Download or read book Advances in Optical Diagnostics Based on Tunable Diode Laser Spectroscopy written by Toni Laurila and published by . This book was released on 2005 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser Diagnostics for Reacting Flows written by and published by . This book was released on 2007 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced optical diagnostic techniques relevant to propulsion were investigated. The techniques studied were based on laser spectroscopy, with emphasis on spectrally-resolved absorption and laser-induced fluorescence (LIF). Laser sources included tunable cw near-infrared diode lasers and tunable (or fixed-wavelength) pulsed lasers operated at ultraviolet (UV) or infrared (IR) wavelengths. The cw lasers were spectrally narrow, allowing study of innovative diagnostics based on spectral lineshapes, while the pulsed lasers provided intense bursts of photons needed for techniques based on LIF. Accomplishments of note included: (1) development of a new imaging diagnostic based on infrared planar laser-induced fluorescence (IR PLIF), (2) investigations of quantitative ultraviolet (UV) PLIF of NO and CO2 in high-pressure combustion environments, (3) the development of a new temperature diagnostic using UV absorption of CO2 for high-temperature combustion environments, (4) development of advanced wavelength-multiplexed diode laser absorption sensing of non-uniform temperature distributions, gas temperature in scramjet flows, and tunable mid-IR-based fuel sensing, and (5) further development of quantitative tracers to image fuel distribution using ketones and the aromatic toluene. The full spectrum of results was published in thirty-eight papers in the AIAA and peer reviewed literature, seven PhD theses, and forty-three presentations and invited lectures.

Download or read book TDLS 2009 written by Frank K. Tittel and published by Springer. This book was released on 2011-05-06 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Special issue of the 7th International Conference on Tunable Diode Laser Spectroscopy, held July 13-17, 2009 in Zermatt, Switzerland. The purpose of these meetings was to report and discuss the progress that has been made in the technical development of diode lasers and their applications in areas of fundamental research as well as real world applications of the technology. This was accomplished in a format encouraging strong interaction between researchers, device developers and semiconductor laser manufacturers. The relevant technologies include the original lead salt lasers, near-infrared diode lasers and the latest developments in mid-infrared quantum and interband cascade lasers, as well as nonlinear optical schemes.

Download or read book Extended NIR Laser Diagnostics for Gas Sensing Applications written by Aamir Farooq and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of diagnostics based on laser-absorption spectroscopy for combustion applications has been an important and active field of research over the past two decades due to the advantages of this non-intrusive optical sensing technique compared to traditional sampling-based sensing methods. Tunable diode laser (TDL) sensors, in particular, have shown the ability to provide in situ, time-resolved, line-of-sight measurements of temperature, gas species concentration, velocity, density, mass flux, and pressure in a variety of combustion environments. This thesis explores three new areas of TDL research: (a) extended near-infrared (NIR) diagnostics, (b) sensing under high-pressures, and (c) applications to chemical kinetics. Water vapor (H2O) and carbon dioxide (CO2) are attractive sensing targets for hydrocarbon-fueled systems as they are primary combustion products and their concentrations can be interpretrated to indicate combustion progress and efficiency. Both these gases have absorption spectra in the infrared (IR) region. Most previous TDL absorption sensors were designed to exploit robust telecommunications diode lasers and optical fiber technology in the 1.3-1.6 [mu]m (NIR) wavelength region. Recent developments in semiconductor diode-laser technology have extended the range of continuous wave (CW) room-temperature single-mode diode lasers to 2.9 [mu]m, allowing access to stronger vibrational bands of H2O and CO2 in the extended-NIR region. The first combustion diagnostics in the extended-NIR wavelength were demonstrated as part of this thesis work. The sensors were designed by selecting optimal transitions and then measuring the pertinent spectroscopic parameters in controlled laboratory environements. These sensors were then tested in the combustion environments of a flat flame and shock tube to validate their performance. These new sensors provide enhanced sensitivity and improved accuracy compared to previous TDL diagnostics. As part of this work, a novel diagnostic based on wavelength modulation spectroscopy (WMS) of CO2 was developed to make precise measurements of temperature behind reflected shock waves. This temperature diagnostic achieved an unprecedented uncertainty of

