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This PDF file contains the front matter associated with SPIE Proceedings Volume 10779, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.
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Atmospheric water vapor and carbon dioxide are important greenhouse gases that significantly contribute to the global radiation budget on Earth. A 2-micron triple-pulse, Integrated Path Differential Absorption (IPDA) lidar instrument for ground and airborne atmospheric carbon dioxide and water vapor concentration measurements using direct detection was developed at NASA Langley Research Center. This active remote sensing instrument provides an alternate approach with significant advantages for measuring atmospheric concentrations of the gases. A high energy pulsed laser transmitter approach coupled with sensitive receiver detection provides a high-precision measurement capability by having a high signal-to-noise ratio. This paper presents the concept, development, integration and testing of the 2-micron triple-pulse IPDA. The integration includes the various IPDA transmitter, receiver and data acquisition subsystems and components. Ground and airborne testing indicated successful operation of the IPDA lidar.
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Most of space-based observing systems make water-vapor- and temperature-related measurements, while spacebased observing systems for wind measurement is limited. The current passive space-based observing systems for wind measurement has a large coverage area and high temporal and horizontal resolutions but has a low vertical resolution. The World Meteorological Organization (WMO) wants to develop space-based wind profiling systems. A Doppler Wind Lidar (DWL) is a useful and power technology for wind measurement and it can be designed as compact mobile, airborne, and space-based systems. DWL would provide us with a wind profile having high vertical resolution, low bias, and good precision, and it is necessary to fill the gap of current observations. The National Institute of Information and Communications Technology (NICT) is developing a single-frequency high-energy Tm,Ho:YLF laser, 2-μm key technology and instrument for a future space-based coherent DWL. We demonstrated the Tm,Ho:YLF laser producing a pulse energy of 125 mJ operating at 30 Hz meeting requirements for the future spacebased coherent DWL. In the paper, we will describe recent progress at NICT.
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Integrated path differential absorption (IPDA) lidar is an active remote sensing technique for monitoring different atmospheric species. The technique relies on wavelength differentiation between strong and weak absorbing features normalized to the transmitted energy. An advanced 2-μm triple-pulse IPDA lidar was developed at NASA Langley Research Center for active sensing of carbon dioxide and water vapor simultaneously. The IPDA transmitter produces three successive laser pulses separated by a short interval (200 μs) with a repetition rate of 50Hz. Measurement of laser pulse energy accurately is a prerequisite for the retrieval of gas mixing ratios from IPDA. Due to the short interval between the three transmitted pulses, conventional thermal energy monitors underestimate the total transmitted energy. The design and calibration of a 2-μm triple-pulse laser energy monitor are presented. The design is based on a high speed, extended range InGaAs pin quantum detector suitable for separating the three pulse events. Pulse integration is applied for converting the detected pulse power into energy. The results obtained from the laser energy monitor were compared to an ultra-fast energy-meter reference for energy scaling and verification. High correlations between the pin energy monitor and the total transmitted energy were obtained. The objective of this development is to reduce measurement biases and errors using the triple-pulse IPDA technique.
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NASA Goddard’s CO2 Sounder is a pulsed, multiple-wavelength, IPDA-lidar. It was flown onboard the NASA DC-8 to measure atmospheric CO2 column concentrations (XCO2) in the lower stratosphere and troposphere of the Arctic region of North America as part of the 2017 ASCENDS airborne campaign. Eight flights covering 40,000 km were flown in late July and August over Alaska and Canada’s Northwest Territories, including a northern transit east of the Rockies and a return transit partly over the ocean between Alaska and California. The Arctic flights were coordinated with the 2017 Arctic-Boreal Vulnerability Experiment (ABoVE) campaign. The metrological conditions were challenging: a non-uniform CO2 distribution, a dynamic atmosphere and varied surface-reflectivity. To assess the accuracy of our lidar the aircraft’s scientific payload included the AVOCET and Picarro instruments. These two instruments measured in-situ XCO2 during the flights and column XCO2 from 47 separate descent spirals from ~12 km altitude to near ground at local airfields distributed throughout the measurement region. Each spiral maneuver allows a direct comparison between the retrievals of XCO2 from the lidar against those computed from insitu instruments. The CO2 Sounder worked very well during all phases of the campaign. Analysis to date shows the lidar measured column concentrations are in close agreement with in-situ column measurements with a precision of better than 0.8 ppm with 1 second averaging. In addition, preliminary analyses of measurements to the ubiquitous cloud tops also produced column concentrations and information on the vertical XCO2 structure.
