Academic literature on the topic 'Eye-safe; lasers; atmospheric measurements'
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Journal articles on the topic "Eye-safe; lasers; atmospheric measurements"
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Spuler, S. M., K. S. Repasky, B. Morley, D. Moen, M. Hayman, and A. R. Nehrir. "Field-deployable diode-laser-based differential absorption lidar (DIAL) for profiling water vapor." Atmospheric Measurement Techniques 8, no. 3 (March 4, 2015): 1073–87. http://dx.doi.org/10.5194/amt-8-1073-2015.
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Abstract. A field-deployable water vapor profiling instrument that builds on the foundation of the preceding generations of diode-laser-based differential absorption lidar (DIAL) laboratory prototypes was constructed and tested. Significant advances are discussed, including a unique shared telescope design that allows expansion of the outgoing beam for eye-safe operation with optomechanical and thermal stability; multistage optical filtering enabling measurement during daytime bright-cloud conditions; rapid spectral switching between the online and offline wavelengths enabling measurements during changing atmospheric conditions; and enhanced performance at lower ranges by the introduction of a new filter design and the addition of a wide field-of-view channel. Performance modeling, testing, and intercomparisons are performed and discussed. In general, the instrument has a 150 m range resolution with a 10 min temporal resolution; 1 min temporal resolution in the lowest 2 km of the atmosphere is demonstrated. The instrument is shown capable of autonomous long-term field operation – 50 days with a > 95% uptime – under a broad set of atmospheric conditions and potentially forms the basis for a ground-based network of eye-safe autonomous instruments needed for the atmospheric sciences research and forecasting communities.
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Spuler, S. M., K. S. Repasky, B. Morley, D. Moen, M. Hayman, and A. R. Nehrir. "Field deployable diode-laser-based differential absorption lidar (DIAL) for profiling water vapor." Atmospheric Measurement Techniques Discussions 7, no. 11 (November 18, 2014): 11265–302. http://dx.doi.org/10.5194/amtd-7-11265-2014.
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Abstract. A field deployable water vapor profiling instrument that builds on the foundation of the preceding generations of diode-laser-based differential absorption lidar (DIAL) laboratory prototypes has been constructed and tested. Significant advances are discussed, including: a unique shared telescope design that allows expansion of the outgoing beam for eye-safe operation with opto-mechanical and thermal stability, multi-stage optical filtering enabling measurement during daytime bright-cloud conditions, rapid spectral switching between the online and offline wavelengths enabling measurements during changing atmospheric conditions, and enhanced performance at lower ranges by the introduction of a new filter design and the addition of a wide field-of-view channel. Performance modeling, testing and intercomparisons have been performed and are discussed. In general, the instrument has 150 m range resolution with 10 min temporal resolution – 1 min temporal resolution in the lowest 2 km of the atmosphere is demonstrated. The instrument was shown capable of autonomous long term field operation – 50 days with a >95% uptime – under a broad set of atmospheric conditions and potentially forms the basis for a ground-based network of eye-safe autonomous instruments needed for the atmospheric sciences research and forecasting communities.
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Spuler, Scott M., Matthew Hayman, Robert A. Stillwell, Joshua Carnes, Todd Bernatsky, and Kevin S. Repasky. "MicroPulse DIAL (MPD) – a diode-laser-based lidar architecture for quantitative atmospheric profiling." Atmospheric Measurement Techniques 14, no. 6 (June 21, 2021): 4593–616. http://dx.doi.org/10.5194/amt-14-4593-2021.