Download or read book Industrial Applications of Laser Diagnostics written by Yoshihiro Deguchi and published by Taylor & Francis. This book was released on 2016-04-19 with total page 301 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tighter regulations of harmful substances such as NOx, CO, heavy metals, particles, emissions from commercial plants and automobiles reflect a growing demand for lowering the anthropogenic burdens on the environment. It is equally important to monitor controlling factors to improve the operation of industrial machinery and plants. Among the many me

Download or read book Advances in Tunable Diode Laser Spectroscopy for Aero Engine Research written by Thomas Benoy and published by . This book was released on 2017 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tunable diode laser spectroscopy (TDLS) is a widely used technique for the measurement of gas species and offers in-situ operation, accuracy and faster response time compared to other optical and non-optical gas sensing techniques.The work in this thesis focusses on the measurement of CO2 in the harsh environment of a gas turbine engine (GTE). The work is part of a much larger initiative called Fibre Laser Imaging of gas Turbine Exhaust Species (FLITES) aimed at obtaining concentration distributions of gas species such as CO2 and NO, unburnt hydrocarbons, and soot in a gas turbine exhaust plume using optical tomography. In the FLITES system, a thulium doped fibre amplifier (TDFA) is used to boost the optical power output from a 2 mW, 1997 nm, multi-quantum well distributed feedback (DFB-MQW) laser to feed 126 measurement channels arranged in dodecagon geometry for optical tomography. Hence, agile TDLS techniques need to be developed which can be scaled up to the multi-channel measurement system.Attributed by the interference from noise in the measurement environment of a GTE, phase sensitive detection using a lock-in amplifier (LIA) has to be employed where an additional current modulation is applied to the DFB laser, creating an instantaneous intensity modulated output and a delayed wavelength modulation (WM) output. This technique falls under a metrology branch known as wavelength modulation spectroscopy (WMS).The unknown measurement conditions expected in a GTE engine necessitates the use of calibration-free WMS techniques for the simultaneous measurement of gas concentration and temperature. Calibration-free techniques in WMS have been developed at the Centre for Microsystems and Photonics (CMP) of Strathclyde University. These are known as the phasor decomposition method (PDM) and the residual amplitude modulation (RAM) technique. They employ the signals obtained using the first harmonic demodulation of the WMS signals, followed by post processing to recover the gas absorption line shape. It was known in the CMP group that the accuracy of these techniques was limited by the variation in the laser modulation parameters such as the phase of the wavelength modulation relative to the intensity modulation (WM-IM phase lag) and the wavelength modulation amplitude across the laser current scan.The solutions to two problems are addressed in this thesis, viz. the implementation of correction procedures to account for the variation in the laser modulation parameters across the current scan and the need for a calibration-free technique for the measurement of CO2 in a GTE exhaust plume scalable to a multi-channel measurement system.Accurate measurements of the wavelength modulation parameters were made across the current scan and correction algorithms were implemented to compensate for its effects on the recovered gas absorption line shape.The gas spectral parameters were measured in the lab for the R48 absorption line of CO2 near 1997.2 nm at the higher temperatures (up to 500°C) expected in a GTE exhaust plume, using a heated gas cell. A Fourier expansion model was developed for the WMS signals which employ the measured laser modulation and gas spectral parameters. 1f normalised 2f WMS technique was chosen as the calibration-free measurement approach due to the advantages of cancellation of the transmission fluctuations as well as signal normalisation. The 2f/1f measurement technique was validated in the lab at higher temperatures for the simultaneous recovery of the CO2 concentration and temperature with an accuracy of 3.39 % and 3.72 %, respectively. Subsequently, field campaigns were conducted at the Rolls-Royce test facility at East Kilbride, yielding concentration and temperature values having good correlation to the engine operating conditions such as the throttle and core temperature.Multi-channel tomographic measurements were conducted on the test phantoms at INTA, Madrid, using TFLAS-WMS (tunable fibre laser absorption spectroscopy). Accurate concentration images could be recovered using tomographic reconstruction algorithms.

