Absorption measurements of water-vapor concentration, temperature, and line-shape parameters using a tunable InGaAsP diode laser

Arroyo, Martha P.; Hanson, Ronald K.

doi:10.1364/ao.32.006104

Cited by 216 publications

(79 citation statements)

References 16 publications

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“…Observed spectral lines exhibit a finite width due to the combined effects of collision, Doppler and other broadening processes. Estimates of total absorption that use a measurement at line center require corrections for the effects of line broadening (Arroyo and Hanson, 1993). Instead, CLH-2 records transmission across the entire broadened absorption feature, and we integrate over wavelength to find the total energy absorbed.…”

Section: Instrument Designmentioning

confidence: 99%

A fiber-coupled laser hygrometer for airborne total water measurement

et al. 2014

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Abstract. The second-generation University of Colorado closed-path tunable-diode laser hygrometer (CLH-2) is an instrument for the airborne in situ measurement of total water content -the sum of vapor-, liquid-and ice-phase waterin clouds. This compact instrument has been flown on the NSF/NCAR Gulfstream-V aircraft in an underwing canister. It operates autonomously and uses fiber-coupled optics to eliminate the need for a supply of dry compressed gas. In operation, sample air is ingested into a forward-facing subisokinetic inlet; this sampling configuration results in particle concentrations that are enhanced relative to ambient and causes greater instrument sensitivity to condensed water particles. Heaters within the inlet vaporize the ingested water particles, and the resulting augmented water vapor mixing ratio is measured by absorption of near-infrared light in a single-pass optical cell. The condensed water content is then determined by subtracting the ambient water vapor content from the total and by accounting for the inertial enhancement of particles into the sampling inlet. The CLH-2 is calibrated in the laboratory over a range of pressures and water vapor mixing ratios; the uncertainty in CLH-2 condensed water retrievals is estimated to be 14.3 % to 16.1 % (1-σ ). A vapor-only laboratory intercomparison with the firstgeneration University of Colorado closed-path tunable-diode laser hygrometer (CLH) shows agreement within the 2-σ uncertainty bounds of both instruments.

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Section: Instrument Designmentioning

confidence: 99%

A fiber-coupled laser hygrometer for airborne total water measurement

et al. 2014

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“…Line-of-sight thermometry by laser absorption spectroscopy is commonly achieved by targeting a pair of molecular absorption transitions of an infra-red active molecule [5,6]. This approach is effective (if an appropriate line pair is chosen) because absorption transitions from ground states with different energy levels are affected differently by the gas temperature (via the Boltzmann populations).…”

Section: Introductionmentioning

confidence: 99%

Optimisation of a tomography sensor for imaging of temperature in a gas turbine engine

Wood

Ozanyan

2013

2013 Ieee Sensors

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Abstract-We present a numerical study of tomographic reconstruction of gas temperature distributions from synthetic data of laser absorption measurements through the imaging plane. A mathematical expression which predicts the reconstruction error as a function of the beam configuration is developed, and a global optimization scheme is employed to minimize this predicted error subject to a constraint on the maximum number of permitted beams. This optimization methodology is applied to an annular measurement region and compared to conventional regular fan-beam arrangements in temperature tomography simulations. Synthetic data generated over the optimized beams led to temperature reconstructions with superior accuracy, provided Tikhonov inversion was used as the method of reconstruction.

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“…[6][7][8][9] In particular, the spectroscopy takes advantage of diode laser devices that have been developed for the telecommunications industry. These types of lasers produce relatively large power densities (~ 10 mW) with good spectral purity (1-3 GHz linewidth) for high sensitivity, high selectivity measurements.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Tunable Diode Spectroscopy for Monitoring Gases in Geothermal Plants

Partin¹

2006

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The results of an investigation directed at the development of instrumenttation for the real-time monitoring of gases, such as hydrogen sulfide (H 2 S) and chloride (HCl), in geothermal process streams are described. The geothermal power industry has an interest in the development of new low maintenance techniques since improved capabilities could lead to considerable cost savings through the optimization of various gas abatement processes.Tunable diode laser spectroscopy was identified as a candidate technology for this application and a commercial instrument was specified and procured for testing. The measurement principle involved the use of solid state diode lasers and frequency modulation techniques. The gallium arsenide diode lasers employed emit light in the 0.7 to 2.0 micron region of the electromagnetic spectrum. This region contains the overtone and combination absorption bands of a number of species of industrial interest, including H 2 S and HCl. A particular device can be tuned over a small range to match the absorption line by changing its applied temperature and current. The diode current can also be sinusoidally modulated in frequency as it is tuned across the line. This modulation allows measurements to be conducted at frequencies where the laser intensity noise is minimal; and therefore, very high signal-to-noise measurements are possible.The feasibility of using this technology in various types of geothermal process streams has been explored. The results of laboratory and field studies are presented along with new advances in laser technology that could allow more sensitive and selective measurements to be performed. iv v ACKNOWLEDGMENTSThe author would like to thank the operations personnel at the Northern California Power Agency; and in particular, Managers Murray Grande and Steve Miller, for their support of the H 2 S field trials. She would also like to thank President Paul Hirtz, Russell Kunzman, and the staff at Thermochem, Inc. for their help with the HCl steam experiments.The contributions of her colleagues, Charles Jeffery, Greg Lancaster, and Greg Mines are also acknowledged. Charles Jeffery assisted with the laboratory experiments. Greg Lancaster participated in the untreated vent gas field experiment. Greg Mines transported and installed the systems at the field sites; and in addition, provided valuable insight into geothermal operations.

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Absorption measurements of water-vapor concentration, temperature, and line-shape parameters using a tunable InGaAsP diode laser

Cited by 216 publications

References 16 publications

A fiber-coupled laser hygrometer for airborne total water measurement

A fiber-coupled laser hygrometer for airborne total water measurement

Optimisation of a tomography sensor for imaging of temperature in a gas turbine engine

Investigation of Tunable Diode Spectroscopy for Monitoring Gases in Geothermal Plants

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