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Abstract. Continuous water vapor and temperature profiles are critically needed for improved understanding of the lower atmosphere and potential advances in weather forecasting skill. Ground-based, national-scale profiling networks are part of a suite of instruments to provide such observations; however, the technological method must be cost-effective and quantitative. We have been developing an active remote sensing technology based on a diode-laser-based lidar technology to address this observational need. Narrowband, high-spectral-fidelity diode lasers enable accurate and calibration-free measurements requiring a minimal set of assumptions based on direct absorption (Beer–Lambert law) and a ratio of two signals. These well-proven quantitative methods are known as differential absorption lidar (DIAL) and high-spectral-resolution lidar (HSRL). This diode-laser-based architecture, characterized by less powerful laser transmitters than those historically used for atmospheric studies, can be made eye-safe and robust. Nevertheless, it also requires solar background suppression techniques such as narrow-field-of-view receivers with an ultra-narrow bandpass to observe individual photons backscattered from the atmosphere. We discuss this diode-laser-based lidar architecture's latest generation and analyze how it addresses a national-scale profiling network's need to provide continuous thermodynamic observations. The work presented focuses on general architecture changes that pertain to both the water vapor and the temperature profiling capabilities of the MicroPulse DIAL (MPD). However, the specific subcomponent testing and instrument validation presented are for the water vapor measurements only. A fiber-coupled seed laser transmitter optimization is performed and shown to meet all of the requirements for the DIAL technique. Further improvements – such as a fiber-coupled near-range receiver, the ability to perform quality control via automatic receiver scanning, advanced multi-channel scalar capabilities, and advanced processing techniques – are discussed. These new developments increase narrowband DIAL technology readiness and are shown to allow higher-quality water vapor measurements closer to the surface via preliminary intercomparisons within the MPD network itself and with radiosondes.
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Pantazis, Alexandros, Alexandros Papayannis, and Georgios Georgoussis. "Novel lidar algorithms for atmospheric slantrange visibility, planetary boundary layer height, meteorogical phenomena and atmospheric layering measurements." EPJ Web of Conferences 176 (2018): 11003. http://dx.doi.org/10.1051/epjconf/201817611003.
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In this paper we present a development of novel algorithms and techniques implemented within the Laser Remote Sensing Laboratory (LRSL) of the National Technical University of Athens (NTUA), in collaboration with Raymetrics S.A., in order to incorporate them into a 3-Dimensional (3D) lidar. The lidar is transmitting at 355 nm in the eye safe region and the measurements then are transposed to the visual range at 550 nm, according to the World Meteorological Organization (WMO) and the International Civil Aviation Organization (ICAO) rules of daytime visibility. These algorithms are able to provide horizontal, slant and vertical visibility for tower aircraft controllers, meteorologists, but also from pilot’s point of view. Other algorithms are also provided for detection of atmospheric layering in any given direction and vertical angle, along with the detection of the Planetary Boundary Layer Height (PBLH).
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Kavaya, Michael J., Jeffrey Y. Beyon, Grady J. Koch, Mulugeta Petros, Paul J. Petzar, Upendra N. Singh, Bo C. Trieu, and Jirong Yu. "The Doppler Aerosol Wind (DAWN) Airborne, Wind-Profiling Coherent-Detection Lidar System: Overview and Preliminary Flight Results." Journal of Atmospheric and Oceanic Technology 31, no. 4 (April 1, 2014): 826–42. http://dx.doi.org/10.1175/jtech-d-12-00274.1.
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Abstract The first airborne wind measurements of a pulsed, 2-μm solid-state, high-energy, wind-profiling lidar system for airborne measurements are presented. The laser pulse energy is the highest to date in an eye-safe airborne wind lidar system. This energy, the 10-Hz laser pulse rate, the 15-cm receiver diameter, and dual-balanced coherent detection together have the potential to provide much-improved lidar sensitivity to low aerosol backscatter levels compared to earlier airborne-pulsed coherent lidar wind systems. Problems with a laser-burned telescope secondary mirror prevented a full demonstration of the lidar’s capability, but the hardware, algorithms, and software were nevertheless all validated. A lidar description, relevant theory, and preliminary results of flight measurements are presented.
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Nehrir, Amin R., Kevin S. Repasky, and John L. Carlsten. "Eye-Safe Diode-Laser-Based Micropulse Differential Absorption Lidar (DIAL) for Water Vapor Profiling in the Lower Troposphere." Journal of Atmospheric and Oceanic Technology 28, no. 2 (February 1, 2011): 131–47. http://dx.doi.org/10.1175/2010jtecha1452.1.
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Abstract A second-generation diode-laser-based master oscillator power amplifier (MOPA) configured micropulse differential absorption lidar (DIAL) instrument for profiling of lower-tropospheric water vapor is presented. The DIAL transmitter is based on a continuous wave (cw) external cavity diode laser (ECDL) master oscillator that is used to injection seed two cascaded tapered semiconductor optical power amplifiers, which deliver up to 2-μJ pulse energies over a 1-μs pulse duration at 830 nm with an average power of ∼40 mW at a pulse repetition frequency of 20 kHz. The DIAL receiver utilizes a commercial 28-cm-diameter Schmidt–Cassegrain telescope, a 250-pm narrowband optical filter, and a fiber-coupled single-photon-counting Avalanche photodiode (APD) detector, yielding a far-field full-angle field of view of 170 μrad. A detailed description of the second-generation Montana State University (MSU) DIAL instrument is presented. Water vapor number density profiles and time–height cross sections collected with the water vapor DIAL instrument are also presented and compared with collocated radiosonde measurements, demonstrating the instruments ability to measure night- and daytime water vapor profiles in the lower troposphere.
