Cavity enhanced optical detector

1. A cavity enhanced optical detector comprising:

i) a source of CW laser light;

ii) a high finesse resonant cavity comprising at least three spaced apart, high-reflectivity mirrors, to receive light from the laser light source;

iii) at least one photo-detector for measuring an extinction coefficient of an analyte that is positioned in the resonant cavity; and

iv) at least a second photo-detector for measuring intensity of fluorescence emission from the analyte.

2. A cavity enhanced optical detector in accordance with claim 1 , further comprising at least a third photo-detector for measuring a light scattering coefficient of said analyte.

3. A cavity enhanced optical detector in accordance with claim 1 , wherein said resonant cavity comprises four mirrors in a bow-tie configuration.

4. A cavity enhanced optical detector in accordance with claim 3 , wherein a first and second of said mirrors are planar and a third and fourth of said mirrors are plano-concave.

5. A cavity enhanced optical detector in accordance with claim 3 , wherein all four of said mirrors are plano-concave.

6. A cavity enhanced optical detector in accordance with claim 1 , configured as a cavity ring-down spectrometer.

7. A cavity enhanced optical detector in accordance with claim 1 , wherein said extinction coefficient and said intensity of said analyte are measured substantially simultaneously.

8. A cavity enhanced optical detector in accordance with claim 1 , further comprising detection means for measuring Raman scattering by said analyte of light provided by said source.

9. A cavity enhanced optical detector in accordance with claim 8 , wherein said detection means comprises a CCD array.

10. A cavity enhanced optical detector in accordance with claim 1 , wherein said analyte is contained in a container having a volume smaller than a volume of said cavity.

11. A cavity enhanced optical detector in accordance with claim 10 , wherein said container is a Brewster Cell.

12. A cavity enhanced optical detector in accordance with claim 1 , wherein said at least one detector for measuring said extinction coefficient is a photo-diode.

13. A cavity enhanced optical detector in accordance with claim 1 , wherein said detector for measuring said intensity of said fluorescence emission is at least one of a photo multiplier tube and an avalanche photo-diode.

14. A cavity enhanced optical detector in accordance with claim 2 , wherein said detector for measuring said scattering coefficient is at least one of a photo multiplier tube and an avalanche photo-diode.

15. A cavity enhanced optical detector in accordance with claim 2 , wherein said at least one detector for measuring said fluorescence emission is a first plurality of detectors, and said at least said third detector for measuring said scattering coefficient is a second plurality of detectors.

16. A cavity enhanced optical detector in accordance with claim 2 , wherein said at least said third detector for measuring said scattering coefficient of said analyte is a plurality of detectors, wherein at least a first of the plurality of the detectors is positioned to measure forward scattering and at least a second of the plurality of detectors is positioned to measure back scattering.

17. A cavity enhanced optical detector in accordance with claim 1 , wherein said photo-detector for measuring said intensity of said fluorescence emission further comprises a fixed frequency filter.

18. A cavity enhanced optical detector in accordance with claim 1 , wherein said photo-detector for measuring said intensity of said fluorescence emission further comprises a filter having a pass frequency that can be varied.

19. A cavity enhanced optical detector in accordance with claim 1 , further comprising a dispersive element and detector array for measuring said intensity of said fluorescence emission.

20. A cavity enhanced optical detector comprising:

i) a source of CW laser light;

ii) a high finesse resonant cavity comprising at least three spaced apart, high-reflectivity mirrors, to receive light from the laser light source;

iii) at least one photo-detector for measuring an extinction coefficient of an analyte that is positioned in the resonant cavity;

iv) at least a second photo-detector for measuring intensity of Raman scattering from the analyte.