Download or read book Advances in Tunable Diode Laser Spectroscopy Using Residual Amplitude Modulation Techniques written by Keith Ruxton and published by . This book was released on 2010 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Precision Spectroscopy Diode Lasers and Optical Frequency Measur written by Leo Hollberg and published by DIANE Publishing. This book was released on 2000 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: A selected set of reprints from the Optical Frequency Measurement Group of the Time and Frequency Div. of the Nat. Inst. of Standards and Technology and consists of work published between 1987 and 1997. The 2 programs represented are (1) development of tunable diode-laser technology for scientific applications and precision measurements, and (2) research toward the goal of realizing optical-frequency measurements and synthesis. The papers are organized in 5 categories: diode laser technology; tunable laser systems; laser spectroscopy; optical synthesis and extended wavelength coverage; and multi-photon interactions and optical coherence.

Download or read book Laser Spectroscopy written by H. R. Schlossberg and published by . This book was released on 1978 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in Spectroscopy for Lasers and Sensing written by Baldassare Di Bartolo and published by Springer Science & Business Media. This book was released on 2006-07-21 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents the Proceedings of "New Development in Optics and Related Fields," held in Italy in June, 2005. This meeting was organized by the International School of Atomic and Molecular Spectroscopy of the "Ettore Majorana" Center for Scientific Culture. The purpose of this Institute was to provide a comprehensive and coherent treatment of the new techniques and contemporary developments in optics and related fields.

Download or read book Scanned Wavelength modulation Absorption Spectroscopy with Application to Hypersonic Impulse Flow Facilities written by Christopher Lyle Strand and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented herein describes several advances in the evolution of combustion diagnostics based upon the technique of tunable diode laser absorption spectroscopy (TDLAS). The primary focus of this work was to provide the theoretical and practical means to perform in-situ TDLAS measurements within the harsh flow environments of hypersonic impulse ground-test facilities. In addition to this primary focus, the development and application of this work led to a comprehensive analytical framework for wavelength-modulation spectroscopy and enhanced the understanding of the complex flow environments within hypersonic flow facilities and hypersonic combustion experiments. Hypersonics is the field of aeronautics concerned with flight speeds that are highly supersonic, typically on the order of Mach 5 and above. Presently, it is the domain of spacecraft during re-entry and a select cadre of rocket-powered and air-breathing test vehicles (e.g., North American X-15, NASA X-43, Boeing X-51, HyShot I-IV, HiFiRE 0-3, etc.). It is also a regime of grand aspirations, including routine inexpensive space access, rapid intercontinental transport, atmospheric entry on other planets, and numerous strategic military applications. The development of hypersonic technology is confounded by the immensity of the problem, especially the complexity of interacting physical phenomena and the shortcomings in the fundamental understanding thereof. Understanding of this complex regime and the development of technologies to utilize this regime for flight require a comprehensive scientific and engineering approach including fundamental theory, computations, ground-testing, and flight testing. Due to the capacity of ground-test facilities to formulate tractable hypersonic experiments and, within those experiments, the capability of specialized diagnostics to extract critical information, ground-testing is the primary approach to cracking the multi-physics puzzle of hypersonic flight. Shock-tube-derived impulse flow facilities are a specific form of hypersonic ground-test facility and fill a critical niche within the field. These facilities are characterized by extremely short test times, often less than a few milliseconds, but excel at producing high-enthalpy flows with realistic flow chemistry. This capability is particularly valuable for the investigation of chemically reacting flows within air-breathing hypersonic vehicles such as the scramjet. Effective use of the short-duration test time is progressively being unlocked by the development of modern high-bandwidth instrumentation. Tunable diode laser absorption spectroscopy (TDLAS) offers the potential to provide quantitative measurement of numerous critical flow parameters within these facilities, including temperature, velocity, and species partial pressure. The violent flow environment of a flow model in an impulse ground-test facility creates a formidable challenge for the implementation of a TDLAS diagnostic. Impulse flow test times on the order of 1 ms necessitate exceptionally high measurement bandwidths to capture relevant transient phenomena. Harsh flow conditions introduce substantial measurement noise through mechanically- and density-gradient-induced beam-steering. Short optical paths within the model limit the magnitude of the optical absorption signal and the confined environment limits the resources available for required optical hardware. Further challenges are introduced through the requirements of generating an academically valuable dataset. Multiple simultaneous quantitative measurement parameters at numerous locations within the flow-field are often desirable in both reacting and non-reacting flows. To address the challenges of TDLAS sensing in impulse flow facilities, the efforts of this work include advances in both diagnostic methodology and optical hardware design. A new analytical framework has been developed for the technique of scanned-wavelength-modulation spectroscopy (scanned-WMS) to reject noise and achieve high-sensitivity while permitting the simultaneous measurement of temperature, partial pressure, and velocity. This new framework has enabled accurate measurements at unprecedented bandwidths in harsh flow environments. Integration of TDLAS optical components into flow models has led to novel approaches for harsh-environment optical alignment hardware, combining precision and sufficient robustness to survive repeated firings of an impulse facility. Furthermore, the intense beam-steering induced by facility vibrations and turbulent density gradients have motivated a comprehensive redesign of conventional beam collection approaches. TDLAS diagnostics leveraging these advances have been implemented in both the Stanford Expansion Tube Flow Facility for the purpose of facility characterization and in the HyShot II scramjet experiment at the High Enthalpy Shock Tunnel in Göttingen, Germany to investigate reacting and non-reacting scramjet flows. Results from each of these campaigns are presented as an illustration of the diagnostic capabilities developed in this work.