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Newsom, R. K., D. D. Turner, R. Lehtinen, C. Münkel, J. Kallio, and R. Roininen. "Evaluation of a Compact Broadband Differential Absorption Lidar for Routine Water Vapor Profiling in the Atmospheric Boundary Layer." Journal of Atmospheric and Oceanic Technology 37, no. 1 (January 2020): 47–65. http://dx.doi.org/10.1175/jtech-d-18-0102.1.
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AbstractThe performance of a novel water vapor broadband differential absorption lidar (BB-DIAL) is evaluated. This compact, eye-safe, diode-laser-based prototype was developed by Vaisala. It was designed to operate unattended in all weather conditions and to provide height-resolved measurements of water vapor mixing ratio in the lower troposphere. Evaluation of the Vaisala prototype was carried out at the U.S. Department of Energy’s Atmospheric Radiation Measurement site in north-central Oklahoma (i.e., the Southern Great Plains site) from 15 May to 12 June 2017. BB-DIAL measurements were compared with observations from radiosondes that were launched within 200 m of the BB-DIAL’s location. Radiosonde measurements are also compared with observations from a collocated Raman lidar and an Atmospheric Emitted Radiance Interferometer. During the evaluation period, the BB-DIAL operated continuously and did not experience any failures or malfunctions. The data availability was greater than 90% below 900 m but then decreased rapidly with height above this level to less than 10% above 1500 m AGL. From 106 radiosonde profiles, the overall mean difference (averaged temporally and vertically up to 1500 m) between the BB-DIAL and the radiosonde was −0.01 g kg−1, with a standard deviation of 0.65 g kg−1, and a linear correlation coefficient of 0.98. For comparison, the overall mean difference between the Raman lidar and the radiosonde was 0.07 g kg−1, with a standard deviation of 0.74 g kg−1, and a linear correlation coefficient of 0.97.
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Weckwerth, Tammy M., Kristy J. Weber, David D. Turner, and Scott M. Spuler. "Validation of a Water Vapor Micropulse Differential Absorption Lidar (DIAL)." Journal of Atmospheric and Oceanic Technology 33, no. 11 (November 2016): 2353–72. http://dx.doi.org/10.1175/jtech-d-16-0119.1.
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AbstractA water vapor micropulse differential absorption lidar (DIAL) instrument was developed collaboratively by the National Center for Atmospheric Research (NCAR) and Montana State University (MSU). This innovative, eye-safe, low-power, diode-laser-based system has demonstrated the ability to obtain unattended continuous observations in both day and night. Data comparisons with well-established water vapor observing systems, including radiosondes, Atmospheric Emitted Radiance Interferometers (AERIs), microwave radiometer profilers (MWRPs), and ground-based global positioning system (GPS) receivers, show excellent agreement. The Pearson’s correlation coefficient for the DIAL and radiosondes is consistently greater than 0.6 from 300 m up to 4.5 km AGL at night and up to 3.5 km AGL during the day. The Pearson’s correlation coefficient for the DIAL and AERI is greater than 0.6 from 300 m up to 2.25 km at night and from 300 m up to 2.0 km during the day. Further comparison with the continuously operating GPS instrumentation illustrates consistent temporal trends when integrating the DIAL measurements up to 6 km AGL.
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Maguire, Paul, and Harold McQuaid. "(Invited) Low Temperature Plasma Electrochemistry with Microscopic Liquid Droplets in Flight." ECS Meeting Abstracts MA2020-01, no. 17 (May 1, 2020): 1105. http://dx.doi.org/10.1149/ma2020-01171105mtgabs.
