Laser beam stop elements and spectroscopy systems including the same
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.
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.