Airborne Measurements of Atmospheric Pressure made Using an IPDA Lidar Operating in the Oxygen A-Band

Science.gov (United States)

Riris, Haris; Abshire, James B.; Stephen, Mark; Rodriquez, Michael; Allan, Graham; Hasselbrack, William; Mao, Jianping

2012-01-01

We report airborne measurements of atmospheric pressure made using an integrated path differential absorption (IPDA) lidar that operates in the oxygen A-band near 765 nm. Remote measurements of atmospheric temperature and pressure are needed for NASA s Active Sensing of CO2 Emissions Over Nights, Days, and Seasons (ASCENDS) mission to measure atmospheric CO2. Accurate measurements of tropospheric CO2 on a global scale are very important in order to better understand its sources and sinks and to improve our predictions of climate change. The goal of ASCENDS is to determine the CO2 dry mixing ratio with lidar measurements from space at a level of 1 ppm. Analysis to date shows that with current weather models, measurements of both the CO2 column density and the column density of dry air are needed. Since O2 is a stable molecule that uniformly mixed in the atmosphere, measuring O2 absorption in the atmosphere can be used to infer the dry air density. We have developed an airborne (IPDA) lidar for Oxygen, with support from the NASA ESTO IIP program. Our lidar uses DFB-based seed laser diodes, a pulsed modulator, a fiber laser amplifier, and a non-linear crystal to generate wavelength tunable 765 nm laser pulses with a few uJ/pulse energy. The laser pulse rate is 10 KHz, and average transmitted laser power is 20 mW. Our lidar steps laser pulses across a selected line O2 doublet near 764.7 nm in the Oxygen A-band. The direct detection lidar receiver uses a 20 cm diameter telescope, a Si APD detector in Geiger mode, and a multi-channel scalar to detect and record the time resolved laser backscatter in 40 separate wavelength channels. Subsequent analysis is used to estimate the transmission line shape of the doublet for the laser pulses reflected from the ground. Ground based data analysis allows averaging from 1 to 60 seconds to increase SNR in the transmission line shape of the doublet. Our retrieval algorithm fits the expected O2 lineshapes against the measurements and

Demonstration of a diode-laser-based high spectral resolution lidar (HSRL) for quantitative profiling of clouds and aerosols.

Science.gov (United States)

Hayman, Matthew; Spuler, Scott

2017-11-27

We present a demonstration of a diode-laser-based high spectral resolution lidar. It is capable of performing calibrated retrievals of aerosol and cloud optical properties at a 150 m range resolution with less than 1 minute integration time over an approximate range of 12 km during day and night. This instrument operates at 780 nm, a wavelength that is well established for reliable semiconductor lasers and detectors, and was chosen because it corresponds to the D2 rubidium absorption line. A heated vapor reference cell of isotopic rubidium 87 is used as an effective and reliable aerosol signal blocking filter in the instrument. In principle, the diode-laser-based high spectral resolution lidar can be made cost competitive with elastic backscatter lidar systems, yet delivers a significant improvement in data quality through direct retrieval of quantitative optical properties of clouds and aerosols.

Wavelength stabilized high pulse power laser diodes for automotive LiDAR

Science.gov (United States)

Knigge, A.; Klehr, A.; Wenzel, H.; Zeghuzi, A.; Fricke, J.; Maaßdorf, A.; Liero, A.; Tränkle, G.

2018-03-01

Diode lasers generating optical pulses with high peak power and lengths in the nanosecond range are key components of systems for free-space communication, metrology, material processing, spectroscopy, and light detection and ranging (LiDAR) as needed for object detection and autonomous driving. Automotive LiDAR systems demand additionally a good beam quality and low wavelength shift with temperature due to the wide operating temperature span. We present here internally wavelength stabilized lasers emitting ns optical pulses from an emission aperture between 30 μm and 100 μm with peak powers of tens of Watts at wavelengths around 905 nm. The vertical structure based on AlGaAs (confinement and cladding layers) and InGaAs (active quantum well) is especially optimized for pulsed operation with respect to the implementation of a surface Bragg grating with a high reflectivity. The fabricated 6 mm long distributed Bragg reflector (DBR) broad area (BA) lasers are electrically driven by an in-house developed high-speed unit generating 3 to 10 ns long nearly rectangular shaped current pulses with amplitudes of up to 250 A. Such lasers emit optical pulses with a peak power of more than 30 W at 95 A pulse current up to a temperature of 85°C with a wavelength shift as low as 65 pm/K and a lateral beam propagation factor less than 10. The influence of the lateral aperture width and the pulse length on the beam quality will be shown. A monolithic integration of 3 DBR BA lasers on a single chip whose emission can be combined into a single beam raises the output power to more than 100 W.

Simulated full-waveform lidar compared to Riegl VZ-400 terrestrial laser scans

Science.gov (United States)

Kim, Angela M.; Olsen, Richard C.; Béland, Martin

2016-05-01

A 3-D Monte Carlo ray-tracing simulation of LiDAR propagation models the reflection, transmission and ab- sorption interactions of laser energy with materials in a simulated scene. In this presentation, a model scene consisting of a single Victorian Boxwood (Pittosporum undulatum) tree is generated by the high-fidelity tree voxel model VoxLAD using high-spatial resolution point cloud data from a Riegl VZ-400 terrestrial laser scanner. The VoxLAD model uses terrestrial LiDAR scanner data to determine Leaf Area Density (LAD) measurements for small volume voxels (20 cm sides) of a single tree canopy. VoxLAD is also used in a non-traditional fashion in this case to generate a voxel model of wood density. Information from the VoxLAD model is used within the LiDAR simulation to determine the probability of LiDAR energy interacting with materials at a given voxel location. The LiDAR simulation is defined to replicate the scanning arrangement of the Riegl VZ-400; the resulting simulated full-waveform LiDAR signals compare favorably to those obtained with the Riegl VZ-400 terrestrial laser scanner.

Field test of an all-semiconductor laser-based coherent continuous-wave Doppler lidar for wind energy applications

DEFF Research Database (Denmark)

Sjöholm, Mikael; Dellwik, Ebba; Hu, Qi

-produced all-semiconductor laser. The instrument is a coherent continuous-wave lidar with two fixed-focus telescopes for launching laser beams in two different directions. The alternation between the telescopes is achieved by a novel switching technique without any moving parts. Here, we report results from...... signal strength from external atmospheric parameters such as relative humidity and concentrations of atmospheric particles is discussed. This novel lidar instrument design seems to offer a promising low-cost alternative for prevision remote sensing of wind turbine inflow....

Linear LIDAR versus Geiger-mode LIDAR: impact on data properties and data quality

Science.gov (United States)

Ullrich, A.; Pfennigbauer, M.

2016-05-01

LIDAR has become the inevitable technology to provide accurate 3D data fast and reliably even in adverse measurement situations and harsh environments. It provides highly accurate point clouds with a significant number of additional valuable attributes per point. LIDAR systems based on Geiger-mode avalanche photo diode arrays, also called single photon avalanche photo diode arrays, earlier employed for military applications, now seek to enter the commercial market of 3D data acquisition, advertising higher point acquisition speeds from longer ranges compared to conventional techniques. Publications pointing out the advantages of these new systems refer to the other category of LIDAR as "linear LIDAR", as the prime receiver element for detecting the laser echo pulses - avalanche photo diodes - are used in a linear mode of operation. We analyze the differences between the two LIDAR technologies and the fundamental differences in the data they provide. The limitations imposed by physics on both approaches to LIDAR are also addressed and advantages of linear LIDAR over the photon counting approach are discussed.

Occurrence and characteristics of mutual interference between LIDAR scanners

Science.gov (United States)

Kim, Gunzung; Eom, Jeongsook; Park, Seonghyeon; Park, Yongwan

2015-05-01

The LIDAR scanner is at the heart of object detection of the self-driving car. Mutual interference between LIDAR scanners has not been regarded as a problem because the percentage of vehicles equipped with LIDAR scanners was very rare. With the growing number of autonomous vehicle equipped with LIDAR scanner operated close to each other at the same time, the LIDAR scanner may receive laser pulses from other LIDAR scanners. In this paper, three types of experiments and their results are shown, according to the arrangement of two LIDAR scanners. We will show the probability that any LIDAR scanner will interfere mutually by considering spatial and temporal overlaps. It will present some typical mutual interference scenario and report an analysis of the interference mechanism.

Sodium temperature/wind lidar based on laser-diode-pumped Nd:YAG lasers deployed at Tromsø, Norway (69.6°N, 19.2°E).

Science.gov (United States)

Kawahara, T D; Nozawa, S; Saito, N; Kawabata, T; Tsuda, T T; Wada, S

2017-06-12

An Nd:YAG laser-based sodium temperature/wind lidar was developed for the measurement of the northern polar mesosphere and lower thermosphere at Tromsø (69.6N, 19.2E), Norway. Coherent light at 589 nm is produced by sum frequency generation of 1064 nm and 1319 nm from two diode laser end-pumped pulsed Nd:YAG lasers. The output power is as high as 4W, with 4 mJ/pulse at 1000 Hz repetition rate. Five tilting Cassegrain telescopes enable us to make five-direction (zenith, north, south, east, west) observation for temperature and wind simultaneously. This highly stable laser system is first of its kind to operate virtually maintenance-free during the observation season (from late September to March) since 2010.

Polarimetric, Two-Color, Photon-Counting Laser Altimeter Measurements of Forest Canopy Structure

Science.gov (United States)

Harding, David J.; Dabney, Philip W.; Valett, Susan

2011-01-01

Laser altimeter measurements of forest stands with distinct structures and compositions have been acquired at 532 nm (green) and 1064 nm (near-infrared) wavelengths and parallel and perpendicular polarization states using the Slope Imaging Multi-polarization Photon Counting Lidar (SIMPL). The micropulse, single photon ranging measurement approach employed by SIMPL provides canopy structure measurements with high vertical and spatial resolution. Using a height distribution analysis method adapted from conventional, 1064 nm, full-waveform lidar remote sensing, the sensitivity of two parameters commonly used for above-ground biomass estimation are compared as a function of wavelength. The results for the height of median energy (HOME) and canopy cover are for the most part very similar, indicating biomass estimations using lidars operating at green and near-infrared wavelengths will yield comparable estimates. The expected detection of increasing depolarization with depth into the canopies due to volume multiple-scattering was not observed, possibly due to the small laser footprint and the small detector field of view used in the SIMPL instrument. The results of this work provide pathfinder information for NASA's ICESat-2 mission that will employ a 532 nm, micropulse, photon counting laser altimeter.

Compact Integrated DBR Laser Source for Absorption Lidar Instruments, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — We propose to demonstrate a compact integrated laser module that addresses the requirements of the laser source in a water vapor differential absorption lidar (DIAL)...

Lidar detection of carbon dioxide in volcanic plumes

Science.gov (United States)

Fiorani, Luca; Santoro, Simone; Parracino, Stefano; Maio, Giovanni; Del Franco, Mario; Aiuppa, Alessandro

2015-06-01

Volcanic gases give information on magmatic processes. In particular, anomalous releases of carbon dioxide precede volcanic eruptions. Up to now, this gas has been measured in volcanic plumes with conventional measurements that imply the severe risks of local sampling and can last many hours. For these reasons and for the great advantages of laser sensing, the thorough development of volcanic lidar has been undertaken at the Diagnostics and Metrology Laboratory (UTAPRAD-DIM) of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA). In fact, lidar profiling allows one to scan remotely volcanic plumes in a fast and continuous way, and with high spatial and temporal resolution. Two differential absorption lidar instruments will be presented in this paper: BILLI (BrIdge voLcanic LIdar), based on injection seeded Nd:YAG laser, double grating dye laser, difference frequency mixing (DFM) and optical parametric amplifier (OPA), and VULLI (VULcamed Lidar), based on injection seeded Nd:YAG laser and optical parametric oscillator (OPO). The first one is funded by the ERC (European Research Council) project BRIDGE and the second one by the ERDF (European Regional Development Fund) project VULCAMED. While VULLI has not yet been tested in a volcanic site, BILLI scanned the gas emitted by Pozzuoli Solfatara (Campi Flegrei volcanic area, Naples, Italy) during a field campaign carried out from 13 to 17 October 2014. Carbon dioxide concentration maps were retrieved remotely in few minutes in the crater area. Lidar measurements were in good agreement with well-established techniques, based on different operating principles. To our knowledge, it is the first time that carbon dioxide in a volcanic plume is retrieved by lidar, representing the first direct measurement of this kind ever performed on an active volcano and showing the high potential of laser remote sensing in geophysical research.

Novel Tunable Dye Laser for Lidar Detection, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — A tunable dye laser for Lidar detection will be fabricated based on the innovative dye-doped Holographic Polymer Dispersed Liquid Crystals (HPDLC) technology. The...

Lidar Technology at the Goddard Laser and Electro-Optics Branch

Science.gov (United States)

Heaps, William S.; Obenschain, Arthur F. (Technical Monitor)

2000-01-01

The Laser and Electro-Optics Branch at Goddard Space flight Center was established about three years ago to provide a focused center of engineering support and technology development in these disciplines with an emphasis on spaced based instruments for Earth and Space Science. The Branch has approximately 15 engineers and technicians with backgrounds in physics, optics, and electrical engineering. Members of the Branch are currently supporting a number of space based lidar efforts as well as several technology efforts aimed at enabling future missions. The largest effort within the Branch is support of the Ice, Cloud, and land Elevation Satellite (ICESAT) carrying the Geoscience Laser Altimeter System (GLAS) instrument. The ICESAT/GLAS primary science objectives are: 1) To determine the mass balance of the polar ice sheets and their contributions to global sea level change; and 2) To obtain essential data for prediction of future changes in ice volume and sea-level. The secondary science objectives are: 1) To measure cloud heights and the vertical structure of clouds and aerosols in the atmosphere; 2) To map the topography of land surfaces; and 3) To measure roughness, reflectivity, vegetation heights, snow-cover, and sea-ice surface characteristics. Our efforts have concentrated on the GLAS receiver component development, the Laser Reference Sensor for the Stellar Reference System, the GLAS fiber optics subsystems, and the prelaunch calibration facilities. We will report on our efforts in the development of the space qualified interference filter [Allan], etalon filter, photon counting detectors, etalor/laser tracking system, and instrument fiber optics, as well as specification and selection of the star tracker and development of the calibration test bed. We are also engaged in development work on lidar sounders for chemical species. We are developing new lidar technology to enable a new class of miniature lidar instruments that are compatible with small

High-energy, 2µm laser transmitter for coherent wind LIDAR

Science.gov (United States)

Singh, Upendra N.; Yu, Jirong; Kavaya, Michael J.; Koch, Grady J.

2017-11-01

A coherent Doppler lidar at 2μm wavelength has been built with higher output energy (300 mJ) than previously available. The laser transmitter is based on the solid-state Ho:Tm:LuLiF, a NASA Langley Research Center invented laser material for higher extraction efficiency. This diode pumped injection seeded MOPA has a transform limited line width and diffraction limited beam quality. NASA Langley Research Center is developing coherent wind lidar transmitter technology at eye-safe wavelength for satellite-based observation of wind on a global scale. The ability to profile wind is a key measurement for understanding and predicting atmospheric dynamics and is a critical measurement for improving weather forecasting and climate modeling. We would describe the development and performance of an engineering hardened 2μm laser transmitter for coherent Doppler wind measurement from ground/aircraft/space platform.

Three-beam aerosol backscatter correlation lidar for wind profiling

Science.gov (United States)

Prasad, Narasimha S.; Radhakrishnan Mylapore, Anand

2017-03-01

The development of a three-beam aerosol backscatter correlation (ABC) light detection and ranging (lidar) to measure wind characteristics for wake vortex and plume tracking applications is discussed. This is a direct detection elastic lidar that uses three laser transceivers, operating at 1030-nm wavelength with ˜10-kHz pulse repetition frequency and nanosec class pulse widths, to directly obtain three components of wind velocities. By tracking the motion of aerosol structures along and between three near-parallel laser beams, three-component wind speed profiles along the field-of-view of laser beams are obtained. With three 8-in. transceiver modules, placed in a near-parallel configuration on a two-axis pan-tilt scanner, the lidar measures wind speeds up to 2 km away. Optical flow algorithms have been adapted to obtain the movement of aerosol structures between the beams. Aerosol density fluctuations are cross-correlated between successive scans to obtain the displacements of the aerosol features along the three axes. Using the range resolved elastic backscatter data from each laser beam, which is scanned over the volume of interest, a three-dimensional map of aerosol density can be generated in a short time span. The performance of the ABC wind lidar prototype, validated using sonic anemometer measurements, is discussed.

Novel short-pulse laser diode source for high-resolution 3D flash lidar

Science.gov (United States)

Canal, Celine; Laugustin, Arnaud; Kohl, Andreas; Rabot, Olivier

2017-06-01

Imaging based on laser illumination is present in various fields of applications such as medicine, security, defense, civil engineering and in the automotive sector. In this last domain, research and development to bring autonomous vehicles on the roads has been intensified the recent years. Among the various technologies currently studied, automotive lidars are a fast-growing one due to their accuracy to detect a wide range of objects at distances up to a few hundreds of meters in various weather conditions. First commercialized devices for ADAS were laser scanners. Since then, new architectures have recently appeared such as solid-state lidar and flash lidar that offer a higher compactness, robustness and a cost reduction. Flash lidars are based on time-of-flight measurements, with the particularity that they do not require beam scanners because only one short laser pulse with a large divergence is used to enlighten the whole scene. Depth of encountered objects can then be recovered from measurement of echoed light at once, hence enabling real-time 3D mapping of the environment. This paper will bring into the picture a cutting edge laser diode source that can deliver millijoule pulses as short as 12 ns, which makes them highly suitable for integration in flash lidars. They provide a 100-kW peak power highly divergent beam in a footprint of 4x5 cm2 (including both the laser diode and driver) and with a 30-% electrical-to-optical efficiency, making them suitable for integration in environments in which compactness and power consumption are a priority. Their emission in the range of 800-1000 nm is considered to be eye safe when taking into account the high divergence of the output beam. An overview of architecture of these state-of-the-art pulsed laser diode sources will be given together with some solutions for their integration in 3D mapping systems. Future work leads will be discussed for miniaturization of the laser diode and drastic cost reduction.

The marbll experiment: towards a martian wind lidar

Directory of Open Access Journals (Sweden)

Määttänen Anni

2018-01-01

Full Text Available Operating a lidar on Mars would fulfill the need of accessing wind and aerosol profiles in the atmospheric boundary layer. This is the purpose of the MARs Boundary Layer Lidar (MARBLL instrument. We report recent developments of this compact direct-detection wind lidar designed to operate from the surface of Mars. A new laser source has been developed and an azimuthal scanning capability has been added. Preliminary results of a field campaign are presented.

Progress towards an Autonomous Field Deployable Diode-Laser-Based Differential Absorption Lidar (DIAL for Profiling Water Vapor in the Lower Troposphere

Directory of Open Access Journals (Sweden)

Kevin S. Repasky

2013-11-01

Full Text Available A laser transmitter has been developed and incorporated into a micro-pulse differential absorption lidar (DIAL for water vapor profiling in the lower troposphere as an important step towards long-term autonomous field operation. The laser transmitter utilizes two distributed Bragg reflector (DBR diode lasers to injection seed a pulsed tapered semiconductor optical amplifier (TSOA, and is capable of producing up to 10 mJ of pulse energy with a 1 ms pulse duration and a 10 kHz pulse repetition frequency. The on-line wavelength of the laser transmitter can operate anywhere along the water vapor absorption feature centered at 828.187 nm (in vacuum depending on the prevailing atmospheric conditions, while the off-line wavelength operates at 828.287 nm. This laser transmitter has been incorporated into a DIAL instrument utilizing a 35.6 cm Schmidt-Cassegrain telescope and fiber coupled avalanche photodiode (APD operating in the photon counting mode. The performance of the DIAL instrument was demonstrated over a ten-day observation period. During this observation period, data from radiosondes were used to retrieve water vapor number density profiles for comparisons with the number density profiles retrieved from the DIAL data.

A Compact Mobile Ozone Lidar for Atmospheric Ozone and Aerosol Profiling

Science.gov (United States)

De Young, Russell; Carrion, William; Pliutau, Denis

2014-01-01

A compact mobile differential absorption lidar (DIAL) system has been developed at NASA Langley Research Center to provide ozone, aerosol and cloud atmospheric measurements in a mobile trailer for ground-based atmospheric ozone air quality campaigns. This lidar is integrated into the Tropospheric Ozone Lidar Network (TOLNet) currently made up of four other ozone lidars across the country. The lidar system consists of a UV and green laser transmitter, a telescope and an optical signal receiver with associated Licel photon counting and analog channels. The laser transmitter consist of a Q-switched Nd:YLF inter-cavity doubled laser pumping a Ce:LiCAF tunable UV laser with all the associated power and lidar control support units on a single system rack. The system has been configured to enable mobile operation from a trailer and was deployed to Denver, CO July 15-August 15, 2014 supporting the DISCOVER-AQ campaign. Ozone curtain plots and the resulting science are presented.

A comparison of Doppler lidar wind sensors for Earth-orbit global measurement applications

Science.gov (United States)

Menzies, Robert T.

1985-01-01

Now, there are four Doppler lidar configurations which are being promoted for the measurement of tropospheric winds: (1) the coherent CO2 Lidar, operating in the 9 micrometer region using a pulsed, atmospheric pressure CO2 gas discharge laser transmitter, and heterodyne detection; (2) the coherent Neodymium doped YAG or Glass Lidar, operating at 1.06 micrometers, using flashlamp or diode laser optical pumping of the solid state laser medium, and heterodyne detection; (3) the Neodymium doped YAG/Glass Lidar, operating at the doubled frequency (at 530 nm wavelength), again using flashlamp or diode laser pumping of the laser transmitter, and using a high resolution tandem Fabry-Perot filter and direct detection; and (4) the Raman shifted Xenon Chloride Lidar, operating at 350 nm wavelength, using a pulsed, atmospheric pressure XeCl gas discharge laser transmitter at 308 nm, Raman shifted in a high pressure hydrogen cell to 350 nm in order to avoid strong stratospheric ozone absorption, also using a high resolution tandem Fabry-Perot filter and direct detection. Comparisons of these four systems can include many factors and tradeoffs. The major portion of this comparison is devoted to efficiency. Efficiency comparisons are made by estimating the number of transmitted photons required for a single pulse wind velocity estimate of + or - 1 m/s accuracy in the middle troposphere, from an altitude of 800 km, which is assured to be reasonable for a polar orbiting platform.

Injection Seeded Laser for Formaldehyde Differential Fluorescence Lidar

Directory of Open Access Journals (Sweden)

Schwemmer G.

2016-01-01

Full Text Available We describe the design and development of an injection seeded Nd:YVO4 laser for use in a differential fluorescence lidar for measuring atmospheric formaldehyde profiles. A high repetition rate Q-switched laser is modified to accept injection seed input to spectrally narrow and tune the output. The third harmonic output is used to excite formaldehyde (HCHO fluorescence when tuned to a HCHO absorption line. Spectral confirmation is made with the use of a photoacoustic cell and grating spectrometer.

Laser transmitter for Lidar In-Space Technology Experiment

Science.gov (United States)

Chang, John; Cimolino, Marc; Petros, Mulugeta

1991-01-01

The Lidar In-Space Technology Experiment (LITE) Laser Transmitter Module (LTM) flight laser optical architecture has been space qualified by extensive testing at the system, subsystem and component level. The projected system output performance has been verified using an optically and electrically similar breadboard version of the laser. Parasitic lasing was closely examined and completely suppressed after design changes were implemented and tested. Oscillator and amplifier type heads were separately tested to 150 million shots. Critical subassemblies have undergone environmental testing to Shuttle qualification levels. A superior three color anti-reflection coating was developed and tested for use on 14 surfaces after the final amplifier.

High Power, Thermally Optimized Blue Laser for Lidar, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — To enable widespread and rapid airborne bathymetric lidar to adequate depths in many ocean regions a low-cost, rugged, and high energy pulsed laser source must be...

High Power, Thermally Optimized Blue Laser for Lidar, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — To enable widespread and rapid airborne bathymetric lidar to adequate depths in many ocean regions a low-cost, rugged, and high energy pulsed laser source must be...

Disruptive laser diode source for embedded LIDAR sensors

Science.gov (United States)

Canal, Celine; Laugustin, Arnaud; Kohl, Andreas; Rabot, Olivier

2017-02-01

Active imaging based on laser illumination is used in various fields such as medicine, security, defense, civil engineering and in the automotive sector. In this last domain, research and development to bring autonomous vehicles on the roads has been intensified these last years with an emphasis on lidar technology that is probably the key to achieve full automation level. Based on time-of-flight measurements, the profile of objects can be measured together with their location in various conditions, creating a 3D mapping of the environment. To be embedded on a vehicle as advanced driver assistance systems (ADAS), these sensors require compactness, low-cost and reliability, as it is provided by a flash lidar. An attractive candidate, especially with respect to cost reduction, for the laser source integrated in these devices is certainly laser diodes as long as they can provide sufficiently short pulses with a high energy. A recent breakthrough in laser diode and diode driver technology made by Quantel (Les Ulis, France) now allows laser emission higher than 1 mJ with pulses as short as 12 ns in a footprint of 4x5 cm2 (including both the laser diode and driver) and an electrical-to-optical conversion efficiency of the whole laser diode source higher than 25% at this level of energy. The components used for the laser source presented here can all be manufactured at low cost. In particular, instead of having several individual laser diodes positioned side by side, the laser diodes are monolithically integrated on a single semiconductor chip. The chips are then integrated directly on the driver board in a single assembly step. These laser sources emit in the range of 800-1000 nm and their emission is considered to be eye safe when taking into account the high divergence of the output beam and the aperture of possible macro lenses so that they can be used for end consumer applications. Experimental characterization of these state-of-the-art pulsed laser diode sources

Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system

Science.gov (United States)

Ponsardin, Patrick; Grossmann, Benoist E.; Browell, Edward V.

1994-01-01

A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two etalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-etalon laser system. High spectral purity (greater than 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by using this laser, which has a finite linewidth of 0.02 cm(exp -1) (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm(exp -1) (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity etalons is presented, and a closed-loop computer control for active stabilization of the two intracavity etalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (approximately 1.5 h) of less than 0.7 pm in the laboratory.

Intercomparison of aerosol measurements performed with multi-wavelength Raman lidars, automatic lidars and ceilometers in the framework of INTERACT-II campaign

Science.gov (United States)

Madonna, Fabio; Rosoldi, Marco; Lolli, Simone; Amato, Francesco; Vande Hey, Joshua; Dhillon, Ranvir; Zheng, Yunhui; Brettle, Mike; Pappalardo, Gelsomina

2018-04-01

Following the previous efforts of INTERACT (INTERcomparison of Aerosol and Cloud Tracking), the INTERACT-II campaign used multi-wavelength Raman lidar measurements to assess the performance of an automatic compact micro-pulse lidar (MiniMPL) and two ceilometers (CL51 and CS135) in providing reliable information about optical and geometric atmospheric aerosol properties. The campaign took place at the CNR-IMAA Atmospheric Observatory (760 m a. s. l. ; 40.60° N, 15.72° E) in the framework of ACTRIS-2 (Aerosol Clouds Trace gases Research InfraStructure) H2020 project. Co-located simultaneous measurements involving a MiniMPL, two ceilometers and two EARLINET multi-wavelength Raman lidars were performed from July to December 2016. The intercomparison highlighted that the MiniMPL range-corrected signals (RCSs) show, on average, a fractional difference with respect to those of CNR-IMAA Atmospheric Observatory (CIAO) lidars ranging from 5 to 15 % below 2.0 km a.s.l. (above sea level), largely due to the use of an inaccurate overlap correction, and smaller than 5 % in the free troposphere. For the CL51, the attenuated backscatter values have an average fractional difference with respect to CIAO lidars performance is similar to the CL51 below 2.0 km a. s. l. , while in the region above 3 km a. s. l. the differences are about ±40 %. The variability of the CS135 normalization constant is within ±47 %.Finally, additional tests performed during the campaign using the CHM15k ceilometer operated at CIAO showed the clear need to investigate the CHM15k historical dataset (2010-2016) to evaluate potential effects of ceilometer laser fluctuations on calibration stability. The number of laser pulses shows an average variability of 10 % with respect to the nominal power which conforms to the ceilometer specifications. Nevertheless, laser pulses variability follows seasonal behavior with an increase in the number of laser pulses in summer and a decrease in winter. This contributes to

SF6 laser remote sensing by CO2 laser DIAL lidar

International Nuclear Information System (INIS)

Parvin, P.; Basam, Z.; Zamanipour, Z.; Kariminezhad, H.; Boyook, N.; Borna, F.; Azari, T.; Eshragi, N.; Ataran, A.; Ghods Ahmad Zadeh, R.

2004-01-01

A DIAL system using tunable CO 2 laser has been demonstrated practically for remote sensing of SF 6 components in Mashad Shahid Motahhari Research Complex. Non toxic components of SF 6 as a rare isotope is studied to calibrate the lidar function in several conditions. The whole system enables us to detect ppm amounts of chemical gases as well as pollutants and poisonous species

Estimating forest structural characteristics using the airborne LiDAR scanning system and a near-real time profiling laser system

Science.gov (United States)

Zhao, Kaiguang

LiDAR (Light Detection and Ranging) directly measures canopy vertical structures, and provides an effective remote sensing solution to accurate and spatially-explicit mapping of forest characteristics, such as canopy height and Leaf Area Index. However, many factors, such as large data volume and high costs for data acquisition, precludes the operational and practical use of most currently available LiDARs for frequent and large-scale mapping. At the same time, a growing need is arising for real-time remote sensing platforms, e.g., to provide timely information for urgent applications. This study aims to develop an airborne profiling LiDAR system, featured with on-the-fly data processing, for near real- or real-time forest inventory. The development of such a system involves implementing the on-board data processing and analysis as well as building useful regression-based models to relate LiDAR measurements with forest biophysical parameters. This work established a paradigm for an on-the-fly airborne profiling LiDAR system to inventory regional forest resources in real- or near real-time. The system was developed based on an existing portable airborne laser system (PALS) that has been previously assembled at NASA by Dr. Ross Nelson. Key issues in automating PALS as an on-the-fly system were addressed, including the design of an archetype for the system workflow, the development of efficient and robust algorithms for automatic data processing and analysis, the development of effective regression models to predict forest biophysical parameters from LiDAR measurements, and the implementation of an integrated software package to incorporate all the above development. This work exploited the untouched potential of airborne laser profilers for real-time forest inventory, and therefore, documented an initial step toward developing airborne-laser-based, on-the-fly, real-time, forest inventory systems. Results from this work demonstrated the utility and effectiveness of

Two Micron Laser Technology Advancements at NASA Langley Research Center

Science.gov (United States)

Singh, Upendra N.

2010-01-01

An Independent Laser Review Panel set up to examine NASA s space-based lidar missions and the technology readiness of lasers appropriate for space-based lidars indicated a critical need for an integrated research and development strategy to move laser transmitter technology from low technical readiness levels to the higher levels required for space missions. Based on the review, a multiyear Laser Risk Reduction Program (LRRP) was initiated by NASA in 2002 to develop technologies that ensure the successful development of the broad range of lidar missions envisioned by NASA. This presentation will provide an overview of the development of pulsed 2-micron solid-state laser technologies at NASA Langley Research Center for enabling space-based measurement of wind and carbon dioxide.

Helios: a Multi-Purpose LIDAR Simulation Framework for Research, Planning and Training of Laser Scanning Operations with Airborne, Ground-Based Mobile and Stationary Platforms

Science.gov (United States)

Bechtold, S.; Höfle, B.

2016-06-01

In many technical domains of modern society, there is a growing demand for fast, precise and automatic acquisition of digital 3D models of a wide variety of physical objects and environments. Laser scanning is a popular and widely used technology to cover this demand, but it is also expensive and complex to use to its full potential. However, there might exist scenarios where the operation of a real laser scanner could be replaced by a computer simulation, in order to save time and costs. This includes scenarios like teaching and training of laser scanning, development of new scanner hardware and scanning methods, or generation of artificial scan data sets to support the development of point cloud processing and analysis algorithms. To test the feasibility of this idea, we have developed a highly flexible laser scanning simulation framework named Heidelberg LiDAR Operations Simulator (HELIOS). HELIOS is implemented as a Java library and split up into a core component and multiple extension modules. Extensible Markup Language (XML) is used to define scanner, platform and scene models and to configure the behaviour of modules. Modules were developed and implemented for (1) loading of simulation assets and configuration (i.e. 3D scene models, scanner definitions, survey descriptions etc.), (2) playback of XML survey descriptions, (3) TLS survey planning (i.e. automatic computation of recommended scanning positions) and (4) interactive real-time 3D visualization of simulated surveys. As a proof of concept, we show the results of two experiments: First, a survey planning test in a scene that was specifically created to evaluate the quality of the survey planning algorithm. Second, a simulated TLS scan of a crop field in a precision farming scenario. The results show that HELIOS fulfills its design goals.