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A long-lived UV laser is an enabling technology for several high-priority, space-based lidar instruments. These include a next generation cloud and aerosol lidar that incorporates a UV channel, a direct detection 3-D wind lidar, and an ozone differential absorption lidar (DIAL) system. To advance the TRL of UV lasers we have designed and built a High Energy UV Demonstrator (HEUVD) that has increased output power and space-qualifiable packaging and that is mechanically robust, thermally-stable, and fully conductively cooled. Contamination control processes and optical coatings have been chosen that are compatible with multi-billion shot lifetimes. The diode pumped laser contains an essentially polymer free internal module that houses the third harmonic generator and beam expansion optics. When operated at 150 Hz the laser has demonstrated 275 mJ per pulse at 1064 nm, second harmonic conversion efficiencies of 70%, and third harmonic conversion efficiencies of 45%, thus meeting the 355 nm 100 mJ/pulse goal with margin. We have successfully completed a full power 532 nm life test, a half power (50 mJ/pulse) UV lifetest, and a full power (100 mJ/pulse @ 150 Hz) lifetest. These tests have validated the importance and success of our approach to contamination control for achieving a long-lived UV laser. They also resurfaced the need for the qualification of the pump laser diodes and more attention to the external optics in a UV lidar system.
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Attainment of National Ambient Air Quality Standard-NAAQS for exposure limits to air pollutants is of great concern to State and Local agencies and communities in the United State because of potential health impacts. This is particularly important and challenging in urban areas because of high population densities and complex terrain. Exceedances of NAAQS requires states to develop implementation plans to address them and as such, studying the horizontal and vertical distribution and mixing of pollutants is key to understanding their transport and evolution. In this study, vertical and scanning horizontal lidar measurements together with in situ observations from particulate matter and trace gas analyzers from state air quality networks are used to shed light on mechanisms that impact movement of aerosol, including emissions from power generating stations at periods of high electricity demand.
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NASA’s Goddard Space Flight Center (GSFC) transported two lidar instruments to the NOAA facility at the Mauna Loa Observatory (MLO) on the Big Island of Hawaii, to participate in an official, extended validation campaign. This site is situated 11,141 ft. above sea level on the side of the mountain. The observatory has been making atmospheric measurements regularly since the 1950’s, and has hosted the GSFC Stratospheric Ozone (STROZ) Lidar and the GSFC Aerosol and Temperature (AT) Lidar on several occasions, most recently between November, 2012 and November, 2015. The purpose of this extended deployment was to participate in Network for the Detection of Atmospheric Composition Change (NDACC) Validation campaigns with the JPL Stratospheric Ozone Lidar and the NOAA Temperature, Aerosol and Water Vapor instruments as part of the routine NDACC Validation Protocol.
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The influence of aerosols to the atmosphere has been discussed in the context of the Earth radiation budget and global climate change. Therefore, precise monitoring of aerosol parameters is important for better understanding of their real characteristics and impacts on the environment. In this study, we report on a novel method of concurrent measurements of aerosol near the surface level by means of slant-path (SP) and plan position indicator (PPI) lidars. The SP lidar utilizes a diode-laser-pumped Nd:YAG laser operating at 532 nm, while the PPI is based on a Nd:YLF laser at 349 nm. The PPI system including the laser transmitter and telescope section is rotated over 360° for covering all the horizontal directions with the maximum observation range up to around 3 km. At the same time, the SP lidar is employed for monitoring the near surface region that cannot be covered by vertical observation lidars. Furthermore, the backscattered signals recorded by both PPI and SP lidars are analyzed using the Fernald method to retrieve aerosol extinction coefficient by employing lidar ratios for 349 and 532 nm. These values of lidar ratio are estimated by adjusting and fitting parameters in the Mie scattering calculation (mode radius, variance, and both real and imaginary parts of refractive index) to real data from ground-based sampling instruments, namely, the scattering coefficient, absorption coefficient, and size distribution observed with an integrating nephelometer, an aethalometer, and an optical particle counter, respectively. Real-time values of the extinction coefficient inside the atmospheric boundary-layer are derived as the summation of scattering and absorption coefficients. The results are then compared with those from a vertical lidar, operated by the National Institute of Environmental Studies (NIES) on the campus of Chiba University. We discuss the observed features of aerosol characteristics that vary both temporally and spatially.
