Raman spectroscopy using multiple excitation wavelengths

• US 8,873,041 B1
• Filed: 01/29/2013
• Issued: 10/28/2014
• Est. Priority Date: 01/29/2013
• Status: Active Grant

• Current Assignee: BaySpec, Inc. (II-VI Incorporated)
• Original Assignee: BaySpec, Inc. (II-VI Incorporated)
• Inventors: Chai, Ming, Zhang, Charlie, Yang, Wei, Lieber, Chad, Yang, Miao
• Primary Examiner(s): Nur, Abdullahi
• Application Number:
  US13/753,150
• Time in Patent Office: 637 Days
• Field of Search: 356/301, 356 72- 73
• US Class Current: 356/301
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01N 21/65 Raman scattering

Abstract

Raman spectrometers are provided that illuminate a sample with two or more different beams of light, each characterized by a different primary frequency. Scattered light from the sample is separated into multiple Raman spectra, one for each primary frequency. The multiple Raman spectra can be evaluated individually, or they can be added together to form a composite spectrum that is then evaluated.

Claims

1. A Raman spectroscopy system comprising:

an illumination system configured to direct multiple beams of light onto a same spot on a sample, each beam of light characterized by a spectral linewidth centered on a different frequency, the illumination system including a diode laser configured to produce a first beam of light, of the multiple beams of light, the first beam of light characterized by a first spectral linewidth centered on a first frequency of either about 785 nm or about 830 nm, and a neodymium-doped yttrium aluminum garnet laser configured to produce a second beam of light, of the multiple beams of light, the second beam of light characterized by a second spectral linewidth centered on a second frequency of about 1064 nm, a first lens system configured to focus the first beam of light to the spot on the sample, the first lens system being configured to direct the first beam of light along a first optical path defined between the first lens system and the spot, and a second lens system configured to focus the second beam of light to the spot on the sample, the second lens system being configured to direct the second beam of light along a second optical path defined between the second lens system and the spot, the first and second optical paths being different; and

a detection system configured to receive scattered light from the sample and produce multiple Raman spectra, one spectrum for each beam of light incident on the sample, the detection system including a first optical detector and a second optical detector, where the first optical detector comprises a silicon-based detector and the second optical detector comprises an indium-gallium-arsenide detector.

2. The Raman spectroscopy system of claim 1 wherein the detection system includes a lens system configured to collect scattered light from the sample and to collimate the scattered light into an optical path.

3. The Raman spectroscopy system of claim 2 wherein the detection system further includes a filter disposed along the optical path and configured to receive the collected and collimated scattered light from the lens system and to filter out photons produced by elastic optical scattering.

4. The Raman spectroscopy system of claim 1 wherein the

detection system further includes a spectra separator configured to

direct to the first optical detector scattered Raman photons from the received scattered light that were produced by the interaction of the first beam of light with the sample, and further configured to

direct to the second optical detector scattered Raman photons from the received scattered light that were produced by the interaction of the second beam of light with the sample.

5. The Raman spectroscopy system of claim 4 further comprising a grating between the spectra separator and the first optical detector.

6. The Raman spectroscopy system of claim 5 wherein the spectra separator comprises a dielectric dichroic filter.

7. The Raman spectroscopy system of claim 4 wherein the spectra separator comprises a grating.