Full two-dimensional rotor plane inflow measurements by a spinner-integrated wind lidar

DEFF Research Database (Denmark)

Sjöholm, Mikael; Pedersen, Anders Tegtmeier; Angelou, Nikolas

2013-01-01

Introduction Wind turbine load reduction and power performance optimization via advanced control strategies is an active area in the wind energy community. In particular, feed-forward control using upwind inflow measurements by lidar (light detection and ranging) remote sensing instruments has...... novel full two-dimensional radial inflow measurements. Approach In order to achieve full two-dimensional radial inflow measurements, a special laser beam scanner has been developed at the DTU Wind Energy Department. It is based on two rotating prisms that each deviate the beam by 15°, resulting......, a proof-of-concept trial with a blade mounted lidar was performed during the measurement campaign and is reported in a separate EWEA 2013 contribution. Conclusion The study presented here is the novel full two-dimensional continuation of the previous inflow measurements on a circle presented in the paper...

Laser Pulse Production for NASA's Global Ecosystem Dynamics Investigation (GEDI) Lidar

Science.gov (United States)

Stysley, Paul R.; Coyle, D. Barry; Clarke, Greg B.; Frese, Erich; Blalock, Gordon; Morey, Peter; Kay, Richard B.; Poulios, Demetrios; Hersh, Michael

2016-01-01

The Lasers and Electro-Optics Branch at Goddard Space Flight Center has been tasked with building the Lasers for the Global Ecosystems Dynamics Investigation (GEDI) Lidar Mission, to be installed on the Japanese Experiment Module (JEM) on the International Space Station (ISS)1. GEDI will use three NASA-developed lasers, each coupled with a Beam Dithering Unit (BDU) to produce three sets of staggered footprints on the Earth's surface to accurately measure global biomass. We will report on the design, assembly progress, test results, and delivery process of this laser system.

Airborne differential absorption lidar system for water vapor investigations

Science.gov (United States)

Browell, E. V.; Carter, A. F.; Wilkerson, T. D.

1981-01-01

Range-resolved water vapor measurements using the differential-absorption lidar (DIAL) technique is described in detail. The system uses two independently tunable optically pumped lasers operating in the near infrared with laser pulses of less than 100 microseconds separation, to minimize concentration errors caused by atmospheric scattering. Water vapor concentration profiles are calculated for each measurement by a minicomputer, in real time. The work is needed in the study of atmospheric motion and thermodynamics as well as in forestry and agriculture problems.

Differential Absorption Measurements of Atmospheric Water Vapor with a Coherent Lidar at 2050.532 nm

Science.gov (United States)

Koch, Grady J.; Dharamsi, Amin; Davis, Richard E.; Petros, Mulugeta; McCarthy, John C.

1999-01-01

Wind and water vapor are two major factors driving the Earth's atmospheric circulation, and direct measurement of these factors is needed for better understanding of basic atmospheric science, weather forecasting, and climate studies. Coherent lidar has proved to be a valuable tool for Doppler profiling of wind fields, and differential absorption lidar (DIAL) has shown its effectiveness in profiling water vapor. These two lidar techniques are generally considered distinctly different, but this paper explores an experimental combination of the Doppler and DIAL techniques for measuring both wind and water vapor with an eye-safe wavelength based on a solid-state laser material. Researchers have analyzed and demonstrated coherent DIAL water vapor measurements at 10 micrometers wavelength based on CO2 lasers. The hope of the research presented here is that the 2 gm wavelength in a holmium or thulium-based laser may offer smaller packaging and more rugged operation that the CO2-based approach. Researchers have extensively modeled 2 um coherent lasers for water vapor profiling, but no published demonstration is known. Studies have also been made, and results published on the Doppler portion, of a Nd:YAG-based coherent DIAL operating at 1.12 micrometers. Eye-safety of the 1.12 micrometer wavelength may be a concern, whereas the longer 2 micrometer and 10 micrometer systems allow a high level of eyesafety.

Field performance of an all-semiconductor laser coherent Doppler lidar

DEFF Research Database (Denmark)

Rodrigo, Peter John; Pedersen, Christian

2012-01-01

We implement and test what, to our knowledge, is the first deployable coherent Doppler lidar (CDL) system based on a compact, inexpensive all-semiconductor laser (SL). To demonstrate the field performance of our SL-CDL remote sensor, we compare a 36 h time series of averaged radial wind speeds...... measured by our instrument at an 80 m distance to those simultaneously obtained from an industry-standard sonic anemometer (SA). An excellent degree of correlation (R2=0.994 and slope=0.996) is achieved from a linear regression analysis of the CDL versus SA wind speed data. The lidar system is capable...

Project ABLE: (Atmospheric Balloonborne Lidar Experiment)

Science.gov (United States)

Shepherd, O.; Aurilio, G.; Bucknam, R. D.; Hurd, A. G.; Sheehan, W. H.

1985-03-01

Project ABLE (Atmospheric Balloonborne Lidar Experiment) is part of the A.F. Geophysics Laboratory's continuing interest in developing techniques for making remote measurements of atmospheric quantities such as density, pressure, temperatures, and wind motions. The system consists of a balloonborne lidar payload designed to measure neutral molecular density as a function of altitude from ground level to 70 km. The lidar provides backscatter data at the doubled and tripled frequencies of a Nd:YAG laser, which will assist in the separation of the molecular and aerosol contributions and subsequent determination of molecular and aerosol contributions and subsequent determination of molecular density vs altitude. The object of this contract was to fabricate and operate in a field test a balloonborne lidar experiment capable of performing nighttime atmospheric density measurements up to 70 km altitude with a resolution of 150 meters. The payload included a frequency-doubled and -tripled Nd:YAG laser with outputs at 355 and 532 nm; a telescoped receiver with PMT detectors; a command-controlled optical pointing system; and support system, including thermal control, telmetry, command, and power. Successful backscatter measurements were made during field operations which included a balloon launch from Roswell, NM and a flight over the White Sands Missile Range.

Progress on Development of an Airborne Two-Micron IPDA Lidar for Water Vapor and Carbon Dioxide Column Measurements

Science.gov (United States)

Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Yu, Jirong; Antill, Charles W.; Taylor, Bryant D.; Bowen, Stephen C.; Welters, Angela M.; Remus, Ruben G.; Wong, Teh-Hwa;

Two-wavelength, passive self-injection-controlled operation of diode-pumped cw Yb-doped crystal lasers.

Science.gov (United States)

Louyer, Yann; Wallerand, Jean-Pierre; Himbert, Marc; Deneva, Margarita; Nenchev, Marin

2003-09-20

We demonstrate and investigate a peculiar mode of cw Yb3+-doped crystal laser operation when two emissions, at two independently tunable wavelengths, are simultaneously produced. Both emissions are generated from a single pumped volume and take place in either a single beam or spatially separated beams. The laser employs original two-channel cavities that use a passive self-injection-locking (PSIL) control to reduce intracavity loss. The advantages of the application of the PSIL technique and some limitations are shown. The conditions for two-wavelength multimode operation of the cw quasi-three-level diode-pumped Yb3+ lasers and the peculiarity of such an operation are carried out both theoretically and experimentally. The results reported are based on the example of a Yb3+:GGG laser but similar results are also obtained with a Yb3+:YAG laser. The laser operates in the 1023-1033-nm (1030-1040-nm) range with a total output power of 0.4 W. A two-wavelength, single longitudinal mode generation is also obtained.

Self-Raman Nd:YVO4 Laser and Electro-Optic Technology for Space-Based Sodium Lidar Instrument

Science.gov (United States)

Krainak, Michael A.; Yu, Anthony W.; Janches, Diego; Jones, Sarah L.; Blagojevic, Branimir; Chen, Jeffrey

2014-01-01

We are developing a laser and electro-optic technology to remotely measure Sodium (Na) by adapting existing lidar technology with space flight heritage. The developed instrumentation will serve as the core for the planning of an Heliophysics mission targeted to study the composition and dynamics of Earth's mesosphere based on a spaceborne lidar that will measure the mesospheric Na layer. We present performance results from our diode-pumped tunable Q-switched self-Raman c-cut Nd:YVO4 laser with intra-cavity frequency doubling that produces multi-watt 589 nm wavelength output. The c-cut Nd:YVO4 laser has a fundamental wavelength that is tunable from 1063-1067 nanometers. A CW (Continuous Wave) External Cavity diode laser is used as a injection seeder to provide single-frequency grating tunable output around 1066 nanometers. The injection-seeded self-Raman shifted Nd:VO4 laser is tuned across the sodium vapor D2 line at 589 nanometers. We will review technologies that provide strong leverage for the sodium lidar laser system with strong heritage from the Ice Cloud and Land Elevation Satellite-2 (ICESat-2) Advanced Topographic Laser Altimeter System (ATLAS). These include a space-qualified frequency-doubled 9 watts-at-532-nanometer wavelength Nd:YVO4 laser, a tandem interference filter temperature-stabilized fused-silica-etalon receiver and high-bandwidth photon-counting detectors.

Identifying Methane Sources with an Airborne Pulsed IPDA Lidar System Operating near 1.65 µm

Science.gov (United States)

Yerasi, A.; Bartholomew, J.; Tandy, W., Jr.; Emery, W. J.

2016-12-01

Methane is a powerful greenhouse gas that is predicted to play an important role in future global climate trends. It would therefore be beneficial to locate areas that produce methane in significant amounts so that these trends can be better understood. In this investigation, some initial performance test results of a lidar system called the Advanced Leak Detector Lidar - Natural Gas (ALDL-NG) are discussed. The feasibility of applying its fundamental principle of operation to methane source identification is also explored. The ALDL-NG was originally created by the Ball Aerospace & Technologies Corp. to reveal leaks emanating from pipelines that transport natural gas, which is primarily composed of methane. It operates in a pulsed integrated path differential absorption (IPDA) configuration and it is carried by a piloted, single-engine aircraft. In order to detect the presence of natural gas leaks, the laser wavelengths of its online and offline channels operate in the 1.65 µm region. The functionality of the ALDL-NG was tested during a recent field campaign in Colorado. It was determined that the ambient concentration of methane in the troposphere ( 1.8 ppm) could indeed be retrieved from ALDL-NG data with a lower-than-expected uncertainty ( 0.2 ppm). Furthermore, when the ALDL-NG scanned over areas that were presumed to be methane sources (feedlots, landfills, etc.), significantly higher concentrations of methane were retrieved. These results are intriguing because the ALDL-NG was not specifically designed to observe anything beyond natural gas pipelines. Nevertheless, they strongly indicate that utilizing an airborne pulsed IPDA lidar system operating near 1.65 µm may very well be a viable technique for identifying methane sources. Perhaps future lidar systems could build upon the heritage of the ALDL-NG and measure methane concentration with even better precision for a variety of scientific applications.

LIDAR Thomson scattering for advanced tokamaks. Final report

International Nuclear Information System (INIS)

Molvik, A.W.; Lerche, R.A.; Nilson, D.G.

1996-01-01

The LIDAR Thomson Scattering for Advanced Tokamaks project made a valuable contribution by combining LLNL expertise from the MFE Program: tokamak design and diagnostics, and the ICF Program and Physics Dept.: short-pulse lasers and fast streak cameras. This multidisciplinary group evaluated issues involved in achieving a factor of 20 higher high spatial resolution (to as small as 2-3 mm) from the present state of the art in LIDAR Thomson scattering, and developed conceptual designs to apply LIDAR Thomson scattering to three tokamaks: Upgraded divertor measurements in the existing DIII-D tokamak; Both core and divertor LIDAR Thomson scattering in the proposed (now cancelled) TPX; and core, edge, and divertor LIDAR Thomson scattering on the presently planned International Tokamak Experimental Reactor, ITER. Other issues were evaluated in addition to the time response required for a few millimeter spatial resolution. These include the optimum wavelength, 100 Hz operation of the laser and detectors, minimizing stray light - always the Achilles heel of Thomson scattering, and time dispersion in optics that could prevent good spatial resolution. Innovative features of our work included: custom short pulsed laser concepts to meet specific requirements, use of a prism spectrometer to maintain a constant optical path length for high temporal and spatial resolution, the concept of a laser focus outside the plasma to ionize gas and form an external fiducial to use in locating the plasma edge as well as to spread the laser energy over a large enough area of the inner wall to avoid laser ablation of wall material, an improved concept for cleaning windows between shots by means of laser ablation, and the identification of a new physics issue - nonlinear effects near a laser focus which could perturb the plasma density and temperature that are to be measured

New generation lidar systems for eye safe full time observations

Science.gov (United States)

Spinhirne, James D.

1995-01-01

The traditional lidar over the last thirty years has typically been a big pulse low repetition rate system. Pulse energies are in the 0.1 to 1.0 J range and repetition rates from 0.1 to 10 Hz. While such systems have proven to be good research tools, they have a number of limitations that prevent them from moving beyond lidar research to operational, application oriented instruments. These problems include a lack of eye safety, very low efficiency, poor reliability, lack of ruggedness and high development and operating costs. Recent advances in solid state laser, detectors and data systems have enabled the development of a new generation of lidar technology that meets the need for routine, application oriented instruments. In this paper the new approaches to operational lidar systems will be discussed. Micro pulse lidar (MPL) systems are currently in use, and their technology is highlighted. The basis and current development of continuous wave (CW) lidar and potential of other technical approaches is presented.

Remote detection and recognition of bio-aerosols by laser-induced fluorescense lidar: practical implementation and field tests

Science.gov (United States)

Boreysho, Anatoly; Savin, Andrey; Morozov, Alexey; Konyaev, Maxim; Konovalov, Konstantin

2007-06-01

Recognition of aerosol clouds material at some significant distance is now a key requirement for the wide range of applications. The elastic backscatter lidar have demonstrated high capabilities in aerosol remote detection, cloud real-time mapping at very long distances for low-concentration natural aerosols as well as artificial ones [1]. However, recognition ability is required to make them more relevant. Laser-induced fluorescence (LIF) looks very promising with respect to the recognition problem. New approach based on mobile lidar complex [2] equipped by spectrally-and range-resolved LIF-sensor is described as well as some results of field tests. The LIF-sensor consists of four-harmonics Nd:YAG laser equipped by an output expander to provide final beam divergence camera collimated with the lidar scanning direction. The LIF-lidar is mounted on a truck-based platform (20-feet container) as a part of multi-purpose mobile lidar complex and adjusted for field conditions.

Robust remote-pumping sodium laser for advanced LIDAR and guide star applications

Science.gov (United States)

Ernstberger, Bernhard; Enderlein, Martin; Friedenauer, Axel; Schwerdt, Robin; Wei, Daoping; Karpov, Vladimir; Leisching, Patrick; Clements, Wallace R. L.; Kaenders, Wilhelm G.

2015-10-01

The performance of large ground-based optical telescopes is limited due to wavefront distortions induced by atmospheric turbulence. Adaptive optics systems using natural guide stars with sufficient brightness provide a practical way for correcting the wavefront errors by means of deformable mirrors. Unfortunately, the sky coverage of bright stars is poor and therefore the concept of laser guide stars was invented, creating an artificial star by exciting resonance fluorescence from the mesospheric sodium layer about 90 km above the earth's surface. Until now, mainly dye lasers or sumfrequency mixing of solid state lasers were used to generate laser guide stars. However, these kinds of lasers require a stationary laser clean room for operation and are extremely demanding in maintenance. Under a development contract with the European Southern Observatory (ESO) and W. M. Keck Observatory (WMKO), TOPTICA Photonics AG and its partner MPB Communications have finalized the development of a next-generation sodium guide star laser system which is available now as a commercial off-the-shelf product. The laser is based on a narrow-band diode laser, Raman fiber amplifier (RFA) technology and resonant second-harmonic generation (SHG), thus highly reliable and simple to operate and maintain. It emits > 22 W of narrow-linewidth (≈ 5 MHz) continuous-wave radiation at sodium resonance and includes a re-pumping scheme for boosting sodium return flux. Due to the SHG resonator acting as spatial mode filter and polarizer, the output is diffraction-limited with RMS wavefront error concept of line-replaceable units (LRU). A comprehensive system software, as well as an intuitive service GUI, allow for remote control and error tracking down to at least the LRU level. In case of a failure, any LRU can be easily replaced. With these fiber-based guide star lasers, TOPTICA for the first time offers a fully engineered, off-the-shelf guide star laser system for groundbased optical telescopes

Atmospheric aerosol and gas sensing using Scheimpflug lidar

Science.gov (United States)

Mei, Liang; Brydegaard, Mikkel

2015-04-01

This work presents a new lidar technique for atmospheric remote sensing based on Scheimpflug principle, which describes the relationship between nonparallel image- and object-planes[1]. When a laser beam is transmitted into the atmosphere, the implication is that the backscattering echo of the entire illuminated probe volume can be in focus simultaneously without diminishing the aperture. The range-resolved backscattering echo can be retrieved by using a tilted line scan or two-dimensional CCD/CMOS camera. Rather than employing nanosecond-pulsed lasers, cascade detectors, and MHz signal sampling, all of high cost and complexity, we have developed a robust and inexpensive atmospheric lidar system based on compact laser diodes and array detectors. We present initial applications of the Scheimpflug lidar for atmospheric aerosol monitoring in bright sunlight, with a 3 W, 808 nm CW laser diode. Kilohertz sampling rates are also achieved with applications for wind speed and entomology [2]. Further, a proof-of-principle demonstration of differential absorption lidar (DIAL) based on the Scheimpflug lidar technique is presented [3]. By utilizing a 30 mW narrow band CW laser diode emitting at around 760 nm, the detailed shape of an oxygen absorption line can be resolved remotely with an integration time of 6 s and measurement cycle of 1 minute during night time. The promising results demonstrated in this work show potential for the Scheimpflug lidar technique for remote atmospheric aerosol and gas sensing, and renews hope for robust and realistic instrumentation for atmospheric lidar sensing. [1] F. Blais, "Review of 20 years of range sensor development," Journal of Electronic Imaging, vol. 13, pp. 231-243, Jan 2004. [2] M. Brydegaard, A. Gebru, and S. Svanberg, "Super resolution laser radar with blinking atmospheric particles - application to interacting flying insects " Progress In Electromagnetics Research, vol. 147, pp. 141-151, 2014. [3] L. Mei and M. Brydegaard

Coherent Doppler lidar for automated space vehicle, rendezvous, station-keeping and capture

Science.gov (United States)

Dunkin, James A.

1991-01-01

Recent advances in eye-safe, short wavelength solid-state lasers offer real potential for the development of compact, reliable, light-weight, efficient coherent lidar. Laser diode pumping of these devices has been demonstrated, thereby eliminating the need for flash lamp pumping, which has been a major drawback to the use of these lasers in space based applications. Also these lasers now have the frequency stability required to make them useful in coherent lidar, which offers all of the advantages of non-coherent lidar, but with the additional advantage that direct determination of target velocity is possible by measurement of the Doppler shift. By combining the Doppler velocity measurement capability with the inherent high angular resolution and range accuracy of lidar it is possible to construct Doppler images of targets for target motion assessment. A coherent lidar based on a Tm,Ho:YAG 2-micrometer wavelength laser was constructed and successfully field tested on atmospheric targets in 1990. This lidar incorporated an all solid state (laser diode pumped) master oscillator, in conjunction with a flash lamp pumped slave oscillator. Solid-state laser technology is rapidly advancing, and with the advent of high efficiency, high power, semiconductor laser diodes as pump sources, all-solid-state, coherent lidars are a real possibility in the near future. MSFC currently has a feasibility demonstration effort under way which will involve component testing, and preliminary design of an all-solid-state, coherent lidar for automatic rendezvous, and capture. This two year effort, funded by the Director's Discretionary Fund is due for completion in 1992.

Lidar Remote Sensing for Industry and Environment Monitoring

Science.gov (United States)

Singh, Upendra N. (Editor); Itabe, Toshikazu (Editor); Sugimoto, Nobuo (Editor)

2000-01-01

Contents include the following: 1. Keynote paper: Overview of lidar technology for industrial and environmental monitoring in Japan. 2. lidar technology I: NASA's future active remote sensing mission for earth science. Geometrical detector consideration s in laser sensing application (invited paper). 3. Lidar technology II: High-power femtosecond light strings as novel atmospheric probes (invited paper). Design of a compact high-sensitivity aerosol profiling lidar. 4. Lasers for lidars: High-energy 2 microns laser for multiple lidar applications. New submount requirement of conductively cooled laser diodes for lidar applications. 5. Tropospheric aerosols and clouds I: Lidar monitoring of clouds and aerosols at the facility for atmospheric remote sensing (invited paper). Measurement of asian dust by using multiwavelength lidar. Global monitoring of clouds and aerosols using a network of micropulse lidar systems. 6. Troposphere aerosols and clouds II: Scanning lidar measurements of marine aerosol fields at a coastal site in Hawaii. 7. Tropospheric aerosols and clouds III: Formation of ice cloud from asian dust particles in the upper troposphere. Atmospheric boundary layer observation by ground-based lidar at KMITL, Thailand (13 deg N, 100 deg. E). 8. Boundary layer, urban pollution: Studies of the spatial correlation between urban aerosols and local traffic congestion using a slant angle scanning on the research vessel Mirai. 9. Middle atmosphere: Lidar-observed arctic PSC's over Svalbard (invited paper). Sodium temperature lidar measurements of the mesopause region over Syowa Station. 10. Differential absorption lidar (dIAL) and DOAS: Airborne UV DIAL measurements of ozone and aerosols (invited paper). Measurement of water vapor, surface ozone, and ethylene using differential absorption lidar. 12. Space lidar I: Lightweight lidar telescopes for space applications (invited paper). Coherent lidar development for Doppler wind measurement from the International Space

Differential absorption lidar measurements of atmospheric water vapor using a pseudonoise code modulated AlGaAs laser. Thesis

Science.gov (United States)

Rall, Jonathan A. R.

1994-01-01

Lidar measurements using pseudonoise code modulated AlGaAs lasers are reported. Horizontal path lidar measurements were made at night to terrestrial targets at ranges of 5 and 13 km with 35 mW of average power and integration times of one second. Cloud and aerosol lidar measurements were made to thin cirrus clouds at 13 km altitude with Rayleigh (molecular) backscatter evident up to 9 km. Average transmitter power was 35 mW and measurement integration time was 20 minutes. An AlGaAs laser was used to characterize spectral properties of water vapor absorption lines at 811.617, 816.024, and 815.769 nm in a multipass absorption cell using derivative spectroscopy techniques. Frequency locking of an AlGaAs laser to a water vapor absorption line was achieved with a laser center frequency stability measured to better than one-fifth of the water vapor Doppler linewidth over several minutes. Differential absorption lidar measurements of atmospheric water vapor were made in both integrated path and range-resolved modes using an externally modulated AlGaAs laser. Mean water vapor number density was estimated from both integrated path and range-resolved DIAL measurements and agreed with measured humidity values to within 6.5 percent and 20 percent, respectively. Error sources were identified and their effects on estimates of water vapor number density calculated.

Multi-Beam Surface Lidar for Lunar and Planetary Mapping

Science.gov (United States)

Bufton, Jack L.; Garvin, James B.

1998-01-01

Surface lidar techniques are now being demonstrated in low Earth orbit with a single beam of pulsed laser radiation at 1064 nm that profiles the vertical structure of Earth surface landforms along the nadir track of a spacecraft. In addition, a profiling laser altimeter, called MOLA, is operating in elliptical Martian orbit and returning surface topography data. These instruments form the basis for suggesting an improved lidar instrument that employs multiple beams for extension of sensor capabilities toward the goal of true, 3-dimensional mapping of the Moon or other similar planetary surfaces. In general the lidar waveform acquired with digitization of a laser echo can be used for laser distance measurement (i.e. range-to-the-surface) by time-of-flight measurement and for surface slope and shape measurements by examining the detailed lidar waveform. This is particularly effective when the intended target is the lunar surface or another planetary body free of any atmosphere. The width of the distorted return pulse is a first order measure of the surface incidence angle, a combination of surface slope and laser beam pointing. Assuming an independent and absolute (with respect to inertial space) measurement of laser beam pointing on the spacecraft, it is possible to derive a surface slope with-respect-to the mean planetary surface or its equipotential gravity surface. Higher-order laser pulse distortions can be interpreted in terms of the vertical relief of the surface or reflectivity variations within the area of the laser beam footprint on the surface.

Airborne Measurements of Atmospheric Methane Using Pulsed Laser Transmitters

Science.gov (United States)

Numata, Kenji; Riris, Haris; Wu, Stewart; Gonzalez, Brayler; Rodriguez, Michael; Hasselbrack, William; Fahey, Molly; Yu, Anthony; Stephen, Mark; Mao, Jianping;

Lidar and Laser Technology for NASA’S Cloud-Aerosol Transport System (CATS Payload on The International Space Station (JEM-EF

Directory of Open Access Journals (Sweden)

Storm Mark

2016-01-01

Full Text Available This paper describes the ISS lidar technology provided by Fibertek, Inc. in support of the NASA GSFC CATS mission and provides an assessment of the in-flight systems performance and lessons learned. During February the systems successfully operated in space for more than 300 hours using 25 W average power lasers and photon counting of aerosol atmospheric returns.

A Survey of LIDAR Technology and Its Use in Spacecraft Relative Navigation

Science.gov (United States)

Christian, John A.; Cryan, Scott P.

2013-01-01

This paper provides a survey of modern LIght Detection And Ranging (LIDAR) sensors from a perspective of how they can be used for spacecraft relative navigation. In addition to LIDAR technology commonly used in space applications today (e.g. scanning, flash), this paper reviews emerging LIDAR technologies gaining traction in other non-aerospace fields. The discussion will include an overview of sensor operating principles and specific pros/cons for each type of LIDAR. This paper provides a comprehensive review of LIDAR technology as applied specifically to spacecraft relative navigation. HE problem of orbital rendezvous and docking has been a consistent challenge for complex space missions since before the Gemini 8 spacecraft performed the first successful on-orbit docking of two spacecraft in 1966. Over the years, a great deal of effort has been devoted to advancing technology associated with all aspects of the rendezvous, proximity operations, and docking (RPOD) flight phase. After years of perfecting the art of crewed rendezvous with the Gemini, Apollo, and Space Shuttle programs, NASA began investigating the problem of autonomous rendezvous and docking (AR&D) to support a host of different mission applications. Some of these applications include autonomous resupply of the International Space Station (ISS), robotic servicing/refueling of existing orbital assets, and on-orbit assembly.1 The push towards a robust AR&D capability has led to an intensified interest in a number of different sensors capable of providing insight into the relative state of two spacecraft. The present work focuses on exploring the state-of-the-art in one of these sensors - LIght Detection And Ranging (LIDAR) sensors. It should be noted that the military community frequently uses the acronym LADAR (LAser Detection And Ranging) to refer to what this paper calls LIDARs. A LIDAR is an active remote sensing device that is typically used in space applications to obtain the range to one or more

Turbulence measurement with a two-beam nacelle lidar

DEFF Research Database (Denmark)

Wagner, Rozenn; Sathe, Ameya; Mioullet, A.

The analysis of the turbulence intensity measurement is performed for a lidar measuring horizontally with two beams. First the turbulence intensity measured by such a system was evaluated theoretically. The Mann model of turbulence was used to evaluate the true value of the turbulence intensity...... of the wind speed and the main effects of the lidar measurement principles on turbulence intensity measurement were modeled: - A lidar senses the wind speed over the probe volume acting as a low pass-filter and thus cannot resolve high frequency turbulence; - The horizontal wind speed is retrieved from...... the combination of the radial speeds measured along two line-of-sights with different orientations; this results in the contamination of the lidar turbulence intensity measurement from the transverse component of the wind field. Secondly, the theoretical results were compared to experimental measurements. A two...

All-Fiber Airborne Coherent Doppler Lidar to Measure Wind Profiles

Directory of Open Access Journals (Sweden)

Liu Jiqiao

2016-01-01

Full Text Available An all-fiber airborne pulsed coherent Doppler lidar (CDL prototype at 1.54μm is developed to measure wind profiles in the lower troposphere layer. The all-fiber single frequency pulsed laser is operated with pulse energy of 300μJ, pulse width of 400ns and pulse repetition rate of 10kHz. To the best of our knowledge, it is the highest pulse energy of all-fiber eye-safe single frequency laser that is used in airborne coherent wind lidar. The telescope optical diameter of monostatic lidar is 100 mm. Velocity-Azimuth-Display (VAD scanning is implemented with 20 degrees elevation angle in 8 different azimuths. Real-time signal processing board is developed to acquire and process the heterodyne mixing signal with 10000 pulses spectra accumulated every second. Wind profiles are obtained every 20 seconds. Several experiments are implemented to evaluate the performance of the lidar. We have carried out airborne wind lidar experiments successfully, and the wind profiles are compared with aerological theodolite and ground based wind lidar. Wind speed standard error of less than 0.4m/s is shown between airborne wind lidar and balloon aerological theodolite.

Visibility and aerosol measurement by diode-laser random-modulation CW lidar

Science.gov (United States)

Takeuchi, N.; Baba, H.; Sakurai, K.; Ueno, T.; Ishikawa, N.

1986-01-01

Examples of diode laser (DL) random-modulation continuous wave (RM-CW) lidar measurements are reported. The ability of the measurement of the visibility, vertical aerosol profile, and the cloud ceiling height is demonstrated. Although the data shown here were all measured at night time, the daytime measurement is, of course, possible. For that purpose, accurate control of the laser frequency to the center frequency of a narrow band filter is required. Now a new system with a frequency control is under construction.

Diode-laser-based water vapor differential absorption lidar (DIAL) profiler evaluation

Science.gov (United States)

Spuler, S.; Weckwerth, T.; Repasky, K. S.; Nehrir, A. R.; Carbone, R.

2012-12-01

We are in the process of evaluating the performance of an eye-safe, low-cost, diode-laser-based, water vapor differential absorption lidar (DIAL) profiler. This class of instrument may be capable of providing continuous water vapor and aerosol backscatter profiles at high vertical resolution in the atmospheric boundary layer (ABL) for periods of months to years. The technology potentially fills a national long term observing facility gap and could greatly benefit micro- and meso-meteorology, water cycle, carbon cycle and, more generally, biosphere-hydrosphere-atmosphere interaction research at both weather and climate variability time scales. For the evaluation, the Montana State University 3rd generation water vapor DIAL was modified to enable unattended operation for a period of several weeks. The performance of this V3.5 version DIAL was tested at MSU and NCAR in June and July of 2012. Further tests are currently in progress with Howard University at Beltsville, Maryland; and with the National Weather Service and Oklahoma University at Dallas/Fort Worth, Texas. The presentation will include a comparison of DIAL profiles against meteorological "truth" at the aforementioned locations including: radiosondes, Raman lidars, microwave and IR radiometers, AERONET and SUOMINET systems. Instrument reliability, uncertainty, systematic biases, detection height statistics, and environmental complications will be evaluated. Performance will be judged in the context of diverse scientific applications that range from operational weather prediction and seasonal climate variability, to more demanding climate system process studies at the land-canopy-ABL interface. Estimating the extent to which such research and operational applications can be satisfied with a low cost autonomous network of similar instruments is our principal objective.

Overview of solid state lasers with applications as LIDAR transmitters and optical image amplifiers

International Nuclear Information System (INIS)

Powell, R.C.; Basiev, T.T.; Zverev, P.G.

2000-01-01

Full text: This talk will review the current status of solid state lasers. Then a specific class of solid state lasers, Raman lasers, will be discussed as a specific example of new technology development. The spectroscopic properties of the materials are used in these lasers is presented and the use of these materials in shared-, coupled-, and external-resonator laser systems is described. System design parameters affecting efficiency, beam quality, and temporal pulse width are discussed. Examples will be presented of the use of these lasers for transmitters in atmospheric and marine imaging light detection and ranging (LIDAR) systems and in optical amplifiers

Development of Prototype Micro-Lidar using Narrow Linewidth Semiconductor Lasers for Mars Boundary Layer Wind and Dust Opacity Profiles

Science.gov (United States)

Menzies, Robert T.; Cardell, Greg; Chiao, Meng; Esproles, Carlos; Forouhar, Siamak; Hemmati, Hamid; Tratt, David

1999-01-01

We have developed a compact Doppler lidar concept which utilizes recent developments in semiconductor diode laser technology in order to be considered suitable for wind and dust opacity profiling in the Mars lower atmosphere from a surface location. The current understanding of the Mars global climate and meteorology is very limited, with only sparse, near-surface data available from the Viking and Mars Pathfinder landers, supplemented by long-range remote sensing of the Martian atmosphere. The in situ measurements from a lander-based Doppler lidar would provide a unique dataset particularly for the boundary layer. The coupling of the radiative properties of the lower atmosphere with the dynamics involves the radiative absorption and scattering effects of the wind-driven dust. Variability in solar irradiance, on diurnal and seasonal time scales, drives vertical mixing and PBL (planetary boundary layer) thickness. The lidar data will also contribute to an understanding of the impact of wind-driven dust on lander and rover operations and lifetime through an improvement in our understanding of Mars climatology. In this paper we discuss the Mars lidar concept, and the development of a laboratory prototype for performance studies, using, local boundary layer and topographic target measurements.

The e-Beam Sustained Laser Technology for Space-based Doppler Wind Lidar

Science.gov (United States)

Brown, M. J.; Holman, W.; Robinson, R. J.; Schwarzenberger, P. M.; Smith, I. M.; Wallace, S.; Harris, M. R.; Willetts, D. V.; Kurzius, S. C.