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When microscopic-sized liquid droplets travel through a low temperature RF plasma [1] at atmospheric pressure a number of remarkable and unexpected effects have been observed. After a short flight time, ~0.1ms, there is evidence that chemical reactions induced by the plasma and gas flux proceed at a rate that is significantly faster that observed in plasma – bulk liquid studies and many orders of magnitude faster than in standard bulk chemistry.[2] We suspect this is due to the complex interplay between droplet charge, electric fields, both internal and external to the droplet, and high chemical fluxes arriving at the droplet surface. There exists a large potential to develop new plasma-liquid processes for medical, chemical, biological, environmental and materials applications, among others and we can highlight some unique features of the plasma – microdroplet system that may provide opportunities for exploitation, namely: (i) a controlled ambient environment, (ii) a large surface area to volume ratio, (iii) small volume, (iv) low droplet temperature, (v) in-flight chemical synthesis and encapsulation, and (iv) remote delivery. These features offer the possibility of delivering high fluxes of active chemical species and nanoparticles remotely and on demand for applications in, for example, plasma-medicine, agriculture and microreaction while keeping the plasma itself at a safe distance. We have measured reactive oxygen species (ROS) flux variation with distance, up to 150 mm beyond the plasma, along with its effect on bacterial cell viability, DNA and amino acids. We have investigated plasma interactions with single cells, each transported in its own droplet. We have used the individual droplets as chemical microreactors to produce nanoparticles in flight, at rates many orders of magnitude higher that via high energy radiolysis or chemical synthesis. These measurements form the basis for numerical simulation in the gas-plasma and liquid droplet phases. New measurement techniques, based on recently acquired facilities, are being investigated. These include mid-IR absorption studies of droplets and their environment in flight, using tunable supercontinuum and quantum cascade lasers, and freezing plasma-treated droplets in flight for in-situ transfer to XPS surface chemical analysis. Current theories of microparticle charging in a collisional plasma environment are very limited. While in-flight charge measurements represent a significant challenge, the relatively large size of the droplet (10 – 20 μm diameter) and the limited evaporation over the flight time, offer the prospect of using droplets as a spherical probe to develop enhanced collisional probe theories in the regime where the particle size is greater than Debye lengths or mean free paths. In-flight measurements indicate a minimum net charge of 105 electrons, considerably higher than that obtained by other charging methods. Analytical – numerical and finite element simulations, in tandem with charge measurements, are being developed to better understand the droplet electrical environment and ultimately to link chemistry and charge in a consistent framework. References [1] PD Maguire et al., Appl. Phys. Lett. 106, 224101 (2015); http://dx.doi.org/10.1063/1.4922034 [2] PD Maguire et al., Nano Lett., 17, 1336–1343 (2017) http://dx.doi.org/10.1021/acs.nanolett.6b03440 Figure 1
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Yue, Wenjie, Tao Chen, Wei Kong, Xin Chen, Genghua Huang, and Rong Shu. "Eye-Safe Aerosol and Cloud Lidar Based on Free-Space Intracavity Upconversion Detection." Remote Sensing 14, no. 12 (June 19, 2022): 2934. http://dx.doi.org/10.3390/rs14122934.
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We report an eye-safe aerosol and cloud lidar with an Erbium-doped fiber laser (EDFL) and a free-space intracavity upconversion detector as the transmitter and receiver, respectively. The EDFL was home-made, which could produce linearly-polarized pulses at a repetition rate of 15 kHz with pulse energies of ~70 μJ and pulse durations of ~7 ns centered at 1550 nm. The echo photons were upconverted to ~631 nm via the sum frequency generation process in a bow-tie cavity, where a Nd:YVO4 and a PPLN crystal served as the pump and nonlinear frequency conversion devices, respectively. The upconverted visible photons were recorded by a photomultiplier tube and their timestamps were registered by a customized time-to-digital converter for distance-resolved measurement. Reflected signals peaked at ~6.8 km from a hard target were measured with a distance resolution of 0.6 m for an integral duration of 10 s. Atmospheric backscattered signals, with a range of ~6 km, were also detectable for longer integral durations. The evolution of aerosols and clouds were recorded by this lidar in a preliminary experiment with a continuous measuring time of over 18 h. Clear boundary and fine structures of clouds were identified with a spatial resolution of 9.6 m during the measurement, showing its great potential for practical aerosol and cloud monitoring.
Dissertations / Theses on the topic "Eye-safe; lasers; atmospheric measurements"
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Heintze, Matthew Carl. "Development and testing of an Er:Yb:glass coherent laser radar for wind field mapping." Thesis, 2010. http://hdl.handle.net/2440/63479.