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Active stand-off detection and hard-target lidars are common methodologies for gas identification, chemical emission tracing, hazardous material sensing, or explosive detection to name a few. By their nature, this type of instrument heavily relies on the reflectivity or backscattering properties of distant targets. While some applications allow the use of retroreflectors, most mobile systems require the use of actual topographic targets, such as the ground, roads, buildings, roofs, or vegetation. In this work, N2O path-averaged mixing ratios are measured with the 10 Hz frequency using a quantum cascade laser open path system operating at 7.7 μm wavelength. Measurements are performed by detecting the light backscattered from common topographic targets located 5.5 m away from the instrument. For each topographic target, the detection limit and accuracy of the retrieved mixing ratios are presented and discussed showing detection limits between 0.008 and 1.36 ppm depending on the target and mixing ratio relative errors between 4 and 80 %.
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We have developed a multiwavelength Scanning Standoff Time-Resolved Raman spectroscopy (S2TR2S)
system to detect minerals and chemicals from a long distance (10-100 m) over a large area. The
multiwavelength SSTRRS system uses 532 and 785 nm pulsed lasers and two separate 5x beam expanders to
excite spontaneous Raman spectra of the chemicals with 10 mm diameter laser beams. The VIS-NIR system
employs a common Meade telescope (F/10, aperture 20.3 cm). In order to improve detection efficiency, the
light collected by the telescope is directly coupled into two f/1.8 transmission spectrograph covering the VIS
and NIR spectral regions by changing the volume Holographic Raman gratings for 532 and 785 nm laser lines,
respectively. The spectrograph is equipped with a gated intensified CCD camera and edge filters are used to
reject the reflected and Rayleigh scattered laser light. The S2TR2S system is operated using pan-tilt pointing
capability for precise measurements of selected distant points (under computer control). By making standoff
Raman measurements over a predefined grid array, a large area can be sampled and Raman composition maps
are constructed off the distant target area. This mapping capability of the instruments has been used to identify a
wide variety of minerals and hazardous chemicals from their Raman fingerprints and Raman images. The use of
pulsed laser and gated detection allow the measurement of the Raman spectra of minerals with minimum
interference from photoluminescence from transition metal ions and rare-earths ions, and ambient light.
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Water vapor and temperature spatial distribution and their temporal evolution are among the most important parameters in numerical weather forecasting and climate models. The operational relative humidity/temperature profiling in meteorology is carried out mostly by radio sondes. Sondes provide profiles with high vertical resolution but suffer from systematic errors and low temporal resolution. The temporal resolution is also a limitation for the now-casting, which has become more and more important for meteorological alerts and for the aviation. Recently, some of national meteorological services have introduced Raman lidars for additional operational humidity/temperature profiling. The lidars allow monitoring of water vapor mixing ratio and temperature with high vertical and temporal resolutions. Here the design and measurement results from the Raman Lidar for Meteorological Observation (RALMO) developed by the Ecole Polytechnique Féderal de Lausanne (EPFL) and operated by MeteoSwiss is presented as an illustration of the potential of Raman lidars in operational meteorology. The first applications of lidar data in numerical weather forecasting is also discussed.
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The “Standoff Biofinder” is a powerful “search for life” instrument that is able to detect biomolecules from a collection of rocks and minerals in a large area with detection time less than a second using a non-contact, non-destructive approach. Biological materials show strong, short-lived fluorescence signals when excited with ultraviolet-visible (UVVis) wavelengths. The Standoff Biofinder takes advantage of the short lifetimes of bio-fluorescent materials to obtain real-time images showing the locations of biological materials among luminescent minerals in a geological context. The Standoff Biofinder uses an expanded and diffused nanosecond pulsed laser to illuminate a large geological region and a gated detector to record time-resolved fluorescence images. The instrument works in daylight as well as nighttime conditions and bio-detection capability is not affected by the background light. The instrument is able to detect both live and dead biological materials, and is a useful tool for detecting the presence of both extant and extinct life on a planetary surface. The Standoff Biofinder instrument will be suitable for locating fluorescent polyaromatic hydrocarbons, amino acids, proteins, bacteria, biominerals, photosynthetic pigments, and diagenetic products of microbial life on dry landscapes and Ocean Worlds of the outer Solar System (e.g., Enceladus, Europa, and Titan). An important feature of the Standoff Biofinder instrument is its capability to detect biomolecules which are inside ice, without sample collection.
