Carbon isotope analysis device and carbon isotope analysis method

Patent metadata

Field	Value
Publication number	US-10012586-B2
Application number	US-201615234554-A
Country	US
Kind code	B2
Filing date	Aug 11, 2016
Priority date	Feb 12, 2014
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

A method and apparatus for analyzing carbon isotope 14 C is provided. A carbon isotope analyzer including an isotopic carbon dioxide generator to generate isotopic carbon dioxide from a carbon isotope; a spectrometer including an optical resonator having a pair of mirrors, and a photodetector to determine the intensity of light transmitted from the optical resonator; and a light generator including a light source, a first optical fiber to transmit a light beam from the light source, a second optical fiber for wavelength conversion, the second optical fiber branching from the first optical fiber at a point and combining with the first optical fiber at another point downstream of the branching point, and a non-linear optical crystal to generate light having the absorption wavelength of the isotopic carbon dioxide on the basis of the difference in frequency between light beams transmitted through the optical crystal.

First claim

The invention claimed is:

1. A carbon isotope analyzer comprising:
an isotopic carbon dioxide generator to generate isotopic carbon dioxide from a carbon isotope;
a spectrometer comprising an optical resonator having a pair of mirrors, and a photodetector to determine the intensity of light transmitted from the optical resonator; and
a light generator comprising a light source, a first optical fiber to transmit a light beam from the light source, a second optical fiber for wavelength conversion, the second optical fiber branching from the first optical fiber at a point and combining with the first optical fiber at another point downstream of the branching point, and a non-linear optical crystal to generate light having the absorption wavelength of the isotopic carbon dioxide on the basis of the difference in frequency between light beams transmitted through the optical crystal,
wherein the intensity of the transmitted light is determined while the isotopic carbon dioxide is cooled, via a cooling device, to 273K (0° C.) or less.

2. The carbon isotope analyzer according to claim 1 , wherein the carbon isotope is radioactive carbon 14 C, and the isotopic carbon dioxide is radioactive carbon dioxide 14 CO 2 .

3. The carbon isotope analyzer according to claim 2 , wherein detection sensitivity of the 14 C analyzer to the radioactive carbon isotope 14 C is 0.1 dpm/mL.

4. The carbon isotope analyzer according to claim 1 , wherein the light source generates an optical frequency comb.

5. The carbon isotope analyzer according to claim 1 , wherein the light source is a fiber laser source.

6. The carbon isotope analyzer according to claim 1 , wherein the light having the absorption wavelength of the isotopic carbon dioxide is light of 4.5 μm region.

7. The carbon isotope analyzer according to claim 1 , wherein the isotopic carbon dioxide generator generates the isotopic carbon dioxide from the carbon isotope with a total organic carbon generator.

8. The carbon isotope analyzer according to claim 1 , wherein the first optical fiber extends from the light source to the optical resonator.

9. The carbon isotope analyzer according to claim 1 , wherein the first optical fiber comprises a first optical fiber segment a extending between the light source and the non-linear optical crystal and a first optical fiber segment b for mid-infrared light extending between the non-linear optical crystal and the optical resonator.

10. The carbon isotope analyzer according to claim 1 , wherein the light generator further comprises a light transmitter to transmit light from the non-linear optical crystal to the optical resonator.

11. The carbon isotope analyzer according to claim 10 , wherein the first optical fiber is the first optical fiber segment a extending between the light source and the non-linear optical crystal.

12. The carbon isotope analyzer according to claim 1 , wherein the light generator further comprises an optical lens between the non-linear optical crystal and the point at which the first optical fiber combines with the second optical fiber, and/or between the non-linear optical crystal and the optical resonator.

13. The carbon isotope analyzer according to claim 1 , wherein a downstream end of the first optical fiber is in contact with one of the mirrors.

14. The carbon isotope analyzer according to claim 1 , wherein the second optical fiber comprises a non-linear fiber.

15. The carbon isotope analyzer according to claim 1 , wherein the spectrometer further comprises a cooler to cool the optical resonator.