1992-01-01

An overview is presented of GEC Avionics activities relating to the Spaceborne Doppler Wind Lidar. In particular, the results of design studies into the use of an e-beam sustained CO2 laser for spaceborne applications, and experimental work on a test bed system are discussed.

The ALOMAR Rayleigh/Mie/Raman lidar: objectives, configuration, and performance

Directory of Open Access Journals (Sweden)

U. von Zahn

2000-07-01

Full Text Available We report on the development and current capabilities of the ALOMAR Rayleigh/Mie/Raman lidar. This instrument is one of the core instruments of the international ALOMAR facility, located near Andenes in Norway at 69°N and 16°E. The major task of the instrument is to perform advanced studies of the Arctic middle atmosphere over altitudes between about 15 to 90 km on a climatological basis. These studies address questions about the thermal structure of the Arctic middle atmosphere, the dynamical processes acting therein, and of aerosols in the form of stratospheric background aerosol, polar stratospheric clouds, noctilucent clouds, and injected aerosols of volcanic or anthropogenic origin. Furthermore, the lidar is meant to work together with other remote sensing instruments, both ground- and satellite-based, and with balloon- and rocket-borne instruments performing in situ observations. The instrument is basically a twin lidar, using two independent power lasers and two tiltable receiving telescopes. The power lasers are Nd:YAG lasers emitting at wavelengths 1064, 532, and 355 nm and producing 30 pulses per second each. The power lasers are highly stabilized in both their wavelengths and the directions of their laser beams. The laser beams are emitted into the atmosphere fully coaxial with the line-of-sight of the receiving telescopes. The latter use primary mirrors of 1.8 m diameter and are tiltable within 30° off zenith. Their fields-of-view have 180 µrad angular diameter. Spectral separation, filtering, and detection of the received photons are made on an optical bench which carries, among a multitude of other optical components, three double Fabry-Perot interferometers (two for 532 and one for 355 nm and one single Fabry-Perot interferometer (for 1064 nm. A number of separate detector channels also allow registration of photons which are produced by rotational-vibrational and rotational Raman scatter on N2 and N2+O2 molecules

The ALOMAR Rayleigh/Mie/Raman lidar: objectives, configuration, and performance

Directory of Open Access Journals (Sweden)

U. von Zahn

Full Text Available We report on the development and current capabilities of the ALOMAR Rayleigh/Mie/Raman lidar. This instrument is one of the core instruments of the international ALOMAR facility, located near Andenes in Norway at 69°N and 16°E. The major task of the instrument is to perform advanced studies of the Arctic middle atmosphere over altitudes between about 15 to 90 km on a climatological basis. These studies address questions about the thermal structure of the Arctic middle atmosphere, the dynamical processes acting therein, and of aerosols in the form of stratospheric background aerosol, polar stratospheric clouds, noctilucent clouds, and injected aerosols of volcanic or anthropogenic origin. Furthermore, the lidar is meant to work together with other remote sensing instruments, both ground- and satellite-based, and with balloon- and rocket-borne instruments performing in situ observations. The instrument is basically a twin lidar, using two independent power lasers and two tiltable receiving telescopes. The power lasers are Nd:YAG lasers emitting at wavelengths 1064, 532, and 355 nm and producing 30 pulses per second each. The power lasers are highly stabilized in both their wavelengths and the directions of their laser beams. The laser beams are emitted into the atmosphere fully coaxial with the line-of-sight of the receiving telescopes. The latter use primary mirrors of 1.8 m diameter and are tiltable within 30° off zenith. Their fields-of-view have 180 µrad angular diameter. Spectral separation, filtering, and detection of the received photons are made on an optical bench which carries, among a multitude of other optical components, three double Fabry-Perot interferometers (two for 532 and one for 355 nm and one single Fabry-Perot interferometer (for 1064 nm. A number of separate detector channels also allow registration of photons which are produced by rotational-vibrational and rotational Raman scatter on N₂ and N₂

ALADIN: an atmospheric laser Doppler wind lidar instrument for wind velocity measurements from space

Science.gov (United States)

Krawczyk, R.; Ghibaudo, JB.; Labandibar, JY.; Willetts, D.; Vaughan, M.; Pearson, G.; Harris, M.; Flamant, P. H.; Salamitou, P.; Dabas, A.; Charasse, R.; Midavaine, T.; Royer, M.; Heimel, H.

2018-04-01

This paper, "ALADIN: an atmospheric laser Doppler wind lidar instrument for wind velocity measurements from space," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.

Initial multi-parameter detection of atmospheric metal layers by Beijing Na–K lidar

International Nuclear Information System (INIS)

Jiao, Jing; Yang, Guotao; Wang, Jihong; Cheng, Xuewu; Du, Lifang; Wang, Zelong; Gong, Wei

2017-01-01

Beijing Na–K lidar has been started running in 2010. This lidar has two laser beams: one dye laser emits a 589-nm laser beam for Na layer detection; the other dye laser emits a 770-nm laser beam for K layer detection. Under similar conditions, the echo signal of K layer is only about 2 orders of magnitude smaller than that of Na layer. This lidar has a sufficient Signal Noise Ratio (SNR). The structure and details of potassium layer can be effectively distinguished from a single original echo. Several examples of co-observation of density of Na and K layer showed some different results with previous studies. This lidar not only can supplement the lack of Na and K layer observation at this latitude region, but also provide evidence for the atmospheric sciences and space environment monitoring. - Highlights: • Full-band dual-beam lidar at 40°N. • Detecting sodium and potassium layer simultaneously. • Providing a supplement to the study of atmospheric metal layers and evidence for atmospheric sciences and space and atmospheric sciences and space environment monitoring.

COHERENT LIDAR SYSTEM BASED ON A SEMICONDUCTOR LASER AND AMPLIFIER

DEFF Research Database (Denmark)

2009-01-01

The present invention relates to a compact, reliable and low-cost coherent LIDAR (Light Detection And Ranging) system for remote wind-speed determination, determination of particle concentration, and/or temperature based on an all semiconductor light source and related methods. The present...... invention provides a coherent LIDAR system comprising a semiconductor laser for emission of a measurement beam of electromagnetic radiation directed towards a measurement volume for illumination of particles in the measurement volume, a reference beam generator for generation of a reference beam, a detector...... for generation of a detector signal by mixing of the reference beam with light emitted from the particles in the measurement volume illuminated by the measurement beam, and a signal processor for generating a velocity signal corresponding to the velocity of the particles based on the detector signal....

2012 MEGIS Topographic Lidar: Statewide Lidar Project Area 1 (Aroostook), Maine

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — LiDAR data is a remotely sensed high resolution elevation data collected by an airborne platform. The LiDAR sensor uses a combination of laser range finding, GPS...

LIDAR Research & Development Lab

Data.gov (United States)

Federal Laboratory Consortium — The LIDAR Research and Development labs are used to investigate and improve LIDAR components such as laser sources, optical signal detectors and optical filters. The...

UV Lidar Receiver Analysis for Tropospheric Sensing of Ozone

Science.gov (United States)

Pliutau, Denis; DeYoung, Russell J.

2013-01-01

A simulation of a ground based Ultra-Violet Differential Absorption Lidar (UV-DIAL) receiver system was performed under realistic daytime conditions to understand how range and lidar performance can be improved for a given UV pulse laser energy. Calculations were also performed for an aerosol channel transmitting at 3 W. The lidar receiver simulation studies were optimized for the purpose of tropospheric ozone measurements. The transmitted lidar UV measurements were from 285 to 295 nm and the aerosol channel was 527-nm. The calculations are based on atmospheric transmission given by the HITRAN database and the Modern Era Retrospective Analysis for Research and Applications (MERRA) meteorological data. The aerosol attenuation is estimated using both the BACKSCAT 4.0 code as well as data collected during the CALIPSO mission. The lidar performance is estimated for both diffuseirradiance free cases corresponding to nighttime operation as well as the daytime diffuse scattered radiation component based on previously reported experimental data. This analysis presets calculations of the UV-DIAL receiver ozone and aerosol measurement range as a function of sky irradiance, filter bandwidth and laser transmitted UV and 527-nm energy

Wind turbine improvements by wind-lidar-based preview and control

DEFF Research Database (Denmark)

Mikkelsen, Torben

2014-01-01

Wind turbines equipped with laser prevision hold potential for up to 6+ years lifetime extension. Forward looking wind lidars integrated within operational wind turbines providing feed-forward control can reduce the daily operation loads. The turbine lifetime may in this way be extended by up to 30...

High energy, single frequency, tunable laser source operating in burst mode for space based lidar applications

Science.gov (United States)

Cosentino, Alberto; Mondello, Alessia; Sapia, Adalberto; D'Ottavi, Alessandro; Brotini, Mauro; Nava, Enzo; Stucchi, Emanuele; Trespidi, Franco; Mariottini, Cristina; Wazen, Paul; Falletto, Nicolas; Fruit, Michel

2017-11-01

This paper describes the laser transmitter assembly used in the ALADIN instrument currently in C/D development phase for the ESA ADM-AEOLUS mission (EADS Astrium as prime contractor for the satellite and the instrument). The Laser Transmitter Assembly (TXA), based on a diode pumped tripled Nd:YAG laser, is used to generate tunable laser pulses of 150 mJ at a nominal wavelength of 355 nm. This laser is operated in burst mode, with a pulse repetition cycle of 100 Hz. The TXA is composed of the following units: a diodepumped CW Nd:YAG Laser named Reference Laser Head (RLH), used to inject a diode-pumped, Q-switched, amplified and frequency tripled Nd:YAG Laser working in the third harmonic referred as Power Laser Head (PLH) and a Transmitter Laser Electronics (TLE) containing all the control and power electronics needed for PLH and RLH operation. The TXA is made by an European consortium under the leadership of Galileo Avionica (It), and including CESI (It), Quantel (Fr), TESAT (Ge) and Thales (Fr).

Enabling Laser and Lidar Technologies for NASA's Science and Exploration Mission's Applications

Science.gov (United States)

Singh, Upendra N.; Kavaya, Michael J.

2005-01-01

NASA s Laser Risk Reduction Program, begun in 2002, has achieved many technology advances in only 3.5 years. The recent selection of several lidar proposals for Science and Exploration applications indicates that the LRRP goal of enabling future space-based missions by lowering the technology risk has already begun to be met.

Advances in Laser/Lidar Technologies for NASA's Science and Exploration Mission's Applications

Science.gov (United States)

Singh, Upendra N.; Kavaya, Michael J.

2005-01-01

NASA's Laser Risk Reduction Program, begun in 2002, has achieved many technology advances in only 3.5 years. The recent selection of several lidar proposals for Science and Exploration applications indicates that the LRRP goal of enabling future space-based missions by lowering the technology risk has already begun to be met.

MULTISPECTRAL AIRBORNE LASER SCANNING - A NEW TREND IN THE DEVELOPMENT OF LIDAR TECHNOLOGY

Directory of Open Access Journals (Sweden)

Bakuła Krzysztof

2015-12-01

Full Text Available Airborne laser scanning (ALS is the one of the most accurate remote sensing techniques for data acquisition where the terrain and its coverage is concerned. Modern scanners have been able to scan in two or more channels (frequencies of the laser recently. This gives the rise to the possibility of obtaining diverse information about an area with the different spectral properties of objects. The paper presents an example of a multispectral ALS system - Titan by Optech - with the possibility of data including the analysis of digital elevation models accuracy and data density. As a result of the study, the high relative accuracy of LiDAR acquisition in three spectral bands was proven. The mean differences between digital terrain models (DTMs were less than 0.03 m. The data density analysis showed the influence of the laser wavelength. The points clouds that were tested had average densities of 25, 23 and 20 points per square metre respectively for green (G, near-infrared (NIR and shortwave-infrared (SWIR lasers. In this paper, the possibility of the generation of colour composites using orthoimages of laser intensity reflectance and its classification capabilities using data from airborne multispectral laser scanning for land cover mapping are also discussed and compared with conventional photogrammetric techniques.

Two-channel Hyperspectral LiDAR with a Supercontinuum Laser Source

Directory of Open Access Journals (Sweden)

Ruizhi Chen

2010-07-01

Full Text Available Recent advances in nonlinear fiber optics and compact pulsed lasers have resulted in creation of broadband directional light sources. These supercontinuum laser sources produce directional broadband light using cascaded nonlinear optical interactions in an optical fibre framework. This system is used to simultaneously measure distance and reflectance to demonstrate a technique capable of distinguishing between a vegetation target and inorganic material using the Normalized Difference Vegetation Index (NDVI parameters, while the range can be obtained from the waveform of the echoes. A two-channel, spectral range-finding system based on a supercontinuum laser source was used to determine its potential application of distinguishing the NDVI for Norway spruce, a coniferous tree, and its three-dimensional parameters at 600 nm and 800 nm. A prototype system was built using commercial components.

Two-frequency operation of a hybrid TEA CO2 laser and its application to two-frequency pulse injection locking

International Nuclear Information System (INIS)

Sasaki, Koichi; Ohno, Hirotaka; Fujii, Takaharu; Tsukishima, Takashige.

1990-10-01

Simultaneous two-frequency oscillation of a hybrid TEA CO 2 laser is exhibited when the cw section is operated in a 'below threshold' state. The output of the hybrid laser thus obtained is injected into a main TEA CO 2 laser to obtain a power-modulated, long-pulse output with a well suppressed gain-switched spike. (author)

Semiconductor Laser Wind Lidar for Turbine Control

DEFF Research Database (Denmark)

Hu, Qi

This thesis describes an experimentally oriented study of continuous wave (CW) coherent Doppler lidar system design. The main application is remote wind sensing for active wind turbine control using nacelle mounted lidar systems; and the primary focus is to devise an industrial instrument that can...... historical overview within the topic of wind lidar systems. Both the potential and the challenges of an industrialized wind lidar has been addressed here. Furthermore, the basic concept behind the heterodyne detection and a brief overview of the lidar signal processing is explained; and a simple...... investigation of the telescope truncation and lens aberrations is conducted, both numerically and experimentally. It is shown that these parameters dictate the spatial resolution of the lidar system, and have profound impact on the SNR. In this work, an all-semiconductor light source is used in the lidar design...

Hydrographic & Topographic LIDAR Acquisition, Northwest Coast, Washington State - Bathymetric Survey Data

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — These data were collected by the SHOALS-1000T(Scanning Hydrographic Operational Airborne Lidar Survey)system which consists of an airborne laser transmitter/receiver...

Compact, High Energy 2-micron Coherent Doppler Wind Lidar Development for NASA's Future 3-D Winds Measurement from Space

Science.gov (United States)

Singh, Upendra N.; Koch, Grady; Yu, Jirong; Petros, Mulugeta; Beyon, Jeffrey; Kavaya, Michael J.; Trieu, Bo; Chen, Songsheng; Bai, Yingxin; Petzar, paul;

A sample design for globally consistent biomass estimation using lidar data from the Geoscience Laser Altimeter System (GLAS)

Science.gov (United States)

Sean P. Healey; Paul L. Patterson; Sassan S. Saatchi; Michael A. Lefsky; Andrew J. Lister; Elizabeth A. Freeman

2012-01-01

Lidar height data collected by the Geosciences Laser Altimeter System (GLAS) from 2002 to 2008 has the potential to form the basis of a globally consistent sample-based inventory of forest biomass. GLAS lidar return data were collected globally in spatially discrete full waveform "shots," which have been shown to be strongly correlated with aboveground forest...

A time-space synchronization of coherent Doppler scanning lidars for 3D measurements of wind fields

DEFF Research Database (Denmark)

Vasiljevic, Nikola

initiates the laser pulse emission and acquisition of the backscattered light, while the two servo motors conduct the scanner head rotation that provides means to direct the laser pulses into the atmosphere. By controlling the rotation of the three motors from the motion controller the strict......-dimensional flow field by emitting the laser beams from the three spatially separated lidars, directing them to intersect, and moving the beam intersection over an area of interest. Each individual lidar was engineered to be powered by two real servo motors, and one virtual stepper motor. The stepper motor...... synchronization and time control of the emission, steering and acquisition were achieved, resulting that the complete lidar measurement process is controlled from the single hardware component. The system was formed using a novel approach, in which the master computer simultaneously coordinates the remote lidars...

Feasibility study for airborne fluorescence/reflectivity lidar bathymetry

Science.gov (United States)

Steinvall, Ove; Kautsky, Hans; Tulldahl, Michael; Wollner, Erika

2012-06-01

There is a demand from the authorities to have good maps of the coastal environment for their exploitation and preservation of the coastal areas. The goal for environmental mapping and monitoring is to differentiate between vegetation and non-vegetated bottoms and, if possible, to differentiate between species. Airborne lidar bathymetry is an interesting method for mapping shallow underwater habitats. In general, the maximum depth range for airborne laser exceeds the possible depth range for passive sensors. Today, operational lidar systems are able to capture the bottom (or vegetation) topography as well as estimations of the bottom reflectivity using e.g. reflected bottom pulse power. In this paper we study the possibilities and advantages for environmental mapping, if laser sensing would be further developed from single wavelength depth sounding systems to include multiple emission wavelengths and fluorescence receiver channels. Our results show that an airborne fluorescence lidar has several interesting features which might be useful in mapping underwater habitats. An example is the laser induced fluorescence giving rise to the emission spectrum which could be used for classification together with the elastic lidar signal. In the first part of our study, vegetation and substrate samples were collected and their spectral reflectance and fluorescence were subsequently measured in laboratory. A laser wavelength of 532 nm was used for excitation of the samples. The choice of 532 nm as excitation wavelength is motivated by the fact that this wavelength is commonly used in bathymetric laser scanners and that the excitation wavelengths are limited to the visual region as e.g. ultraviolet radiation is highly attenuated in water. The second part of our work consisted of theoretical performance calculations for a potential real system, and comparison of separability between species and substrate signatures using selected wavelength regions for fluorescence sensing.

Atmospheric lidar: legislative, scientific and technological aspects; Lidar atmosferico. Aspetti legislativi, scientifici e tecnologici

Energy Technology Data Exchange (ETDEWEB)

Barbini, R.; Colao, F.; Fiorani, L.; Palucci, A. [ENEA, Divisione Fisica Applicata, Centro Ricerche Frascati, Frascati, RM (Italy)

2000-07-01

The Atmospheric Lidar is one of the systems of the Mobile Laboratory of Laser Remote Sensing under development at the ENEA Research Center of Frascati. This technical report addresses the legislative, scientific and technological aspects that are the basis for the identification of the requirements, the definition of the architecture and the fixation of the specifications of the Atmospheric Lidar. The problems of air pollution are introduced in section 2. A summary of the Italian laws on that topic is then given. Section 4 provides a survey of the atmospheric measurements that can be achieved with the lidar. The sensitivity in the monitoring of pollutants is discussed in section 5. The other systems of the Mobile Laboratory of Laser Remote Sensing are shortly described in section 6. The last section is devoted to conclusions and perspectives. [Italian] Il lidar atmosferico e' uno dei sistemi del Laboratorio Mobile di Telerilevamento Laser in corso di realizzazione presso il Centro Ricerche di Frascati dell'ENEA. Questo rapporto tecnico discute gli aspetti legislativi, scientifici, tecnologici che sono alla base dell'individuazione dei requisiti, della definizione dell'architettura e della fissazione delle specifiche del Lidar atmosferico. La problematica dell'inquinamento dell'aria e' introdotta nella sezione 2. Segue un riassunto della legislazione italiana su tale tematica. La sezione 4 offre una panoramica delle misure atmosferiche realizzabili con il Lidar. La sensibilita' nel monitoraggio di inquinanti e' discussa nella sezione 5. Gli altri sistemi del Laboratorio Mobile di Telerilevamento Laser sono descritti brevemente nella sezione 6. L'ultima sezione e' dedicata alle conclusioni e alle prospettive.

Atmospheric aerosol measurements by employing a polarization scheimpflug lidar system

Science.gov (United States)

Mei, Liang; Guan, Peng; Yang, Yang

2018-04-01

A polarization Scheimpflug lidar system based on the Scheimpflug principle has been developed by employing a compact 808-nm multimode highpower laser diode and two highly integrated CMOS sensors in Dalian University of Technology (DLUT), Dalian, China. The parallel and orthogonal polarized backscattering signal are recorded by two 45 degree tilted image sensors, respectively. Atmospheric particle measurements were carried out by employing the polarization Scheimpflug lidar system.

Development of lidar techniques for environmental studies

Energy Technology Data Exchange (ETDEWEB)

Andersson, Mats

1996-09-01

The lidar group in Lund has performed many DIAL measurements with a mobile lidar system that was first described in 1987. The lidar system is based on a Nd:YAG-pumped dye laser. During the last few years the lidar group has focused on fluorescence imaging and mercury measurements in the troposphere. In 1994 we performed two campaigns: one fluorescence imaging measurement campaign outside Avignon, France and one unique lidar campaign at a mercury mine in Almaden, Spain. Both campaigns are described in this thesis. This thesis also describes how the mobile lidar system was updated with the graphical programming language LabVIEW to obtain a user friendly lidar system. The software controls the lidar system and analyses measured data. The measurement results are shown as maps of species concentration. All electronics and the major parts of the program are described. A new graphical technique to estimate wind speed from plumes is also discussed. First measurements have been performed with the new system. 31 refs, 19 figs, 1 tab

Column carbon dioxide and water vapor measurements by an airborne triple-pulse integrated path differential absorption lidar: novel lidar technologies and techniques with path to space

Science.gov (United States)

Singh, U. N.; Petros, M.; Refaat, T. F.; Yu, J.; Ismail, S.

2017-09-01

The 2-micron wavelength region is suitable for atmospheric carbon dioxide (CO2) measurements due to the existence of distinct absorption features for the gas at this wavelength region [1]. For more than 20 years, researchers at NASA Langley Research Center (LaRC) have developed several high-energy and high repetition rate 2-micron pulsed lasers [2]. Currently, LaRC team is engaged in designing, developing and demonstrating a triple-pulsed 2-micron direct detection Integrated Path Differential Absorption (IPDA) lidar to measure the weighted-average column dry-air mixing ratios of carbon dioxide (XCO2) and water vapor (XH2O) from an airborne platform [1, 3-5]. This novel technique allows measurement of the two most dominant greenhouse gases, simultaneously and independently, using a single instrument. This paper will provide status and details of the development of this airborne 2-micron triple-pulse IPDA lidar. The presented work will focus on the advancement of critical IPDA lidar components. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver and detector upgrades, laser packaging and lidar integration. Future plans for IPDA lidar ground integration, testing and flight validation will also be discussed. This work enables new Earth observation measurements, while reducing risk, cost, size, volume, mass and development time of required instruments.

Water vapor differential absorption lidar development and evaluation

Science.gov (United States)

Browell, E. V.; Wilkerson, T. D.; Mcllrath, T. J.

1979-01-01

A ground-based differential absorption lidar (DIAL) system is described which has been developed for vertical range-resolved measurements of water vapor. The laser transmitter consists of a ruby-pumped dye laser, which is operated on a water vapor absorption line at 724.372 nm. Part of the ruby laser output is transmitted simultaneously with the dye laser output to determine atmospheric scattering and attenuation characteristics. The dye and ruby laser backscattered light is collected by a 0.5-m diam telescope, optically separated in the receiver package, and independently detected using photomultiplier tubes. Measurements of vertical water vapor concentration profiles using the DIAL system at night are discussed, and comparisons are made between the water vapor DIAL measurements and data obtained from locally launched rawinsondes. Agreement between these measurements was found to be within the uncertainty of the rawinsonde data to an altitude of 3 km. Theoretical simulations of this measurement were found to give reasonably accurate predictions of the random error of the DIAL measurements. Confidence in these calculations will permit the design of aircraft and Shuttle DIAL systems and experiments using simulation results as the basis for defining lidar system performance requirements

Advancement of High Power Quasi-CW Laser Diode Arrays For Space-based Laser Instruments

Science.gov (United States)

Amzajerdian, Farzin; Meadows, Byron L.; Baker, nathaniel R.; Baggott, Renee S.; Singh, Upendra N.; Kavaya, Michael J.

2004-01-01

Space-based laser and lidar instruments play an important role in NASA s plans for meeting its objectives in both Earth Science and Space Exploration areas. Almost all the lidar instrument concepts being considered by NASA scientist utilize moderate to high power diode-pumped solid state lasers as their transmitter source. Perhaps the most critical component of any solid state laser system is its pump laser diode array which essentially dictates instrument efficiency, reliability and lifetime. For this reason, premature failures and rapid degradation of high power laser diode arrays that have been experienced by laser system designers are of major concern to NASA. This work addresses these reliability and lifetime issues by attempting to eliminate the causes of failures and developing methods for screening laser diode arrays and qualifying them for operation in space.

Registration of vehicle based panoramic image and LiDAR point cloud

Science.gov (United States)

Chen, Changjun; Cao, Liang; Xie, Hong; Zhuo, Xiangyu

2013-10-01

Higher quality surface information would be got when data from optical images and LiDAR were integrated, owing to the fact that optical images and LiDAR point cloud have unique characteristics that make them preferable in many applications. While most previous works focus on registration of pinhole perspective cameras to 2D or 3D LiDAR data. In this paper, a method for the registration of vehicle based panoramic image and LiDAR point cloud is proposed. Using the translation among panoramic image, single CCD image, laser scanner and Position and Orientation System (POS) along with the GPS/IMU data, precise co-registration between the panoramic image and the LiDAR point cloud in the world system is achieved. Results are presented under a real world data set collected by a new developed Mobile Mapping System (MMS) integrated with a high resolution panoramic camera, two laser scanners and a POS.

Korea-China Joint R and D on Doppler Lidar Technology

International Nuclear Information System (INIS)

Cha, Hyung Ki; Kim, D. H.; Kwon, S. O.; Yang, K. H.; Song, I. K.

2009-03-01

Doppler lidar technology is to monitor atmospheric wind velocity by measuring the light scattering signals between a laser and aerosol particles or molecules existing in the atmosphere. When the particles (or molecules) in the atmosphere are moving by wind force, the frequency of backscattering light is shifted by doppler effect, so that the wind velocity profile can be obtained by measurement of the shifted frequencies. When the laser radiation is scanned in four different direction, three dimensional wind profiles are obtained. The Anhui Institute of Optics and Fine Mechanics under the China Academy of Sciences has developed and operated the doppler lidar system for long time. In this project we want to developed a new technologies adopted to the chinese doppler system and to test the updated In the process of collaboration between China and Korea research teams, we want to learn the state-of-art technology involved in the doppler lidar system

Lidar to lidar calibration phase 2

DEFF Research Database (Denmark)

Yordanova, Ginka; Courtney, Michael

This report presents the results from phase 2 of a lidar to lidar (L2L) calibration procedure. Phase two of the project included two measurement campaigns conducted at given sites. The purpose was to find out if the lidar-to-lidar calibration procedure can be conducted with similar results...

2012 MEGIS Topographic Lidar: Statewide Lidar Project Areas 2 and 3 (Mid-Coastal Cleanup), Maine

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — LiDAR data is a remotely sensed high resolution elevation data collected by an airborne platform. The LiDAR sensor uses a combination of laser range finding, GPS...

LIDAR and atmosphere remote sensing [DST Space Science Initiatives

CSIR Research Space (South Africa)

Venkataraman, S

2009-04-01

Full Text Available Energy Source included in the measurement. Slide 2 © CSIR 2008 www.csir.co.za The observer can control the source Eg. Radar, Lidar, Sodar, Sonar etc. (b) Passive remote sensors. Energy source is not included in the measurement... Instrument Passive Slide 3 © CSIR 2008 www.csir.co.za Active LiDAR Principle • LIDAR (Light Detection and Ranging) • LiDAR employs a laser as a source of pulsed energy • Lasers are advantageous because – checkbld Monochromatic...

Remote imaging laser-induced breakdown spectroscopy and laser-induced fluorescence spectroscopy using nanosecond pulses from a mobile lidar system.

Science.gov (United States)

Grönlund, Rasmus; Lundqvist, Mats; Svanberg, Sune

2006-08-01

A mobile lidar system was used in remote imaging laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF) experiments. Also, computer-controlled remote ablation of a chosen area was demonstrated, relevant to cleaning of cultural heritage items. Nanosecond frequency-tripled Nd:YAG laser pulses at 355 nm were employed in experiments with a stand-off distance of 60 meters using pulse energies of up to 170 mJ. By coaxial transmission and common folding of the transmission and reception optical paths using a large computer-controlled mirror, full elemental imaging capability was achieved on composite targets. Different spectral identification algorithms were compared in producing thematic data based on plasma or fluorescence light.

Investigation of turbulence measurements with a continuous wave, conically scanning LiDAR

DEFF Research Database (Denmark)

Wagner, Rozenn; Mikkelsen, Torben; Courtney, Michael

averaging is done in two steps: 1) the weighted averaging of the wind speed in the probe volume of the laser beam; 2) the averaging of the wind speeds occurring on the circular path described by the conically scanning lidar. Therefore the standard deviation measured by a lidar resolves only the turbulence...... of a continuous wave, conically scanning Zephir lidar. First, the wind speed standard deviation measured by such a lidar gives on average 80% of the standard deviation measured by a cup anemometer. This difference is due to the spatial averaging inherently made by a cw conically scanning lidar. The spatial...

Eye safety report 1 (dual wavelength). Human risk analysis simulator for space lidars

International Nuclear Information System (INIS)

Schulmeister, K.; Mellerio, J.; Sonneck, G.

2001-09-01

This report contains the results of a risk study for a satellite based lidar mission that uses two different laser wavelengths to measure atmospheric properties. A lidar can be considered as a laser radar and is an acronym for light detection and ranging. The lidar measures properties of the atmosphere by analysis of laser radiation that is directed back to the lidar. As only part of the laser radiation is scattered ir absorbed by the atmosphere, the remaining laser radiation emitted from the spacecraft is incident on the earth's surface, where it might lead to injuries, especially to the eye, if biological thresholds are exceeded. For the analysed mission there is no hazard to the skin, only a potential one to the eye. Because the footprint of the satellite's laser beam on the surface of the earth is so small and it moves so fast, the chance of the naked eye being exposed to the laser is small. Because of the magnification provided by an optical instrument, and the concomitant reduction in the field of view, the probability of exposure of an eye that is using such an instrument decreases with increasing optical power. However, because an increased optical power implies increased diameter of the light gathering optics, the laser energy delivered to an eye increases with instrument size so that if exposure did occur, the probability of delivering energy to the eye that exceeds the threshold for damage increases. There are thus two conflicting processes at work for viewing with optical instruments: an increase in diameter increases the energy delivered but reduces the probability of lidar beam interception. Energy delivered to the eye is such that damage thresholds will not be exceeded for naked eye viewing or for the use of small optical instruments. Exposure via telescopes with diameter larger than 12 cm could result in retinal damage of the exposed eye. (author)

Demonstration of a 100-mJ OPO/OPA for future lidar applications and laser-induced damage threshold testing of optical components for MERLIN

Science.gov (United States)

Elsen, Florian; Livrozet, Marie; Strotkamp, Michael; Wüppen, Jochen; Jungbluth, Bernd; Kasemann, Raphael; Löhring, Jens; Meissner, Ansgar; Meyer, Rudolf; Hoffmann, Hans-Dieter; Poprawe, Reinhart

2018-02-01

In the field of atmospheric research, lidar is a powerful technology that can measure gas or aerosol concentrations, wind speed, or temperature profiles remotely. To conduct such measurements globally, spaceborne systems are advantageous. Pulse energies in the 100-mJ range are required to achieve highly accurate, longitudinal resolved measurements. Measuring concentrations of specific gases, such as CH4 or CO2, requires output wavelengths in the IR-B, which can be addressed by optical-parametric frequency conversion. An OPO/OPA frequency conversion setup was designed and built as a demonstration module to address the 1.6-μm range. The pump laser is an Nd:YAG-MOPA system, consisting of a stable oscillator and two subsequent Innoslab-based amplifier stages that deliver up to 500 mJ of output pulse energy at 100 Hz repetition frequency. The OPO is inherited from the OPO design for the CH4 lidar instrument on the French-German climate satellite methane remote-sensing lidar mission (MERLIN). To address the 100-mJ regime, the OPO output beam is amplified in a subsequent multistage OPA. With potassium titanyl phosphate as nonlinear medium, the OPO/OPA delivered more than 100 mJ of output energy at 1645 nm from 450 mJ of the pump energy and a pump pulse duration of 30 ns. This corresponds to a quantum conversion efficiency of about 25%. In addition to demonstrating optical performance for future lidar systems, this laser will be part of a laser-induced damage thresholds test facility, which will be used to qualify optical components especially for the MERLIN.

Comparison of Two Independent LIDAR-Based Pitch Control Designs

Energy Technology Data Exchange (ETDEWEB)

Dunne, F.; Schlipf, D.; Pao, L. Y.

