US7504068-B2  A. O'Keefe & D. Deacon, Cavity Ring-Down Optical Spectrometer for Absorption Measurements Using Pulsed Laser Sources, 59 Rev. Sci. Instrum., 2544 (Dec. 1988).;  A. Pipino et al., Evanascent Wave Cavity Ring-Down Spectroscopy with a Total-Internal Reflection Minicavity, 68 (8) Rev. Sci, Instrum., 2978 (Aug. 1997).;  Blair S, Chen Y. "Resonant-enhanced evanescent-wave fluorescence biosensing with cylindrical optical cavities." Applied Optics. 40: 570-582 (2001).;  Boisde G, Harmer A. Chemical and Biological Sensing with Optical Fibers and Waveguides. Boston, MA: Artech House (1996).;  D. Heriott et al., Off-Axis Paths in Spherical Mirror Interferometers, 3 Appl. Opt. (4), 523 (Apr. 1964).;  D. Romanini & K. Lehmann, Ring-Down Cavity Absorportionn Spectroscopy of the Very Weak HCN Overtone Bands With Six, Seven, and Eight Stretching Quanta, 99 J. Chem. Phys. (9), 6287 (Nov. 1, 1993).;  Dmirtiev AL, Yanshen Z, Xinyu M. "Optical-fiber passive ring resonator in a low-mode radiation-propogration regime." J. Opt. Technol. 67: 219-221 (2000).;  F. Stoelkel & G. Atkinson, Time Evolution of a Broadband Quasi-cw Dye Laser: Limitation of Sensitivity in Intracavity Laser Spectroscopy, 24 Applied Optics (21), 3591 (Nov. 1, 1985).;  G. Gould et al., Crossed Roof Prism Interferometer, 1 Applied Optics (4), 533 (Jul. 1962).;  G. Meijer et al., Coherent Cavity Ring Down Spectroscopy, 217 Chemical Physics Letters (1,2), 112 (Jan. 7, 1994).;  G. Rempe et al., Measurement of Ultralow Losses in an Optical Interferometer, 17 Opt. Letters (5), 363 (Mar. 1, 1992).;  George Stewart et al.; "Intra-Cavity and Ring-Down Cavity Absorption with Fibre Amplifiers for Trace Gas Detection;" SPIE vol. 4185 (2000) pp. 448-451.;  International Search Report dated May 16, 2003, application No. PCT/US 02/38421.;  International Search Report dated May 20, 2003, application No. PCT/US 02/41689.;  International Search Report for PCT International Application No. PCT/US2005/046160 mailed Apr. 28, 2006.;  J. Scherer et al., Cavity Ring Down Dye Laser Spectrosopy of Jet-Cooled Metal Clusters: CU2 and CU3, 172 Chemical Physics Letters (3,4), 214 (Sep. 7, 1990).;  J. White, Long Optical Paths of Large Aperture, 32 J. Opt. Soc. Amer., 285 (May 1942).;  K. Atherton et al.; "Fibre optic intra cavity spectroscopy-combined ring down and ICLAS architectures using fibre lasers;" SPIE vol. 4204 (2001) pp. 124-130.;  K. Lehmann & D. Romanini, Molecules in the Stellar Environment, Experimental Measurement of Weak Band Intensities in Molecules in the Stellar Environment, (Springer, 1994).;  Lee, SM, Yang C, Pan W. "Evanescent-coupling Fiber Optic Pollution Monitoring System Using Etched D-Shape E-Core Fiber." SPIE-Int. Soc. Opt. Eng. 2836: 267-274.;  Lerber Von T. et al.; Cavity-ring-down principle for fiber-optic resonators: experimental realization of bending loss and evanescent-field sensing; Applied Optics, OSA, Optical Society of America, Washington, DC, US, vol. 41, No. 18, Jun. 20, 2002, pp. 3567-3575.;  Littlejohn D, Lucas D, Han L. "Bent Silica Fiber Evanescent Absorption Sensors for Near-Infrared Spectroscopy." Applied Spectroscopy. 53: 845-849 (1999).;  Messica A, Greenstein A, Katzir A. "Theory of fiber-optic evanescent-wave spectroscopy and sensors." Applied Optics 35: 2274-2284 (1996).;  Moar PN, Huntington ST, Katsifolis J, Cahill LW, Roberts A, Nugent KA. "Fabrication, modeling and direct evanescent field measurement of tapered optical fiber sensors." J. Appl. Phys. 85: 3395-3398 (1999).;  Spammer, S, Swart, P, Booysen, A. "Interferometric distributed optical-fiber sensor", Applied Optics vol. 35, No. 22: 4522-4525 (Aug. 1996).;  Stewart G, Atherton K, Yu H, Culshaw B. "An investigation of an optical fibre amplifier loop for intra-cavity and ring-down cacity loss measurements." Meas. Sci. Technol. 12: 843-849 (2001).;  T. Yu & M. Lin, Kinetics of Phenyl Radical Reactions Studied by the "Cavity-Ring-Down" Method, 115 J. Am. Chem. Soc., 4371 (1993).;  Trautmann et al., "Determination of the Deuterium Abundance in Water Using a CW Chemical DF Laser", Appl Phys., 24: No. 1, 49-53 (1981).;  Zaatar Y, Zaouk D, Bechara J, Khoury A, Llinaress C, Charles JP. "Fabrication and characterization of an evanescent wave fiber optic sensor for air pollution control." Mat. Sci. Eng. B74: 296-298 (2000).