Apparatus and methods relating to enhanced spectral measurement systems

• US 8,018,589 B2
• Filed: 04/05/2010
• Issued: 09/13/2011
• Est. Priority Date: 09/26/2003
• Status: Expired due to Fees

• Current Assignee: Tidal Photonics Incorporated
• Original Assignee: Tidal Photonics Incorporated
• Inventors: Stange, Ulrich, MacKinnon, Nicholas B.
• Primary Examiner(s): Chowdhury; Tarifur R
• Assistant Examiner(s): Stock, Jr.; Gordon J
• Application Number:
  US12/754,507
• Publication Number:
  US 20100253935A1
• Time in Patent Office: 526 Days
• Field of Search: None
• US Class Current: 356/300
• CPC Class Codes: G01J 1/32 adapted for automatic variation of the measured or reference value regulation of light intensity G05D25/00
• CPC Class Codes: G01J 2003/1282 Spectrum tailoring
• CPC Class Codes: G01J 2003/1286 Polychromator in general
• CPC Class Codes: G01J 3/027 Control of working procedures of a spectrometer; Failure detection; Bandwidth calculation
• CPC Class Codes: G01J 3/0286 Constructional arrangements for compensating for fluctuations caused by temperature, humidity or pressure, or using cooling or temperature stabilization of parts of the device; Controlling the atmosphere inside a spectrometer, e.g. vacuum
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/12 Generating the spectrum; Monochromators
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G01J 3/2803 using photoelectric array detector
• CPC Class Codes: G01J 3/42 Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08
• CPC Class Codes: G01J 3/4406 Fluorescence spectrometry
• CPC Class Codes: G01N 2021/3155 Measuring in two spectral ranges, e.g. UV and visible
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 21/39 using tunable lasers

Abstract

The apparatus and methods herein provide light sources and spectral measurement systems that can improve the quality of images and the ability of users to distinguish desired features when making spectroscopy measurements by providing methods and apparatus that can improve the dynamic range of data from spectral measurement systems.

Claims

1. A method for measuring spectral properties of a target material, the method comprising:

generating an illumination light containing a desired variable spectral output and desired variable wavelength dependent intensity distribution from a computer-controlled illumination system comprising a tunable light source configured to emit the illumination light and a controller operably connected to the tunable light source and configured to vary the desired spectral output and desired wavelength dependent intensity distribution of the illumination light to provide the desired spectral output and desired wavelength dependent intensity distribution;

directing the illumination light toward the target material;

sensing light from the target material with a spectral measurement sensor;

determining target spectral data that represents at least a spectral distribution and wavelength dependent intensity distribution of light emanating from the target material;

transmitting the target spectral data to the controller, wherein the controller receives the target spectral data and incorporates the target spectral data to tune the tunable light source;

wherein generating the illumination light comprises;

emitting light from a light source;

passing the light by a spectrum former optically connected to and downstream from the light source to provide a spectrum from the light emitted from the light source;

passing the spectrum via a pixelated spatial light modulator (SLM) located downstream from and optically connected to the spectrum former, the pixelated SLM configured to pass substantially only the desired spectral output and wavelength dependent intensity distribution of the light from the light source to provide the illumination light; and

wherein passing the spectrum via the pixelated SLM comprises reflecting the spectrum off the SLM to provide the desired spectral output and wavelength dependent intensity distribution of the illumination light.

2. The method of claim 1 wherein passing the spectrum via the pixelated SLM comprises controlling an on/off pattern of pixels in the pixelated SLM with computer-implemented programming contained in the controller, to pass substantially only the spectral output and wavelength dependent intensity distribution of illumination light.

3. The method of claim 1 further comprising detecting light reflecting from the target material.

4. The method of claim 1 or 3 further comprising detecting light transmitted through the target material.

5. The method of claim 1 further comprising detecting light emitting from the target material.

6. The method of claim 1 wherein the desired variable wavelength dependent intensity distribution of the illumination light comprises at least two of infrared light, ultraviolet light or visible light.

7. The method of claim 1 further comprising varying the desired selected spectral output and desired wavelength dependent intensity distribution of the illumination light to illuminate the target material with a narrow wavelength band illumination light that sweeps through a desired portion of a light spectrum.

8. The method of claim 1 wherein the method further comprises varying the desired selected spectral output and desired wavelength dependent intensity distribution of the illumination light in response to the target spectral data to evoke a substantially flat intensity of light emanating from the target material across all desired detected wavelengths, the substantially flat intensity of light being substantially greater than zero, and determining from the varying spectral properties of the target material.

9. The method of claim 1 wherein generating the illumination light comprises generating at least two different types of illumination light in sequence, wherein one of the types comprises a spectral output and wavelength dependent intensity distribution for measuring a first spectral characteristic of the target material, and a second type comprises a spectral output and wavelength dependent intensity distribution for measuring a second spectral characteristic of the target material.

10. The method of claim 1 wherein generating the illumination light comprises generating illumination light that remains substantially the same over time and the method further comprises measuring changes in spectral characteristics of the target material over time.

11. The method of claim 1 wherein generating the illumination light comprises varying the illumination light to compensate for over-saturation or underexposure of the spectral measurement sensor in a specific wavelength range but without substantially changing the illumination light in acceptable wavelength distributions, thereby enhancing the dynamic range of the system relative to the spectral measurement sensor alone.

12. The method of claim 1 further comprising comparing the target spectral data to reference spectral data of at least one known reference material.

13. The method of claim 12 wherein the method further comprises comparing the target spectral data to reference spectral data of a plurality of known reference materials, and determining whether the target spectral data substantially matches a matching reference spectral data.

14. The method of claim 13 wherein the method further comprises comparing the target spectral data to reference spectral data of a plurality of known reference materials, and determining whether the target spectral data substantially matches a combination of at least two matching reference spectral data.