2012-08-01

Two different lidar-based feedforward controllers have previously been designed for the NREL 5 MW wind turbine model under separate studies. Feedforward controller A uses a finite-impulse-response design, with 5 seconds of preview, and three rotating lidar measurements. Feedforward controller B uses a static-gain design, with the preview time defined by the pitch actuator dynamics, a simulation of a real nacelle-based scanning lidar system, and a lowpass filter defined by the lidar configuration. These controllers are now directly compared under the same lidar configuration, in terms of fatigue load reduction, rotor speed regulation, and power capture. The various differences in design choices are discussed and compared. We also compare frequency plots of individual pitch feedforward and collective pitch feedforward load reductions, and we see that individual pitch feedforward is effective mainly at the once-per-revolution and twice-per-revolution frequencies. We also explain how to determine the required preview time by breaking it down into separate parts, and we then compare it to the expected preview time available.

Pointing Verification Method for Spaceborne Lidars

Directory of Open Access Journals (Sweden)

Axel Amediek

2017-01-01

Full Text Available High precision acquisition of atmospheric parameters from the air or space by means of lidar requires accurate knowledge of laser pointing. Discrepancies between the assumed and actual pointing can introduce large errors due to the Doppler effect or a wrongly assumed air pressure at ground level. In this paper, a method for precisely quantifying these discrepancies for airborne and spaceborne lidar systems is presented. The method is based on the comparison of ground elevations derived from the lidar ranging data with high-resolution topography data obtained from a digital elevation model and allows for the derivation of the lateral and longitudinal deviation of the laser beam propagation direction. The applicability of the technique is demonstrated by using experimental data from an airborne lidar system, confirming that geo-referencing of the lidar ground spot trace with an uncertainty of less than 10 m with respect to the used digital elevation model (DEM can be obtained.

Unidirectional ring-laser operation using sum-frequency mixing

DEFF Research Database (Denmark)

Tidemand-Lichtenberg, Peter; Cheng, Haynes Pak Hay; Pedersen, Christian

2010-01-01

A technique enforcing unidirectional operation of ring lasers is proposed and demonstrated. The approach relies on sum-frequency mixing between a single-pass laser and one of the two counterpropagating intracavity fields of the ring laser. Sum-frequency mixing introduces a parametric loss for the...... where lossless second-order nonlinear materials are available. Numerical modeling and experimental demonstration of parametric-induced unidirectional operation of a diode-pumped solid-state 1342 nm cw ring laser are presented.......A technique enforcing unidirectional operation of ring lasers is proposed and demonstrated. The approach relies on sum-frequency mixing between a single-pass laser and one of the two counterpropagating intracavity fields of the ring laser. Sum-frequency mixing introduces a parametric loss...

Telescope aperture optimization for spacebased coherent wind lidar

Science.gov (United States)

Ge, Xian-ying; Zhu, Jun; Cao, Qipeng; Zhang, Yinchao; Yin, Huan; Dong, Xiaojing; Wang, Chao; Zhang, Yongchao; Zhang, Ning

2015-08-01

Many studies have indicated that the optimum measurement approach for winds from space is a pulsed coherent wind lidar, which is an active remote sensing tool with the characteristics that high spatial and temporal resolutions, real-time detection, high mobility, facilitated control and so on. Because of the significant eye safety, efficiency, size, and lifetime advantage, 2μm wavelength solid-state laser lidar systems have attracted much attention in spacebased wind lidar plans. In this paper, the theory of coherent detection is presented and a 2μm wavelength solid-state laser lidar system is introduced, then the ideal aperture is calculated from signal-to-noise(SNR) view at orbit 400km. However, considering real application, even if the lidar hardware is perfectly aligned, the directional jitter of laser beam, the attitude change of the lidar in the long round trip time of the light from the atmosphere and other factors can bring misalignment angle. So the influence of misalignment angle is considered and calculated, and the optimum telescope diameter(0.45m) is obtained as the misalignment angle is 4 μrad. By the analysis of the optimum aperture required for spacebased coherent wind lidar system, we try to present the design guidance for the telescope.

SAR and LIDAR fusion: experiments and applications

Science.gov (United States)

Edwards, Matthew C.; Zaugg, Evan C.; Bradley, Joshua P.; Bowden, Ryan D.

2013-05-01

In recent years ARTEMIS, Inc. has developed a series of compact, versatile Synthetic Aperture Radar (SAR) systems which have been operated on a variety of small manned and unmanned aircraft. The multi-frequency-band SlimSAR has demonstrated a variety of capabilities including maritime and littoral target detection, ground moving target indication, polarimetry, interferometry, change detection, and foliage penetration. ARTEMIS also continues to build upon the radar's capabilities through fusion with other sensors, such as electro-optical and infrared camera gimbals and light detection and ranging (LIDAR) devices. In this paper we focus on experiments and applications employing SAR and LIDAR fusion. LIDAR is similar to radar in that it transmits a signal which, after being reflected or scattered by a target area, is recorded by the sensor. The differences are that a LIDAR uses a laser as a transmitter and optical sensors as a receiver, and the wavelengths used exhibit a very different scattering phenomenology than the microwaves used in radar, making SAR and LIDAR good complementary technologies. LIDAR is used in many applications including agriculture, archeology, geo-science, and surveying. Some typical data products include digital elevation maps of a target area and features and shapes extracted from the data. A set of experiments conducted to demonstrate the fusion of SAR and LIDAR data include a LIDAR DEM used in accurately processing the SAR data of a high relief area (mountainous, urban). Also, feature extraction is used in improving geolocation accuracy of the SAR and LIDAR data.

Linear models for airborne-laser-scanning-based operational forest inventory with small field sample size and highly correlated LiDAR data

Science.gov (United States)

Junttila, Virpi; Kauranne, Tuomo; Finley, Andrew O.; Bradford, John B.

2015-01-01

Modern operational forest inventory often uses remotely sensed data that cover the whole inventory area to produce spatially explicit estimates of forest properties through statistical models. The data obtained by airborne light detection and ranging (LiDAR) correlate well with many forest inventory variables, such as the tree height, the timber volume, and the biomass. To construct an accurate model over thousands of hectares, LiDAR data must be supplemented with several hundred field sample measurements of forest inventory variables. This can be costly and time consuming. Different LiDAR-data-based and spatial-data-based sampling designs can reduce the number of field sample plots needed. However, problems arising from the features of the LiDAR data, such as a large number of predictors compared with the sample size (overfitting) or a strong correlation among predictors (multicollinearity), may decrease the accuracy and precision of the estimates and predictions. To overcome these problems, a Bayesian linear model with the singular value decomposition of predictors, combined with regularization, is proposed. The model performance in predicting different forest inventory variables is verified in ten inventory areas from two continents, where the number of field sample plots is reduced using different sampling designs. The results show that, with an appropriate field plot selection strategy and the proposed linear model, the total relative error of the predicted forest inventory variables is only 5%–15% larger using 50 field sample plots than the error of a linear model estimated with several hundred field sample plots when we sum up the error due to both the model noise variance and the model’s lack of fit.

The study on the lidar's detection limit for Iodine Gas

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong-lyul; Baik, Seung-Hoon; Park, Seung-Kyu; Park, Nak-Gyu; Ahn, Yong-Jin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-05-15

A powerful and reliable tool for range-resolved remote sensing of gas concentrations that has proven its capabilities in a variety of studies is the differential absorption lidar (DIAL). Differential absorption lidar (DIAL) is frequently used for atmospheric gas monitoring to detect impurities such as nitrogen dioxide, sulfur dioxide, iodine, and ozone. DIAL can measure air pollutant concentrations with a high spatial resolution by adopting two laser systems with different degrees of absorption between the two different wavelengths. The absorption of the reference wavelength is very weak, while the absorption of the other wavelength is very strong. In this paper, we measured the limit of detection capability of our designed DIAL system. The DIAL measurements were performed using a target iodine cell in the laboratory. We confirmed that the concentration of iodine gas ratio increased after the laser passed through the iodine cell. The system of DIAL(Differential Absorption Lidar) was effective to detect the iodine gas. We obtained the signals from the iodine target cell and the lidar signal from the iodine target cell was proportional to frequency locking ratios.

Balloonborne lidar payloads for remote sensing

Science.gov (United States)

Shepherd, O.; Aurilio, G.; Hurd, A. G.; Rappaport, S. A.; Reidy, W. P.; Rieder, R. J.; Bedo, D. E.; Swirbalus, R. A.

1994-02-01

A series of lidar experiments has been conducted using the Atmospheric Balloonborne Lidar Experiment payload (ABLE). These experiments included the measurement of atmospheric Rayleigh and Mie backscatter from near space (approximately 30 km) and Raman backscatter measurements of atmospheric constituents as a function of altitude. The ABLE payload consisted of a frequency-tripled Nd:YAG laser transmitter, a 50 cm receiver telescope, and filtered photodetectors in various focal plane configurations. The payload for lidar pointing, thermal control, data handling, and remote control of the lidar system. Comparison of ABLE performance with that of a space lidar shows significant performance advantages and cost effectiveness for balloonborne lidar systems.

Detection of biological warfare agents using ultra violet-laser induced fluorescence LIDAR.

Science.gov (United States)

Joshi, Deepti; Kumar, Deepak; Maini, Anil K; Sharma, Ramesh C

2013-08-01

This review has been written to highlight the threat of biological warfare agents, their types and detection. Bacterial biological agent Bacillus anthracis (bacteria causing the disease anthrax) which is most likely to be employed in biological warfare is being discussed in detail. Standoff detection of biological warfare agents in aerosol form using Ultra violet-Laser Induced Fluorescence (UV-LIF) spectroscopy method has been studied. Range-resolved detection and identification of biological aerosols by both nano-second and non-linear femto-second LIDAR is also discussed. Calculated received fluorescence signal for a cloud of typical biological agent Bacillus globigii (Simulants of B. anthracis) at a location of ~5.0 km at different concentrations in presence of solar background radiation has been described. Overview of current research efforts in internationally available working UV-LIF LIDAR systems are also mentioned briefly. Copyright © 2013 Elsevier B.V. All rights reserved.

Water vapor spectroscopy in the 815-nm wavelength region for Differential Absorption Lidar measurements

Science.gov (United States)

Ponsardin, Patrick; Browell, Edward V.

1995-01-01

The differential absorption lidar (DIAL) technique was first applied to the remote measurement of atmospheric water vapor profiles from airborne platforms in 1981. The successful interpretation of the lidar profiles relies strongly on an accurate knowledge of specific water vapor absorption line parameters: line strength, pressure broadening coefficient, pressure-induced shift coefficient and the respective temperature-dependence factors. NASA Langley Research Center has developed and is currently testing an autonomous airborne water vapor lidar system: LASE (Lidar Atmospheric Sensing Experiment). This DIAL system uses a Nd:YAG-pumped Ti:Sapphire laser seeded by a diode laser as a lidar transmitter. The tunable diode has been selected to operate in the 813-818 nm wavelength region. This 5-nm spectral interval offers a large distribution of strengths for temperature-insensitive water vapor absorption lines. In support of the LASE project, a series of spectroscopic measurements were conducted for the 16 absorption lines that have been identified for use in the LASE measurements. Prior to this work, the experimental data for this water vapor absorption band were limited - to our knowledge - to the line strengths and to the line positions.

Quasi-CW Laser Diode Bar Life Tests

Science.gov (United States)

Stephen, Mark A.; Krainak, Michael A.; Dallas, Joseph L.

1997-01-01

NASA's Goddard Space Flight Center is developing technology for satellite-based, high peak power, LIDAR transmitters requiring 3-5 years of reliable operation. Semi-conductor laser diodes provide high efficiency pumping of solid state lasers with the promise of long-lived, reliable operation. 100-watt quasi- CW laser diode bars have been baselined for the next generation laser altimeters. Multi-billion shot lifetimes are required. The authors have monitored the performance of several diodes for billions of shots and investigated operational modes for improving diode lifetime.

Innovative LIDAR 3D Dynamic Measurement System to estimate fruit-tree leaf area.

Science.gov (United States)

Sanz-Cortiella, Ricardo; Llorens-Calveras, Jordi; Escolà, Alexandre; Arnó-Satorra, Jaume; Ribes-Dasi, Manel; Masip-Vilalta, Joan; Camp, Ferran; Gràcia-Aguilá, Felip; Solanelles-Batlle, Francesc; Planas-DeMartí, Santiago; Pallejà-Cabré, Tomàs; Palacin-Roca, Jordi; Gregorio-Lopez, Eduard; Del-Moral-Martínez, Ignacio; Rosell-Polo, Joan R

2011-01-01

In this work, a LIDAR-based 3D Dynamic Measurement System is presented and evaluated for the geometric characterization of tree crops. Using this measurement system, trees were scanned from two opposing sides to obtain two three-dimensional point clouds. After registration of the point clouds, a simple and easily obtainable parameter is the number of impacts received by the scanned vegetation. The work in this study is based on the hypothesis of the existence of a linear relationship between the number of impacts of the LIDAR sensor laser beam on the vegetation and the tree leaf area. Tests performed under laboratory conditions using an ornamental tree and, subsequently, in a pear tree orchard demonstrate the correct operation of the measurement system presented in this paper. The results from both the laboratory and field tests confirm the initial hypothesis and the 3D Dynamic Measurement System is validated in field operation. This opens the door to new lines of research centred on the geometric characterization of tree crops in the field of agriculture and, more specifically, in precision fruit growing.

Integrated remote sensing and visualization (IRSV) system for transportation infrastructure operations and management, phase two, volume 3 : advanced consideration in LiDAR technology for bridge evaluation.

Science.gov (United States)

2012-03-01

This report describes Phase Two enhancement of terrestrial LiDAR scanning for bridge damage : evaluation that was initially developed in Phase One. Considering the spatial and reflectivity : information contained in LiDAR scans, two detection algorit...

Laser remote sensing of water vapor: Raman lidar development

International Nuclear Information System (INIS)

Goldsmith, J.E.M.; Lapp, M.; Bisson, S.E.; Melfi, S.H.; Whiteman, D.N.; Ferrare, R.A.; Evans, K.D.

1994-01-01

The goal of this research is the development of a critical design for a Raman lidar system optimized to match ARM Program needs for profiling atmospheric water vapor at CART sites. This work has emphasized the development of enhanced daytime capabilities using Raman lidar techniques. This abstract touches briefly on the main components of the research program, summarizing results of the efforts. A detailed Raman lidar instrument model has been developed to predict the daytime and nighttime performance capabilities of Raman lidar systems. The model simulates key characteristics of the lidar system, using realistic atmospheric profiles, modeled background sky radiance, and lidar system parameters based on current instrument capabilities. The model is used to guide development of lidar systems based on both the solar-blind concept and the narrowband, narrow field-of-view concept for daytime optimization

Scanning, Multibeam, Single Photon Lidars for Rapid, Large Scale, High Resolution, Topographic and Bathymetric Mapping

Directory of Open Access Journals (Sweden)

John J. Degnan

2016-11-01

Full Text Available Several scanning, single photon sensitive, 3D imaging lidars are herein described that operate at aircraft above ground levels (AGLs between 1 and 11 km, and speeds in excess of 200 knots. With 100 beamlets and laser fire rates up to 60 kHz, we, at the Sigma Space Corporation (Lanham, MD, USA, have interrogated up to 6 million ground pixels per second, all of which can record multiple returns from volumetric scatterers such as tree canopies. High range resolution has been achieved through the use of subnanosecond laser pulsewidths, detectors and timing receivers. The systems are presently being deployed on a variety of aircraft to demonstrate their utility in multiple applications including large scale surveying, bathymetry, forestry, etc. Efficient noise filters, suitable for near realtime imaging, have been shown to effectively eliminate the solar background during daytime operations. Geolocation elevation errors measured to date are at the subdecimeter level. Key differences between our Single Photon Lidars, and competing Geiger Mode lidars are also discussed.

5 V Compatible Two-Axis PZT Driven MEMS Scanning Mirror with Mechanical Leverage Structure for Miniature LiDAR Application.

Science.gov (United States)

Ye, Liangchen; Zhang, Gaofei; You, Zheng

2017-03-05

The MEMS (Micro-Electronical Mechanical System) scanning mirror is an optical MEMS device that can scan laser beams across one or two dimensions. MEMS scanning mirrors can be applied in a variety of applications, such as laser display, bio-medical imaging and Light Detection and Ranging (LiDAR). These commercial applications have recently created a great demand for low-driving-voltage and low-power MEMS mirrors. However, no reported two-axis MEMS scanning mirror is available for usage in a universal supplying voltage such as 5 V. In this paper, we present an ultra-low voltage driven two-axis MEMS scanning mirror which is 5 V compatible. In order to realize low voltage and low power, a two-axis MEMS scanning mirror with mechanical leverage driven by PZT (Lead zirconate titanate) ceramic is designed, modeled, fabricated and characterized. To further decrease the power of the MEMS scanning mirror, a new method of impedance matching for PZT ceramic driven by a two-frequency mixed signal is established. As experimental results show, this MEMS scanning mirror reaches a two-axis scanning angle of 41.9° × 40.3° at a total driving voltage of 4.2 Vpp and total power of 16 mW. The effective diameter of reflection of the mirror is 2 mm and the operating frequencies of two-axis scanning are 947.51 Hz and 1464.66 Hz, respectively.

High energy, single frequency, tunable laser source operating in burst mode for space based lidar applications

Science.gov (United States)

Cosentino, Alberto; Mondello, Alessia; Sapia, Adalberto; D'Ottavi, Alessandro; Brotini, Mauro; Gironi, Gianna; Suetta, Enrico

2017-11-01

This paper describes energetic, spatial, temporal and spectral characterization measurements of the Engineering Qualification Model (EQM) of the Laser Transmitter Assembly (TXA) used in the ALADIN instrument currently under development for the ESA ADM-AEOLUS mission (EADS Astrium as prime contractor for the satellite and the instrument). The EQM is equivalent to the Flight Model, with the exception of some engineering grade components. The Laser Transmitter Assembly, based on a diode pumped tripled Nd:YAG laser, is used to generate laser pulses at a nominal wavelength of 355 nm. This laser is operated in burst mode, with a pulse repetition cycle of 100 Hz during bursts. It is capable to operate in Single Longitudinal Mode and to be tuned over 25 GHz range. An internal "network" of sensors has been implemented inside the laser architecture to allow "in flight" monitoring of transmitter. Energy in excess of 100 mJ, with a spatial beam quality factor (M2) lower than 3, a spectral linewidth less than 50 MHz with a frequency stability better than 4 MHz on short term period have been measured on the EQM. Most of the obtained results are well within the expected values and match the Instrument requirements. They constitute an important achievement, showing the absence of major critical areas in terms of performance and the capability to obtain them in a rugged and compact structure suitable for space applications. The EQM will be submitted in the near future to an Environmental test campaign.

Lidar technologies for airborne and space-based applications

International Nuclear Information System (INIS)

Henson, T.D.; Schmitt, R.L.; Sobering, T.J.; Raymond, T.D.; Stephenson, D.A.

1994-10-01

This study identifies technologies required to extend the capabilities of airborne light detection and ranging (lidar) systems and establish the feasibility of autonomous space-based lidars. Work focused on technologies that enable the development of a lightweight, low power, rugged and autonomous Differential Absorption Lidar (DIAL) instruments. Applications for airborne or space-based DIAL include the measurement of water vapor profiles in support of climate research and processing-plant emissions signatures for environmental and nonproliferation monitoring. A computer-based lidar performance model was developed to allow trade studies to be performed on various technologies and system configurations. It combines input from the physics (absorption line strengths and locations) of the problem, the system requirements (weight, power, volume, accuracy), and the critical technologies available (detectors, lasers, filters) to produce the best conceptual design. Conceptual designs for an airborne and space-based water vapor DIAL, and a detailed design of a ground-based water vapor DIAL demonstration system were completed. Future work planned includes the final testing, integration, and operation of the demonstration system to prove the capability of the critical enabling technologies identified

Optimum efficiency lidar sensing of multilayer hydrometeors through a turbid atmosphere

Science.gov (United States)

Evgenieva, Ts T.; Gurdev, L. L.

2018-03-01

The detected lidar return power is a basic factor determining the brightness of the detected lidar images and the signal-to-noise ratio (SNR) of a given measurement. At equal other characteristics, the laser radiation wavelength should influence the lidar return signal and assume an optimum value depending on the specificity of the objects investigated. As such a problem had not been considered systematically, we recently began developing a modeling approach to solving it, based on evaluating the mean and the noisy lidar profiles and the SNR profile of the measurement along the lidar line of sight by using the lidar equation and well known realistic models of the atmospheric objects and background. The main purpose of the present work is to estimate by numerical modeling the detectability of the lidar return from different distances and multilayer cirrus clouds, depending on the laser radiation wavelengths. The results obtained confirm the expectations that at a higher atmospheric turbidity, a relatively higher sensing efficiency (return power) is achievable by longer-wavelength laser radiation, within the NIR range.

Uncertainty of power curve measurement with a two-beam nacelle-mounted lidar

DEFF Research Database (Denmark)

Wagner, Rozenn; Courtney, Michael Stephen; Friis Pedersen, Troels

2015-01-01

Nacelle lidars are attractive for offshore measurements since they can provide measurements of the free wind speed in front of the turbine rotor without erecting a met mast, which significantly reduces the cost of the measurements. Nacelle-mounted pulsed lidars with two lines of sight (LOS) have...... lies between 1 and 2% for the wind speed range between cut-in and rated wind speed. Finally, the lidar was mounted on the nacelle of a wind turbine in order to perform a power curve measurement. The wind speed was simultaneously measured with a mast-top mounted cup anemometer placed two rotor diameters...... lidar was less than 10% larger on average than that obtained with the mast mounted cup anemometer. Copyright © 2015 John Wiley & Sons, Ltd....

Lidar to lidar calibration phase 1

DEFF Research Database (Denmark)

Yordanova, Ginka; Courtney, Michael

This report presents a feasibility study of a lidar to lidar (L2L) calibration procedure. Phase one of the project was conducted at Høvsøre, Denmark. Two windcubes were placed next to the 116m met mast and different methods were applied to obtain the sensing height error of the lidars. The purpose...... is to find the most consistent method and use it in a potential lidar to lidar calibration procedure....

New lidar challenges for gas hazard management in industrial environments

Science.gov (United States)

Cézard, Nicolas; Liméry, Anasthase; Bertrand, Johan; Le Méhauté, Simon; Benoit, Philippe; Fleury, Didier; Goular, Didier; Planchat, Christophe; Valla, Matthieu; Augère, Béatrice; Dolfi-Bouteyre, Agnès.

2017-10-01

The capability of Lidars to perform range-resolved gas profiles makes them an appealing choice for many applications. In order to address new remote sensing challenges, arising from industrial contexts, Onera currently develops two lidar systems, one Raman and one DIAL. On the Raman side, a high spatial-resolution multi-channel Raman Lidar is developed in partnership with the French National Radioactive Waste Management Agency (Andra). This development aims at enabling future monitoring of hydrogen gas and water vapor profiles inside disposal cells containing radioactive wastes. We report on the development and first tests of a three-channel Raman Lidar (H2, H2O, N2) designed to address this issue. Simultaneous hydrogen and water vapor profiles have been successfully performed along a 5m-long gas cell with 1m resolution at a distance of 85 m. On the DIAL side, a new instrumental concept is being explored and developed in partnership with Total E and P. The objective is to perform methane plume monitoring and flux assessment in the vicinity of industrials plants or platforms. For flux assessment, both gas concentration and air speed must be profiled by lidar. Therefore, we started developing a bi-function, all-fiber, coherent DIAL/Doppler Lidar. The first challenge was to design and build an appropriate fiber laser source. The achieved demonstrator delivers 200 W peak power, polarized, spectrally narrow (<15 MHz), 110 ns pulses of light out of a monomode fiber at 1645 nm. It fulfills the requirements for a future implementation in a bi-function Dial/Doppler lidar with km-range expectation. We report on the laser and lidar architecture, and on first lidar tests at 1645 nm.

INTERACT-II campaign:comparison of commercial lidars and ceilometers with advanced multi-wavelength Raman lidars

Science.gov (United States)

Rosoldi, Marco; Madonna, Fabio; Pappalardo, Gelsomina; Vande Hey, Joshua; Zheng, Yunhui; Vaisala Team

2017-04-01

aim to improve the data consistency and comparability (D'Amico et al., 2016; Mattis et al., 2016). A first statistical analysis of simultaneous observations performed by all the instruments during the campaign reveals that ceilometers have fairly good performances in aerosol profiling in the lower troposphere, up to an altitude of about 2000 m above the ground, but they are limited at higher altitudes. Among the considered devices, the mini-MPL shows the best performances with discrepancies limited to 10 % throughout the troposphere. Further analysis is ongoing also to assess the stability of the considered lidar technologies with respect to variation of working and environment temperature, aerosol loading, laser operation.

2012 NRCS-USGS Tupelo, MS Lidar Survey

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — LiDAR data is a remotely sensed high resolution elevation data collected by an airborne platform. The LiDAR sensor uses a combination of laser range finding, GPS...

3D pulsed chaos lidar system.

Science.gov (United States)

Cheng, Chih-Hao; Chen, Chih-Ying; Chen, Jun-Da; Pan, Da-Kung; Ting, Kai-Ting; Lin, Fan-Yi

2018-04-30

We develop an unprecedented 3D pulsed chaos lidar system for potential intelligent machinery applications. Benefited from the random nature of the chaos, conventional CW chaos lidars already possess excellent anti-jamming and anti-interference capabilities and have no range ambiguity. In our system, we further employ self-homodyning and time gating to generate a pulsed homodyned chaos to boost the energy-utilization efficiency. Compared to the original chaos, we show that the pulsed homodyned chaos improves the detection SNR by more than 20 dB. With a sampling rate of just 1.25 GS/s that has a native sampling spacing of 12 cm, we successfully achieve millimeter-level accuracy and precision in ranging. Compared with two commercial lidars tested side-by-side, namely the pulsed Spectroscan and the random-modulation continuous-wave Lidar-lite, the pulsed chaos lidar that is in compliance with the class-1 eye-safe regulation shows significantly better precision and a much longer detection range up to 100 m. Moreover, by employing a 2-axis MEMS mirror for active laser scanning, we also demonstrate real-time 3D imaging with errors of less than 4 mm in depth.

Optimization of eyesafe avalanche photodiode lidar for automobile safety and autonomous navigation systems

Science.gov (United States)

Williams, George M.

2017-03-01

Newly emerging accident-reducing, driver-assistance, and autonomous-navigation technology for automobiles is based on real-time three-dimensional mapping and object detection, tracking, and classification using lidar sensors. Yet, the lack of lidar sensors suitable for meeting application requirements appreciably limits practical widespread use of lidar in trucking, public livery, consumer cars, and fleet automobiles. To address this need, a system-engineering perspective to eyesafe lidar-system design for high-level advanced driver-assistance sensor systems and a design trade study including 1.5-μm spot-scanned, line-scanned, and flash-lidar systems are presented. A cost-effective lidar instrument design is then proposed based on high-repetition-rate diode-pumped solid-state lasers and high-gain, low-excess-noise InGaAs avalanche photodiode receivers and focal plane arrays. Using probabilistic receiver-operating-characteristic analysis, derived from measured component performance, a compact lidar system is proposed that is capable of 220 m ranging with 5-cm accuracy, which can be readily scaled to a 360-deg field of regard.

Capability Assessment and Performance Metrics for the Titan Multispectral Mapping Lidar

Directory of Open Access Journals (Sweden)

Juan Carlos Fernandez-Diaz

2016-11-01

Full Text Available In this paper we present a description of a new multispectral airborne mapping light detection and ranging (lidar along with performance results obtained from two years of data collection and test campaigns. The Titan multiwave lidar is manufactured by Teledyne Optech Inc. (Toronto, ON, Canada and emits laser pulses in the 1550, 1064 and 532 nm wavelengths simultaneously through a single oscillating mirror scanner at pulse repetition frequencies (PRF that range from 50 to 300 kHz per wavelength (max combined PRF of 900 kHz. The Titan system can perform simultaneous mapping in terrestrial and very shallow water environments and its multispectral capability enables new applications, such as the production of false color active imagery derived from the lidar return intensities and the automated classification of target and land covers. Field tests and mapping projects performed over the past two years demonstrate capabilities to classify five land covers in urban environments with an accuracy of 90%, map bathymetry under more than 15 m of water, and map thick vegetation canopies at sub-meter vertical resolutions. In addition to its multispectral and performance characteristics, the Titan system is designed with several redundancies and diversity schemes that have proven to be beneficial for both operations and the improvement of data quality.

ALADIN: the first european lidar in space

Science.gov (United States)

Morançais, Didier; Fabre, Frédéric; Schillinger, Marc; Barthès, Jean-Claude; Endemann, Martin; Culoma, Alain; Durand, Yannig

2017-11-01

The Atmospheric LAser Doppler INstrument (ALADIN) is the payload of the ESA's ADMAEOLUS mission, which aims at measuring wind profiles as required by the climatology and meteorology users. ALADIN belongs to a new class of Earth Observation payloads and will be the first European Lidar in space. The instrument comprises a diode-pumped high energy Nd:YAG laser and a direct detection receiver operating on aerosol and molecular backscatter signals in parallel. In addition to the Proto- Flight Model (PFM)., two instrument models are developed: a Pre-development Model (PDM) and an Opto-Structure-Thermal Model (OSTM). The flight instrument design and the industrial team has been finalised and the major equipment are now under development. This paper describes the instrument design and performance as well as the development and verification approach. The main results obtained during the PDM programme are also reported. The ALADIN instrument is developed under prime contractorship from EADS Astrium SAS with a consortium of thirty European companies.

Lidar/DIAL detection of acetone at 3.3 μm by a tunable OPO laser system

Science.gov (United States)

Puiu, A.; Fiorani, L.; Rosa, O.; Borelli, R.; Pistilli, M.; Palucci, A.

2014-08-01

In this paper we report, for the first time to our knowledge, on lidar/DIAL detection of acetone vapors at 3.3 μm by means of an optical parametric tunable laser system. After a preliminary spectroscopic study in an absorption cell, the feasibility of a differential absorption (DIAL) lidar for the detection of acetone vapors has been investigated in the laboratory, simulating the experimental conditions of a field campaign. Having in mind measurements in a real scenario, a study of possible atmospheric intereferents has been performed, looking for all known compounds that share acetone IR absorption in the spectral band selected for its detection. Possible interfering species from urban and industrial atmospheres were investigated and limits of acetone detection in both environments were identified. This study confirmed that a lidar system can detect a low concentration of acetone at considerable distances.

Continuous anti-Stokes Raman laser operation

International Nuclear Information System (INIS)

Feitisch, A.; Muller, T.; Welling, H.; Wellegehausen, B.

1988-01-01

The anti-Stokes Raman laser (ASRL) process has proved to be a method that works well for frequency upconversion and for the generation of powerful tunable narrowband (pulsed) laser radiation in the UV and VUV spectral range. This conversion process allows large-frequency shifts in single step, high output energies, and high efficiencies. A basic requirement is population inversion on a two-photon transition, where, in general, the upper level of the transition should be metastable. Up to now the ASRL technique has only been demonstrated for the pulsed regime, where the necessary population inversion was generated by photodissociation or inner shell photoionization. These inversion techniques, however, cannot be transferred to cw operation of an ASRL, and, therefore, other inversion techniques have to be developed. Here a novel approach for the creation of the necessary population inversion is proposed, that uses well-known cw gas lasers as the active material for the conversion process. The basic idea is to use either existing two-photon population inversions in a cw laser material or to generate the necessary population inversion by applying a suitable population transfer process to the material. A natural two-photon inversion situation in a laser material is evident whenever a cascade laser can be operated. Cascade laser-based anti-Stokes schemes are possible in a He-Ne laser discharge, and investigations of these schemes are discussed

LOSA-M3: multi-wave polarization scanning lidar for research of the troposphere and cirrus clouds

Science.gov (United States)

Kokhanenko, G. P.; Balin, Yu. S.; Klemasheva, M. G.; Penner, I. E.; Nasonov, S. V.; Samoilova, S. V.

2017-11-01

Lidar is designed to study the aerosol fields of the troposphere and the polarization characteristics of crystal clouds. Two laser wavelengths are used - 1064 and 532 nm, elastic scattering signals and spontaneous Raman scattering of nitrogen (607 nm) are recorded. Lidar is made in a mobile version, allowing its transportation by road and working under expeditionary conditions. The lidar transceiver is placed on a scanning column, which allows to change the direction of sounding within the upper hemisphere at a speed of 1 degree per second. The polarization characteristics of the transmitter and receiver can be changed by rotating the phase plates synchronously with the the laser pulses. In combination with conical scanning of the lidar, this makes it possible to detect the anisotropy of scattering and the possible azimuthal orientation of the crystal particles.

