Noise in single-shot broadband coherent anti-Stokes Raman spectroscopy that employs a modeless dye laser

Snelling, David R.; Sawchuk, Robert A.; Parameswaran, T.

doi:10.1364/ao.33.008295

Cited by 37 publications

(21 citation statements)

References 22 publications

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“…Frequency measurements are typically more precise than intensity measurements. For example, precisions of single-shot CARS measurements under optimum conditions using a single-mode pump laser and modeless Stokes are of order 2-5% [115]. In comparison a single-shot precision of <0.2% has been reported using LIGS [187].…”

Section: Concentration Measurements and Thermometry Applicationsmentioning

confidence: 99%

“…The use of a modeless laser also reduced the spectral noise that is a feature of conventional broadband lasers [113][114][115]. Accurate and precise temperature measurements of an oxy-acetylene flame were obtained since a large number of transitions were probed simultaneously.…”

Section: The Potential Of Resonant Dfwm For Thermometry Was Demonstramentioning

confidence: 99%

“…Using this method temperatures were measured using Improved accuracy and precision was achieved by using the fundamental output of a broadband modeless laser operating in the blue spectral region to access transitions in the C 2 molecule by Kaminski et al [112]. The use of a modeless laser also reduced the spectral noise that is a feature of conventional broadband lasers [113][114][115]. Accurate and precise temperature measurements of an oxy-acetylene flame were obtained since a large number of transitions were probed simultaneously.…”

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confidence: 99%

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Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Kiefer

Ewart

2011

Progress in Energy and Combustion Science

131

112

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Laser-based methods have transformed combustion diagnostics in the past few decades. The high intensity, coherence, high spectral resolution and frequency tunability available from laser radiation has provided powerful tools for studying microscopic processes and macroscopic phenomena in combustion by linear and nonlinear optical processes. This review focuses on nonlinear optical techniques based on resonant four-wave mixing for non-intrusive measurements of minor species in combustion. The importance of minor species such as reaction intermediates is outlined together with the challenges they present for detection and measurement in the hostile environments of flames, technical combustors, and engines. The limitations of conventional optical methods for such measurements are described and the particular advantages of coherent methods using nonlinear optical techniques are discussed.The basic physics underlying four-wave wave mixing processes and theoretical models for signal calculation are then presented together with a discussion of how combustion parameters may be derived from analysis of signals generated in various four-wave mixing processes. The most important four-wave mixing processes, in this context, are then reviewed:Degenerate Four-Wave Mixing (DFWM), Coherent Anti-Stokes Raman Scattering (CARS), Laser Induced Grating Spectroscopy (LIGS) and Polarization Spectroscopy (PS). In each case the fundamental physics is outlined to explain the particular properties and diagnostic advantages of each technique. The application of the methods mentioned to molecular physics studies of combustion species is then reviewed along with their application in measurement of concentration, temperature and other combustion parameters. Related nonlinear techniques and recent extensions to the ultra-fast regime are briefly reviewed. Finally practical considerations relevant to multi-dimensional and multi-species measurements, as well as applications in technical combustion systems are discussed.Keywords: nonlinear optical spectroscopy, four-wave mixing, combustion diagnostics, minor species detection, laser-induced gratings, polarization spectroscopy IntroductionEnergy from renewable sources such as solar and wind power is the goal of much current research and technological development. Combustion, however, is and is likely to remain for the foreseeable future, the most important energy source for heat, electrical power and especially for transportation. In technical combustion systems the chemical energy of fossil fuels such as coal, crude oil and natural gas is converted into heat through oxidation with oxygen from air. However, fossil fuel resources are limited and alternatives like biofuels [1] or novel technologies such as fuel cells [2] are not yet able to meet the demand. Consequently, for a sustainable use of fossil fuels it is desirable to further improve the efficiency, maintainability and reliability of existing combustion devices. Achieving such improvements depends upon an improved understanding of t...

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Section: Concentration Measurements and Thermometry Applicationsmentioning

confidence: 99%

Section: The Potential Of Resonant Dfwm For Thermometry Was Demonstramentioning

confidence: 99%

mentioning

confidence: 99%

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Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Kiefer

Ewart

2011

Progress in Energy and Combustion Science

131

112

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“…[2][3][4][5][6][7][8] Over the past 15 years, single-shot imprecision has been reported in the 24 -100 K range, from room temperature to 2000 K flame temperature. 9 -13 Several combinations of single-mode or multimode pump lasers 14 -16 with dye lasers of modeless design or otherwise [17][18][19] were selected. The combination of a single-mode Nd:YAG laser and a modeless dye laser turned out to be favorable for reducing intensity fluctuations in the spectrum.…”

Section: Introductionmentioning

confidence: 99%

Thermometry for turbulent flames by coherent anti-Stokes Raman spectroscopy with simultaneous referencing to the modeless excitation profile

Veen

Roekaerts

2005

Appl. Opt.

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An optimal system for temperature measurements by coherent anti-Stokes Raman spectroscopy (CARS) in turbulent flames and flows is presented. In addition to a single-mode pump laser and a modeless dye laser, an echelle spectrometer with a cross disperser is used. This system permits simultaneous measurement of the N 2 CARS spectrum and the broadband dye laser profile. A procedure is developed to use software to transform this profile into the excitation profile by which the spectrum is referenced. Simultaneous shot-to-shot referencing is compared to sequential averaged referencing for data obtained in flat flames and in room air. At flame temperatures, the resultant 1.5% imprecision is limited by flame fluctuations, indicating that the system may have a single-shot imprecision below 1%. At room temperature, the 3.8% single-shot imprecision is of the same order as the best values reported for dualbroadband pure-rotational CARS. Using the unique shot-to-shot excitation profiles, simultaneous referencing eliminates systematic errors. At 2000 and 300 K, the 95% confidence intervals are estimated to be Ϯ20 and Ϯ10 K, respectively.

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“…11 fail to consistently match the associated theoretical peaks. These discrepancies are primarily attributed to shot-to-shot variations 8,39,40 in the broadband dye laser profile. Notwithstanding these differences, CARSFIT still provides reasonable pressure and temperature values of 3.09 atm, 247 K and 3.81 atm, 256 K for Figs.…”

Section: Single-shot Measurementsmentioning

confidence: 99%

Pressure, temperature, and density measurements using high-resolution N2 CARS

Woodmansee

Kuehner

Lucht

et al. 1998

34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit

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Noise in single-shot broadband coherent anti-Stokes Raman spectroscopy that employs a modeless dye laser

Cited by 37 publications

References 22 publications

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Thermometry for turbulent flames by coherent anti-Stokes Raman spectroscopy with simultaneous referencing to the modeless excitation profile

Pressure, temperature, and density measurements using high-resolution N2 CARS

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