16. The carbon isotope analyzer according to claim 1 , wherein the spectrometer further comprises a vacuum unit accommodating the optical resonator.

17. The carbon isotope analyzer according to claim 1 , wherein the spectrometer further comprises a vibration absorber.

18. The carbon isotope analyzer according to claim 1 , wherein the spectrometer further comprises a diffraction grating to disperse the transmitted light into spectral components of different wavelengths, and the photodetector comprises a sub-photodetector a and a sub-photodetector b to detect the spectral components of different wavelengths.

19. A method of analyzing a carbon isotope, comprising:
forming isotopic carbon dioxide from a carbon isotope;
feeding the isotopic carbon dioxide into an optical resonator having a pair of mirrors;
generating a plurality of light beams having different wavelengths from a light source, and transmitting the light beams through a non-linear optical crystal, to generate incident light on the basis of the difference in frequency between the light beams, the incident light having the absorption wavelength of the isotopic carbon dioxide;
applying the incident light to the isotopic carbon dioxide, and determining the intensity of transmitted light generated through resonance of the incident light; and
calculating the concentration of the carbon isotope on the basis of the intensity of the transmitted light,
wherein the intensity of the transmitted light is determined while the isotopic carbon dioxide is cooled to 273K (0° C.) or less.

20. The method according to claim 17 , wherein the carbon isotope is radioactive carbon 14 C, and the isotopic carbon dioxide is radioactive carbon dioxide 14 CO 2 .

21. The method according to claim 17 , wherein the incident light is light of 4.5 μm region.

22. The method according to claim 17 , wherein an optical frequency comb is generated from the light source.

23. The method according to claim 17 , wherein the light source is a fiber laser source.

24. The method according to claim 17 , wherein the intensity of the transmitted light is determined while a downstream end of a first optical fiber is brought into contact with one of the mirrors to prevent the transmitted light from coming into contact with air.

25. The method according to claim 17 , wherein first light from the light source is transmitted through the first optical fiber; the first light is also transmitted through a second optical fiber for wavelength conversion, to generate second light having a wavelength different from that of the first light, the second optical fiber branching from the first optical fiber at a point; the second light is combined with the first light transmitted through the first optical fiber downstream of the point; and the first light and the second light are transmitted through the non-linear optical crystal, to generate incident light on the basis of the difference in frequency between the first light and the second light, the incident light having the absorption wavelength of the isotopic carbon dioxide.

26. The method according to claim 17 , wherein the first optical fiber extends from the light source to the optical resonator.

27. The method according to claim 17 , wherein the first optical fiber comprises a first optical fiber segment a extending between the light source and the non-linear optical crystal and a first optical fiber segment b for mid-infrared light extending between the non-linear optical crystal and the optical resonator.

28. The method according to claim 17 , wherein the second optical fiber comprises a non-linear fiber.

29. The method according to claim 17 , wherein the isotopic carbon dioxide is cooled before being introduced into the spectrometer.

30. The method according to claim 1

Assignees

• Sekisui Medical Co Ltd
• Univ Nagoya Nat Univ Corp

Inventors

• Iguchi Tetsuo
• Tomita Hideki
• Nishizawa Norihiko
• Oh-Hara Toshinari
• Ideno Akira

Classifications

• G02F1/3534

  Three-wave interaction, e.g. sum-difference frequency generation (G02F1/3532 takes precedence) · CPC title

• G01N21/3504 Primary

  for analysing gases, e.g. multi-gas analysis · CPC title

• G01N21/031

  Multipass arrangements · CPC title

• G02B17/004

  Systems comprising a plurality of reflections between two or more surfaces, e.g. cells, resonators (multipass arrangements for optical cuvettes G01N21/031; laser resonators H01S3/05) · CPC title

• G01N21/39

  using tunable lasers · CPC title