Helicopter Flight Test of 3-D Imaging Flash LIDAR Technology for Safe, Autonomous, and Precise Planetary Landing

Science.gov (United States)

Roback, Vincent; Bulyshev, Alexander; Amzajerdian, Farzin; Reisse, Robert

2013-01-01

Two flash lidars, integrated from a number of cutting-edge components from industry and NASA, are lab characterized and flight tested for determination of maximum operational range under the Autonomous Landing and Hazard Avoidance Technology (ALHAT) project (in its fourth development and field test cycle) which is seeking to develop a guidance, navigation, and control (GN&C) and sensing system based on lidar technology capable of enabling safe, precise crewed or robotic landings in challenging terrain on planetary bodies under any ambient lighting conditions. The flash lidars incorporate pioneering 3-D imaging cameras based on Indium-Gallium-Arsenide Avalanche Photo Diode (InGaAs APD) and novel micro-electronic technology for a 128 x 128 pixel array operating at 30 Hz, high pulse-energy 1.06 micrometer Nd:YAG lasers, and high performance transmitter and receiver fixed and zoom optics. The two flash lidars are characterized on the NASA-Langley Research Center (LaRC) Sensor Test Range, integrated with other portions of the ALHAT GN&C system from partner organizations into an instrument pod at NASA-JPL, integrated onto an Erickson Aircrane Helicopter at NASA-Dryden, and flight tested at the Edwards AFB Rogers dry lakebed over a field of human-made geometric hazards during the summer of 2010. Results show that the maximum operational range goal of 1 km is met and exceeded up to a value of 1.2 km. In addition, calibrated 3-D images of several hazards are acquired in real-time for later reconstruction into Digital Elevation Maps (DEM's).

Radiometric Calibration of a Dual-Wavelength, Full-Waveform Terrestrial Lidar.

Science.gov (United States)

Li, Zhan; Jupp, David L B; Strahler, Alan H; Schaaf, Crystal B; Howe, Glenn; Hewawasam, Kuravi; Douglas, Ewan S; Chakrabarti, Supriya; Cook, Timothy A; Paynter, Ian; Saenz, Edward J; Schaefer, Michael

2016-03-02

Radiometric calibration of the Dual-Wavelength Echidna(®) Lidar (DWEL), a full-waveform terrestrial laser scanner with two simultaneously-pulsing infrared lasers at 1064 nm and 1548 nm, provides accurate dual-wavelength apparent reflectance (ρ(app)), a physically-defined value that is related to the radiative and structural characteristics of scanned targets and independent of range and instrument optics and electronics. The errors of ρ(app) are 8.1% for 1064 nm and 6.4% for 1548 nm. A sensitivity analysis shows that ρ(app) error is dominated by range errors at near ranges, but by lidar intensity errors at far ranges. Our semi-empirical model for radiometric calibration combines a generalized logistic function to explicitly model telescopic effects due to defocusing of return signals at near range with a negative exponential function to model the fall-off of return intensity with range. Accurate values of ρ(app) from the radiometric calibration improve the quantification of vegetation structure, facilitate the comparison and coupling of lidar datasets from different instruments, campaigns or wavelengths and advance the utilization of bi- and multi-spectral information added to 3D scans by novel spectral lidars.

Water vapour and wind measurements by a two micron space lidar

Science.gov (United States)

Ghibaudo, J.-B.; Labandibar, J.-Y.

2018-04-01

AEROSPATIALE presents the main results of the feasibility study under ESA contract on a coherent 2μm lidar instrument capable of measuring water vapour and wind velocity in the planetary boundary layer. The selected instrument configuration and the associated performance are provided, and the main critical subsystems identified (laser configuration, coherent receiver chain architecture, frequency locking and offsetting architecture. The second phase of this study is dedicated to breadboard the most critical elements of such an instrument in order to technologically consolidate its feasibility.

Aerosol and cloud sensing with the Lidar In-space Technology Experiment (LITE)

Science.gov (United States)

Winker, D. M.; McCormick, M. P.

1994-01-01

The Lidar In-space Technology Experiment (LITE) is a multi-wavelength backscatter lidar developed by NASA Langley Research Center to fly on the Space Shuttle. The LITE instrument is built around a three-wavelength ND:YAG laser and a 1-meter diameter telescope. The laser operates at 10 Hz and produces about 500 mJ per pulse at 1064 nm and 532 nm, and 150 mJ per pulse at 355 nm. The objective of the LITE program is to develop the engineering processes required for space lidar and to demonstrate applications of space-based lidar to remote sensing of the atmosphere. The LITE instrument was designed to study a wide range of cloud and aerosol phenomena. To this end, a comprehensive program of scientific investigations has been planned for the upcoming mission. Simulations of on-orbit performance show the instrument has sufficient sensitivity to detect even thin cirrus on a single-shot basis. Signal averaging provides the capability of measuring the height and structure of the planetary boundary layer, aerosols in the free troposphere, the stratospheric aerosol layer, and density profiles to an altitude of 40 km. The instrument has successfully completed a ground-test phase and is scheduled to fly on the Space Shuttle Discovery for a 9-day mission in September 1994.

Development of an advanced Two-Micron triple-pulse IPDA lidar for carbon dioxide and water vapor measurements

Science.gov (United States)

Petros, Mulugeta; Refaat, Tamer F.; Singh, Upendra N.; Yu, Jirong; Antill, Charles; Remus, Ruben; Taylor, Bryant D.; Wong, Teh-Hwa; Reithmaier, Karl; Lee, Jane; Ismail, Syed; Davis, Kenneth J.

2018-04-01

An advanced airborne triple-pulse 2-μm integrated path differential absorption (IPDA) lidar is under development at NASA Langley Research Center that targets both carbon dioxide (CO2) and water vapor (H2O) measurements simultaneously and independently. This lidar is an upgrade to the successfully demonstrated CO2 2-μm double-pulse IPDA. Upgrades include high-energy, highrepetition rate 2-μm triple-pulse laser transmitter, innovative wavelength control and advanced HgCdTe (MCT) electron-initiated avalanche photodiode detection system. Ground testing and airborne validation plans are presented.

A Raman Lidar as Operational Tool for Long-Term Water Vapor, Temperature and Aerosol Profiling in the Swiss Meteorological Office

Science.gov (United States)

Simeonov, Dr; Dinoev, Dr; Serikov, Dr; Calpini, Dr; Bobrovnikov, Dr; Arshinov, Dr; Ristori, Dr; van den Bergh, Dr; Parlange, Dr

2010-09-01

To satisfy the rising demands on the quality and frequency of atmospheric water vapor, temperature and aerosol measurements used for numerical weather prediction models, climate change observations and special events (volcanoes, dust and smoke transport) monitoring, MeteoSwiss decided to implement a lidar at his main aerological station in Payerne. The instrument is narrow field of view, narrowband UV Raman lidar designed for continuous day and night operational profiling of tropospheric water vapor, aerosol and temperature The lidar was developed and built by the Swiss Federal Institute of Technology- Lausanne (EPFL) within a joint project with MeteoSwiss. To satisfy the requirements for operational exploitation in a meteorological network the lidar had to satisfy a number of criteria, the most important of which are: accuracy and precision, traceability of the measurement, long-term data consistency, long-term system stability, automated operation, requiring minimal maintenance by a technician, and eye safety. All this requirements were taken into account during the design phase of the lidar. After a ten months test phase of the lidar at Payerne it has been in regular operation since August 2008. Selected data illustrating interesting atmospheric phenomena captured by the lidar as well as long-term intercomparison with collocated microwave radiometer, GPS, radiosonding and an airborne DIAL will be presented and discussed. The talk will address also the technical availability, alignment and calibration stabilities of the instrument.

The transformation of optical bistability effect and of generated pulses in operation of a DFB laser with two sections

International Nuclear Information System (INIS)

Nguyen Van Phu; Dinh Van Hoang

2005-01-01

In this paper is presented the transformation of characteristics of optical bistability effect and of generated pulses in operation of a DFB laser with two sections. By solving the rate equations describing the operation of this laser the appearance of optical bistability effect in stationary regime and of short pulses in transient regime is obtained. With the variation of dynamical laser parameter we can evaluate the transformation indicated above. The method of examination used here is simple for determining the influence of any dynamical laser parameter on characteristics of optical bistability effect and generated pulses. (author)

Advances in High Energy Solid-State Pulsed 2-Micron Lidar Development for Ground and Airborne Wind, Water Vapor and CO2 Measurements

Science.gov (United States)

Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Kavaya, Michael J.; Remus, Ruben

2015-01-01

NASA Langley Research Center has a long history of developing 2-micron lasers. From fundamental spectroscopy research, theoretical prediction of new materials, laser demonstration and engineering of lidar systems, it has been a very successful program spanning around two decades. Successful development of 2-micron lasers has led to development of a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement with an unprecedented laser pulse energy of 250 millijoules in a rugged package. This high pulse energy is produced by a Ho:Tm:LuLiF laser with an optical amplifier. While the lidar is meant for use as an airborne instrument, ground-based tests were carried out to characterize performance of the lidar. Atmospheric measurements will be presented, showing the lidar's capability for wind measurement in the atmospheric boundary layer and free troposphere. Lidar wind measurements are compared to a balloon sonde, showing good agreement between the two sensors. Similar architecture has been used to develop a high energy, Ho:Tm:YLF double-pulsed 2-micron Integrated Differential Absorption Lidar (IPDA) instrument based on direct detection technique that provides atmospheric column CO2 measurements. This instrument has been successfully used to measure atmospheric CO2 column density initially from a ground mobile lidar trailer, and then it was integrated on B-200 plane and 20 hours of flight measurement were made from an altitude ranging 1500 meters to 8000 meters. These measurements were compared to in-situ measurements and National Oceanic and Atmospheric Administration (NOAA) airborne flask measurement to derive the dry mixing ratio of the column CO2 by reflecting the signal by various reflecting surfaces such as land, vegetation, ocean surface, snow and sand. The lidar measurements when compared showed a very agreement with in-situ and airborne flask measurement. NASA Langley Research Center is currently developing a

Triple-Pulse Integrated Path Differential Absorption Lidar for Carbon Dioxide Measurement - Novel Lidar Technologies and Techniques with Path to Space

Science.gov (United States)

Singh, Upendra N.; Refaat, Tamer F.; Petros, Mulugeta

2017-01-01

The societal benefits of understanding climate change through identification of global carbon dioxide sources and sinks led to the desired NASA's active sensing of carbon dioxide emissions over nights, days, and seasons (ASCENDS) space-based missions of global carbon dioxide measurements. For more than 15 years, NASA Langley Research Center (LaRC) have developed several carbon dioxide active remote sensors using the differential absorption lidar (DIAL) technique operating at the two-micron wavelength. Currently, an airborne two-micron triple-pulse integrated path differential absorption (IPDA) lidar is under development. This IPDA lidar measures carbon dioxide as well as water vapor, the dominant interfering molecule on carbon dioxide remote sensing. Advancement of this triple-pulse IPDA lidar development is presented.

Raman Lidar for Meteorological Observations, RALMO – Part 1: Instrument description

Directory of Open Access Journals (Sweden)

T. Dinoev

2013-05-01

Full Text Available A new Raman lidar for unattended, round-the-clock measurement of vertical water vapor profiles for operational use by the MeteoSwiss has been developed during the past years by the Swiss Federal Institute of Technology, Lausanne. The lidar uses narrow field-of-view, narrowband configuration, a UV laser, and four 30 cm in diameter mirrors, fiber-coupled to a grating polychromator. The optical design allows water vapor retrieval from the incomplete overlap region without instrument-specific range-dependent corrections. The daytime vertical range covers the mid-troposphere, whereas the nighttime range extends to the tropopause. The near range coverage is extended down to 100 m AGL by the use of an additional fiber in one of the telescopes. This paper describes the system layout and technical realization. Day- and nighttime lidar profiles compared to Vaisala RS92 and Snow White® profiles and a six-day continuous observation are presented as an illustration of the lidar measurement capability.

An All-Fiber, Modular, Compact Wind Lidar for Wind Sensing and Wake Vortex Applications

Science.gov (United States)

Prasad, Narasimha S.; Sibell, Russ; Vetorino, Steve; Higgins, Richard; Tracy, Allen

2015-01-01

This paper discusses an innovative, compact and eyesafe coherent lidar system developed for wind and wake vortex sensing applications. With an innovative all-fiber and modular transceiver architecture, the wind lidar system has reduced size, weight and power requirements, and provides enhanced performance along with operational elegance. This all-fiber architecture is developed around fiber seed laser coupled to uniquely configured fiber amplifier modules. The innovative features of this lidar system, besides its all fiber architecture, include pulsewidth agility and user programmable 3D hemispherical scanner unit. Operating at a wavelength of 1.5457 microns and with a PRF of up to 20 KHz, the lidar transmitter system is designed as a Class 1 system with dimensions of 30"(W) x 46"(L) x 60"(H). With an operational range exceeding 10 km, the wind lidar is configured to measure wind velocities of greater than 120 m/s with an accuracy of +/- 0.2 m/s and allow range resolution of less than 15 m. The dynamical configuration capability of transmitted pulsewidths from 50 ns to 400 ns allows high resolution wake vortex measurements. The scanner uses innovative liquid metal slip ring and is built using 3D printer technology with light weight nylon. As such, it provides continuous 360 degree azimuth and 180 degree elevation scan angles with an incremental motion of 0.001 degree. The lidar system is air cooled and requires 110 V for its operation. This compact and modular lidar system is anticipated to provide mobility, reliability, and ease of field deployment for wind and wake vortex measurements. Currently, this wind lidar is undergoing validation tests under various atmospheric conditions. Preliminary results of these field measurements of wind characteristics that were recently carried out in Colorado are discussed.

Digital operation and eye diagrams in spin-lasers

International Nuclear Information System (INIS)

Wasner, Evan; Bearden, Sean; Žutić, Igor; Lee, Jeongsu

2015-01-01

Digital operation of lasers with injected spin-polarized carriers provides an improved operation over their conventional counterparts with spin-unpolarized carriers. Such spin-lasers can attain much higher bit rates, crucial for optical communication systems. The overall quality of a digital signal in these two types of lasers is compared using eye diagrams and quantified by improved Q-factors and bit-error-rates in spin-lasers. Surprisingly, an optimal performance of spin-lasers requires finite, not infinite, spin-relaxation times, giving a guidance for the design of future spin-lasers

BUILDING EDGE DETECTION USING SMALL-FOOTPRINT AIRBORNE FULL-WAVEFORM LIDAR DATA

Directory of Open Access Journals (Sweden)

J.-C. Michelin

2012-07-01

Full Text Available The full-waveform lidar technology allows a complete access to the information related to the emitted and backscattered laser signals. Although most of the common applications of full-waveform lidar are currently dedicated to the study of forested areas, some recent studies have shown that airborne full-waveform data is relevant for urban area analysis. We extend the field to pattern recognition with a focus on retrieval. Our proposed approach combines two steps. In a first time, building edges are coarsely extracted. Then, a physical model based on the lidar equation is used to retrieve a more accurate position of the estimated edge than the size of the lidar footprint. Another consequence is the estimation of more accurate planimetric positions of the extracted echoes.

An Aerosol Extinction-to-Backscatter Ratio Database Derived from the NASA Micro-Pulse Lidar Network: Applications for Space-based Lidar Observations

Science.gov (United States)

Welton, Ellsworth J.; Campbell, James R.; Spinhime, James D.; Berkoff, Timothy A.; Holben, Brent; Tsay, Si-Chee; Bucholtz, Anthony

2004-01-01

Backscatter lidar signals are a function of both backscatter and extinction. Hence, these lidar observations alone cannot separate the two quantities. The aerosol extinction-to-backscatter ratio, S, is the key parameter required to accurately retrieve extinction and optical depth from backscatter lidar observations of aerosol layers. S is commonly defined as 4*pi divided by the product of the single scatter albedo and the phase function at 180-degree scattering angle. Values of S for different aerosol types are not well known, and are even more difficult to determine when aerosols become mixed. Here we present a new lidar-sunphotometer S database derived from Observations of the NASA Micro-Pulse Lidar Network (MPLNET). MPLNET is a growing worldwide network of eye-safe backscatter lidars co-located with sunphotometers in the NASA Aerosol Robotic Network (AERONET). Values of S for different aerosol species and geographic regions will be presented. A framework for constructing an S look-up table will be shown. Look-up tables of S are needed to calculate aerosol extinction and optical depth from space-based lidar observations in the absence of co-located AOD data. Applications for using the new S look-up table to reprocess aerosol products from NASA's Geoscience Laser Altimeter System (GLAS) will be discussed.

LIDAR for atmosphere research over Africa

CSIR Research Space (South Africa)

Sivakumar, V

2008-11-01

Full Text Available d’aéronomie, CNRS, Paris, France 1Email: SVenkataraman@csir.co.za – www.csir.co.za K-6665 [www.kashangroup.com] Lidar for atmospheric studies: The CSIR’s laser research into monitoring various pollutants in the lower atmosphere via... to lidar applications for atmosphere studies including pollutant monitoring. The following salient features emanated from the survey: • Around 80% of the lidars are in the northern hemisphere • Of the 20% in the southern hemisphere region...

THE RAILMAPPER – A DEDICATED MOBILE LIDAR MAPPING SYSTEM FOR RAILWAY NETWORKS

Directory of Open Access Journals (Sweden)

J. Kremer

2012-07-01

Full Text Available The Mobile LiDAR Mapping System StreetMapper from IGI and 3D Laser Mapping (Bingham Nottingham, UK is mounted on a large variety of road vehicles to cover different mission specifications. In addition to the operation on the road, the system finds its applications on other kinds of vehicles, like boats or trains. The modular and flexible system concept even allows utilizing the same LiDAR Mapping system for Mobile Mapping on the ground and for airborne missions on helicopters, respectively. Besides this general flexibility, each application has its own special requirements. Special hardware and software components are needed to complete the core components, like the laser scanner and the GNSS/IMU systems, to build a dedicated system for the chosen task. Compared to the typical dynamics of a road vehicle mounted Mobile Mapping system, a dedicated rail mapping system operates under conditions that are much more challenging for a high accuracy GNSS/IMU trajectory determination. Furthermore, the typical rail mapping tasks, like the exact measurement of the rail track geometry, require the operation of the most accurate laser scanners and of specialized post-processing software. In this paper, the RailMapper, a specialized Mobile Mapping system for railway surveys is presented. The system is described with focus on the railway specific requirements and results of practical surveys are given.

Development of atmospheric polarization LIDAR System

International Nuclear Information System (INIS)

Ghalumyan, A.S.; Ghazaryan, V.R.

2016-01-01

LIDAR (Light Detection And Ranging) system sensitive to the polarization of the backscattered signal is being developed in Yerevan Physics Institute. The system is designed primarily for remote sensing of the atmospheric electric fields. At present, the system is being tuned for measuring vertical atmospheric backscatter profiles of aerosols and hydrometeors, analyze the depolarization ratio of elastic backscattered laser beams and investigate the influence of external factors on the beam polarization. In this paper, we describe the complete LIDAR system – the laser transmitter, receiving telescope and the polarization separator. The data acquisition and processing techniques are also described. (author)

Alexandrite Lidar Receiver

National Research Council Canada - National Science Library

Wilkerson, Thomas

2000-01-01

...". The chosen vendor, Orca Photonics, In. (Redmond, WA), in close collaboration with USU personnel, built a portable, computerized lidar system that not only is suitable as a receiver for a near IR alexandrite laser, but also contains an independent Nd...

2003 Oahu Coastline Lidar

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. Using a combination of laser rangefinding, GPS positioning...

Temporal correlation measurements of pulsed dual CO2 lidar returns. [for atmospheric pollution detection

Science.gov (United States)

Menyuk, N.; Killinger, D. K.

1981-01-01

A pulsed dual-laser direct-detection differential-absorption lidar DIAL system, operating near 10.6 microns, is used to measure the temporal correlation and statistical properties of backscattered returns from specular and diffuse topographic targets. Results show that atmospheric-turbulence fluctuations can effectively be frozen for pulse separation times on the order of 1-3 msec or less. The diffuse target returns, however, yielded a much lower correlation than that obtained with the specular targets; this being due to uncorrelated system noise effects and different statistics for the two types of target returns.

Laser scan of the Grimming Mts. (Austria) with the latest LiDAR VZ-4000 equipment: preliminary results

Science.gov (United States)

Bauer, Harald; Hatzenbichler, Georg; Amon, Philipp; Fallah, Mohammad; Tari, Gabor; Grasemann, Bernhard

2013-04-01

As part of a cooperation project between OMV, RIEGL and the University of Vienna the new LiDAR (Light Detection and Ranging) VZ-4000 laser scanner was tested at the Grimming Mts. of the Eastern Alps in Austria. The prominent Grimming Mts. lies in the eastern part of the Dachstein Massif at the southern margin of the Northern Calcareous Alps. The Grimming, with a peak of 2,351 m above sea level, is one of the highest isolated mountains in Europe. Because of its spectacular topography, the Grimming has been used as an important surface reference mark since 1822. From a structural geology standpoint, the Grimming forms a huge antiform made up of dominantly well-bedded Triassic Dachstein Limestone. Because of the relatively well exposed bedrock surfaces above the tree-line and the fairly complex internal structure, the Grimming Mts. provides an ideal target for testing new high resolution laser scan techniques and devices. The maximum distance from the scanning positions on the nearby valley floor to the mountain face was about 4,500 m and the generated point cloud has an average resolution of 25 points per square meter. The purpose of this work was to test the latest version of the high resolution LiDAR laser equipment in a setting which falls beyond the capabilities of most existing LiDAR devices. The results of the pilot study include high-resolution spatial data on bedding planes, fault planes and the thickness variations of individual beds within the Dachstein Limestone. For the first time, the data obtained can be directly used to generate the proper 3D geometry of folds and faults observed on the Grimming Mts. This leads to a modern understanding of this prominent Alpine anticline in terms of structural geology.

Theory of CW lidar aerosol backscatter measurements and development of a 2.1 microns solid-state pulsed laser radar for aerosol backscatter profiling

Science.gov (United States)

Kavaya, Michael J.; Henderson, Sammy W.; Frehlich, R. G.

1991-01-01

The performance and calibration of a focused, continuous wave, coherent detection CO2 lidar operated for the measurement of atmospheric backscatter coefficient, B(m), was examined. This instrument functions by transmitting infrared (10 micron) light into the atmosphere and collecting the light which is scattered in the rearward direction. Two distinct modes of operation were considered. In volume mode, the scattered light energy from many aerosols is detected simultaneously, whereas in the single particle mode (SPM), the scattered light energy from a single aerosol is detected. The analysis considered possible sources of error for each of these two cases, and also considered the conditions where each technique would have superior performance. The analysis showed that, within reasonable assumptions, the value of B(m) could be accurately measured by either the VM or the SPM method. The understanding of the theory developed during the analysis was also applied to a pulsed CO2 lidar. Preliminary results of field testing of a solid state 2 micron lidar using a CW oscillator is included.

Airborne and Ground-Based Measurements Using a High-Performance Raman Lidar

Science.gov (United States)

Whiteman, David N.; Rush, Kurt; Rabenhorst, Scott; Welch, Wayne; Cadirola, Martin; McIntire, Gerry; Russo, Felicita; Adam, Mariana; Venable, Demetrius; Connell, Rasheen;

Lidar system for air-pollution monitoring over urban areas

Science.gov (United States)

Moskalenko, Irina V.; Shcheglov, Djolinard A.; Molodtsov, Nikolai A.

1997-05-01

The atmospheric environmental situation over the urban area of a large city is determined by a complex combination of anthropogenic pollution and meteorological factors. The efficient way to provide three-dimensional mapping of gaseous pollutants over wide areas is utilization of lidar systems employing tunable narrowband transmitters. The paper presented describes activity of RRC 'Kurchatov Institute' in the field of lidar atmospheric monitoring. The project 'mobile remote sensing system based on tunable laser transmitter for environmental monitoring' is developed under financial support of International Scientific and Technology Center (Moscow). The objective of the project is design, construction and field testing of a DIAL-technique system. The lidar transmitter consists of an excimer laser pumping dye laser, BBO crystal frequency doubler, and scanning flat mirror. Sulfur dioxide and atomic mercury have been selected as pollutants for field tests of the lidar system under development. A recent large increase in Moscow traffic stimulated taking into consideration also the remote sensing of lower troposphere ozone because of the photochemical smog problem. The status of the project is briefly discussed. The current activity includes also collecting of environmental data relevant to lidar remote sensing. Main attention is paid to pollutant concentration levels over Moscow city and Moscow district areas.

A Study on Factors Affecting Airborne LiDAR Penetration

Directory of Open Access Journals (Sweden)

Wei-Chen Hsu

2015-01-01

Full Text Available This study uses data from different periods, areas and parameters of airborne LiDAR (light detection and ranging surveys to understand the factors that influence airborne LiDAR penetration rate. A discussion is presented on the relationships between these factors and LiDAR penetration rate. The results show that the flight height above ground level (AGL does not have any relationship with the penetration rate. There are some factors that should have larger influence. For example, the laser is affected by a wet ground surface by reducing the number of return echoes. The field of view (FOV has a slightly negative correlation with the penetration rate, which indicates that the laser incidence angle close to zero should achieve the best penetration. The vegetation cover rate also shows a negative correlation with the penetration rate, thus bare ground and reduced vegetation in the aftermath of a typhoon also cause high penetration rate. More return echoes could be extracted from the full-waveform system, thereby effectively improving the penetration rate. This study shows that full-waveform LiDAR is an effective method for increasing the number of surface reflected echoes. This study suggests avoiding LiDAR survey employment directly following precipitation to prevent laser echo reduction.

Lidar/DIAL detection of acetone at 3.3 μm by a tunable OPO laser system

International Nuclear Information System (INIS)

Puiu, A; Fiorani, L; Borelli, R; Pistilli, M; Palucci, A; Rosa, O

2014-01-01

In this paper we report, for the first time to our knowledge, on lidar/DIAL detection of acetone vapors at 3.3 μm by means of an optical parametric tunable laser system. After a preliminary spectroscopic study in an absorption cell, the feasibility of a differential absorption (DIAL) lidar for the detection of acetone vapors has been investigated in the laboratory, simulating the experimental conditions of a field campaign. Having in mind measurements in a real scenario, a study of possible atmospheric intereferents has been performed, looking for all known compounds that share acetone IR absorption in the spectral band selected for its detection. Possible interfering species from urban and industrial atmospheres were investigated and limits of acetone detection in both environments were identified. This study confirmed that a lidar system can detect a low concentration of acetone at considerable distances. (paper)

Upgrade of the MAGIC telescopes single wavelength micro power LIDAR system

Energy Technology Data Exchange (ETDEWEB)

Mueller, Dominik [Max-Planck-Institut fuer Physik, Muenchen (Germany); Collaboration: MAGIC-Collaboration

2016-07-01

Since 2011 a single wavelength LIDAR system is operated alongside the observations of the MAGIC telescopes. It is used for real-time monitoring of the atmospheric transmission and for detecting cloud layers within the field of view of MAGIC. The system uses a pulsed Nd:YAG laser with 532 nm wavelength and a pulse energy of 5 μJ as transmitter. The receiver is mounted to a 60 cm spherical single mirror telescope with a F/D ratio of 2.5. To compensate for the low light intensities a sensitive detector with the capability of single photon detection as well as charge integration is needed. For this purpose, a hybrid photo diode with a peak quantum efficiency of 55% an a pulse width of 2.5ns is used in a custom designed detector. The analog signal is recorded by a computer mounted 8-bit FADC with 200 MS/s. A signal analysis algorithm converts the LIDAR return signal into a number of single photoelectron counts per range bin. The atmospheric transmission is calculated by fitting a Rayleigh back-scattering model with a sliding window. The resulting transmission profile is used to correct the MAGIC gamma ray data for adverse weather conditions. After five years of data taking the MAGIC LIDAR system is upgraded with a stronger laser and a new detector unit in order to extend the measurement range and to optimize the operation.

Nonlinear filtering for LIDAR signal processing

Directory of Open Access Journals (Sweden)

D. G. Lainiotis

1996-01-01

Full Text Available LIDAR (Laser Integrated Radar is an engineering problem of great practical importance in environmental monitoring sciences. Signal processing for LIDAR applications involves highly nonlinear models and consequently nonlinear filtering. Optimal nonlinear filters, however, are practically unrealizable. In this paper, the Lainiotis's multi-model partitioning methodology and the related approximate but effective nonlinear filtering algorithms are reviewed and applied to LIDAR signal processing. Extensive simulation and performance evaluation of the multi-model partitioning approach and its application to LIDAR signal processing shows that the nonlinear partitioning methods are very effective and significantly superior to the nonlinear extended Kalman filter (EKF, which has been the standard nonlinear filter in past engineering applications.

Highly-reliable laser diodes and modules for spaceborne applications

Science.gov (United States)

Deichsel, E.

2017-11-01

Laser applications become more and more interesting in contemporary missions such as earth observations or optical communication in space. One of these applications is light detection and ranging (LIDAR), which comprises huge scientific potential in future missions. The Nd:YAG solid-state laser of such a LIDAR system is optically pumped using 808nm emitting pump sources based on semiconductor laser-diodes in quasi-continuous wave (qcw) operation. Therefore reliable and efficient laser diodes with increased output powers are an important requirement for a spaceborne LIDAR-system. In the past, many tests were performed regarding the performance and life-time of such laser-diodes. There were also studies for spaceborne applications, but a test with long operation times at high powers and statistical relevance is pending. Other applications, such as science packages (e.g. Raman-spectroscopy) on planetary rovers require also reliable high-power light sources. Typically fiber-coupled laser diode modules are used for such applications. Besides high reliability and life-time, designs compatible to the harsh environmental conditions must be taken in account. Mechanical loads, such as shock or strong vibration are expected due to take-off or landing procedures. Many temperature cycles with high change rates and differences must be taken in account due to sun-shadow effects in planetary orbits. Cosmic radiation has strong impact on optical components and must also be taken in account. Last, a hermetic sealing must be considered, since vacuum can have disadvantageous effects on optoelectronics components.

Lidar investigations of atmospheric aerosols over Sofia

International Nuclear Information System (INIS)

Dreischuh, T.; Deleva, A.; Peshev, Z.; Grigorov, I.; Kolarov, G.; Stoyanov, D.

2016-01-01

An overview is given of the laser remote sensing of atmospheric aerosols and related processes over the Sofia area performed in the Institute of Electronics, Bulgarian Academy of Sciences, during the last three years. Results from lidar investigations of the optical characteristics of atmospheric aerosols obtained in the frame of the European Aerosol Research Lidar Network, as well as from the lidar mapping of near-surface aerosol fields for remote monitoring of atmospheric pollutants are presented and discussed in this paper.

Research on the space-borne coherent wind lidar technique and the prototype experiment

Science.gov (United States)

Gao, Long; Tao, Yuliang; An, Chao; Yang, Jukui; Du, Guojun; Zheng, Yongchao

2016-10-01

Space-borne coherent wind lidar technique is considered as one of the most promising and appropriate remote Sensing methods for successfully measuring the whole global vector wind profile between the lower atmosphere and the middle atmosphere. Compared with other traditional methods, the space-borne coherent wind lidar has some advantages, such as, the all-day operation; many lidar systems can be integrated into the same satellite because of the light-weight and the small size, eye-safe wavelength, and being insensitive to the background light. Therefore, this coherent lidar could be widely applied into the earth climate research, disaster monitoring, numerical weather forecast, environment protection. In this paper, the 2μm space-borne coherent wind lidar system for measuring the vector wind profile is proposed. And the technical parameters about the sub-system of the coherent wind lidar are simulated and the all sub-system schemes are proposed. For sake of validating the technical parameters of the space-borne coherent wind lidar system and the optical off-axis telescope, the weak laser signal detection technique, etc. The proto-type coherent wind lidar is produced and the experiments for checking the performance of this proto-type coherent wind lidar are finished with the hard-target and the soft target, and the horizontal wind and the vertical wind profile are measured and calibrated, respectively. For this proto-type coherent wind lidar, the wavelength is 1.54μm, the pulse energy 80μJ, the pulse width 300ns, the diameter of the off-axis telescope 120mm, the single wedge for cone scanning with the 40°angle, and the two dualbalanced InGaAs detector modules are used. The experiment results are well consisted with the simulation process, and these results show that the wind profile between the vertical altitude 4km can be measured, the accuracy of the wind velocity and the wind direction are better than 1m/s and +/-10°, respectively.

Installation report - Lidar

DEFF Research Database (Denmark)

Georgieva Yankova, Ginka; Villanueva, Héctor

The report describes the installation, configuration and data transfer for the ground-based lidar. The unit is provided by a customer but is installed and operated by DTU while in this project.......The report describes the installation, configuration and data transfer for the ground-based lidar. The unit is provided by a customer but is installed and operated by DTU while in this project....

2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement

Science.gov (United States)

Singh, Upendra N.; Bai, Yingxin; Yu, Jirong

2009-01-01

Carbon dioxide (CO2) has been recognized as one of the most important greenhouse gases. It is essential for the study of global warming to accurately measure the CO2 concentration in the atmosphere and continuously record its variation. A high repetition rate, highly efficient, Q-switched 2-micron laser system as the transmitter of a coherent differential absorption lidar for CO2 measurement has been developed in NASA Langley Research Center. This laser system is capable of making a vertical profiling of CO2 from ground and column measurement of CO2 from air and space-borne platform. The transmitter is a master-slave laser system. The master laser operates in a single frequency, either on-line or off-line of a selected CO2 absorption line. The slave laser is a Q-switched ring-cavity Ho:YLF laser which is pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz. The injection seeding success rate is from 99.4% to 99.95%. For 1 kHz operation, the output pulse energy is 5.5mJ with the pulse length of 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. A Ho:YLF laser operating in the range of 2.05 micrometers can be tuned over several characteristic lines of CO2 absorption. Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of CO2 with a repetition rate of 5 Hz and pulse energy of 75 mJ. For coherent detection, high repetition rate is required for speckle averaging to obtain highly precise measurements. However, a diode pumped Ho:Tm:YLF laser can not operate in high repetition rate due to the large heat loading and up-conversion. A Tm:fiber laser pumped Ho:YLF laser with low heat loading can operate in high repetition rate. A theoretical model has been established to simulate the performance of Tm:fiber laser pumped Ho:YLF lasers. For continuous wave (CW) operation, high pump intensity with small beam

Atmospheric lidar: Legal, scientific and technological aspects

International Nuclear Information System (INIS)

Barbini, R.; Colao, F.; Fiorani, L.; Palucci, A.