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Amino acids and nucleobases are of particular interest to NASA’s science goal of “Search for life” because they are essential for life as the basic constituents of proteins and deoxyribonucleic acids (DNA). Their detection would point to possible biosignatures and potential life bearing processes and thus there is a need for technologies capable of identifying them. Raman spectroscopy provides univocal and accurate chemical characterization of organic and inorganic compounds and can be used to detect biological materials and biomarkers in the context of planetary exploration. While micro-Raman systems are useful, a remote Raman instrument can increase the analysis area around a rover or lander. At the University of Hawai‘i we developed a portable, compact time-resolved remote-Raman instrument using a small 3” diameter mirror lens telescope, and used it to demonstrate daytime detection of amino acids and nucleobases from a distance of 8 m. The measured spectra allowed us to univocally identify 20 proteinogenic amino acids, four nucleobases, and some non-proteinogenic amino acids, despite the presence of native fluorescence, especially in aromatic compounds. We were also able to distinguish between α and β amino acids, as well as between different polymorphs. We found the remote Raman system is well suited for planetary exploration applications, with no requirement for sample preparation or collection, and rapid measurement times.
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A spatial heterodyne Raman spectrometer (SHRS) is a variant of a Michelson interferometer where the mirrors in a Michelson are replaced with stationary diffraction gratings. Instead of generating an interferogram in the time domain, as in the case of a Michelson interferometer, the SHRS interferogram is generated in the spatial domain as a superposition of two-dimensional cosinusoidal spatial fringes. The spatial interferogram is recorded by an intensified charge-coupled device (ICCD) camera, and the Raman spectrum is recovered by taking the Fourier transform of the spatial interferogram. In the modified SHRS utilized in the present work, a λ/10 mirror has replaced one of the diffraction gratings. This alteration has a few effects. First, the ICCD records a greater number of photons because photons are not lost into unused diffraction orders. Second, the spectral bandpass of the modified SHRS has been doubled allowing the measurement of Raman spectra from 100-4000 cm-1. In this work, the authors present Raman spectra of organic compounds taken at remote distances of 19 meters with this modified SHRS.
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It is commonly said that the global environment structure is formed from the atmosphere, hydrosphere, geosphere, and biosphere, which are natural environment systems. In addition to this, we add another system “livingsphere” which is an artificial system, but holds strong relations between the daily lives of humans and the natural systems. It would then be appropriate to consider the global environment structure with the idea that natural systems and the artificial one are interconnected. We propose using fluorescence as a common parameter to understand the interconnection. Since a large variety of substances exhibit their own unique auto-fluorescence spectrum more or less if they are irradiated by light, they are good targets for fluorescence lidars. Lidar observation results about substances moving freely among the systems might offer information about the interconnection of each type of environment system. In this presentation, we show several experiments done using the fluorescence lidar we have developed for observing aerosol in the atmosphere, lake/river water quality in the hydrosphere, vegetation growth status in the biosphere, and pre-observing ground surface substances in the geosphere and waste substances of daily necessities in the livingsphere. We also describe a fluorescence database which is an EEM (Excitation-Emission-Matrix) of substances found elsewhere in the systems, and discuss an adaptation of the database to the atmospheric aerosols observation done by the fluorescence lidar.
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Mosquito-borne diseases are a major challenge for Human health as they affect nearly 700 million people every year. Monitoring insects is generally done through trapping methods that are tedious to set up, costly and present scientific biases. Entomological lidars are a potential solution to remotely count and identify mosquito species and gender in realtime. In this contribution, a dual-wavelength polarization sensitive lidar is used in laboratory conditions to retrieve the wingbeat frequency as well as optical properties of flying mosquitoes transiting through the laser beam. From the lidar signals, predictive variables are retrieved and used in a Bayesian classification. This paper focuses on determining the relative importance of the predictive variables used in the classification. Results show a strong dominance of the wingbeat frequency, the impact of predictive variables based on depolarization and backscattering ratios are discussed, showing a significant increase in classification accuracy.
