Apparatus and methods relating to enhanced spectral measurement systems

• US 7,692,784 B2
• Filed: 09/27/2004
• Issued: 04/06/2010
• 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
• Assistant Examiner(s): Stock, Jr.; Gordon J
• Application Number:
  US10/952,374
• Publication Number:
  US 20050213092A1
• Time in Patent Office: 2,017 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 non-imaging spectral measurement system comprising at least one of a spectroscope, a spectroradiometer, or a spectrophotometer, the spectral measurement system comprising:

a computer-controlled illumination system comprising;

a tunable light source configured to emit illumination light comprising a variable selected spectral output and a variable selected wavelength dependent intensity distribution toward a target material, wherein the tunable light source comprises;

a light source;

a spectrum former comprising a prism or diffraction grating configured to provide a flail spectrum from a light beam traveling along a light path from the light source without scanning the light beam across the spectrum former,

a pixelated spatial light modulator (SLM) located downstream from and optically connected to the spectrum former, the pixelated SLM configured to pass substantially only a selected spectral output and wavelength dependent intensity distribution of the light from the light source, the pixelated SLM operably connected to a controller which contains computer-implemented programming that controls an on/off pattern of pixels in the pixelated SLM to pass substantially only desired wavelength distribution of illumination light, and

the controller operably connected to the tunable light source and containing computer-implemented programming configured to vary a pattern of the pixelated SLM corresponding to the variable selected spectral output and the variable selected wavelength dependent intensity distribution in the illumination light to provide a desired spectral output and wavelength dependent intensity distribution configured for measuring spectral properties of the target material; and

a spectral measurement sensor configured to detect light emanating from the target material and determine spectral data of the light emanating from the target material to provide target spectral data, the spectral measurement sensor operably connected to the computer-controlled illumination system to communicate the target spectral data to the computer-controlled illumination system;

wherein the controller and the computer-implemented programming are configured to receive the target spectral data and incorporate the target spectral data to tune the tunable light source to vary the variable selected spectral output and the variable selected wavelength dependent intensity distribution in the illumination light to enhance the desired spectral output and wavelength dependent intensity distribution of the illumination light, wherein the controller is configured to vary the selected spectral output and wavelength dependent intensity distribution of the illumination light in response to the target spectral data to provide an enhanced dynamic range for the spectroscope, spectroradiometer, or spectrophotometer such that the spectroscope, spectroradiometer, or spectrophotometer measures more spectral properties of the target material compared to the spectral measurement sensor alone.

2. The spectral measurement system of claim 1 wherein the spectral measurement sensor detects light reflected from the target material.

3. The spectral measurement system of claim 1 wherein the spectral measurement sensor detects light emitted from the target material.

4. The spectral measurement system of claim 1 wherein the illumination light comprises at least two forms of light comprising at least infrared light, ultraviolet light or visible light.

5. The spectral measurement system of claim 1 wherein the computer-controlled illumination system comprises an illumination light detector configured to detect the illumination light, determine illumination light spectral data, and transmit the illumination light spectral data to the controller, and wherein the controller is configured to receive the illumination light spectral data and incorporate the illumination light spectral data to tune the tunable light source to vary the variable selected spectral output and the variable selected wavelength dependent intensity distribution in the illumination light to enhance the desired spectral output and wavelength dependent intensity distribution of the illumination light.

6. The spectral measurement system of claim 1 wherein the controller at least stores the target spectral data, analyzes the target spectral data, and displays the target spectral data.

7. The spectral measurement system of claim 1 wherein the controller is configured to vary the selected spectral output and 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 the controller determining from the varying spectral properties of the target material.

8. The spectral measurement system of claim 1 wherein the enhanced dynamic range is achieved by compensating in the illumination light for overexposure or underexposure of the spectral measurement sensor in a specific wavelength distribution but without substantially changing the illumination light in acceptable wavelength distributions.

9. The spectral measurement system of claim 1 wherein the computer-implemented programming is configured to provide a substantially constant selected spectral output and wavelength dependent intensity distribution of illumination light over time to measure changes in a spectral characteristic of spectral properties of the target material over time.

10. The spectral measurement system of claim 1 wherein the computer-implemented programming is configured to selectively vary over time the selected spectral output and wavelength dependent intensity distribution of the illumination light to measure different spectral characteristics of spectral properties of the target material.

11. The spectral measurement system of claim 1 wherein the spectral measurement system comprises a long pass filter configured to substantially block UV light and to pass at least visible light, and wherein the computer-implemented programming is configured to illuminate the target material with substantially only UV light and the measurement sensor is configured to measure at least visible light comprising fluorescent light.

12. The spectral measurement system of claim 1 wherein the controller is configured to vary the selected spectral output and 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, wherein individual spectra of the emanating light from the target material that correspond with each sequential spectrum of illumination light are combined to make a return spectrum.

13. The spectral measurement system of claim 1 wherein the computer-implemented programming is configured to compare the target spectral data to reference spectral data of at least one known reference material.

14. The spectral measurement system of claim 13 wherein the computer-implemented programming is configured to compare the target spectral data to reference spectral data of a plurality of known reference materials, and to determine whether the target spectral data substantially matches a matching reference spectral data.

15. The spectral measurement system of claim 13 wherein the computer-implemented programming is configured to compare the target spectral data to reference spectral data of a plurality of known reference materials, and to determine whether the target spectral data substantially matches reference spectral data of a combination of at least two materials.

16. The spectral measurement system of claim 12 wherein the desired portion of the light spectrum consists essentially only of visible light.

17. The spectral measurement system of claim 12 wherein the desired portion of the light spectrum consists essentially only of UV light.

18. The spectral measurement system of claim 12 wherein the desired portion of the light spectrum consists essentially only of infrared light.