2000-01-01

The Atmospheric Lidar is one of the systems of the Mobile Laboratory of Laser Remote Sensing under development at the ENEA Research Center of Frascati. This technical report addresses the legislative, scientific and technological aspects that are the basis for the identification of the requirements, the definition of the architecture and the fixation of the specifications of the Atmospheric Lidar. The problems of air pollution are introduced in section 2. A summary of the Italian laws on that topic is then given. Section 4 provides a survey of the atmospheric measurements that can be achieved with the lidar. The sensitivity in the monitoring of pollutants is discussed in section 5. The other systems of the Mobile Laboratory of Laser Remote Sensing are shortly described in section 6. The last section is devoted to conclusions and perspectives [it

Mineralogy and Astrobiology Detection Using Laser Remote Sensing Instrument

Science.gov (United States)

Abedin, M. Nurul; Bradley, Arthur T.; Sharma, Shiv K.; Misra, Anupam K.; Lucey, Paul G.; Mckay, Chistopher P.; Ismail, Syed; Sandford, Stephen P.

2015-01-01

A multispectral instrument based on Raman, laser-induced fluorescence (LIF), laser-induced breakdown spectroscopy (LIBS), and a lidar system provides high-fidelity scientific investigations, scientific input, and science operation constraints in the context of planetary field campaigns with the Jupiter Europa Robotic Lander and Mars Sample Return mission opportunities. This instrument conducts scientific investigations analogous to investigations anticipated for missions to Mars and Jupiter's icy moons. This combined multispectral instrument is capable of performing Raman and fluorescence spectroscopy out to a >100 m target distance from the rover system and provides single-wavelength atmospheric profiling over long ranges (>20 km). In this article, we will reveal integrated remote Raman, LIF, and lidar technologies for use in robotic and lander-based planetary remote sensing applications. Discussions are focused on recently developed Raman, LIF, and lidar systems in addition to emphasizing surface water ice, surface and subsurface minerals, organics, biogenic, biomarker identification, atmospheric aerosols and clouds distributions, i.e., near-field atmospheric thin layers detection for next robotic-lander based instruments to measure all the above-mentioned parameters. OCIS codes: (120.0280) Remote sensing and sensors; (130.0250) Optoelectronics; (280.3640) Lidar; (300.2530) Fluorescence, laser-induced; (300.6450) Spectroscopy, Raman; (300.6365) Spectroscopy, laser induced breakdown

Eye safety report 2 (355 nm). Human risk analysis simulator for space lidars

International Nuclear Information System (INIS)

Schulmeister, K.; Mellerio, J.; Sonneck, G.

2001-09-01

This report contains the results of a risk study for a satellite based lidar mission that uses a laser in the ultraviolet wavelength range to measure atmospheric properties. A lidar can be considered as a laser radar and is an acronym for light detection and ranging. The lidar measures properties of the atmosphere by analysis of laser radiation that is directed back to the lidar. As only part of the laser radiation is scattered or absorbed by the atmosphere, the remaining laser radiation emitted from the spacecraft is incident on the earth's surface, where it might lead to injuries, especially to the eye, if biological thresholds are exceeded. For the analysed mission there is no hazard to the skin, only a potential one to the eye, but only if ocular exposure occurs with very large telescopes. The wavelength of the laser is 355 nm, which is absorbed by the cornea and lens of the eye. That is, it is not focussed onto the retina of the eye as, for instance, visible wavelengths, and therefore comparatively high levels of laser exposure, are needed to produce an injury in the lens and cornea. Because the footprint of the satellite's laser beam on the surface of the earth is so small and it moves so fast, the chance of the naked eye being exposed to the laser is small. Because of the magnification provided by an optical instrument, and the concomitant reduction in the field of view, the probability of exposure of an eye that is using such an instrument decreases with increasing optical power. However, because an increased optical power implies increased diameter of the light gathering optics, the laser energy delivered to an eye increases with instrument size so that if exposure did occur, the probability of delivering energy to the eye that exceeds the thresholds for damage increases. There are thus two conflicting processes at work for viewing with optical instruments: an increase in diameter increases the energy delivered but reduces the probability of lidar beam

Coaxial direct-detection lidar-system

DEFF Research Database (Denmark)

2014-01-01

The invention relates to a coaxial direct-detection LIDAR system for measuring velocity, temperature and/or particulate density. The system comprises a laser source for emitting a laser light beam having a lasing center frequency along an emission path. The system further comprises an optical....... Finally, the system comprises a detector system arranged to receive the return signal from the optical delivery system, the detector system comprising a narrowband optical filter and a detector, the narrowband optical filter having a filter center frequency of a pass-band, wherein the center lasing...... frequency and/or the center filter frequency may be scanned. The invention further relates to an aircraft airspeed measurement device, and a wind turbine airspeed measurement device comprising the LIDAR system....

Multi-component wind measurements of wind turbine wakes performed with three LiDARs

Science.gov (United States)

Iungo, G. V.; Wu, Y.-T.; Porté-Agel, F.

2012-04-01

Field measurements of the wake flow produced from the interaction between atmospheric boundary layer and a wind turbine are performed with three wind LiDARs. The tested wind turbine is a 2 MW Enercon E-70 located in Collonges, Switzerland. First, accuracy of mean values and frequency resolution of the wind measurements are surveyed as a function of the number of laser rays emitted for each measurement. Indeed, measurements performed with one single ray allow maximizing sampling frequency, thus characterizing wake turbulence. On the other hand, if the number of emitted rays is increased accuracy of mean wind is increased due to the longer sampling period. Subsequently, two-dimensional measurements with a single LiDAR are carried out over vertical sections of the wind turbine wake and mean wake flow is obtained by averaging 2D measurements consecutively performed. The high spatial resolution of the used LiDAR allows characterizing in details velocity defect present in the central part of the wake and its downstream recovery. Single LiDAR measurements are also performed by staring the laser beam at fixed directions for a sampling period of about ten minutes and maximizing the sampling frequency in order to characterize wake turbulence. From these tests wind fluctuation peaks are detected in the wind turbine wake at blade top-tip height for different downstream locations. The magnitude of these turbulence peaks is generally reduced by moving downstream. This increased turbulence level at blade top-tip height observed for a real wind turbine has been already detected from previous wind tunnel tests and Large Eddy simulations, thus confirming the presence of a source of dangerous fatigue loads for following wind turbines within a wind farm. Furthermore, the proper characterization of wind fluctuations through LiDAR measurements is proved by the detection of the inertial subrange from spectral analysis of these velocity signals. Finally, simultaneous measurements with two

Some New Lidar Equations for Laser Pulses Scattered Back from Optically Thick Media Such as Clouds, Dense Aerosol Plumes, Sea Ice, Snow, and Turbid Coastal Waters

Science.gov (United States)

Davis, Anthony B.

2013-01-01

I survey the theoretical foundations of the slowly-but-surely emerging field of multiple scattering lidar, which has already found applications in atmospheric and cryospheric optics that I also discuss. In multiple scattering lidar, returned pulses are stretched far beyond recognition, and there is no longer a one-to-one connection between range and return-trip timing. Moreover, one can exploit the radial profile of the diffuse radiance field excited by the laser source that, by its very nature, is highly concentrated in space and collimated in direction. One needs, however, a new class of lidar equations to explore this new phenomenology. A very useful set is derived from radiative diffusion theory, which is found at the opposite asymptotic limit of radiative transfer theory than the conventional (single-scattering) limit used to derive the standard lidar equation. In particular, one can use it to show that, even if the simple time-of-flight-to-range connection is irretrievably lost, multiply-scattered lidar light can be used to restore a unique profiling capability with coarser resolution but much deeper penetration into a wide variety of optical thick media in nature. Several new applications are proposed, including a laser bathymetry technique that should work for highly turbid coastal waters.

Design and study of the performance of a Raman lidar model, combining a pulsed laser source and a holographic grating double monochromator; Realisation et etudes des performances d'une maquette de lidar Raman combinant une source laser impulsionnelle et un double monochromateur a reseaux holographiques

Energy Technology Data Exchange (ETDEWEB)

Nacass, Philippe

1976-03-16

The various techniques for the analysis of air constituents are studied briefly to help design an apparatus for detecting, localizing, identifying and measuring atmospheric pollution. The optical methods known under the name of Lidar (Light direction and ranging) appear to give good qualitative and quantitative results since they do not involve any sampling of the observed medium. Amongst these methods, the Raman laser back-scattering in which the characteristic frequency of a molecule can be isolated from those of the other constituents of air is studied in more details. The design and realization, based on the conclusions of this study, and the measurements of the performance of a Raman Lidar preliminary model are then described. Its originality lies in the use of holographic grating monochromators and the overall simplicity of operation of the system. Using this system, it was possible to make in-situ Raman back-scattering measurements on N{sub 2}, O{sub 2}, H{sub 2}O in the atmosphere and on large concentrations of CO{sub 2} at distances between 30 and 40 m, which give a reasonable estimate of the sensitivity and of the range of a full scale, more performing final design. (author) [French] En vue de la realisation d'un dispositif permettant la detection, la localisation, l'identification et le dosage a distance de la pollution atmospherique, les differentes techniques d'analyse des constituants de l'air sont etudiees rapidement. Les methodes optiques appelees Lidar (Light Detection And Ranging) paraissent les plus adaptees pour des mesures qualitatives et quantitatives, car elles ne necessitent pas de prelevement du milieu observe. Parmi ces methodes, la retrodiffusion Raman Laser, qui permet d'isoler la frequence propre caracteristique d'une molecule sans interference avec les autres constituants de l'air est etudiee plus en details. La realisation, basee sur les conclusions de cette etude, puis la mesure des performances d'une maquette preliminaire de Lidar

Efficient, space-based, PM 100W thulium fiber laser for pumping Q-switched 2μm Ho:YLF for global winds and carbon dioxide lidar

Science.gov (United States)

Engin, Doruk; Mathason, Brian; Storm, Mark

2017-08-01

Global wind measurements are critically needed to improve and extend NOAA weather forecasting that impacts U.S. economic activity such as agriculture crop production, as well as hurricane forecasting, flooding, and FEMA disaster planning.1 NASA and the 2007 National Research Council (NRC) Earth Science Decadal Study have also identified global wind measurements as critical for global change research. NASA has conducted aircraft-based wind lidar measurements using 2 um Ho:YLF lasers, which has shown that robust wind measurements can be made. Fibertek designed and demonstrated a high-efficiency, 100 W average power continuous wave (CW) 1940 nm thulium (Tm)- doped fiber laser bread-board system meeting all requirements for a NASA Earth Science spaceflight 2 μm Ho:YLF pump laser. Our preliminary design shows that it is possible to package the laser for high-reliability spaceflight operation in an ultra-compact 2″x8″x14″ size and weight <8.5 lbs. A spaceflight 100 W polarization maintaining (PM) Tm laser provides a path to space for a pulsed, Q-switched 2 μm Ho:YLF laser with 30-80 mJ/pulse range at 100-200 Hz repletion rates.

Airborne LIDAR borsight error calibration based on surface coincide

International Nuclear Information System (INIS)

Yuan, Fangyan; Li, Guoqing; Zuo, Zhengli; Li, Dong; Qi, Zengying; Qiu, Wen; Tan, Junxiang

2014-01-01

Light Detection and Ranging (LIDAR) is a system which can directly collect three-dimensional coordinate information of ground point and laser reflection strength information. With the wide application of LIDAR system, users hope to get more accurate results. Boresight error has an important effect on data accuracy and thus, it is thought that eliminating the error is very important. In recent years, many methods have been proposed to eliminate the error. Generally, they can be categorized into tie point method and surface matching method. In this paper, we propose another method called try value method based on surface coincide that is used in actual production by many companies. The method is simple and operable. Further, the efficacy of the method was demonstrated by analyzing the data from Zhangye city

Helicopter Flight Test of a Compact, Real-Time 3-D Flash Lidar for Imaging Hazardous Terrain During Planetary Landing

Science.gov (United States)

Roback, VIncent E.; Amzajerdian, Farzin; Brewster, Paul F.; Barnes, Bruce W.; Kempton, Kevin S.; Reisse, Robert A.; Bulyshev, Alexander E.

2013-01-01

A second generation, compact, real-time, air-cooled 3-D imaging Flash Lidar sensor system, developed from a number of cutting-edge components from industry and NASA, is lab characterized and helicopter flight tested under the Autonomous Precision Landing and Hazard Detection and Avoidance Technology (ALHAT) project. The ALHAT project is seeking to develop a guidance, navigation, and control (GN&C) and sensing system based on lidar technology capable of enabling safe, precise crewed or robotic landings in challenging terrain on planetary bodies under any ambient lighting conditions. The Flash Lidar incorporates a 3-D imaging video camera based on Indium-Gallium-Arsenide Avalanche Photo Diode and novel micro-electronic technology for a 128 x 128 pixel array operating at a video rate of 20 Hz, a high pulse-energy 1.06 µm Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser, a remote laser safety termination system, high performance transmitter and receiver optics with one and five degrees field-of-view (FOV), enhanced onboard thermal control, as well as a compact and self-contained suite of support electronics housed in a single box and built around a PC-104 architecture to enable autonomous operations. The Flash Lidar was developed and then characterized at two NASA-Langley Research Center (LaRC) outdoor laser test range facilities both statically and dynamically, integrated with other ALHAT GN&C subsystems from partner organizations, and installed onto a Bell UH-1H Iroquois "Huey" helicopter at LaRC. The integrated system was flight tested at the NASA-Kennedy Space Center (KSC) on simulated lunar approach to a custom hazard field consisting of rocks, craters, hazardous slopes, and safe-sites near the Shuttle Landing Facility runway starting at slant ranges of 750 m. In order to evaluate different methods of achieving hazard detection, the lidar, in conjunction with the ALHAT hazard detection and GN&C system, operates in both a narrow 1deg FOV raster

Study on analysis from sources of error for Airborne LIDAR

Science.gov (United States)

Ren, H. C.; Yan, Q.; Liu, Z. J.; Zuo, Z. Q.; Xu, Q. Q.; Li, F. F.; Song, C.

2016-11-01

With the advancement of Aerial Photogrammetry, it appears that to obtain geo-spatial information of high spatial and temporal resolution provides a new technical means for Airborne LIDAR measurement techniques, with unique advantages and broad application prospects. Airborne LIDAR is increasingly becoming a new kind of space for earth observation technology, which is mounted by launching platform for aviation, accepting laser pulses to get high-precision, high-density three-dimensional coordinate point cloud data and intensity information. In this paper, we briefly demonstrates Airborne laser radar systems, and that some errors about Airborne LIDAR data sources are analyzed in detail, so the corresponding methods is put forwarded to avoid or eliminate it. Taking into account the practical application of engineering, some recommendations were developed for these designs, which has crucial theoretical and practical significance in Airborne LIDAR data processing fields.

2013 USGS Lidar: Norfolk (VA)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Laser Mapping Specialist, Inc (LMSI) and The Atlantic Group (Atlantic) provided high accuracy, calibrated multiple return LiDAR for roughly 1,130 square miles around...

Lidar signal-to-noise ratio improvements: Considerations and techniques

Science.gov (United States)

Hassebo, Yasser Y.

The primary objective of this study is to improve lidar signal-to-noise ratio (SNR) and hence extend attainable lidar ranges through reduction of the sky background noise (BGP), which dominates other sources of noise in daytime operations. This is particularly important for Raman lidar techniques where the Raman backscattered signal of interest is relatively weak compared with the elastic backscatter lidars. Two approaches for reduction of sky background noise are considered: (1) Improvements in lidar SNR by optimization of the design of the lidar receiver were examined by a series of simulations. This part of the research concentrated on biaxial lidar systems, where overlap between laser beam and receiver field of view (FOV) is an important aspect of noise considerations. The first optimized design evolved is a wedge shaped aperture. While this design has the virtue of greatly reducing background light, it is difficult to implement practically, requiring both changes in area and position with lidar range. A second more practical approach, which preserves some of the advantages of the wedge design, was also evolved. This uses a smaller area circular aperture optimally located in the image plane for desired ranges. Simulated numerical results for a biaxial lidar have shown that the best receiver parameters selection is one using a small circular aperture (field stop) with a small telescope focal length f, to ensure the minimum FOV that accepts all return signals over the entire lidar range while at the same time minimizing detected BGP and hence maximizing lidar SNR and attainable lidar ranges. The improvement in lidar SNR was up to 18%. (2) A polarization selection technique was implemented to reduce sky background signal for linearly polarized monostatic elastic backscatter lidar measurements. The technique takes advantage of naturally occurring polarization properties in scattered sky light, and then ensures that both the lidar transmitter and receiver track and

Coherent dual-frequency lidar system design for distance and speed measurements

Science.gov (United States)

Zheng, Xingyuan; Zhao, Changming; Zhang, Haiyang; Zheng, Zheng; Yang, Hongzhi

2018-01-01

Lidars have a wide range of applications in military detection and civilian remote sensing. Coherent Dual-Frequency Lidar (CDFL) is a new concept of laser radar that is using electrical coherence instead of optical coherence. It uses laser with two coherent frequency components as transmitting wave. The method is based on the use of an optically-carried radio frequency (RF) signal, which is the frequency difference between the two components, which is specially designed for distance and speed measurements. It not only ensures the system has the characteristics of high spatial resolution, high ranging and velocity precision of laser radar, but also can use mature signal processing technology of microwave radar, and it is a research direction that attracts more concern in recent years. A CDFL detection system is constructed and field experiment is carried out. In the system, a narrow linewidth fiber laser with a wavelength of 1064nm is adopted. The dual-frequency laser with frequency difference of 200MHz and 200.6MHz is obtained by acousto-optic frequency shift and recombination. The maximum output power of dual frequency laser is 200mW. The receiver consists of all-fiber balanced InGaAs photo-detector and homemade analog signal processing board. The experimental results show that the distance resolution and velocity resolution of the system are 0.1m and 0.1m/s separately when the working distance is greater than 200m, and the spatial resolution is 0.5mrad.

Differential Absorption Lidar to Measure Subhourly Variation of Tropospheric Ozone Profiles

Science.gov (United States)

Kuang, Shi; Burris, John F.; Newchurch, Michael J.; Johnson, Steve; Long, Stephania

2011-01-01

A tropospheric ozone Differential Absorption Lidar system, developed jointly by The University of Alabama in Huntsville and the National Aeronautics and Space Administration, is making regular observations of ozone vertical distributions between 1 and 8 km with two receivers under both daytime and nighttime conditions using lasers at 285 and 291 nm. This paper describes the lidar system and analysis technique with some measurement examples. An iterative aerosol correction procedure reduces the retrieval error arising from differential aerosol backscatter in the lower troposphere. Lidar observations with coincident ozonesonde flights demonstrate that the retrieval accuracy ranges from better than 10% below 4 km to better than 20% below 8 km with 750-m vertical resolution and 10-min 17 temporal integration.

CW and AO Q-switched operation of a dual-crystal Tm, Ho:GdVO4 laser pumped by two diodes

International Nuclear Information System (INIS)

Li, L J; Bai, Y F; Liu, Y W; He, Z L; Wang, J; Yao, B Q; Zhou, S; Xing, M N

2013-01-01

Continuous wave (CW) mode and acousto-optic (AO) Q-switched mode operation of a dual-crystal Tm, Ho:GdVO 4 laser is reported. The dual-crystal Tm, Ho:GdVO 4 laser with output wavelength of 2.05 μm was pumped by two laser diodes (LDs). The Tm, Ho:GdVO 4 crystals were cooled by liquid nitrogen and pumped by two fiber-coupled LDs with a center output wavelength of 801.0 nm. A 20.5 W output power was obtained at a 255 mm physical cavity length in CW mode operation, and a 19.6 W average power was obtained at a pulse repetition frequency (PRF) of 10 kHz with a 19 ns pulse duration. Also, the efficiency loss of the laser is not more than 4.4% from CW mode to Q-switch mode, and the M 2 factor, which is measured by the traveling knife-edge method, does not exceed 1.2. (paper)

Diode laser lidar wind velocity sensor using a liquid-crystal retarder for non-mechanical beam-steering

DEFF Research Database (Denmark)

Rodrigo, Peter John; Iversen, Theis Faber Quist; Hu, Qi

2014-01-01

it either transmits throughor reflects off a polarization splitter. The room-temperature switching timebetween the two LOS is measured to be in the order of 100μs in one switchdirection but 16 ms in the opposite transition. Radial wind speedmeasurement (at 33 Hz rate) while the lidar beam is repeatedly...... the lidar probe beam in two different lines-of-sight (LOS) with a 60° angular separation. Dual-LOS beam-steering isimplemented optically with no moving parts by means of a controllableliquid-crystal retarder (LCR). The LCR switches the polarization betweentwo orthogonal linear states of the lidar beam so...

Remotely measuring the wind using turbine-mounted lidars: Application to power performance testing

DEFF Research Database (Denmark)

Borraccino, Antoine

the so-called whitebox approach. It consists mainly in calibrating the lidar primary measurementsof line-of-sight velocities. The line-of-sight velocity is the projection of the wind vector onto the laser beam propagation path. The calibration is performed in situ, by comparing the lidar velocity...... measurements to a reference quantity itself traceable to the international standards of units. The uncertainty of the line-ofsight velocity measurements was assessed using a normative methodology (GUM) which is based on the law of propagation of uncertainties. The generic calibration procedure was applied...... to two commercially developed nacelle lidars systems, the Avent 5-beam Demonstrator and the ZephIR Dual Mode lidars. Further, the lineof-sight positioning quantities such as inclination angles or beam trajectory werealso calibrated and their uncertainties assessed. Calibration results were of high...

Small Imaging Depth LIDAR and DCNN-Based Localization for Automated Guided Vehicle.

Science.gov (United States)

Ito, Seigo; Hiratsuka, Shigeyoshi; Ohta, Mitsuhiko; Matsubara, Hiroyuki; Ogawa, Masaru

2018-01-10

We present our third prototype sensor and a localization method for Automated Guided Vehicles (AGVs), for which small imaging LIght Detection and Ranging (LIDAR) and fusion-based localization are fundamentally important. Our small imaging LIDAR, named the Single-Photon Avalanche Diode (SPAD) LIDAR, uses a time-of-flight method and SPAD arrays. A SPAD is a highly sensitive photodetector capable of detecting at the single-photon level, and the SPAD LIDAR has two SPAD arrays on the same chip for detection of laser light and environmental light. Therefore, the SPAD LIDAR simultaneously outputs range image data and monocular image data with the same coordinate system and does not require external calibration among outputs. As AGVs travel both indoors and outdoors with vibration, this calibration-less structure is particularly useful for AGV applications. We also introduce a fusion-based localization method, named SPAD DCNN, which uses the SPAD LIDAR and employs a Deep Convolutional Neural Network (DCNN). SPAD DCNN can fuse the outputs of the SPAD LIDAR: range image data, monocular image data and peak intensity image data. The SPAD DCNN has two outputs: the regression result of the position of the SPAD LIDAR and the classification result of the existence of a target to be approached. Our third prototype sensor and the localization method are evaluated in an indoor environment by assuming various AGV trajectories. The results show that the sensor and localization method improve the localization accuracy.

Lidar to lidar calibration of Ground-based Lidar

DEFF Research Database (Denmark)

Fernandez Garcia, Sergio; Courtney, Michael

This report presents the result of the lidar to lidar calibration performed for ground-based lidar. Calibration is here understood as the establishment of a relation between the reference lidar wind speed measurements with measurement uncertainties provided by measurement standard and corresponding...... lidar wind speed indications with associated measurement uncertainties. The lidar calibration concerns the 10 minute mean wind speed measurements. The comparison of the lidar measurements of the wind direction with that from the reference lidar measurements are given for information only....

LIDAR pulse coding for high resolution range imaging at improved refresh rate.

Science.gov (United States)

Kim, Gunzung; Park, Yongwan

2016-10-17

In this study, a light detection and ranging system (LIDAR) was designed that codes pixel location information in its laser pulses using the direct- sequence optical code division multiple access (DS-OCDMA) method in conjunction with a scanning-based microelectromechanical system (MEMS) mirror. This LIDAR can constantly measure the distance without idle listening time for the return of reflected waves because its laser pulses include pixel location information encoded by applying the DS-OCDMA. Therefore, this emits in each bearing direction without waiting for the reflected wave to return. The MEMS mirror is used to deflect and steer the coded laser pulses in the desired bearing direction. The receiver digitizes the received reflected pulses using a low-temperature-grown (LTG) indium gallium arsenide (InGaAs) based photoconductive antenna (PCA) and the time-to-digital converter (TDC) and demodulates them using the DS-OCDMA. When all of the reflected waves corresponding to the pixels forming a range image are received, the proposed LIDAR generates a point cloud based on the time-of-flight (ToF) of each reflected wave. The results of simulations performed on the proposed LIDAR are compared with simulations of existing LIDARs.

Lidar to lidar calibration

DEFF Research Database (Denmark)

Fernandez Garcia, Sergio; Villanueva, Héctor

This report presents the result of the lidar to lidar calibration performed for ground-based lidar. Calibration is here understood as the establishment of a relation between the reference lidar wind speed measurements with measurement uncertainties provided by measurement standard and corresponding...... lidar wind speed indications with associated measurement uncertainties. The lidar calibration concerns the 10 minute mean wind speed measurements. The comparison of the lidar measurements of the wind direction with that from the reference lidar measurements are given for information only....

A lidar for water vapour measurements in daytime at Lampedusa, Italy

Directory of Open Access Journals (Sweden)

F. Marenco

2003-06-01

Full Text Available ENEA is planning to develop a lidar system for measurement of the vertical profi le of water vapour mixing ratio in daytime at a remote site, the Station for Climate Observations located in Lampedusa, Italy. The Raman lidar technique has been retained because of its experimental simplicity with respect to DIAL, and the UV spectral range has been chosen because Raman cross-sections and detector effi ciencies are larger. For a wavelength larger than ~ 300 nm the signal is limited in daytime by sky background, but extinction is acceptable, and the aims of the system can be reached with a strong laser source. The 355 nm wavelength of a frequency-tripled Nd:YAG laser has been retained as this laser source permits to reach a large pulse energy while keeping the system simple to operate. Geometrical form factor calculations need to be performed to evaluate the near-range overlap between the laser beam and the fi eld-of-view of the receiver. Among several options, a dual-receiver system has been retained to account for the several orders of magnitude expected in the backscattered signal intensity: a smaller receiver, with a primary mirror of 200 mm diameter for the 0.2-1 km range, and a larger 500 mm receiver for the 1-3 km range.

Experimental Advanced Airborne Research Lidar (EAARL) Data Processing Manual

Science.gov (United States)

Bonisteel, Jamie M.; Nayegandhi, Amar; Wright, C. Wayne; Brock, John C.; Nagle, David

2009-01-01

The Experimental Advanced Airborne Research Lidar (EAARL) is an example of a Light Detection and Ranging (Lidar) system that utilizes a blue-green wavelength (532 nanometers) to determine the distance to an object. The distance is determined by recording the travel time of a transmitted pulse at the speed of light (fig. 1). This system uses raster laser scanning with full-waveform (multi-peak) resolving capabilities to measure submerged topography and adjacent coastal land elevations simultaneously (Nayegandhi and others, 2009). This document reviews procedures for the post-processing of EAARL data using the custom-built Airborne Lidar Processing System (ALPS). ALPS software was developed in an open-source programming environment operated on a Linux platform. It has the ability to combine the laser return backscatter digitized at 1-nanosecond intervals with aircraft positioning information. This solution enables the exploration and processing of the EAARL data in an interactive or batch mode. ALPS also includes modules for the creation of bare earth, canopy-top, and submerged topography Digital Elevation Models (DEMs). The EAARL system uses an Earth-centered coordinate and reference system that removes the necessity to reference submerged topography data relative to water level or tide gages (Nayegandhi and others, 2006). The EAARL system can be mounted in an array of small twin-engine aircraft that operate at 300 meters above ground level (AGL) at a speed of 60 meters per second (117 knots). While other systems strive to maximize operational depth limits, EAARL has a narrow transmit beam and receiver field of view (1.5 to 2 milliradians), which improves the depth-measurement accuracy in shallow, clear water but limits the maximum depth to about 1.5 Secchi disk depth (~20 meters) in clear water. The laser transmitter [Continuum EPO-5000 yttrium aluminum garnet (YAG)] produces up to 5,000 short-duration (1.2 nanosecond), low-power (70 microjoules) pulses each second

Improving Reliability of High Power Quasi-CW Laser Diode Arrays for Pumping Solid State Lasers

Science.gov (United States)

Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Baggott, Renee S.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.

2005-01-01

Most Lidar applications rely on moderate to high power solid state lasers to generate the required transmitted pulses. However, the reliability of solid state lasers, which can operate autonomously over long periods, is constrained by their laser diode pump arrays. Thermal cycling of the active regions is considered the primary reason for rapid degradation of the quasi-CW high power laser diode arrays, and the excessive temperature rise is the leading suspect in premature failure. The thermal issues of laser diode arrays are even more drastic for 2-micron solid state lasers which require considerably longer pump pulses compared to the more commonly used pump arrays for 1-micron lasers. This paper describes several advanced packaging techniques being employed for more efficient heat removal from the active regions of the laser diode bars. Experimental results for several high power laser diode array devices will be reported and their performance when operated at long pulsewidths of about 1msec will be described.

Beyond 3-D: The New Spectrum of Lidar Applications for Earth and Ecological Sciences

Science.gov (United States)

Eitel, Jan U. H.; Hofle, Bernhard; Vierling, Lee A.; Abellan, Antonio; Asner, Gregory P.; Deems, Jeffrey S.; Glennie, Craig L.; Joerg, Phillip C.; LeWinter, Adam L.; Magney, Troy S.;

Demystifying LiDAR technologies for temperate rainforest in the Pacific Northwest

Science.gov (United States)

Rhonda Mazza; Demetrios Gatziolis

2013-01-01

Light detection and ranging (LiDAR), also known as airborne laser scanning, is a rapidly emerging technology for remote sensing. Used to help map, monitor, and assess natural resources, LiDAR data were first embraced by forestry professionals in Scandinavia as a tool for conducting forest inventories in the mid to late 1990s. Thus early LiDAR theory and applications...

Raster Vs. Point Cloud LiDAR Data Classification

Science.gov (United States)

El-Ashmawy, N.; Shaker, A.

2014-09-01

Airborne Laser Scanning systems with light detection and ranging (LiDAR) technology is one of the fast and accurate 3D point data acquisition techniques. Generating accurate digital terrain and/or surface models (DTM/DSM) is the main application of collecting LiDAR range data. Recently, LiDAR range and intensity data have been used for land cover classification applications. Data range and Intensity, (strength of the backscattered signals measured by the LiDAR systems), are affected by the flying height, the ground elevation, scanning angle and the physical characteristics of the objects surface. These effects may lead to uneven distribution of point cloud or some gaps that may affect the classification process. Researchers have investigated the conversion of LiDAR range point data to raster image for terrain modelling. Interpolation techniques have been used to achieve the best representation of surfaces, and to fill the gaps between the LiDAR footprints. Interpolation methods are also investigated to generate LiDAR range and intensity image data for land cover classification applications. In this paper, different approach has been followed to classifying the LiDAR data (range and intensity) for land cover mapping. The methodology relies on the classification of the point cloud data based on their range and intensity and then converted the classified points into raster image. The gaps in the data are filled based on the classes of the nearest neighbour. Land cover maps are produced using two approaches using: (a) the conventional raster image data based on point interpolation; and (b) the proposed point data classification. A study area covering an urban district in Burnaby, British Colombia, Canada, is selected to compare the results of the two approaches. Five different land cover classes can be distinguished in that area: buildings, roads and parking areas, trees, low vegetation (grass), and bare soil. The results show that an improvement of around 10 % in the

Special Relativity Corrections for Space-Based Lidars

Science.gov (United States)

RaoGudimetla, Venkata S.; Kavaya, Michael J.

1999-01-01

The theory of special relativity is used to analyze some of the physical phenomena associated with space-based coherent Doppler lidars aimed at Earth and the atmosphere. Two important cases of diffuse scattering and retroreflection by lidar targets are treated. For the case of diffuse scattering, we show that for a coaligned transmitter and receiver on the moving satellite, there is no angle between transmitted and returned radiation. However, the ray that enters the receiver does not correspond to a retroreflected ray by the target. For the retroreflection case there is misalignment between the transmitted ray and the received ray. In addition, the Doppler shift in the frequency and the amount of tip for the receiver aperture when needed are calculated, The error in estimating wind because of the Doppler shift in the frequency due to special relativity effects is examined. The results are then applied to a proposed space-based pulsed coherent Doppler lidar at NASA's Marshall Space Flight Center for wind and aerosol backscatter measurements. The lidar uses an orbiting spacecraft with a pulsed laser source and measures the Doppler shift between the transmitted and the received frequencies to determine the atmospheric wind velocities. We show that the special relativity effects are small for the proposed system.

