.

28. A method for adjusting one or more spectral measurements from a Raman beam to produce a standard Raman spectrum of a sample, comprising the steps of:

obtaining a first Raman spectral measurement;

collecting one or more subsequent Raman spectral measurements from an incident beam, the incident beam having a different wavelength from the first Raman spectral measurement; and

applying one or more spectral data modifications to the spectral measurements to determine the standard Raman spectrum of a sample.

29. A method for adjusting one or more spectral measurements from a Raman beam to produce a standard Raman spectrum of a sample as recited in claim 28, wherein the obtaining step may include the substep of scaling.

30. A method for adjusting one or more spectral measurements from a Raman beam to produce a standard Raman spectrum of a sample as recited in claim 28, wherein the collecting step includes the substep of scaling.

31. A method for adjusting one or more spectral measurements from a Raman beam to produce a standard Raman spectrum of a sample as recited in claim 28, wherein the measuring step includes the substep of subtracting the one or more subsequent Raman spectral measurements from the first Raman spectral measurement to obtain one or more results.

32. A method for adjusting one or more spectral measurements from a Raman beam to produce a standard Raman spectrum of a sample as recited in claim 28, wherein the measuring step includes the substep of monitoring the incident beam substantially simultaneously with the Raman beam.

33. A method for adjusting one or more spectral measurements from a Raman beam to produce a standard Raman spectrum of a sample as recited in claim 28, wherein the measuring step includes the substep of applying one or more integral transforms to the one or more results to produce the standard Raman spectrum of the sample.

34. A method for adjusting one or more spectral measurements from a Raman beam to produce a standard Raman spectrum of a sample, comprising the steps of:

selecting a first Raman spectral measurement;

obtaining one or more Raman spectral data having a shifted frequency axis; and

applying one or more spectral data modifications to the spectral data to determine the standard Raman spectrum of a sample.

35. A method for adjusting one or more spectral measurements from a Raman beam to produce a standard Raman spectrum of a sample as recited in claim 34, further comprising the substeps of subtracting the first Raman spectral measurement from the one or more Raman spectral data having a shifted frequency axis.

36. A method for adjusting one or more spectral measurements from a Raman beam to produce a standard Raman spectrum of a sample as recited in claim 34, further comprising the substeps of scaling the first Raman spectral measurement and the one or more Raman spectral data.

37. A method for adjusting one or more spectral measurements from a Raman beam to produce a standard Raman spectrum of a sample as recited in claim 34, further comprising the substeps of flattening any difference between the first Raman spectral measurement and the one or more Raman spectral data.