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The 2016 Kumamoto earthquake was a series of earthquake events, including the moment-magnitude (Mw) 7.0 mainshock on April 16, 2016 and the Mw 6.2 foreshock on April 14. Due to the strong shaking, more than 8,000 buildings were collapsed and about 30,000 buildings were severely damaged. Geospatial Information Authority of Japan (GSI) acquired high density (5.93 point/m2 ) Lidar data on May 8, 2016, three weeks after the earthquakes. In this study, the pre- and postevent Lidar data were used to detect the collapsed buildings in Mashiki town, Kumamoto Prefecture, Japan, which was one of the most severely affected regions. The pre-event Lidar data were taken on May 15, 2006 with the 0.72 point/m2 density. A report of building damage grades obtained by the field surveys of the Architectural Institute of Japan (AIJ) was introduced as the reference. First, the statistics of height differences within each building outline were calculated. Then the characteristics of the different damage grades were investigated. As a result, the average values of the height differences were adopted to extract collapsed buildings. 618 buildings were extracted as collapsed from 3,408 buildings existed in 2006. Comparing with the reference, 91% collapsed buildings were detected successfully, and the F-score was 0.88.
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With recent advancements in unmanned aircraft system (UAS) technology, along with the miniaturization of airborne laser scanning systems, capabilities of unmanned laser scanning (ULS) systems have increased. Traditional terrestrial laser scanning surveys provide high density point clouds (hundreds - thousands of pts/m2) of a focus area, but have limited field-of-view and line-of-sight due to the constrained static nature of the system. While airborne and mobile laser scanning platforms relieve many of these limitations, lower point density (airborne), confined operation pathways (mobile), and higher operational costs become a factor. Here we present results from ULS data acquired over the Hilo Deep Draft Harbor Breakwater in Hawaii in June 2018. Inspecting the breakwater for failures and instabilities is of vital importance for Hilo. At three kilometers length and exposure to open ocean, a terrestrial laser scanning survey of the breakwater is not possible. Airborne and mobile laser scanning are not ideal due to reduced point densities and site access, respectively. In June 2018, using a RIEGL RiCOPTER with VUX laser system, the authors collected highresolution data over the above water breakwater extents. For below water surfaces, a Riegl BDF-1 bathymetric depth finder was operated from the same UAS, used to generate profiles of subaqueous surfaces of the breakwater. These bathymetric transects supplement the detailed topographic data collected above water on the breakwater. We discuss the operational concerns in both project planning and acquisition phases, as well as detailed analysis of the resulting data, used for a rigorous structure inspection program.
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Light Detection And Ranging (LiDAR) is an important branch of remote sensing (RS) technology, and its hardware and software in practical applications are getting more and more mature. Now, it is time for the community to think about its future, and a potential way of further pushing forward LiDAR RS technical progress, no doubt, is to develop its nextgeneration systems and approaches. Hyperspectral LiDAR is such a representative case, which, theoretically, is designed to synchronously collect the spectral and range information of objects. This advantage can inherently handle the errors caused when fusing those corresponding hypespectral images and point clouds in the traditional routines of 4D mapping, and hence, has attracted numerous attention on developing its prototype systems. With the performance enhancements of such prototype systems, more efforts need to be deployed onto pushing these prototypes to practical applications. In the case of the hyperspectral LiDAR prototype system developed by the Finnish Geospatial Research Institute, this study examined its applicability for investigating the intraday 3D variations of tree biophysics and biochemistry. The collected point clouds proved to be able to characterize the biophysical variation of trees in terms of laser point-represented tree geometrical centre. For the aspect of biochemical characterization, the hyperspectral LiDAR was validated through the retrievals of the 3D distributions of the fractions of photosynthetically active radiation (FAPARs), crown chlorophyll concentrations, and crown nitrogen concentrations, and the intraday biochemical variations were characterized by their day-and-night differences. The tests showed that hyperspectral LiDAR will be a kind of technology of high potentials for mapping biophysics and biochemistry and their dynamics.