2005 Oahu/Maui Lidar Mapping Project

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. Using a combination of laser rangefinding, GPS positioning...

Software design of control system of CCD side-scatter lidar

Science.gov (United States)

Kuang, Zhiqiang; Liu, Dong; Deng, Qian; Zhang, Zhanye; Wang, Zhenzhu; Yu, Siqi; Tao, Zongming; Xie, Chenbo; Wang, Yingjian

2018-03-01

Because of the existence of blind zone and transition zone, the application of backscattering lidar in near-ground is limited. The side-scatter lidar equipped with the Charge Coupled Devices (CCD) can separate the transmitting and receiving devices to avoid the impact of the geometric factors which is exited in the backscattering lidar and, detect the more precise near-ground aerosol signals continuously. Theories of CCD side-scatter lidar and the design of control system are introduced. The visible control of laser and CCD and automatic data processing method of the side-scatter lidar are developed by using the software of Visual C #. The results which are compared with the calibration of the atmospheric aerosol lidar data show that signals from the CCD side- scatter lidar are convincible.

Automatic extraction of pavement markings on streets from point cloud data of mobile LiDAR

International Nuclear Information System (INIS)

Gao, Yang; Zhong, Ruofei; Liu, Xianlin; Tang, Tao; Wang, Liuzhao

2017-01-01

Pavement markings provide an important foundation as they help to keep roads users safe. Accurate and comprehensive information about pavement markings assists the road regulators and is useful in developing driverless technology. Mobile light detection and ranging (LiDAR) systems offer new opportunities to collect and process accurate pavement markings’ information. Mobile LiDAR systems can directly obtain the three-dimensional (3D) coordinates of an object, thus defining spatial data and the intensity of (3D) objects in a fast and efficient way. The RGB attribute information of data points can be obtained based on the panoramic camera in the system. In this paper, we present a novel method process to automatically extract pavement markings using multiple attribute information of the laser scanning point cloud from the mobile LiDAR data. This method process utilizes a differential grayscale of RGB color, laser pulse reflection intensity, and the differential intensity to identify and extract pavement markings. We utilized point cloud density to remove the noise and used morphological operations to eliminate the errors. In the application, we tested our method process on different sections of roads in Beijing, China, and Buffalo, NY, USA. The results indicated that both correctness ( p ) and completeness ( r ) were higher than 90%. The method process of this research can be applied to extract pavement markings from huge point cloud data produced by mobile LiDAR. (paper)

Automatic extraction of pavement markings on streets from point cloud data of mobile LiDAR

Science.gov (United States)

Gao, Yang; Zhong, Ruofei; Tang, Tao; Wang, Liuzhao; Liu, Xianlin

2017-08-01

Pavement markings provide an important foundation as they help to keep roads users safe. Accurate and comprehensive information about pavement markings assists the road regulators and is useful in developing driverless technology. Mobile light detection and ranging (LiDAR) systems offer new opportunities to collect and process accurate pavement markings’ information. Mobile LiDAR systems can directly obtain the three-dimensional (3D) coordinates of an object, thus defining spatial data and the intensity of (3D) objects in a fast and efficient way. The RGB attribute information of data points can be obtained based on the panoramic camera in the system. In this paper, we present a novel method process to automatically extract pavement markings using multiple attribute information of the laser scanning point cloud from the mobile LiDAR data. This method process utilizes a differential grayscale of RGB color, laser pulse reflection intensity, and the differential intensity to identify and extract pavement markings. We utilized point cloud density to remove the noise and used morphological operations to eliminate the errors. In the application, we tested our method process on different sections of roads in Beijing, China, and Buffalo, NY, USA. The results indicated that both correctness (p) and completeness (r) were higher than 90%. The method process of this research can be applied to extract pavement markings from huge point cloud data produced by mobile LiDAR.

MSFC Doppler Lidar Science experiments and operations plans for 1981 airborne test flight

Science.gov (United States)

Fichtl, G. H.; Bilbro, J. W.; Kaufman, J. W.

1981-01-01

The flight experiment and operations plans for the Doppler Lidar System (DLS) are provided. Application of DLS to the study of severe storms and local weather penomena is addressed. Test plans involve 66 hours of flight time. Plans also include ground based severe storm and local weather data acquisition.

Cloud properties derived from two lidars over the ARM SGP site

Energy Technology Data Exchange (ETDEWEB)

Dupont, Jean-Charles; Haeffelin, Martial; Morille, Y.; Comstock, Jennifer M.; Flynn, Connor J.; Long, Charles N.; Sivaraman, Chitra; Newsom, Rob K.

2011-02-16

[1] Active remote sensors such as lidars or radars can be used with other data to quantify the cloud properties at regional scale and at global scale (Dupont et al., 2009). Relative to radar, lidar remote sensing is sensitive to very thin and high clouds but has a significant limitation due to signal attenuation in the ability to precisely quantify the properties of clouds with a 20 cloud optical thickness larger than 3. In this study, 10-years of backscatter lidar signal data are analysed by a unique algorithm called STRucture of ATmosphere (STRAT, Morille et al., 2007). We apply the STRAT algorithm to data from both the collocated Micropulse lidar (MPL) and a Raman lidar (RL) at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site between 1998 and 2009. Raw backscatter lidar signal is processed and 25 corrections for detector deadtime, afterpulse, and overlap are applied. (Campbell et al.) The cloud properties for all levels of clouds are derived and distributions of cloud base height (CBH), top height (CTH), physical cloud thickness (CT), and optical thickness (COT) from local statistics are compared. The goal of this study is (1) to establish a climatology of macrophysical and optical properties for all levels of clouds observed over the ARM SGP site 30 and (2) to estimate the discrepancies induced by the two remote sensing systems (pulse energy, sampling, resolution, etc.). Our first results tend to show that the MPLs, which are the primary ARM lidars, have a distinctly limited range where all of these cloud properties are detectable, especially cloud top and cloud thickness, but even actual cloud base especially during summer daytime period. According to the comparisons between RL and MPL, almost 50% of situations show a signal to noise ratio too low (smaller than 3) for the MPL in order to detect clouds higher than 7km during daytime period in summer. Consequently, the MPLderived annual cycle of cirrus cloud base (top) altitude is

Methods from Information Extraction from LIDAR Intensity Data and Multispectral LIDAR Technology

Science.gov (United States)

Scaioni, M.; Höfle, B.; Baungarten Kersting, A. P.; Barazzetti, L.; Previtali, M.; Wujanz, D.

2018-04-01

LiDAR is a consolidated technology for topographic mapping and 3D reconstruction, which is implemented in several platforms On the other hand, the exploitation of the geometric information has been coupled by the use of laser intensity, which may provide additional data for multiple purposes. This option has been emphasized by the availability of sensors working on different wavelength, thus able to provide additional information for classification of surfaces and objects. Several applications ofmonochromatic and multi-spectral LiDAR data have been already developed in different fields: geosciences, agriculture, forestry, building and cultural heritage. The use of intensity data to extract measures of point cloud quality has been also developed. The paper would like to give an overview on the state-of-the-art of these techniques, and to present the modern technologies for the acquisition of multispectral LiDAR data. In addition, the ISPRS WG III/5 on `Information Extraction from LiDAR Intensity Data' has collected and made available a few open data sets to support scholars to do research on this field. This service is presented and data sets delivered so far as are described.

METHODS FROM INFORMATION EXTRACTION FROM LIDAR INTENSITY DATA AND MULTISPECTRAL LIDAR TECHNOLOGY

Directory of Open Access Journals (Sweden)

M. Scaioni

2018-04-01

Full Text Available LiDAR is a consolidated technology for topographic mapping and 3D reconstruction, which is implemented in several platforms On the other hand, the exploitation of the geometric information has been coupled by the use of laser intensity, which may provide additional data for multiple purposes. This option has been emphasized by the availability of sensors working on different wavelength, thus able to provide additional information for classification of surfaces and objects. Several applications ofmonochromatic and multi-spectral LiDAR data have been already developed in different fields: geosciences, agriculture, forestry, building and cultural heritage. The use of intensity data to extract measures of point cloud quality has been also developed. The paper would like to give an overview on the state-of-the-art of these techniques, and to present the modern technologies for the acquisition of multispectral LiDAR data. In addition, the ISPRS WG III/5 on ‘Information Extraction from LiDAR Intensity Data’ has collected and made available a few open data sets to support scholars to do research on this field. This service is presented and data sets delivered so far as are described.

Doppler lidar sensor for precision navigation in GPS-deprived environment

Science.gov (United States)

Amzajerdian, F.; Pierrottet, D. F.; Hines, G. D.; Petway, L. B.; Barnes, B. W.

2013-05-01

Landing mission concepts that are being developed for exploration of solar system bodies are increasingly ambitious in their implementations and objectives. Most of these missions require accurate position and velocity data during their descent phase in order to ensure safe, soft landing at the pre-designated sites. Data from the vehicle's Inertial Measurement Unit will not be sufficient due to significant drift error after extended travel time in space. Therefore, an onboard sensor is required to provide the necessary data for landing in the GPS-deprived environment of space. For this reason, NASA Langley Research Center has been developing an advanced Doppler lidar sensor capable of providing accurate and reliable data suitable for operation in the highly constrained environment of space. The Doppler lidar transmits three laser beams in different directions toward the ground. The signal from each beam provides the platform velocity and range to the ground along the laser line-of-sight (LOS). The six LOS measurements are then combined in order to determine the three components of the vehicle velocity vector, and to accurately measure altitude and attitude angles relative to the local ground. These measurements are used by an autonomous Guidance, Navigation, and Control system to accurately navigate the vehicle from a few kilometers above the ground to the designated location and to execute a gentle touchdown. A prototype version of our lidar sensor has been completed for a closed-loop demonstration onboard a rocket-powered terrestrial free-flyer vehicle.

Lidar sounding of volcanic plumes

Science.gov (United States)

Fiorani, Luca; Aiuppa, Alessandro; Angelini, Federico; Borelli, Rodolfo; Del Franco, Mario; Murra, Daniele; Pistilli, Marco; Puiu, Adriana; Santoro, Simone

2013-10-01

Accurate knowledge of gas composition in volcanic plumes has high scientific and societal value. On the one hand, it gives information on the geophysical processes taking place inside volcanos; on the other hand, it provides alert on possible eruptions. For this reasons, it has been suggested to monitor volcanic plumes by lidar. In particular, one of the aims of the FP7 ERC project BRIDGE is the measurement of CO2 concentration in volcanic gases by differential absorption lidar. This is a very challenging task due to the harsh environment, the narrowness and weakness of the CO2 absorption lines and the difficulty to procure a suitable laser source. This paper, after a review on remote sensing of volcanic plumes, reports on the current progress of the lidar system.

2006 FEMA Lidar: Rhode Island Coastline

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. By positioning laser range finding with the use of 1...

Studies on Ytterbium-doped Fibre Laser Operating in Different Regimes

International Nuclear Information System (INIS)

Gan, Y; Xiang, W H; Zhang, G Z

2006-01-01

An ytterbium-doped fibre laser with a unidirectional ring cavity containing a polarizer placed between two in-line polarization controllers is presented. Depending on an equivalent saturable absorber, this laser operates in continuous, Q-switched mode-locked or CW mode-locked regimes. The passive method described here allowed us to choose the operating regime of the fibre laser by rotating the two polarization controllers and adjusting the pump power. Results of numerical simulations of pulse propagation in such a mode-locked fibre ring laser are presented, which reveals that the Q-switched mode-locked or CW modelocked regimes can be achieved by aligning the polarizer near the slow or the fast axes of the fibre

Dimensionless parameterization of lidar for laser remote sensing of the atmosphere and its application to systems with SiPM and PMT detectors.

Science.gov (United States)

Agishev, Ravil; Comerón, Adolfo; Rodriguez, Alejandro; Sicard, Michaël

2014-05-20

In this paper, we show a renewed approach to the generalized methodology for atmospheric lidar assessment, which uses the dimensionless parameterization as a core component. It is based on a series of our previous works where the problem of universal parameterization over many lidar technologies were described and analyzed from different points of view. The modernized dimensionless parameterization concept applied to relatively new silicon photomultiplier detectors (SiPMs) and traditional photomultiplier (PMT) detectors for remote-sensing instruments allowed predicting the lidar receiver performance with sky background available. The renewed approach can be widely used to evaluate a broad range of lidar system capabilities for a variety of lidar remote-sensing applications as well as to serve as a basis for selection of appropriate lidar system parameters for a specific application. Such a modernized methodology provides a generalized, uniform, and objective approach for evaluation of a broad range of lidar types and systems (aerosol, Raman, DIAL) operating on different targets (backscatter or topographic) and under intense sky background conditions. It can be used within the lidar community to compare different lidar instruments.

Lidar calibration experiments

DEFF Research Database (Denmark)

Ejsing Jørgensen, Hans; Mikkelsen, T.; Streicher, J.

1997-01-01

detection to test the reproducibility and uncertainty of lidars. Lidar data were obtained from both single-ended and double-ended Lidar configurations. A backstop was introduced in one of the experiments and a new method was developed where information obtained from the backstop can be used in the inversion...... algorithm. Independent in-situ aerosol plume concentrations were obtained from a simultaneous tracer gas experiment with SF6, and comparisons with the two lidars were made. The study shows that the reproducibility of the lidars is within 15%, including measurements from both sides of a plume...

a Voxel-Based Filtering Algorithm for Mobile LIDAR Data

Science.gov (United States)

Qin, H.; Guan, G.; Yu, Y.; Zhong, L.

2018-04-01

This paper presents a stepwise voxel-based filtering algorithm for mobile LiDAR data. In the first step, to improve computational efficiency, mobile LiDAR points, in xy-plane, are first partitioned into a set of two-dimensional (2-D) blocks with a given block size, in each of which all laser points are further organized into an octree partition structure with a set of three-dimensional (3-D) voxels. Then, a voxel-based upward growing processing is performed to roughly separate terrain from non-terrain points with global and local terrain thresholds. In the second step, the extracted terrain points are refined by computing voxel curvatures. This voxel-based filtering algorithm is comprehensively discussed in the analyses of parameter sensitivity and overall performance. An experimental study performed on multiple point cloud samples, collected by different commercial mobile LiDAR systems, showed that the proposed algorithm provides a promising solution to terrain point extraction from mobile point clouds.

Prediction of topographic and bathymetric measurement performance of airborne low-SNR lidar systems

Science.gov (United States)

Cossio, Tristan

Low signal-to-noise ratio (LSNR) lidar (light detection and ranging) is an alternative paradigm to traditional lidar based on the detection of return signals at the single photoelectron level. The objective of this work was to predict low altitude (600 m) LSNR lidar system performance with regards to elevation measurement and target detection capability in topographic (dry land) and bathymetric (shallow water) scenarios. A modular numerical sensor model has been developed to provide data for further analysis due to the dearth of operational low altitude LSNR lidar systems. This simulator tool is described in detail, with consideration given to atmospheric effects, surface conditions, and the effects of laser phenomenology. Measurement performance analysis of the simulated topographic data showed results comparable to commercially available lidar systems, with a standard deviation of less than 12 cm for calculated elevation values. Bathymetric results, although dependent largely on water turbidity, were indicative of meter-scale horizontal data spacing for sea depths less than 5 m. The high prevalence of noise in LSNR lidar data introduces significant difficulties in data analysis. Novel algorithms to reduce noise are described, with particular focus on their integration into an end-to-end target detection classifier for both dry and submerged targets (cube blocks, 0.5 m to 1.0 m on a side). The key characteristic exploited to discriminate signal and noise is the temporal coherence of signal events versus the random distribution of noise events. Target detection performance over dry earth was observed to be robust, reliably detecting over 90% of targets with a minimal false alarm rate. Comparable results were observed in waters of high clarity, where the investigated system was generally able to detect more than 70% of targets to a depth of 5 m. The results of the study show that CATS, the University of Florida's LSNR lidar prototype, is capable of high fidelity

Two-stage free electron laser research

Science.gov (United States)

Segall, S. B.

1984-10-01

KMS Fusion, Inc. began studying the feasibility of two-stage free electron lasers for the Office of Naval Research in June, 1980. At that time, the two-stage FEL was only a concept that had been proposed by Luis Elias. The range of parameters over which such a laser could be successfully operated, attainable power output, and constraints on laser operation were not known. The primary reason for supporting this research at that time was that it had the potential for producing short-wavelength radiation using a relatively low voltage electron beam. One advantage of a low-voltage two-stage FEL would be that shielding requirements would be greatly reduced compared with single-stage short-wavelength FEL's. If the electron energy were kept below about 10 MeV, X-rays, generated by electrons striking the beam line wall, would not excite neutron resonance in atomic nuclei. These resonances cause the emission of neutrons with subsequent induced radioactivity. Therefore, above about 10 MeV, a meter or more of concrete shielding is required for the system, whereas below 10 MeV, a few millimeters of lead would be adequate.

Tenth Biennial Coherent Laser Radar Technology and Applications Conference

Science.gov (United States)

Kavaya, Michael J. (Compiler)

1999-01-01

The tenth conference on coherent laser radar technology and applications is the latest in a series beginning in 1980 which provides a forum for exchange of information on recent events current status, and future directions of coherent laser radar (or lidar or lader) technology and applications. This conference emphasizes the latest advancement in the coherent laser radar field, including theory, modeling, components, systems, instrumentation, measurements, calibration, data processing techniques, operational uses, and comparisons with other remote sensing technologies.

Observation of stratospheric ozone with NIES lidar system in Tsukuba, Japan

International Nuclear Information System (INIS)

Nakane, H.; Hayashida, S.; Sasano, Y.; Sugimoto, N.; Matsui, I.; Minato, A.

1992-01-01

Lidars are expected to play important roles in an international monitoring network of the stratosphere such as the Network for the Detection of Stratospheric Change (NDSC). The National Institute for Environmental Studies (NIES) in Tsukuba constructed an ozone lidar system in March 1988 and started observation in August 1988. The lidar system has a 2-m telescope and injection locked XeCl and XeF excimer lasers which can measure ozone profiles (15-45 km) and temperature profiles (30-80 km). From December 1991, lidar observations have been carried out in which the second Stokes line of the stimulated Raman scattering of a KrF laser has been used. Ozone profiles obtained with the NIES lidar system are compared with the data provided by the SAGE II satellite sensor. Results showed good agreement for the individual and the zonal mean profiles. Variations of ozone with various time scales at each altitude can be studied using the data obtained with the NIES ozone lidar system. Seasonal variations are easily found at 20 km, 30 km, and 35 km, which are qualitatively understood as a result of dynamical and photochemical effects. Systematic errors of ozone profiles due to the Pinatubo stratospheric aerosols have been detected using multi-wavelength observation

Coherent Doppler lidar for automated space vehicle rendezvous, stationkeeping and capture

Science.gov (United States)

Bilbro, James A.

1991-01-01

The inherent spatial resolution of laser radar makes ladar or lidar an attractive candidate for Automated Rendezvous and Capture application. Previous applications were based on incoherent lidar techniques, requiring retro-reflectors on the target vehicle. Technology improvements (reduced size, no cryogenic cooling requirement) have greatly enhanced the construction of coherent lidar systems. Coherent lidar permits the acquisition of non-cooperative targets at ranges that are limited by the detection capability rather than by the signal-to-noise ratio (SNR) requirements. The sensor can provide translational state information (range, velocity, and angle) by direct measurement and, when used with any array detector, also can provide attitude information by Doppler imaging techniques. Identification of the target is accomplished by scanning with a high pulse repetition frequency (dependent on the SNR). The system performance is independent of range and should not be constrained by sun angle. An initial effort to characterize a multi-element detection system has resulted in a system that is expected to work to a minimum range of 1 meter. The system size, weight and power requirements are dependent on the operating range; 10 km range requires a diameter of 3 centimeters with overall size at 3 x 3 x 15 to 30 cm, while 100 km range requires a 30 cm diameter.

Temperature lidar measurements from 1 to 105 km altitude using resonance, Rayleigh, and Rotational Raman scattering

Directory of Open Access Journals (Sweden)

M. Alpers

2004-01-01

Full Text Available For the first time, three different temperature lidar methods are combined to obtain time-resolved complete temperature profiles with high altitude resolution over an altitude range from the planetary boundary layer up to the lower thermosphere (about 1–105 km. The Leibniz-Institute of Atmospheric Physics (IAP at Kühlungsborn, Germany (54° N, 12° E operates two lidar instruments, using three different temperature measurement methods, optimized for three altitude ranges: (1 Probing the spectral Doppler broadening of the potassium D1 resonance lines with a tunable narrow-band laser allows atmospheric temperature profiles to be determined at metal layer altitudes (80–105 km. (2 Between about 20 and 90 km, temperatures were calculated from Rayleigh backscattering by air molecules, where the upper start values for the calculation algorithm were taken from the potassium lidar results. Correction methods have been applied to account for, e.g. Rayleigh extinction or Mie scattering of aerosols below about 32 km. (3 At altitudes below about 25 km, backscattering in the Rotational Raman lines is strong enough to obtain temperatures by measuring the temperature dependent spectral shape of the Rotational Raman spectrum. This method works well down to about 1 km. The instrumental configurations of the IAP lidars were optimized for a 3–6 km overlap of the temperature profiles at the method transition altitudes. We present two night-long measurements with clear wave structures propagating from the lower stratosphere up to the lower thermosphere.

Simulation of Satellite, Airborne and Terrestrial LiDAR with DART (I):Waveform Simulation with Quasi-Monte Carlo Ray Tracing

Science.gov (United States)

Gastellu-Etchegorry, Jean-Philippe; Yin, Tiangang; Lauret, Nicolas; Grau, Eloi; Rubio, Jeremy; Cook, Bruce D.; Morton, Douglas C.; Sun, Guoqing

2016-01-01

Light Detection And Ranging (LiDAR) provides unique data on the 3-D structure of atmosphere constituents and the Earth's surface. Simulating LiDAR returns for different laser technologies and Earth scenes is fundamental for evaluating and interpreting signal and noise in LiDAR data. Different types of models are capable of simulating LiDAR waveforms of Earth surfaces. Semi-empirical and geometric models can be imprecise because they rely on simplified simulations of Earth surfaces and light interaction mechanisms. On the other hand, Monte Carlo ray tracing (MCRT) models are potentially accurate but require long computational time. Here, we present a new LiDAR waveform simulation tool that is based on the introduction of a quasi-Monte Carlo ray tracing approach in the Discrete Anisotropic Radiative Transfer (DART) model. Two new approaches, the so-called "box method" and "Ray Carlo method", are implemented to provide robust and accurate simulations of LiDAR waveforms for any landscape, atmosphere and LiDAR sensor configuration (view direction, footprint size, pulse characteristics, etc.). The box method accelerates the selection of the scattering direction of a photon in the presence of scatterers with non-invertible phase function. The Ray Carlo method brings traditional ray-tracking into MCRT simulation, which makes computational time independent of LiDAR field of view (FOV) and reception solid angle. Both methods are fast enough for simulating multi-pulse acquisition. Sensitivity studies with various landscapes and atmosphere constituents are presented, and the simulated LiDAR signals compare favorably with their associated reflectance images and Laser Vegetation Imaging Sensor (LVIS) waveforms. The LiDAR module is fully integrated into DART, enabling more detailed simulations of LiDAR sensitivity to specific scene elements (e.g., atmospheric aerosols, leaf area, branches, or topography) and sensor configuration for airborne or satellite LiDAR sensors.

LSNR Airborne LIDAR Mapping System Design and Early Results (Invited)

Science.gov (United States)

Shrestha, K.; Carter, W. E.; Slatton, K. C.

2009-12-01

Low signal-to-noise ratio (LSNR) detection techniques allow for implementation of airborne light detection and range (LIDAR) instrumentation aboard platforms with prohibitive power, size, and weight restrictions. The University of Florida has developed the Coastal Area Tactical-mapping System (CATS), a prototype LSNR LIDAR system capable of single photon laser ranging. CATS is designed to operate in a fixed-wing aircraft flying 600 m above ground level, producing 532 nm, 480 ps, 3 μJ output pulses at 8 kHz. To achieve continuous coverage of the terrain with 20 cm spatial resolution in a single pass, a 10x10 array of laser beamlets is scanned. A Risley prism scanner (two rotating V-coated optical wedges) allows the array of laser beamlets to be deflected in a variety of patterns, including conical, spiral, and lines at selected angles to the direction of flight. Backscattered laser photons are imaged onto a 100 channel (10x10 segmented-anode) photomultiplier tube (PMT) with a micro-channel plate (MCP) amplifier. Each channel of the PMT is connected to a multi-stop 2 GHz event timer. Here we report on tests in which ranges for known targets were accumulated for repeated laser shots and statistical analyses were applied to evaluate range accuracy, minimum separation distance, bathymetric mapping depth, and atmospheric scattering. Ground-based field test results have yielded 10 cm range accuracy and sub-meter feature identification at variable scan settings. These experiments also show that a secondary surface can be detected at a distance of 15 cm from the first. Range errors in secondary surface identification for six separate trials were within 7.5 cm, or within the timing resolution limit of the system. Operating at multi-photon sensitivity may have value for situations in which high ambient noise precludes single-photon sensitivity. Low reflectivity targets submerged in highly turbid waters can cause detection issues. CATS offers the capability to adjust the

UAV-borne lidar with MEMS mirror-based scanning capability

Science.gov (United States)

Kasturi, Abhishek; Milanovic, Veljko; Atwood, Bryan H.; Yang, James

2016-05-01

Firstly, we demonstrated a wirelessly controlled MEMS scan module with imaging and laser tracking capability which can be mounted and flown on a small UAV quadcopter. The MEMS scan module was reduced down to a small volume of smartphone via Bluetooth while flying on a drone, and could project vector content, text, and perform laser based tracking. Also, a "point-and-range" LiDAR module was developed for UAV applications based on low SWaP (Size, Weight and Power) gimbal-less MEMS mirror beam-steering technology and off-the-shelf OEM LRF modules. For demonstration purposes of an integrated laser range finder module, we used a simple off-the-shelf OEM laser range finder (LRF) with a 100m range, +/-1.5mm accuracy, and 4Hz ranging capability. The LRFs receiver optics were modified to accept 20° of angle, matching the transmitter's FoR. A relatively large (5.0mm) diameter MEMS mirror with +/-10° optical scanning angle was utilized in the demonstration to maintain the small beam divergence of the module. The complete LiDAR prototype can fit into a small volume of battery. The MEMS mirror based LiDAR system allows for ondemand ranging of points or areas within the FoR without altering the UAV's position. Increasing the LRF ranging frequency and stabilizing the pointing of the laser beam by utilizing the onboard inertial sensors and the camera are additional goals of the next design.

Initial Results From The Micro-pulse Lidar Network (MPL-Net)

Science.gov (United States)

Welton, E. J.; Campbell, J. R.; Berkoff, T. A.; Spinhirne, J. D.; Ginoux, P.

2001-12-01

The micro-pulse lidar system (MPL) was developed in the early 1990s and was the first small, eye-safe, and autonomous lidar built for fulltime monitoring of cloud and aerosol vertical distributions. In 2000, a new project using MPL systems was started at NASA Goddard Space Flight Center. This new project, the Micro-pulse Lidar Network or MPL-Net, was created to provide long-term observations of aerosol and cloud vertical profiles at key sites around the world. This is accomplished using both NASA operated sites and partnerships with other organizations owning MPL systems. The MPL-Net sites are co-located with NASA AERONET sunphotometers to provide aerosol optical depth data needed for calibration of the MPL. In addition to the long-term sites, MPL-Net provides lidar support for a limited number of field experiments and ocean cruises each year. We will present an overview of the MPL-Net project and show initial results from the first two MPL-Net sites at the South Pole and at Goddard Space Flight Center. Observations of dust layers transported from the desert regions of China, across the Pacific Ocean, to the east coast of the United States will also be shown. MPL-Net affiliated instruments were in place at the desert source region in China, on a research vessel in the Sea of Japan, at ARM sites in Alaska and Oklahoma, and finally at our home site in Maryland (GSFC) during the massive dust storms that occurred in April 2001. The MPL observations of dust layers at each location are shown in comparison to dust layers predicted using the Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport model (GOCART). Finally, the MPL-Net project is the primary ground-validation program for the Geo-Science Laser Altimeter System (GLAS) satellite lidar project (launch date 2002). We will present an overview demonstrating how MPL-Net results are used to help prepare the GLAS data processing algorithms and assist in the calibration/validation of the GLAS data

Initial Results from the Micro-pulse Lidar Network (MPL-Net)

Science.gov (United States)

Welton, Ellsworth J.; Campbell, James R.; Berkoff, Timothy A.; Spinhirne, James D.; Ginoux, Paul; Starr, David OC. (Technical Monitor)

2001-01-01

The micro-pulse lidar system (MPL) was developed in the early 1990s and was the first small, eye-safe, and autonomous lidar built for full time monitoring of cloud and aerosol vertical distributions. In 2000, a new project using MPL systems was started at NASA Goddard Space Flight Center. This new project, the Micro-pulse Lidar Network or MPL-Net, was created to provide long-term observations of aerosol and cloud vertical profiles at key sites around the world. This is accomplished using both NASA operated sites and partnerships with other organizations owning MPL systems. The MPL-Net sites are co-located with NASA AERONET sunphotometers to provide aerosol optical depth data needed for calibration of the MPL. In addition to the long-term sites, MPL-Net provides lidar support for a limited number of field experiments and ocean cruises each year. We will present an overview of the MPL-Net project and show initial results from the first two MPL-Net sites at the South Pole and at Goddard Space Flight Center. Observations of dust layers transported from the Gobi desert, across the Pacific Ocean, to the east coast of the United States will also be shown. MPL-Net affiliated instruments were in place at the desert source region in China, on a research vessel in the Sea of Japan, at ARM sites in Alaska and Oklahoma, and finally at our home site in Maryland (GSFC) during the massive dust storms that occurred in April 2001. The MPL observations of dust layers at each location are shown in comparison to dust layers predicted using the Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport model (GOCART). Finally, the MPL-Net project is the primary ground-validation program for the Geo-Science Laser Altimeter System (GLAS) satellite lidar project (launch date 2002). We will present an overview demonstrating how MPL-Net results are used to help prepare the GLAS data processing algorithms and assist in the calibration/validation of the GLAS data products.

Progress in coherent laser radar

Science.gov (United States)

Vaughan, J. M.

1986-01-01

Considerable progress with coherent laser radar has been made over the last few years, most notably perhaps in the available range of high performance devices and components and the confidence with which systems may now be taken into the field for prolonged periods of operation. Some of this increasing maturity was evident at the 3rd Topical Meeting on Coherent Laser Radar: Technology and Applications. Topics included in discussions were: mesoscale wind fields, nocturnal valley drainage and clear air down bursts; airborne Doppler lidar studies and comparison of ground and airborne wind measurement; wind measurement over the sea for comparison with satellite borne microwave sensors; transport of wake vortices at airfield; coherent DIAL methods; a newly assembled Nd-YAG coherent lidar system; backscatter profiles in the atmosphere and wavelength dependence over the 9 to 11 micrometer region; beam propagation; rock and soil classification with an airborne 4-laser system; technology of a global wind profiling system; target calibration; ranging and imaging with coherent pulsed and CW system; signal fluctuations and speckle. Some of these activities are briefly reviewed.

Compressive full waveform lidar

Science.gov (United States)

Yang, Weiyi; Ke, Jun

2017-05-01

To avoid high bandwidth detector, fast speed A/D converter, and large size memory disk, a compressive full waveform LIDAR system, which uses a temporally modulated laser instead of a pulsed laser, is studied in this paper. Full waveform data from NEON (National Ecological Observatory Network) are used. Random binary patterns are used to modulate the source. To achieve 0.15 m ranging resolution, a 100 MSPS A/D converter is assumed to make measurements. SPIRAL algorithm with canonical basis is employed when Poisson noise is considered in the low illuminated condition.

