Apparatus and methods for launching and receiving a broad wavelength range source

1. An apparatus for simultaneous detection of X gas species through laser radiation attenuation techniques, where at least one of the X gas species has a spectral absorption band whose wavelength is shorter than the cutoff wavelength for the other spectral absorption band, the apparatus comprising:

a) N laser sources, wherein each of the N laser sources is adapted to operate at a wavelength λ N in a spectral absorption band separated by the cutoff wavelength for single mode transmission, each laser source corresponding to a spectral region for detecting a gas species;

b) each of the N laser sources adapted to transmit radiation through an optical fiber constructed and arranged to provide single-mode transmission with minimal power loss to a beam splitter[BV1], said beam splitter sending a first portion of each of the N laser's radiation to a balanced ratiometric detector, and a second portion to a compound ferrule;

c) the compound ferrule constructed and arranged so that each single-mode optical fiber terminating therein is held at a separation distance substantially less than a focal length of a collimating optical component to which the N beams are directed by the compound ferrule, the collimating optical component adapted to route N collimated laser beams through a process containing N gas species to be detected; and

d) means for receiving and detecting nonabsorbed radiation from each laser and creating N outputs for each laser wavelength λ N .

2. The apparatus of claim 1 wherein each of said N laser sources transmits through a dedicated corresponding single-mode optical fiber to said compound ferrule.

3. The apparatus of claim 1 wherein said compound ferrule is positioned within said beam launch module.

4. The apparatus of claim 1 wherein said compound ferrule allows said N laser sources to radiate onto means for collimating said N laser radiation beams and directing said collimated beams through a gas containing said N species to be detected.

5. The apparatus of claim 4 wherein said means for collimating is an off-axis parabolic mirror.

6. The apparatus of claim 4 further comprising a multi-chromic mirror having reflectance only for narrow bandpasses around said 8 N wavelengths, said multi-chromic mirror directing nonabsorbed radiation onto a second off-axis parabolic mirror, then through an iris, and then to a photodetector having a spectral response bandwidth encompassing λ n wavelengths, the photodetector producing an output for each λ N wavelength.

7. The apparatus of claim 5 wherein said N lasers are launched such that each beam is spatially separated from the other beams.

8. The apparatus of claim 7 wherein said gas being measured is bound by inlet and outlet windows coated on a portion thereof with antireflection coatings specific to each of said λ N wavelengths.

9. The apparatus of claim 8 wherein the receiving module includes N mirrors each having a narrow bandpass reflectance specific to each λ N wavelength and letting all other wavelengths pass through.

10. The apparatus of claim 9 wherein each N mirror has a corresponding off-axis parabolic mirror, an iris, and a detector.

11. The apparatus of claim 5 wherein said off-axis parabolic mirror directs said N through the gas and hence onto a grating.

12. The apparatus of claim 9 wherein each N mirror has a corresponding off-axis parabolic mirror, an iris, and a detector, each detector optically connected to a balanced ratiometric detector.

13. The apparatus of claim 12 wherein beams from said grating are reflected by and forwarded by N spherical mirrors, to respective iris and detectors.

14. A method for simultaneous detection of N gas species through laser radiation attenuation techniques comprising:

(a) launching N laser wavelengths from N laser sources, wherein each of the N laser sources operates at a wavelength λ N in a spectral absorption band, the wavelength λ N being separated by a cutoff wavelength for single mode transmission, and each laser source corresponding to a gas species;

(b) transmitting radiation from each of the N laser sources through an optical fiber, each optical fiber being constructed and arranged to provide single-mode transmission with minimal power loss to a compound ferrule;

(c) separating each single-mode optical fiber using the compound ferrule thus creating N collimated laser beams;

(d) routing the N collimated laser beams through a medium having N species to be detected; and

(e) receiving and detecting radiation corresponding to the N gas species to be detected.

15. The method of claim 14 further comprising transmitting each of said N lasers through a dedicated corresponding single-mode optical fiber to said compound ferrule.

16. The method of claim 14 further comprising positioning said compound ferrule within said beam launch module.

17. The method of claim 14 , further comprising routing said N laser beams using said ferrule onto means for collimating said N laser radiation beams and directing said collimated beams through a gas containing said N species or N spectral features to be detected.

