Temperature and water mole fraction measurements by time-domain-based supercontinuum absorption spectroscopy in a flame

Werblinski, Thomas; Mittmann, F.; Altenhoff, Michael; Seeger, Thomas; Zigan, Lars; Will, Stefan

doi:10.1007/s00340-014-5964-1

Cited by 27 publications

(13 citation statements)

References 20 publications

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“…However, the detection bandwidth of absorption techniques based on continuous wave lasers such as wavelength modulation spectroscopy (WMS) [11,12] and cavity ring-down spectroscopy [13][14][15][16] is usually limited to 1-2 cm −1 [17,18]. Much larger detection bandwidth is provided by techniques based on broadband sources such as optical frequency combs [19][20][21], supercontinuum sources [22,23] and Fourier-domain mode-locked lasers [24]. Spectrometers employing these sources have been used to determine water concentration and/or temperature in combustion environments with time resolution of the order of hundreds of microseconds or milliseconds [21,[23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Time-resolved continuous-filtering Vernier spectroscopy of H₂O and OH radical in a flame

2019

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We use broadband near-infrared continuous-filtering Vernier spectroscopy (CF-VS) for time-resolved detection of H 2 O and OH radical in a premixed CH 4 /air flat flame. The CF-VS spectrometer is based on a femtosecond Er:fiber laser, an external cavity that contains the flame, and a detection system comprising a rotating diffraction grating and photodetectors. Spectra of H 2 O and OH radical around 1570 nm are continuously recorded with 6.6 GHz spectral resolution, 4.0 × 10 −7 cm −1 absorption sensitivity, and 25 ms time resolution, while the fuel-air equivalence ratio is periodically modulated with a square wave. The concentrations of the two analytes are retrieved with percent level precision by a fit of a Vernier model to each spectrum spanning 13 nm. The temporal profiles of both concentrations in each modulation cycle are repeatable and the steady-state concentration levels are in good agreement with predictions based on one-dimensional simulations of a static flat flame. The robust CF-VS spectrometer opens up for quantitative monitoring of multiple products of time-varying combustion processes with relatively simple data acquisition procedures.

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Section: Introductionmentioning

confidence: 99%

Time-resolved continuous-filtering Vernier spectroscopy of H₂O and OH radical in a flame

2019

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“…line data). This approach has already been applied to SCLAS data 8,11,14 . The preference for the physical model approach is easily explained regarding the availability of line databases like HITRAN 17 and the possibility to avoid calibration measurements.…”

Section: Methodsmentioning

confidence: 99%

“…The sampling rate is known and the pulse response function of the high bandwidth photo diode is either supplied by the manufacturer or can be measured using pulsed lasers 14,19 . Nonetheless the SCL pulse profile is still unknown and the transfer of the manufacturer supplied photo diode response function to a different measurement system with even minimal deviations in the electrical characteristics is critical.…”

Section: Methodsmentioning

confidence: 99%

“…These advantages mainly become visible in measurements with strong absorption, which are often unavoidable due to boundary conditions of the experiment. Regarding the unknown initial intensity distribution a simultaneous fitting approach 13 is applied, while previous evaluation procedures used estimation algorithms for the background 11,14 . These components are combined to a comprehensive SCLAS data analysis method, that enables the evaluation of mole fraction, temperature and pressure from SCLAS measurements even for partial total absorption.…”

Section: Introductionmentioning

confidence: 99%

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Data analysis and uncertainty estimation in supercontinuum laser absorption spectroscopy

Emmert

Blume

Dreizler

et al. 2018

Sci Rep

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A set of algorithms is presented that facilitates the evaluation of super continuum laser absorption spectroscopy (SCLAS) measurements with respect to temperature, pressure and species concentration without the need for simultaneous background intensity measurements. For this purpose a non-linear model fitting approach is employed. A detailed discussion of the influences on the instrument function of the spectrometer and a method for the in-situ determination of the instrument function without additional hardware are given. The evaluation procedure is supplemented by a detailed measurement precision assessment by applying an error propagation through the non-linear model fitting approach. While the algorithms are tailored to SCLAS, they can be transferred to other spectroscopic methods, that similarly require an instrument function. The presented methods are validated using gas cell measurements of methane in the near infrared region at pressures up to 8.7 bar.

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“…On the other hand, SCG in optical fibres is currently an active field of research due to the numerous applications such as optical coherence tomography, microscopy techniques, spectroscopic analysis of air and water pollutants, optical communications or optical metrology in which supercontinuum sources are needed [15][16][20][21][22][23][24][25][26][27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Octave-spanning supercontinuum generation in highly nonlinear silica fibres based on cost-effective fibre amplifiers

2016

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We report a simple method for supercontinuum generation. The set-up consists of an Er-doped mode-locked fibre laser, used as seed, and a highly nonlinear fibre with zero dispersion at 1550 nm. Thus, all the components are easily attainable. With this novel system the requirements in terms of control of dispersion are reduced. In addition, the spectral width is optimized using fibres with positive and negative dispersion. The supercontinuum emission is characterized by means of an Optical Spectrum Analyser and a PbS photodetector, showing an octave-spanning spectral width, with a flat profile from 1100 nm up to 2100 nm. Compared to other supercontinuum sources, this new proposal results in a very competitive and attainable system, particularly in the 1500-2100 nm region.

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Temperature and water mole fraction measurements by time-domain-based supercontinuum absorption spectroscopy in a flame

Cited by 27 publications

References 20 publications

Time-resolved continuous-filtering Vernier spectroscopy of H₂O and OH radical in a flame

Time-resolved continuous-filtering Vernier spectroscopy of H₂O and OH radical in a flame

Data analysis and uncertainty estimation in supercontinuum laser absorption spectroscopy

Octave-spanning supercontinuum generation in highly nonlinear silica fibres based on cost-effective fibre amplifiers

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Temperature and water mole fraction measurements by time-domain-based supercontinuum absorption spectroscopy in a flame

Cited by 27 publications

References 20 publications

Time-resolved continuous-filtering Vernier spectroscopy of H2O and OH radical in a flame

Time-resolved continuous-filtering Vernier spectroscopy of H2O and OH radical in a flame

Data analysis and uncertainty estimation in supercontinuum laser absorption spectroscopy

Octave-spanning supercontinuum generation in highly nonlinear silica fibres based on cost-effective fibre amplifiers

Contact Info

Product

Resources

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Time-resolved continuous-filtering Vernier spectroscopy of H₂O and OH radical in a flame

Time-resolved continuous-filtering Vernier spectroscopy of H₂O and OH radical in a flame