Methods and systems for determining the presence of a molecule in a sample and method and system for determining a range-resolved concentration of a molecule in a scene

Patent metadata

Field	Value
Publication number	US-11119044-B2
Application number	US-201716326763-A
Country	US
Kind code	B2
Filing date	Aug 18, 2017
Priority date	Aug 22, 2016
Publication date	Sep 14, 2021
Grant date	Sep 14, 2021

Abstract

The method for determining the presence of a molecule having a Raman resonance generally comprises illuminating a sample with a first radiation beam, the first radiation beam having a first excitation wavelength being tuned to a Raman resonance of the molecule; receiving a first return signal from the sample following illumination of the sample with the first radiation beam; measuring a first intensity of the first return signal using an intensity detector; illuminating the sample with a second radiation beam, the second radiation beam lacking the first excitation wavelength and having a second excitation wavelength being different from the first excitation wavelength; receiving a second return signal from the sample following illumination of the sample with the second radiation beam; measuring a second intensity of the second return signal using an intensity detector; and determining the presence of the molecule in the sample based on the first and second intensities.

First claim

What is claimed is:

1. A method for determining the presence of a molecule in a sample, the method comprising the steps of:
a) selecting a Raman resonance of the molecule from an optical absorption spectrum of the molecule;
b) illuminating the sample with a first radiation beam, the first radiation beam having a first excitation wavelength being tuned to the selected Raman resonance of the molecule;
c) receiving a first return signal from the sample following illumination of the sample with the first radiation beam, the first return signal being received within a detection spectral band encompassing given Raman scattering features of the molecule;
d) measuring a first intensity of the first return signal using an intensity detector;
e) illuminating the sample with a second radiation beam, the second radiation beam lacking the first excitation wavelength and having a second excitation wavelength being different from the first excitation wavelength, the second excitation wavelength being close to the first excitation wavelength so that the given Raman scattering features of the molecule are encompassed within the detection spectral band upon illumination of the sample with the second radiation beam;
f) receiving a second return signal from the sample following illumination of the sample with the second radiation beam, the second return signal being received within the detection spectral band;
q) measuring a second intensity of the second return signal using an intensity detector; and
h) determining that the molecule is present in the sample when a difference between the first intensity and the second intensity exceeds a given threshold, the difference being indicative of a Raman resonance interaction that occurred between the first radiation beam and the molecule.

2. The method of claim 1 wherein said illuminating the sample with the first radiation beam includes generating the first radiation beam with a first radiation generator and wherein said illuminating the sample with the second radiation beam includes generating the second radiation beam with a second radiation generator.

3. The method of claim 1 wherein said illuminating the sample with the first radiation beam includes generating the first radiation beam at the first excitation wavelength using a tunable radiation generator and wherein said illuminating the sample with the second radiation beam includes tuning the tunable radiation generator to generate the second radiation beam at the second excitation wavelength.

4. The method of claim 1 wherein said illuminating the sample with the first radiation beam includes generating a broadband radiation beam and illuminating the sample with the broadband radiation beam and wherein illuminating the sample with the second radiation beam includes filtering out the first excitation wavelength from the broadband radiation beam and illuminating the sample with the filtered broadband radiation beam.

5. The method of claim 4 wherein said filtering out includes propagating the broadband radiation beam into a gas cell containing the molecule.

6. The method of claim 4 wherein said generating a broadband radiation beam includes generating the broadband radiation beam with one or more light-emitting diodes (LEDs).

7. The method of claim 1 wherein said determining includes determining a concentration of the molecule in the sample.

8. The method of claim 1 wherein the steps of illuminating and measuring are synchronized with one another, allowing determining a range resolved concentration of the molecule in the sample.

9. A system for determining the presence of a molecule in a sample, the system comprising:
a) a housing;
b) at least one radiation generator mounted to the housing and adapted to illuminate a sample with a first radiation beam, the first radiation beam having a first excitation wavelength being tuned to a Raman resonance of the molecule, and adapted to illuminate the sample with a second radiation beam, the second radiation beam lacking the first excitation wavelength and having a second excitation wavelength being different from the first excitation wavelength;
c) at least one receiving assembly mounted to the housing and adapted to receive first and second return signals from the sample following illumination of the sample with a corresponding one of the first and second radiation beams, the receiving assembly having a detection spectral band encompassing given Raman scattering features of the molecule when the sample is illuminated by either one of the first and second radiation beams;
d) at least one intensity detector mounted to the housing and adapted to measure a first intensity of the first return signal and a second intensity of the second return signal; and
e) a computer communicatively coupled to the at least one intensity detector and configured to determine that the molecule is present in the sample when a difference between the first intensity and the second intensity exceeds a given threshold, the difference being indicative of a Raman resonance interaction that occurred between the first radiation beam and the molecule.

10. The system of claim 9 wherein the at least one radiation generator includes a broadband radiation generator for generating the first radiation beam as a broadband radiation beam, the system further comprising a first beam path along which the broadband radiation beam is propagated, a second beam path along which the broadband radiation beam is propagated, and a resonance filtering element mounted to the housing, in which the second beam path passes, the resonance filtering element filtering out the first excitation wavelength from the broadband radiation beam and obtaining the second radiation beam.

11. The system of claim 10 wherein the broadband radiation generator includes one or more light-emitting diodes (LEDs).

Assignees

• Institut Nat Doptique

Inventors

• Babin François

Classifications

• G01M3/18

  for pipes, cables or tubes; for pipe joints or seals; for valves; {for welds; for containers, e.g. radiators} · CPC title

• G01N21/65 Primary

  Raman scattering · CPC title

• G01N2201/0214

  Airborne · CPC title

• G01N2021/1797

  in landscape, e.g. crops · CPC title

• G01J3/44

  Raman spectrometry; Scattering spectrometry {; Fluorescence spectrometry} · CPC title