18. The method of claim 17 , comprising collimating said N beams using an off-axis parabolic mirror.

19. The method of claim 18 , further comprising routing the N beams using a multi-chromic mirror having reflectance for narrow bandpasses around said λ N wavelengths, said multi-chromic mirror directing nonabsorbed radiation onto a second off-axis parabolic mirror, where it is then directed through an iris, and subsequently to a photodetector having a spectral response bandwidth encompassing λ n wavelengths, the photodetector producing an output for each λ N wavelength.

20. The method of claim 14 , further comprising producing an output, and digitizing and analyzing said output by a means for data acquisition.

21. The method of claim 18 , further comprising launching said N lasers and spatially separating each beam from the other beams.

22. The method of claim 21 , further comprising routing said N beams through the gas, the gas being bound by inlet and outlet windows coated on a portion thereof with antireflection coatings specific to each of said λ N wavelengths.

23. The method of claim 22 , further comprising routing the N beams to a receiving module including N mirrors each having a narrow bandpass reflectance specific to each λ N wavelength and letting all other wavelengths pass through.

24. The method of claim 23 , further comprising routing each beam from said N mirrors to a corresponding off-axis parabolic mirror, an iris, and a detector.

25. The method of claim 18 , further comprising routing said N beams from said off-axis parabolic mirror through the gas and hence onto a grating.

26. The method of claim 23 , further comprising routing each N beam from said N mirrors to a corresponding off-axis parabolic mirror, an iris, and a detector.

27. The method of claim 26 , further comprising routing said N beams from said grating to N spherical mirrors, and then from said N spherical mirrors to respective irises and detectors.

28. An apparatus for simultaneous detection of N gas species through laser radiation attenuation techniques comprising:

(a) N laser sources, each of the N laser sources being adapted to operate at a wavelength λ N in a spectral absorption band separated by the cutoff wavelength for single mode transmission, each laser source corresponding to a gas species;

(b) each of the N laser sources adapted to transmit radiation through an optical fiber constructed and arranged to provide single-mode transmission with minimal power loss to N achromat lenses adapted to create N collimated laser beams;

(c) means for launching the N collimated laser beams into a medium containing the N gas species to be detected; and

(d) means for receiving and detecting portions of the N collimated laser beams.

29. The apparatus of claim 28 wherein the means for receiving and detecting portions of the N collimated laser beams comprises a prism, an achromat lens, and a spherical lens combination.

30. The apparatus of claim 28 wherein each of the N laser sources is adapted to transmit radiation through N dedicated optical fibers, each of the N optical fibers having single-mode optical fiber characteristics sufficient to insure single-mode transmission with minimal power loss.

31. The apparatus of claim 28 wherein the means for launching is selected from the group consisting of a dichroic beam combiner and a system of mirrors.

32. A method for simultaneous detection of N gas species through laser radiation attenuation techniques comprising:

(a) providing N laser sources, wherein each of the N laser sources is adapted to operate at a wavelength λ N in a spectral absorption band separated by the cutoff wavelength far single mode transmission, each laser source corresponding to a gas species;

(b) transmitting each of the wavelengths λ N through an optical fiber, each optical fiber having single-mode optical fiber characteristics sufficient to insure single-mode transmission with minimal power loss to N achromat lenses, each achromat lens having a proper wavelength-specific anti-reflective coating, the N achromat lenses adapted to create N collimated laser beams;

(c) launching the N collimated laser beams into the process containing the N gas species to be detected; and

(d) receiving and detecting nonabsorbed portions of the N collimated laser beams.

33. The apparatus of claim 28 , wherein:

the means for receiving and detecting portions of the N collimated laser beams comprises a prism, a convex lens paired with a concave lens, a spherical mirror, and N detectors;

the prism, the paired convex and concave lenses, the spherical mirror and the N detectors being configured and adapted to allow the N collimated laser beams to pass through the prism to the paired convex and concave lenses where the N collimated laser beams are decollimated and focused towards the spherical mirror where the N decollimated laser beams are reflected thereby onto N detectors; and

each of the N detectors receives and detects radiation corresponding to a different wavelength λ N .

34. The method of claim 32 , wherein the receiving and detecting step comprises the steps of:

allowing the N collimated laser beams to pass through the prism to paired convex and concave lenses;

allowing the N collimated laser beams to be decollimated by the paired convex and concave lenses and focused thereby towards a spherical mirror; and

allowing the spherical mirror to reflect the focused N decollimated laser beams onto N detectors where radiation associated with the nonabsorbed portions is detected, each of the N detectors being associated with a different wavelength λ N .