Laser beam stop elements and spectroscopy systems including the same

Patent metadata

Field	Value
Publication number	US-9759655-B2
Application number	US-201514870425-A
Country	US
Kind code	B2
Filing date	Sep 30, 2015
Priority date	Sep 30, 2014
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

Laser-based spectroscopy systems and methods including a laser source that emits a beam of radiation, an optical resonant cavity having at least two cavity mirrors, and at least one beam filtering element positioned along a path of the beam external to the cavity and having a front surface, wherein the front surface is oriented such that an intersection of the beam and the surface is at an angle, such as the Brewster's angle or a pseudo-Brewster's, that reduces or eliminates reflection of a predominant polarization component of the beam by the filtering element.

First claim

What is claimed:

1. A laser-based spectroscopy system, the system comprising:
a laser source that emits a beam of radiation;
an optical resonant cavity having at least two cavity mirrors; and
at least one beam filtering element positioned along a path of the beam external to the cavity and having a front surface, wherein the front surface is oriented such that an intersection of the beam and the surface is at an angle that reduces or eliminates reflection of a predominant polarization component of the beam by the filtering element.

2. The system of claim 1 , wherein the laser source is a diode laser source.

3. The system of claim 1 , wherein the at least one beam filtering element comprises an absorptive glass material.

4. The system of claim 3 , wherein the angle is at a pseudo-Brewster angle.

5. The system of claim 1 , wherein the angle is at a Brewster angle.

6. The system of claim 1 , comprising at least two beam filtering elements, each positioned along a path of the beam and having a front surface, wherein each said front surface is oriented such that an intersection of the beam and said front surface is at an angle that reduces reflection of a predominant polarization component of the beam by said surface.

7. The system of claim 1 , wherein the at least one beam filtering element is positioned to receive light reflected off of one of said cavity mirrors.

8. The system of claim 1 , wherein the at least one beam filtering element is positioned to receive light emerging from one of said cavity mirrors.

9. The system of claim 1 , wherein the at least one beam filtering element comprises a neutral density filter.

10. The system of claim 1 , further comprising a second beam filtering element positioned to interact with light reflected from the at least one beam filtering element.

11. An apparatus for detecting one or more analyte species present in a gaseous or liquid medium, the apparatus comprising:
a resonant optical cavity having at least two cavity mirrors, one of which is a cavity coupling mirror;
a laser that emits a beam of laser light;
mode matching optics configured to couple the beam of laser light to the cavity via the cavity coupling mirror;
a detector configured to measure an intensity of intracavity optical power of light circulating in the cavity and to generate a signal representing the intracavity optical power of light circulating in the cavity; and
a first beam stop element positioned external to the resonant optical cavity and arranged such that an intersection of the beam and a front surface of the first beam stop element is at an angle that reduces or eliminates reflection of a predominant polarization component of the beam by the first beam stop element.

12. The apparatus of claim 11 , wherein the laser is a diode laser.

13. The apparatus of claim 11 , wherein the first beam stop element comprises an absorptive glass material, and wherein the angle is at a pseudo-Brewster angle.

14. The apparatus of claim 11 , wherein the angle is at a Brewster angle.

15. The apparatus of claim 11 , wherein the first beam stop element is positioned to receive light reflected off of one of said at least two cavity mirrors.

16. The apparatus of claim 11 , wherein the first beam stop element is positioned to receive light emerging from one of said at least two cavity mirrors.

17. The apparatus of claim 11 , wherein the first beam stop element comprises a neutral density filter.

18. The apparatus of claim 11 , further comprising a second beam stop element positioned to interact with light reflected from the first beam stop element.

Assignees

• Li Cor Inc

Inventors

• Koulikov Serguei

Classifications

• G02B5/3066

  involving the reflection of light at a particular angle of incidence, e.g. Brewster's angle · CPC title

• H01S5/0078

  for frequency filtering · CPC title

• H01S5/0014

  Measuring characteristics or properties thereof (measuring techniques per se G01J, G01K, G01N, G01R) · CPC title

• G01N2021/1704

  in gases · CPC title

• G02B5/205

  Neutral density filters · CPC title