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During intense spring and early summer storms, substantial volumes of dust from east Asian desert regions are lofted over the continent and transported by prevailing winds across the Pacific Ocean. The phenomenon has wide reaching effects including long range nutrient and sediment transport as well as radiative forcing. Mauna Loa Observatory (MLO) is an atmospheric baseline station in Hawaii at an altitude of 3397-m.a.s.l.. MLO’s CCD Camera Lidar (CLidar) has fine near-ground altitude resolution, which makes it a useful system for Asian dust detection, especially at high altitude sites such as MLO. A 20-Watt, 532-nm Nd:YAG laser was vertically transmitted into the atmosphere above MLO. The side-scatter from atmospheric constituents, such as clouds, aerosols, and air molecules was detected by a wide-angle CCD camera situated 139-m from the laser. The obtained signal was range-normalized using a molecular scattering model and corrected for transmission with a column-averaged aerosol phase function derived from MLO-based AERONET photometer measurements. In several of the resulting aerosol extinction profiles, notable aerosol layers were observed near altitude ranges in which Asian dust is typically transported by prevailing winds. Corresponding relative humidity measurements made by nearby radiosondes were examined to differentiate aerosol scattering from cloud scattering. To further examine layers exhibiting both aerosol extinction peaks and relative humidity levels below that of tenuous ice clouds, back trajectories were conducted using NOAA’s Hybrid Single Particle Lagrangian Integrated Trajectory model. Several layers from 2008 and 2009 were traced back to East Asian deserts.
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The realization of three-dimensional global wind profile measurements provides significant benefits, such as improvement in the precision of numerical weather forecasts and understanding of the causes of climate change. A spaceborne coherent Doppler wind lidar is considered to be the most powerful instrument for providing accurate tropospheric wind profiles with high spatial and temporal resolutions. Conductively cooled techniques are also important for spaceborne lidar applications because they have several advantages over liquid cooling systems. The National Institute of Information and Communications Technology (NICT) is conducting feasibility studies of conductively cooled, Q-switched 2 μm Tm,Ho:YLF lasers to meet a requirement for a spaceborne CDWL. In recent years, the energy extraction efficiency from Tm,Ho:YLF lasers has been improved dramatically by reviewing the laser rod parameters and the resonator design. In this study, we report on a single-frequency, Q-switched Tm,Ho:YLF master oscillator power amplifier (MOPA), which meets the specifications of a spaceborne CDWL transmitter. The MOPA consists of a 3.86-mlong ring oscillator and a single-pass amplifier. For the single-pass amplification, an average output power of 3.95 W, which corresponds to a pulse energy of 131.7 mJ, was obtained at a pulse repetition frequency of 30 Hz and a cooling temperature of -40°C.
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Most airborne LiDAR point cloud filter algorithms are low-precision, ineffective and low-robust in mountain region. In order to improve the precision, efficiency and robustness in this region, a normalization CSF- modified algorithm presented in this paper based on CSF (Cloth Simulation Filtering). This algorithm has high precision and robustness in a wide range of complex scenes. In the first place, the pretreatment of point cloud reject gross error. Then, establish a grid index by grid and use the lowest point of each grid mesh surface equation. Thirdly, calculate the distance between raw point cloud and fitting surface, getting normalized point cloud. Finally use CSF algorithm to simulate filtering process, getting the final shape of cloth and filtering result obtained by the shape of cloth and limit of threshold. Use a big campus area to verify the algorithm, the result shows that the algorithm can effectively correct the top information of mountains removed by CSF algorithm and improve the accuracy and robustness of point cloud filtering.
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In the southern South America, various types of aerosols have been observed including biomass burning aerosols from the Amazon region, flying ashes from the volcanic eruptions coming from the Andean Volcanic Belt, mineral dust from the Patagonian Desert, and air pollution aerosols from urban areas. To monitor such aerosols continuously, we developed a lidar observation network in Argentina and Chile. Eight lidars were installed in Argentina and one in Punta Arenas, Chile. Backscattering signals are measured at three wavelengths: 355, 532, and 1064 nm. Eight of those instruments are measuring depolarization ratio at 355 and 532 nm to detect non-spherical aerosols. In addition, four lidars are equipped Ramans channels and two high-spectral-resolution channels to measure backscattering and extinction coefficients quantitatively. Lidar operation, data analysis, and products release are implemented within the South American Environmental Risk Management Network (SAVER-Net) system, which was developed by a trinational project among Japan, Argentina, and Chile. Using lidar data, hazard information on the aerosol type and extinction coefficient at low altitude is provided for public in a near real time. In addition, plume height and qualitatively concentration for volcanic ashes are estimated. The information on volcanic ashes may be effectively used for advising aircraft landing and departing when volcanic eruptions occurs.
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Publisher’s Note: This paper, originally published on 24 October 2018, was replaced with a corrected/revised version on 10 July 2019. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance.
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