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Doppler or coherent laser radars (CLR’s) can measure range-resolved velocities of distant hard and diffuse targets. Critical applications include wind shear and wake vortex detection, clear air turbulence warning, wind field mapping, and pollution dispersion monitoring. To monitor these at different geographic locations in the atmosphere in real time requires a system with high temporal resolution. A laser transmitter that provides eye-safe, transform-limited energetic pulses with good beam quality and a sensitive transceiver is suitable for such applications.
In this thesis I describe the development of an eye-safe coherent laser radar that has a range resolution of 75 m with single-shot velocity resolution of ∼1.5 ms⁻¹. I also present measurements of atmospheric wind speeds using this laser.
The laser source is a travelling-wave oscillator that uses a conduction-cooled, Coplanar Pumped Folded Slab (CPFS) with an Er:Yb:phosphate glass gain medium that is side pumped using fast-axis collimated laser diodes. The laser uses polarisation-controlled outcoupling and is injection-seeded to produce eye-safe, transform-limited long duration Q-switched pulses at a frequency close to that of the master laser. This thesis describes the complete characterisation and development of that laser.
It also describes the design and development of the monostatic heterodyne receiver used to detect backscattered returns from targets. Measurements validating the performance of the CLR using stationary and moving hard targets are reported. The thesis also presents initial measurements of atmospheric wind speeds using the CLR. Reproducible range-resolved single-pulse measurements to ≥2 km are reported and compared to results from a boundary layer radar.Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2010
Conference papers on the topic "Eye-safe; lasers; atmospheric measurements"
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Pierrard, Philippe, Jerome Prieur, J. L. Gaumet, J. C. Heinrich, and M. Cluzeau. "Atmospheric extinction coefficient and cloud base height determination by using a single-pulse eye-safe lidar." In Air Pollution and Visibility Measurements. SPIE, 1995. http://dx.doi.org/10.1117/12.221055.
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Harrell-Klein, Sarah, William E. Wilcox, Dennis K. Killinger, Glen A. Rines, and Richard A. Schwarz. "High-power eye-safe 1.57-um optical parametric oscillator (OPO) lidar for atmospheric boundary-layer measurements." In Optical Sensing for Environmental and Process Monitoring, edited by Joseph Leonelli, Dennis K. Killinger, William Vaughan, and Michael G. Yost. SPIE, 1995. http://dx.doi.org/10.1117/12.205578.
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Sangl, J., C. Mayer, and T. Sattelmayer. "Dynamic Adaptation of Aerodynamic Flame Stabilization of a Premix Swirl Burner to Fuel Reactivity Using Fuel Momentum." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22340.
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Due to the expected increase in available fuel gas variants in the future and the interest in independence from a specific fuel, fuel flexible combustion systems are required for future gas turbine applications. Changing the fuel used for lean premixed combustion can lead to serious reliability problems in gas turbine engines caused by the different physical and chemical properties of these gases. A new innovative approach to reach efficient, safe and low-emissions operation for fuels like natural gas, syntheses gas and hydrogen with the same burner is presented in this paper. The basic idea is to use the additionally available fuel momentum of highly reactive gases stemming from their lower Wobbe index (lower volumetric heating value and density) compared to lowly reactive fuels. Using fuel momentum opens the opportunity to influence the vortex dynamics of swirl burners designed for lowly reactive gases in a favorable way for proper flame stabilization of highly reactive fuels without changing the hardware geometry. The investigations presented in the paper cover the development of the optimum basic aerodynamics of the burner and the determination of the potential of the fuel momentum in water channel experiments using particle image velocimetry (PIV). The results show that a proper usage of the fuel momentum has enough potential to adjust the flow field to the different fuels and their corresponding flame behavior. As the main challenge is to reach flashback safe fuel flexible burner operation, the main focus of the study lies on avoiding combustion induced vortex breakdown (CIVB). The mixing quality of the resulting injection strategy is determined applying laser induced fluorescence (LIF) in water channel tests. Additional OH* chemiluminescence and flashback measurements in an atmospheric combustion test rig confirm the water channel results for CH4, CH4/H2 mixtures, H2 with N2 dilution and pure H2 combustion. They also indicate a large operating window between flashback and lean blow out and show expected NOx emission levels. In summary, it is shown for a conical four slot swirl generator geometry that the proposed concept of using the fuel momentum for tuning of the vortex dynamics allows aerodynamic flame stabilization for different fuels in the same burner.