Cavity Phase Shift Method For High Reflectance Measurements At Mid-Infrared Wavelengths

Kwok, Munson A.; Herbelin, John M.; Ueunten, R. H.

doi:10.1117/12.7973018

Cited by 13 publications

(10 citation statements)

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“…mirrors include SiC>2, Ti02, Zr02, and ThF4 (41). It was in the development and characterization of these high reflectivity mirrors that cavity approaches were first employed to measure mirror reflectivity (1)(2)(3)(4). While multilayer dielectric mirrors are more durable than metallic mirrors, and can be fabricated for any desired reflectance, the high reflectance is only realized over a narrow wavelength range.…”

Section: Mirror Mirrormentioning

confidence: 99%

“…In many respects, traditional absorption spectrometry has many desirable characteristics for the real-time determination of gaseous species. If the analyte is the only absorbing species in the beam of radiation at a particular wavelength, and if it is present in sufficient amount, its concentration can be determined directly with absorption spectrometry by means of the Beer-Lambert law, where / t is the transmitted intensity, I 0 is the incident intensity, a is the cross section of the absorbing species at the wavelength of the measurement in cm 2 , L is the path length of the absorbing medium in cm, and N is the number density of the absorbing species in cm 3 . While the technique is robust and well developed theoretically, the primary difficulties encountered with the use of conventional absorption spectrometric measurements for the determination of gaseous species in challenging situations are insufficient sensitivity, and a certain lack of specificity in the UV/visible region because of the possibility of overlapping absorption bands from concomitants.…”

Section: The Need For Gas-phase Absorption Measurementsmentioning

confidence: 99%

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Introduction to Cavity-Ringdown Spectroscopy

Busch

1999

ACS Symposium Series

122

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Cavity-ringdown spectroscopy is an alternative way of measuring small fractional absorptions down to sub-ppm levels per pass in the cavity.In this chapter, the basic principles behind cavity-ringdown spectroscopy are discussed. The areas where ultra-sensitive absorption measurements in the gas phase are important are illustrated, and existing methods of making these measurements are presented. The experimental requirements for performing cavity-ringdown spectroscopy are discussed, and an expression for the detection limit in cavity-ringdown spectroscopy is derived from statistical considerations. Finally, future prospects for the technique are discussed.Cavity-ringdown spectroscopy is an alternative way of making ultra-sensitive absorption measurements, particularly with gas-phase samples. This volume will discuss the research being conducted on cavity-ringdown spectroscopy by the leading research groups in the area. In the chapters that follow, various aspects of the cavity-ringdown experiment will be discussed and its applications described. Although the origins of the technique can be traced back to attempts to measure mirror reflectivities in the early 1980s (1-4), the spectroscopic application of the concept has only recently been reviewed (5,6) and is still not widely known to the general scientific community. Because the technique can provide the ability to measure small fractional absorptions (down to sub-ppm levels per pass), it should be of interest to broad segments of the analytical-, physical-, and engineering communities. This includes analytical chemists, spectroscopists, physical chemists doing laser spectroscopy and molecular beam work, combustion scientists, atmospheric chemists, and chemical engineers involved with process measurements-in fact, anyone involved with measuring trace components in gas-phase samples by absorption spectroscopy.This chapter will provide a basic introduction to cavity-ringdown spectroscopy for the reader who is not familiar with the technique. The intent is to show the basic principles of the technique without introducing undue mathematical complexity at the outset. However, before describing the technique, it is worthwhile to review some of the areas where sensitive gas-phase absorption measurements are important.

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Section: Mirror Mirrormentioning

confidence: 99%

Section: The Need For Gas-phase Absorption Measurementsmentioning

confidence: 99%

Introduction to Cavity-Ringdown Spectroscopy

Busch

1999

ACS Symposium Series

122

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“…In the original work, two and three mirror cavities were used in the visible and near-infrared. Experiments that followed focused on two mirror cavities and extended to the mid-infrared , . From the photon lifetime, the resonator mirror reflectivities are deduced, given the mirror spacing.…”

Section: Crlas History and Developmentmentioning

confidence: 99%

Cavity Ringdown Laser Absorption Spectroscopy: History, Development, and Application to Pulsed Molecular Beams

et al. 1997

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“…Cavity ringdown spectroscopy (CRDS) has its origins in technology developed by the aerospace industry for characterising high reflectivity mirrors. 1,2 Its application to molecular absorption measurements was first described by O'Keefe and Deacon in 1988, 3 and over the past ten years or so it has become established as the ultra-sensitive spectroscopic detection technique of choice for a wide variety of applications, ranging from fundamental studies of molecular spectroscopy, kinetics and dynamics through to atmospheric and environmental sensing. A literature search using a popular citations database reveals an almost linear growth in publications in the field over the past decade, from around 10 per year in 1994 to over 100 in 2004.…”

Section: Introductionmentioning

confidence: 99%