Download or read book Advances in Laser Spectroscopy written by F. T. Arecchi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Tunable Diode Laser Development and Spectroscopy Applications written by Abraham Katzir and published by . This book was released on 1983 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book State of the art Laser Gas Sensing Technologies written by Yufei Ma and published by MDPI. This book was released on 2020-03-05 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trace gas sensing technologies are widely used in many applications, such as environmental monitoring, life science, medical diagnostics, and planetary exploration. On the one hand, laser sources have developed greatly due to the rapid development of laser media and laser techniques in recent years. Some novel lasers such as solid-state, diode, and quantum cascade lasers have experienced significant progress. At present, laser wavelengths can cover the range from ultraviolet to terahertz, which could promote the development of laser gas sensing technologies significantly. On the other hand, some new gas sensing methods have appeared, such as photothermal spectroscopy and photoacoustic spectroscopy. Laser spectroscopy-based gas sensing techniques have the advantages of high sensitivity, non-invasiveness, and allowing in situ, real-time observation. Due to the rapid and recent developments in laser source as well as the great merits of laser spectroscopy-based gas sensing techniques, this book aims to provide an updated overview of the state-of-the-art laser gas sensing technologies.

Download or read book Precision Spectroscopy Diode Lasers and Optical Frequency Measurement Technology written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This compilation is a selected set of reprints from the Optical Frequency Measurement Group of the Time and Frequency Division of the National Institute of Standards and Technology, and consists of work published between 1987 and 1997. The two main programs represented here are (1) development of tunable diode-laser technology for scientific applications and precision measurements, and (2) research toward the goal of realizing optical-frequency measurements and synthesis. The papers are organized chronologically in five, somewhat arbitrarily chosen categories: Diode Laser Technology, Tunable Laser Systems, Laser Spectroscopy, Optical Synthesis and Extended Wavelength Coverage, and Multi-Photon Interactions and Optical Coherences.

Download or read book Novel Techniques for Tunable Diode Laser Spectroscopy and Their Application in Solid Oxide Fuel Cell Diagnostics written by Andrew James McGettrick and published by . This book was released on 2007 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advanced Diagnostics for Reacting Flows written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Progress is reported for the past three years of a research program on advanced diagnostic techniques for combustion gases and plasmas. The techniques studied are based on laser spectroscopy, particularly spectrally-resolved absorption and laser-induced fluorescence. Laser sources include tunable cw diode lasers and tunable (or fixed-frequency) pulsed lasers. The cw lasers are spectrally narrow, allowing study of innovative techniques based on spectral lineshapes, while the pulsed lasers provide intense bursts of photons needed for techniques based on light-scattering phenomena. Accomplishments of note include: successful development of wavelength-multiplexing schemes which allow diode laser absorption measurements of multiple flow parameters along a common optical path; the first application of frequency-doubled diode lasers for combustion species measurements; establishment of a simple and sensitive means of imaging temperature in flows of air seeded with acetone; innovation and validation of a fluorescence-based plasma diagnostic for static pressure and kinetic temperature; and development and demonstration of a new class of sensors, based on multiplexed diode laser absorption, for near-real-time combustion control.