Diode laser absorption tomography using data compression techniques

Lindstrom, C. D.; Tam, Chung-Jen; Givens, Ryan N.; Davis, D. J.; Williams, Skip

doi:10.1117/12.766323

Cited by 12 publications

(6 citation statements)

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“…Doppler shifting of the line center positions can be used to extract velocity and the spectral linewidth of particular transitions can be used to extract the pressure. 11 As an example of TDLAS-derived simultaneous temperature, water concentration, and velocity measurements, we briefly summarize some work done in the isolator of an ethylene-fueled axisymmetric scramjet engine. 10 The engine was operated in direct connect mode using a Mach 2 facility nozzle.…”

Section: Absorption and Emissionmentioning

confidence: 99%

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Application of Diode-Laser-Based Measurements in Hypersonic Flows

Brown

2012

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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The development of optical techniques capable of measuring in-stream flow properties of air breathing hypersonic engines is a goal of the Aerospace Propulsion Division at AFRL. This goal is motivated by the need for in-stream data to support both ground and flight tests of scramjet engine designs. While particular fundamental hypersonic flow problems are addressable using well-established laser-based techniques, advanced engine concepts using axisymmetric hardware typically have minimal optical access making some of the more traditional techniques difficult to deploy. To meet the need we have an ongoing in-house program to mature diode-laser-based techniques for application in hypersonic flows. Additional motivation for developing diode-laser-based measurement strategies comes from the need for flight sensors. Flight-worthy packages must be small, light, low-power and rugged. For measurement objectives in both ground and flight experiments we have adopted tunable diode laser absorption spectroscopy making heavy use of fiber coupling and integrated optomechanics. Water-based measurements of temperature, pressure, velocity, and water mole fraction are executed using time-multiplexed near-infrared diodes. These fundamental flow parameters can be combined to yield optical mass capture and thrust. Similar measurements can be made in inlets using an oxygen-based strategy employing visible diodes. In this paper we summarize the absorption sensor work done to date in AFRL. Particular attention will be paid to the fact that a single hardware platform can be used to capture absorption, non-resonant transmission, and optical emission signals all three of which provide relevant information.

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Section: Absorption and Emissionmentioning

confidence: 99%

“…Details of the hardware setup and implementation can be found elsewhere. 9,10,11,12 To better understand the three types of signals collected we examine a sample raw signal trace shown in Fig. 1.…”

Section: Absorption and Emissionmentioning

confidence: 99%

Application of Diode-Laser-Based Measurements in Hypersonic Flows

Brown

2012

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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“…In recent years, it has been possible to simulate the flow fields using computational fluid dynamics (CFD) simulated images of molecular concentration and temperature fields [10], [22]. These CFD simulated images can improve the reconstruction quality by providing training examples for the prior model [7].…”

Section: Introductionmentioning

confidence: 99%

“…DATA MODEL In TDLAT imaging [33]- [35], projection measurements corresponding to a particular target molecule, in our case water, are made along a few projection paths and few discrete frequencies [7], [22]. The different discrete frequencies correspond to different absorption transitions [36].…”

Section: Introductionmentioning

confidence: 99%

Gaussian mixture prior models for imaging of flow cross sections from sparse hyperspectral measurements

Nadir

Brown

Comer

et al. 2015

2015 IEEE Global Conference on Signal and Information Processing (GlobalSIP)

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Tunable diode laser absorption tomography (TD-LAT) has emerged as a popular non-intrusive technique for simultaneous sensing of gas concentration and temperature. Major challenges of TDLAT include availability of limited projection measurements and limited training data. Conventional tomographic techniques are therefore not directly applicable. Usually approximations are made which are limited in scope. In this paper, we propose a novel model-based iterative reconstruction (MBIR) framework for TDLAT imaging of gas concentration and temperature. First, we propose a novel prior model that captures non-homogeneous and non-Gaussian characteristics of the images by modeling their distribution as a Gaussian mixture and impose constraints on the mixture parameters to avoid overfitting of the sparse training set. Next, we present the nonlinear forward model of TDLAT. We formulate the inversion problem into a MAP estimation problem and propose a multigrid optimization algorithm that solves the resulting optimization problem in eigenimage basis using surrogate functions for the non-convex prior. We demonstrate the efficacy of our approach by performing reconstructions of simulated TDLAT data.

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“…L. Ma used a widely tunable laser called "fiber Fabry-Perot tunable filter laser (FFP TFL)" to scan over the 1333-1377 nm range at �200 Hz in the 2D reconstruction of temperature and H2O concentration distributions over a Hencken burner flame [11]. C. Lindstrom reconstructed similar parameters in supersonic flows with three time-multiplexed tunable distributed feedback (DFB) lasers probing four water absorption transitions at 1391.67, 1392.53, 1392.81, 1396.37 nm [12]. Additionally, R.Villarreal and P. Varghese measured the profiles of temperature and C02 mole fraction simultaneously in methane-air flame burner attached to a translation stage by a 4.…”

mentioning

confidence: 99%

Numerical investigation of two-dimensional imaging for temperature and species concentration using tunable diode laser absorption spectroscopy

Zhou³

et al. 2012

Proceedings of 2012 International Conference on Measurement, Information and Control

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A technique has been developed to obtain simultaneous tomographic images of temperature and species concentration based on line-of-sight (LOS) diode laser absorption spectroscopy. Multiple LOS measurement paths divide the combustion zone into an M X N grid. With the assumption of uniform distribution around the grid intersection points, spatial distribution of temperature or a particular chemical species can be inferred from the M+N path averages because each measurement path passes through different grid boxes and carries their information of temperature and species concentration. The measurement accuracy and resolution depend on the total number of paths measured. The feasibility of this method is verified by simulated image reconstruction of an engine temperature distribution.

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Diode laser absorption tomography using data compression techniques

Cited by 12 publications

References 0 publications

Application of Diode-Laser-Based Measurements in Hypersonic Flows

Application of Diode-Laser-Based Measurements in Hypersonic Flows

Gaussian mixture prior models for imaging of flow cross sections from sparse hyperspectral measurements

Numerical investigation of two-dimensional imaging for temperature and species concentration using tunable diode laser absorption spectroscopy

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