Airborne measurements of CO2 column concentrations made with a pulsed IPDA lidar using a multiple-wavelength-locked laser and HgCdTe APD detector

Science.gov (United States)

Abshire, James B.; Ramanathan, Anand K.; Riris, Haris; Allan, Graham R.; Sun, Xiaoli; Hasselbrack, William E.; Mao, Jianping; Wu, Stewart; Chen, Jeffrey; Numata, Kenji; Kawa, Stephan R.; Yang, Mei Ying Melissa; DiGangi, Joshua

2018-04-01

Here we report on measurements made with an improved CO2 Sounder lidar during the ASCENDS 2014 and 2016 airborne campaigns. The changes made to the 2011 version of the lidar included incorporating a rapidly wavelength-tunable, step-locked seed laser in the transmitter, using a much more sensitive HgCdTe APD detector and using an analog digitizer with faster readout time in the receiver. We also improved the lidar's calibration approach and the XCO2 retrieval algorithm. The 2014 and 2016 flights were made over several types of topographic surfaces from 3 to 12 km aircraft altitudes in the continental US. The results are compared to the XCO2 values computed from an airborne in situ sensor during spiral-down maneuvers. The 2014 results show significantly better performance and include measurement of horizontal gradients in XCO2 made over the Midwestern US that agree with chemistry transport models. The results from the 2016 airborne lidar retrievals show precisions of ˜ 0.7 parts per million (ppm) with 1 s averaging over desert surfaces, which is an improvement of about 8 times compared to similar measurements made in 2011. Measurements in 2016 were also made over fresh snow surfaces that have lower surface reflectance at the laser wavelengths. The results from both campaigns showed that the mean values of XCO2 retrieved from the lidar consistently agreed with those based on the in situ sensor to within 1 ppm. The improved precision and accuracy demonstrated in the 2014 and 2016 flights should benefit future airborne science campaigns and advance the technique's readiness for a space-based instrument.

Systematic variations in multi-spectral lidar representations of canopy height profiles and gap probability

Science.gov (United States)

Chasmer, L.; Hopkinson, C.; Gynan, C.; Mahoney, C.; Sitar, M.

2015-12-01

Airborne and terrestrial lidar are increasingly used in forest attribute modeling for carbon, ecosystem and resource monitoring. The near infra-red wavelength at 1064nm has been utilised most in airborne applications due to, for example, diode manufacture costs, surface reflectance and eye safety. Foliage reflects well at 1064nm and most of the literature on airborne lidar forest structure is based on data from this wavelength. However, lidar systems also operate at wavelengths further from the visible spectrum (e.g. 1550nm) for eye safety reasons. This corresponds to a water absorption band and can be sensitive to attenuation if surfaces contain moisture. Alternatively, some systems operate in the visible range (e.g. 532nm) for specialised applications requiring simultaneous mapping of terrestrial and bathymetric surfaces. All these wavelengths provide analogous 3D canopy structure reconstructions and thus offer the potential to be combined for spatial comparisons or temporal monitoring. However, a systematic comparison of wavelength-dependent foliage profile and gap probability (index of transmittance) is needed. Here we report on two multispectral lidar missions carried out in 2013 and 2015 over conifer, deciduous and mixed stands in Ontario, Canada. The first used separate lidar sensors acquiring comparable data at three wavelengths, while the second used a single sensor with 3 integrated laser systems. In both cases, wavelenegths sampled were 532nm, 1064nm and 1550nm. The experiment revealed significant differences in proportions of returns at ground level, the vertical foliage distribution and gap probability across wavelengths. Canopy attenuation was greatest at 532nm due to photosynthetic plant tissue absorption. Relative to 1064nm, foliage was systematically undersampled at the 10% to 60% height percentiles at both 1550nm and 532nm (this was confirmed with coincident terrestrial lidar data). When using all returns to calculate gap probability, all

Assessment of the CALIPSO Lidar 532 nm attenuated backscatter calibration using the NASA LaRC airborne High Spectral Resolution Lidar

Directory of Open Access Journals (Sweden)

R. R. Rogers

2011-02-01

Full Text Available The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO spacecraft has provided global, high-resolution vertical profiles of aerosols and clouds since it became operational on 13 June 2006. On 14 June 2006, the NASA Langley Research Center (LaRC High Spectral Resolution Lidar (HSRL was deployed aboard the NASA Langley B-200 aircraft for the first of a series of 86 underflights of the CALIPSO satellite to provide validation measurements for the CALIOP data products. To better assess the range of conditions under which CALIOP data products are produced, these validation flights were conducted under both daytime and nighttime lighting conditions, in multiple seasons, and over a large range of latitudes and aerosol and cloud conditions. This paper presents a quantitative assessment of the CALIOP 532 nm calibration (through the 532 nm total attenuated backscatter using internally calibrated airborne HSRL underflight data and is the most extensive study of CALIOP 532 nm calibration. Results show that HSRL and CALIOP 532 nm total attenuated backscatter agree on average within 2.7% ± 2.1% (CALIOP lower at night and within 2.9% ± 3.9% (CALIOP lower during the day, demonstrating the accuracy of the CALIOP 532 nm calibration algorithms. Additionally, comparisons with HSRL show consistency of the CALIOP calibration before and after the laser switch in 2009 as well as improvements in the daytime version 3.01 calibration scheme compared with the version 2 calibration scheme. Potential biases and uncertainties in the methodology relevant to validating satellite lidar measurements with an airborne lidar system are discussed and found to be less than 4.5% ± 3.2% for this validation effort with HSRL. Results from this study are also compared with prior assessments of the CALIOP 532 nm attenuated backscatter calibration.

Object Classification Using Airborne Multispectral LiDAR Data

Directory of Open Access Journals (Sweden)

PAN Suoyan

2018-02-01

Full Text Available Airborne multispectral LiDAR system,which obtains surface geometry and spectral data of objects,simultaneously,has become a fast effective,large-scale spatial data acquisition method.Multispectral LiDAR data are characteristics of completeness and consistency of spectrum and spatial geometric information.Support vector machine (SVM,a machine learning method,is capable of classifying objects based on small samples.Therefore,by means of SVM,this paper performs land cover classification using multispectral LiDAR data. First,all independent point cloud with different wavelengths are merged into a single point cloud,where each pixel contains the three-wavelength spectral information.Next,the merged point cloud is converted into range and intensity images.Finally,land-cover classification is performed by means of SVM.All experiments were conducted on the Optech Titan multispectral LiDAR data,containing three individual point cloud collected by 532 nm,1024 nm,and 1550 nm laser beams.Experimental results demonstrate that ①compared to traditional single-wavelength LiDAR data,multispectral LiDAR data provide a promising solution to land use and land cover applications;②SVM is a feasible method for land cover classification of multispectral LiDAR data.

The Two-Beam Free Electron Laser Oscillator

CERN Document Server

Thompson, Neil R

2004-01-01

A one-dimensional model of a free-electron laser operating simultaneously with two electron beams of different energies [1] is extended to an oscillator configuration. The electron beam energies are chosen so that an harmonic of the lower energy beam is at the fundamental radiation wavelength of the higher energy beam. Potential benefits over a single-beam free-electron laser oscillator are discussed.

Challenges in miniaturized automotive long-range lidar system design

Science.gov (United States)

Fersch, Thomas; Weigel, Robert; Koelpin, Alexander

2017-05-01

This paper discusses the current technical limitations posed on endeavors to miniaturize lidar systems for use in automotive applications and how to possibly extend those limits. The focus is set on long-range scanning direct time of flight LiDAR systems using APD photodetectors. Miniaturization evokes severe problems in ensuring absolute laser safety while maintaining the systems' performance in terms of maximum range, signal-to-noise ratio, detection probability, pixel density, or frame rate. Based on hypothetical but realistic specifications for an exemplary system the complete lidar signal path is calculated. The maximum range of the system is used as a general performance indicator. It is determined with the minimum signal-to-noise ratio required to detect an object. Various system parameters are varied to find their impact on the system's range. The reduction of the laser's pulse width and the right choice for the transimpedance amplifier's amplification have shown to be practicable measures to double the system's range.

Opo lidar sounding of trace atmospheric gases in the 3 - 4 μm spectral range

Science.gov (United States)

Romanovskii, Oleg A.; Sadovnikov, Sergey A.; Kharchenko, Olga V.; Yakovlev, Semen V.

2018-04-01

The applicability of a KTA crystal-based laser system with optical parametric oscillators (OPO) generation to lidar sounding of the atmosphere in the spectral range 3-4 μm is studied in this work. A technique developed for lidar sounding of trace atmospheric gases (TAG) is based on differential absorption lidar (DIAL) method and differential optical absorption spectroscopy (DOAS). The DIAL-DOAS technique is tested to estimate its efficiency for lidar sounding of atmospheric trace gases. The numerical simulation performed shows that a KTA-based OPO laser is a promising source of radiation for remote DIAL-DOAS sounding of the TAGs under study along surface tropospheric paths. A possibility of using a PD38-03-PR photodiode for the DIAL gas analysis of the atmosphere is shown.

Single-Photon Avalanche Diode with Enhanced NIR-Sensitivity for Automotive LIDAR Systems.

Science.gov (United States)

Takai, Isamu; Matsubara, Hiroyuki; Soga, Mineki; Ohta, Mitsuhiko; Ogawa, Masaru; Yamashita, Tatsuya

2016-03-30

A single-photon avalanche diode (SPAD) with enhanced near-infrared (NIR) sensitivity has been developed, based on 0.18 μm CMOS technology, for use in future automotive light detection and ranging (LIDAR) systems. The newly proposed SPAD operating in Geiger mode achieves a high NIR photon detection efficiency (PDE) without compromising the fill factor (FF) and a low breakdown voltage of approximately 20.5 V. These properties are obtained by employing two custom layers that are designed to provide a full-depletion layer with a high electric field profile. Experimental evaluation of the proposed SPAD reveals an FF of 33.1% and a PDE of 19.4% at 870 nm, which is the laser wavelength of our LIDAR system. The dark count rate (DCR) measurements shows that DCR levels of the proposed SPAD have a small effect on the ranging performance, even if the worst DCR (12.7 kcps) SPAD among the test samples is used. Furthermore, with an eye toward vehicle installations, the DCR is measured over a wide temperature range of 25-132 °C. The ranging experiment demonstrates that target distances are successfully measured in the distance range of 50-180 cm.

Detection and monitoring of pollutant sources with Lidar/Dial techniques

International Nuclear Information System (INIS)

Gaudio, P; Gelfusa, M; Malizia, A; Parracino, S; Richetta, M; De Leo, L; Perrimezzi, C; Bellecci, C

2015-01-01

It's well known that air pollution due to anthropogenic sources can have adverse effects on humans and the ecosystem. Therefore, in the last years, surveying large regions of the atmosphere in an automatic way has become a strategic objective of various public health organizations for early detection of pollutant sources in urban and industrial areas.The Lidar and Dial techniques have become well established laser based methods for the remote sensing of the atmosphere. They are often implemented to probe almost any level of the atmosphere and to acquire information to validate theoretical models about different topics of atmospheric physics. They can also be used for environment surveying by monitoring particles, aerosols and molecules.The aim of the present work is to demonstrate the potential of these methods to detect pollutants emitted from local sources (such as particulate and/or chemical compounds) and to evaluate their concentration. This is exemplified with the help of experimental data acquired in an industrial area in the south of Italy by mean of experimental campaign by use of pollutants simulated source. For this purpose, two mobile systems Lidar and Dial have been developed by the authors. In this paper there will be presented the operating principles of the system and the results of the experimental campaign. (paper)

"LOSA-S" - basic lidar of the CSF "ATMOSPHERE" IAO SB RAS for tropospheric studies

Science.gov (United States)

Balin, Yu. S.; Kokhanenko, G. P.; Klemasheva, M. G.; Penner, I. E.; Nasonov, S. V.; Samoilova, S. V.

2017-11-01

Stationary lidar "LOSA-S" of the center of shared facilities (CSF) "ATMOSPHERE" IAO SB RAS is intended for the study of aerosol fields in the boundary layer of the troposphere in the height range 0.5 up to 15 km, as well as for the study of crystal clouds using the polarization unit with linear and circular polarization of radiation. The scheme of simultaneous observation of the elastic and Raman scattering signals when irradiating the medium at the wavelengths of 1064, 532 and 355 nm is realized in the lidar. The lidar is based on the LOTIS-2135 Nd:YAG laser and the receiving specular telescope of the Cassegrain system with the diameter of 300 mm. In addition to the return signals of elastic scattering recorded in analog mode, the lidar records the Raman scattering signals on molecular nitrogen (387 and 607 nm) and water vapor (407 nm) in the photon counting mode. To realize the aforementioned height range, two receiving telescopes are used in the lidar for near and far zones, the signals are recorded by the same photodetectors.

Fast widely-tunable single-frequency 2-micron laser for remote-sensing applications

Science.gov (United States)

Henderson, Sammy W.; Hale, Charley P.

2017-08-01

We are developing a family of fast, widely-tunable cw diode-pumped single frequency solid-state lasers, called Swift. The Swift laser architecture is compatible with operation using many different solid-state laser crystals for operation at various emission lines between 1 and 2.1 micron. The initial prototype Swift laser using a Tm,Ho:YLF laser crystal near 2.05 micron wavelength achieved over 100 mW of single frequency cw output power, up to 50 GHz-wide, fast, mode-hop-free piezoelectric tunability, and 100 kHz/ms frequency stability. For the Tm,Ho:YLF laser material, the fast 50 GHz tuning range can be centered at any wavelength from 2047-2059 nm using appropriate intracavity spectral filters. The frequency stability and power are sufficient to serve as the local oscillator (LO) laser in long-range coherent wind-measuring lidar systems, as well as a frequency-agile master oscillator (MO) or injection-seed source for larger pulsed transmitter lasers. The rapid and wide frequency tunablity meets the requirements for integrated-path or range-resolved differential absorption lidar or applications where targets with significantly different line of sight velocities (Doppler shifts) must be tracked. Initial demonstration of an even more compact version of the Swift is also described which requires less prime power and produces less waste heat.

Lidar for Wind and Optical Turbulence Profiling

Directory of Open Access Journals (Sweden)

Fastig Shlomo

2018-01-01

Full Text Available A field campaign for the comparison investigation of systems to measure wind and optical turbulence profiles was conducted in northern Germany. The experimental effort was to compare the performance of the LIDAR, SODAR-RASS and ultrasonic anemometers for the measurement of the above mentioned atmospheric parameters. Soreq's LIDAR is a fiber laser based system demonstrator for the vertical profiling of the wind and turbulence, based on the correlation of aerosol density variations. It provides measurements up to 350m with 20m resolution.

A flat spectral Faraday filter for sodium lidar.

Science.gov (United States)

Yang, Yong; Cheng, Xuewu; Li, Faquan; Hu, Xiong; Lin, Xin; Gong, Shunsheng

2011-04-01

We report a flat spectral Faraday anomalous dispersion optical filter (FS-FADOF) for sodium lidar. The physical and technical considerations for obtaining a FS-FADOF with a 3.5 GHz flat spectral transmission function are presented. It was found that the effective transmission of this filter was much higher (>94%) and more uniform than that of the ultranarrowband FADOF, and therefore were less sensitive to laser-frequency drift. Thus, the FS-FADOF can improve lidar efficiency and precision.

Vertical profiles of atmospheric fluorescent aerosols observed by a mutil-channel lidar spectrometer system

Science.gov (United States)

Huang, Z.; Huang, J.; Zhou, T.; Sugimoto, N.; Bi, J.

2015-12-01

Zhongwei Huang1*, Jianping Huang1, Tian Zhou1, Nobuo Sugimoto2, Jianrong Bi1 and Jinsen Shi11Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, China. 2Atmospheric Environment Division, National Institutes for Environmental Studies, Tsukuba, Japan Email: huangzhongwei@lzu.edu.cn Abstract Atmospheric aerosols have a significant impact on regional and globe climate. The challenge in quantifying aerosol direct radiative forcing and aerosol-cloud interactions arises from large spatial and temporal heterogeneity of aerosol concentrations, compositions, sizes, shape and optical properties (IPCC, 2007). Lidar offers some remarkable advantages for determining the vertical structure of atmospheric aerosols and their related optical properties. To investigate the characterization of atmospheric aerosols (especially bioaerosols) with high spatial and temporal resolution, we developed a Raman/fluorescence/polarization lidar system employed a multi-channel spectrometer, with capabilities of providing measurements of Raman scattering and laser-induced fluorescence excitation at 355 nm from atmospheric aerosols. Meanwhile, the lidar system operated polarization measurements both at 355nm and 532nm wavelengths, aiming to obtain more information of aerosols. It employs a high power pulsed laser and a received telescope with 350mm diameter. The receiver could simultaneously detect a wide fluorescent spectrum about 178 nm with spectral resolution 5.7 nm, mainly including an F/3.7 Crossed Czerny-Turner spectrograph, a grating (1200 gr/mm) and a PMT array with 32 photocathode elements. Vertical structure of fluorescent aerosols in the atmosphere was observed by the developed lidar system at four sites across northwest China, during 2014 spring field observation that conducted by Lanzhou University. It has been proved that the developed lidar could detect the fluorescent aerosols with high temporal and

Three-dimension imaging lidar

Science.gov (United States)

Degnan, John J. (Inventor)

2007-01-01

This invention is directed to a 3-dimensional imaging lidar, which utilizes modest power kHz rate lasers, array detectors, photon-counting multi-channel timing receivers, and dual wedge optical scanners with transmitter point-ahead correction to provide contiguous high spatial resolution mapping of surface features including ground, water, man-made objects, vegetation and submerged surfaces from an aircraft or a spacecraft.

Multi-operational tuneable Q-switched mode-locking Er fibre laser

Science.gov (United States)

Qamar, F. Z.

2018-01-01

A wavelength-spacing tuneable, Q-switched mode-locking (QML) erbium-doped fibre laser based on non-linear polarization rotation controlled by four waveplates and a cube polarizer is proposed. A mode-locked pulse train using two quarter-wave plates and a half-wave plate (HWP) is obtained first, and then an extra HWP is inserted into the cavity to produce different operation regimes. The evolutions of temporal and spectral dynamics with different orientation angles of the extra HWP are investigated. A fully modulated stable QML pulse train is observed experimentally. This is, to the author’s best knowledge, the first experimental work reporting QML operation without adding an extra saturable absorber inside the laser cavity. Multi-wavelength pulse laser operation, multi-pulse train continuous-wave mode-locking operation and pulse-splitting operations are also reported at certain HWP angles. The observed operational dynamics are interpreted as a mutual interaction of dispersion, non-linear effect and insertion loss. This work provides a new mechanism for fabricating cheap tuneable multi-wavelength lasers with QML pulses.

Conventional operation and laser therapy in the treatment of varicose veins

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

Objective: To evaluate the effectiveness of endovenous laser therapy and conventional therapy on the varicose of great saphenous vein. Methods: Thirty-two patients received endovenous laser therapy and 32 patients were operated by conventional therapy (high ligation and stripping). The observation results of great saphenous vein(GSV) were recorded by clinical evaluation and duplex ultrasound examination. And the operating time, intraoperative blood loss, time to become moveable, duration of hospitalization and degree of feeling pain were compared between the two groups. Results: Compared with conventional therapy, laser therapy had good curative effect with less complications and no scars and no pains. There were significant differences between the two groups (P＜0.01). Conclusion: Laser therapy for varicose of great saphenous vein is better than the conventional therapy. It deserves to be widely used in clinical treatment.

Comparing RIEGL RiCOPTER UAV LiDAR Derived Canopy Height and DBH with Terrestrial LiDAR.

Science.gov (United States)

Brede, Benjamin; Lau, Alvaro; Bartholomeus, Harm M; Kooistra, Lammert

2017-10-17

In recent years, LIght Detection And Ranging (LiDAR) and especially Terrestrial Laser Scanning (TLS) systems have shown the potential to revolutionise forest structural characterisation by providing unprecedented 3D data. However, manned Airborne Laser Scanning (ALS) requires costly campaigns and produces relatively low point density, while TLS is labour intense and time demanding. Unmanned Aerial Vehicle (UAV)-borne laser scanning can be the way in between. In this study, we present first results and experiences with the RIEGL RiCOPTER with VUX ® -1UAV ALS system and compare it with the well tested RIEGL VZ-400 TLS system. We scanned the same forest plots with both systems over the course of two days. We derived Digital Terrain Model (DTMs), Digital Surface Model (DSMs) and finally Canopy Height Model (CHMs) from the resulting point clouds. ALS CHMs were on average 11.5 c m higher in five plots with different canopy conditions. This showed that TLS could not always detect the top of canopy. Moreover, we extracted trunk segments of 58 trees for ALS and TLS simultaneously, of which 39 could be used to model Diameter at Breast Height (DBH). ALS DBH showed a high agreement with TLS DBH with a correlation coefficient of 0.98 and root mean square error of 4.24 c m . We conclude that RiCOPTER has the potential to perform comparable to TLS for estimating forest canopy height and DBH under the studied forest conditions. Further research should be directed to testing UAV-borne LiDAR for explicit 3D modelling of whole trees to estimate tree volume and subsequently Above-Ground Biomass (AGB).

Toward a New Capability for Upper Atmospheric Research using Atomic Oxygen Lidar

Science.gov (United States)

Clemmons, J. H.; Steinvurzel, P.; Mu, X.; Beck, S. M.; Lotshaw, W. T.; Rose, T. S.; Hecht, J. H.; Westberg, K. R.; Larsen, M. F.; Chu, X.; Fritts, D. C.

2017-12-01

Progress on development of a lidar system for probing the upper atmosphere based on atomic oxygen resonance is presented and discussed. The promise of a fully-developed atomic oxygen lidar system, which must be based in space to measure the upper atmosphere, for yielding comprehensive new insights is discussed in terms of its potential to deliver global, height-resolved measurements of winds, temperature, and density at a high cadence. An overview of the system is given, and its measurement principles are described, including its use of 1) a two-photon transition to keep the optical depth low; 2) laser tuning to provide the Doppler information needed to measure winds; and 3) laser tuning to provide a Boltzmann temperature measurement. The current development status is presented with a focus on what has been done to demonstrate capability in the laboratory and its evolution to a funded sounding rocket investigation designed to make measurements of three-dimensional turbulence in the upper mesosphere and lower thermosphere.

Development of two color laser diagnostics for the ITER poloidal polarimeter.

Science.gov (United States)

Kawahata, K; Akiyama, T; Tanaka, K; Nakayama, K; Okajima, S

2010-10-01

Two color laser diagnostics using terahertz laser sources are under development for a high performance operation of the Large Helical Device and for future fusion devices such as ITER. So far, we have achieved high power laser oscillation lines simultaneously oscillating at 57.2 and 47.7 μm by using a twin optically pumped CH(3)OD laser, and confirmed the original function, compensation of mechanical vibration, of the two color laser interferometer. In this article, application of the two color laser diagnostics to the ITER poloidal polarimeter and recent hardware developments will be described.

Development of two color laser diagnostics for the ITER poloidal polarimeter

International Nuclear Information System (INIS)

Kawahata, K.; Akiyama, T.; Tanaka, K.; Nakayama, K.; Okajima, S.

2010-01-01

Two color laser diagnostics using terahertz laser sources are under development for a high performance operation of the Large Helical Device and for future fusion devices such as ITER. So far, we have achieved high power laser oscillation lines simultaneously oscillating at 57.2 and 47.7 μm by using a twin optically pumped CH 3 OD laser, and confirmed the original function, compensation of mechanical vibration, of the two color laser interferometer. In this article, application of the two color laser diagnostics to the ITER poloidal polarimeter and recent hardware developments will be described.

Enhancement of Stereo Imagery by Artificial Texture Projection Generated Using a LIDAR

Science.gov (United States)

Veitch-Michaelis, Joshua; Muller, Jan-Peter; Walton, David; Storey, Jonathan; Foster, Michael; Crutchley, Benjamin

2016-06-01

Passive stereo imaging is capable of producing dense 3D data, but image matching algorithms generally perform poorly on images with large regions of homogenous texture due to ambiguous match costs. Stereo systems can be augmented with an additional light source that can project some form of unique texture onto surfaces in the scene. Methods include structured light, laser projection through diffractive optical elements, data projectors and laser speckle. Pattern projection using lasers has the advantage of producing images with a high signal to noise ratio. We have investigated the use of a scanning visible-beam LIDAR to simultaneously provide enhanced texture within the scene and to provide additional opportunities for data fusion in unmatched regions. The use of a LIDAR rather than a laser alone allows us to generate highly accurate ground truth data sets by scanning the scene at high resolution. This is necessary for evaluating different pattern projection schemes. Results from LIDAR generated random dots are presented and compared to other texture projection techniques. Finally, we investigate the use of image texture analysis to intelligently project texture where it is required while exploiting the texture available in the ambient light image.

ENHANCEMENT OF STEREO IMAGERY BY ARTIFICIAL TEXTURE PROJECTION GENERATED USING A LIDAR

Directory of Open Access Journals (Sweden)

J. Veitch-Michaelis

2016-06-01

Full Text Available Passive stereo imaging is capable of producing dense 3D data, but image matching algorithms generally perform poorly on images with large regions of homogenous texture due to ambiguous match costs. Stereo systems can be augmented with an additional light source that can project some form of unique texture onto surfaces in the scene. Methods include structured light, laser projection through diffractive optical elements, data projectors and laser speckle. Pattern projection using lasers has the advantage of producing images with a high signal to noise ratio. We have investigated the use of a scanning visible-beam LIDAR to simultaneously provide enhanced texture within the scene and to provide additional opportunities for data fusion in unmatched regions. The use of a LIDAR rather than a laser alone allows us to generate highly accurate ground truth data sets by scanning the scene at high resolution. This is necessary for evaluating different pattern projection schemes. Results from LIDAR generated random dots are presented and compared to other texture projection techniques. Finally, we investigate the use of image texture analysis to intelligently project texture where it is required while exploiting the texture available in the ambient light image.

Lidar Inter-Comparison Exercise Final Campaign Report

Energy Technology Data Exchange (ETDEWEB)

Protat, A [Australian Bureau of Meterology; Young, S

2015-02-01

The objective of this field campaign was to evaluate the performance of the new Leosphere R-MAN 510 lidar, procured by the Australian Bureau of Meteorology, by testing it against the MicroPulse Lidar (MPL) and Raman lidars, at the Darwin Atmospheric Radiation Measurement (ARM) site. This lidar is an eye-safe (355 nm), turn-key mini Raman lidar, which allows for the detection of aerosols and cloud properties, and the retrieval of particulate extinction profiles. To accomplish this evaluation, the R-MAN 510 lidar has been operated at the Darwin ARM site, next to the MPL, Raman lidar, and Vaisala ceilometer (VCEIL) for three months (from 20 January 2013 to 20 April 2013) in order to collect a sufficient sample size for statistical comparisons.

Aircraft Wake Vortex Measurement with Coherent Doppler Lidar

Directory of Open Access Journals (Sweden)

Wu Songhua

2016-01-01

Full Text Available Aircraft vortices are generated by the lift-producing surfaces of the aircraft. The variability of near-surface conditions can change the drop rate and cause the cell of the wake vortex to twist and contort unpredictably. The pulsed Coherent Doppler Lidar Detection and Ranging is an indispensable access to real aircraft vortices behavior which transmitting a laser beam and detecting the radiation backscattered by atmospheric aerosol particles. Experiments for Coherent Doppler Lidar measurement of aircraft wake vortices has been successfully carried out at the Beijing Capital International Airport (BCIA. In this paper, the authors discuss the Lidar system, the observation modes carried out in the measurements at BCIA and the characteristics of vortices.

Assessing Accuracy in Varying LIDAR Data Point Densities in Digital Elevation Maps

National Research Council Canada - National Science Library

Anderson, Brian C

2008-01-01

... (Laser or Light Detection And Ranging) collection. Additionally, this thesis contains information on the multiple space missions that use laser altimetry or Lidar to gather data about planet earth, the moon, asteroids, Mars and Mercury...

Wide Angle Imaging Lidar (WAIL): Theory of Operation and Results from Cross-Platform Validation at the ARM Southern Great Plains Site

Science.gov (United States)

Polonsky, I. N.; Davis, A. B.; Love, S. P.

2004-05-01

WAIL was designed to determine physical and geometrical characteristics of optically thick clouds using the off-beam component of the lidar return that can be accurately modeled within the 3D photon diffusion approximation. The theory shows that the WAIL signal depends not only on the cloud optical characteristics (phase function, extinction and scattering coefficients) but also on the outer thickness of the cloud layer. This makes it possible to estimate the mean optical and geometrical thicknesses of the cloud. The comparison with Monte Carlo simulation demonstrates the high accuracy of the diffusion approximation for moderately to very dense clouds. During operation WAIL is able to collect a complete data set from a cloud every few minutes, with averaging over horizontal scale of a kilometer or so. In order to validate WAIL's ability to deliver cloud properties, the LANL instrument was deployed as a part of the THickness from Off-beam Returns (THOR) validation IOP. The goal was to probe clouds above the SGP CART site at night in March 2002 from below (WAIL and ARM instruments) and from NASA's P3 aircraft (carrying THOR, the GSFC counterpart of WAIL) flying above the clouds. The permanent cloud instruments we used to compare with the results obtained from WAIL were ARM's laser ceilometer, micro-pulse lidar (MPL), millimeter-wavelength cloud radar (MMCR), and micro-wave radiometer (MWR). The comparison shows that, in spite of an unusually low cloud ceiling, an unfavorable observation condition for WAIL's present configuration, cloud properties obtained from the new instrument are in good agreement with their counterparts obtained by other instruments. So WAIL can duplicate, at least for single-layer clouds, the cloud products of the MWR and MMCR together. But WAIL does this with green laser light, which is far more representative than microwaves of photon transport processes at work in the climate system.

Statistical properties of mean stand biomass estimators in a LIDAR-based double sampling forest survey design.

Science.gov (United States)

H.E. Anderson; J. Breidenbach

2007-01-01

Airborne laser scanning (LIDAR) can be a valuable tool in double-sampling forest survey designs. LIDAR-derived forest structure metrics are often highly correlated with important forest inventory variables, such as mean stand biomass, and LIDAR-based synthetic regression estimators have the potential to be highly efficient compared to single-stage estimators, which...

Application of a Terrestrial LIDAR System for Elevation Mapping in Terra Nova Bay, Antarctica

Directory of Open Access Journals (Sweden)

Hyoungsig Cho

2015-09-01

Full Text Available A terrestrial Light Detection and Ranging (LIDAR system has high productivity and accuracy for topographic mapping, but the harsh conditions of Antarctica make LIDAR operation difficult. Low temperatures cause malfunctioning of the LIDAR system, and unpredictable strong winds can deteriorate data quality by irregularly shaking co-registration targets. For stable and efficient LIDAR operation in Antarctica, this study proposes and demonstrates the following practical solutions: (1 a lagging cover with a heating pack to maintain the temperature of the terrestrial LIDAR system; (2 co-registration using square planar targets and two-step point-merging methods based on extracted feature points and the Iterative Closest Point (ICP algorithm; and (3 a georeferencing module consisting of an artificial target and a Global Navigation Satellite System (GNSS receiver. The solutions were used to produce a topographic map for construction of the Jang Bogo Research Station in Terra Nova Bay, Antarctica. Co-registration and georeferencing precision reached 5 and 45 mm, respectively, and the accuracy of the Digital Elevation Model (DEM generated from the LIDAR scanning data was ±27.7 cm.

Application of a Terrestrial LIDAR System for Elevation Mapping in Terra Nova Bay, Antarctica.

Science.gov (United States)

Cho, Hyoungsig; Hong, Seunghwan; Kim, Sangmin; Park, Hyokeun; Park, Ilsuk; Sohn, Hong-Gyoo

2015-09-16

A terrestrial Light Detection and Ranging (LIDAR) system has high productivity and accuracy for topographic mapping, but the harsh conditions of Antarctica make LIDAR operation difficult. Low temperatures cause malfunctioning of the LIDAR system, and unpredictable strong winds can deteriorate data quality by irregularly shaking co-registration targets. For stable and efficient LIDAR operation in Antarctica, this study proposes and demonstrates the following practical solutions: (1) a lagging cover with a heating pack to maintain the temperature of the terrestrial LIDAR system; (2) co-registration using square planar targets and two-step point-merging methods based on extracted feature points and the Iterative Closest Point (ICP) algorithm; and (3) a georeferencing module consisting of an artificial target and a Global Navigation Satellite System (GNSS) receiver. The solutions were used to produce a topographic map for construction of the Jang Bogo Research Station in Terra Nova Bay, Antarctica. Co-registration and georeferencing precision reached 5 and 45 mm, respectively, and the accuracy of the Digital Elevation Model (DEM) generated from the LIDAR scanning data was ±27.7 cm.

Demonstration of measuring sea fog with an SNSPD-based Lidar system.

Science.gov (United States)

Zhu, Jiang; Chen, Yajun; Zhang, Labao; Jia, Xiaoqing; Feng, Zhijun; Wu, Ganhua; Yan, Xiachao; Zhai, Jiquan; Wu, Yang; Chen, Qi; Zhou, Xiaoying; Wang, Zhizhong; Zhang, Chi; Kang, Lin; Chen, Jian; Wu, Peiheng

2017-11-08

The monitor of sea fogs become more important with the rapid development of marine activities. Remote sensing through laser is an effective tool for monitoring sea fogs, but still challengeable for large distance. We demonstrated a Long-distance Lidar for sea fog with superconducting nanowire single-photon detector (SNSPD), which extended the ranging area to a 180-km diameter area. The system, which was verified by using a benchmark distance measurement of a known island, is applied to the Mie scattering weather prediction Lidar system. The fog echo signal distribution in the range of 42.3∼63.5 km and 53.2∼74.2 km was obtained by the Lidar system. Then the fog concentration and the velocity of the fog were deduced from the distribution, which is consistent with the weather prediction. The height of the sea fog is about two hundred meter while the visibility at this height is about 90 km due to the Earth's radius of curvature. