Dispersive near-IR Raman spectrometer

• US 6,373,567 B1
• Filed: 12/17/1999
• Issued: 04/16/2002
• Est. Priority Date: 12/17/1999
• Status: Expired due to Fees

• Current Assignee: Micron Optical Systems, Inc.
• Original Assignee: Micron Optical Systems, Inc.
• Inventors: Schoen, Christian Lee, Wise, Kent Lawson, Cooper, John Brittain
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US09/466,295
• Time in Patent Office: 851 Days
• Field of Search: 356/301
• US Class Current: 356/301
• CPC Class Codes: G01J 3/0205 Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
• CPC Class Codes: G01J 3/1838 Holographic gratings
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry

Abstract

A compact dispersive near-IR Raman spectrometer is disclosed. The Raman spectrometer consists of a diode pumped solid state (DPSS) laser emitting light at 1064 nm and an InGaAs diode array detector. The DPSS laser is used as an excitation source for stimulating Raman scattering of the sample being analyzed. The Raman signal is collected and filtered to remove the DPSS laser Rayleigh scatter. The collected and filtered Raman signal is dispersed using a volume holographic grating. The dispersed Raman signal is detected using a linear InGaAs diode array detector that is sensitive to light in the wavelength region 900-1700 nm. The dispersive near-IR Raman spectrometer is rugged and compact and enables the collection of high signal-to-noise Raman spectra with high wavelength stability and without the presence of interfering fluorescent backgrounds.

Claims

1. An apparatus for generating Raman scatter of a sample and measuring said Raman scatter of sample, said apparatus comprising:

an excitation means for irradiating said sample and generating Raman scatter;

said excitation means comprising a diode pumped solid state (DPSS) laser which emits light at wavelengths at least greater than 900 nm;

a collection means for collecting said Raman scatter;

a detection means comprising a dispersive means for separating said Raman scatter by respective wavelength into a dispersed signal;

said detection means comprising a diode array detector for detecting said dispersed signal;

said detection means comprising an entrance for transmission of said Raman scatter into said detection means;

said diode array detector comprising an array of photo sensitive elements sensitive to at least light at wavelengths greater than 1200 nm.

2. The apparatus of claim 1 wherein said diode array detector comprises indium gallium arsenide (InGaAs).

3. The apparatus of claim 1 wherein said detection means comprises a spectrograph.

4. The apparatus of claim 1 wherein said entrance of said detection means comprises a slit.

5. The apparatus of claim 1 wherein said entrance of said detection means comprises a fiber optic.

6. The apparatus of claim 1 wherein said entrance of said detection means comprises a linear array of fiber optics.

7. The apparatus of claim 1 wherein said excitation means is delivered to said sample using fiber optic means.

8. The apparatus of claim 1 wherein a collection means is used to transmit said Raman scatter to said detection means.

9. The apparatus of claim 1 wherein said Raman scatter is delivered to said detection means using fiber optic means.

10. The apparatus of claim 1 wherein a filtering means is used to at least reduce the intensity of Rayleigh scattered light after it is generated by said sample being said irradiated.

11. The apparatus of claim 1 wherein a filtering means is used to at least reduce the intensity of Rayleigh scattered light after it is generated by said sample being said irradiated;

said detection means comprises said filtering means.

12. The apparatus of claim 8 wherein a filtering means is used to at least reduce the intensity of Rayleigh scattered light after it is generated by said sample being said irradiated;

said collection means comprises said filtering means.

13. The apparatus of claim 1 wherein said dispersive means comprises a reflection grating.

14. The apparatus of claim 1 wherein said dispersive means comprises a transmission grating.

15. The apparatus of claim 1 wherein said dispersive means comprises a volume holographic transmission grating.

16. The apparatus of claim 1 wherein said detection means is comprised of integrated electronics means for converting said detected signal from an analog format signal into a digital format signal.

17. The apparatus of claim 16 wherein said detection means and said integrated electronics means comprises a board mounted directly into a computer bus slot.

18. The apparatus of claim 16 wherein said digital format signal is transferred to a computer means.

19. The apparatus of claim 1 wherein said detection means is comprised of integrated electronics means for reading out said detected signal in an analog format;

said analog format of detected signal is transferred to a computer means containing an analog-to-digital converter which subsequently converts the signal from an analog format into a digital format.

20. An apparatus for generating Raman scatter of a sample and measuring said Raman scatter of sample, said apparatus comprising:

an excitation means for irradiating said sample and generating Raman scatter;

said excitation means comprising a DPSS laser which emits light at 1064 nm;

a collection means for collecting said Raman scatter;

a detection means comprising a dispersive means for separating said Raman scatter by respective wavelength into a dispersed signal;

said detection means comprising a diode array detector for detecting said dispersed signal;

said detection means comprising an entrance for transmission of said Raman scatter into said detection means;

said diode array detector comprising an array of photo sensitive elements sensitive to at least light at wavelengths greater than 1200 nm.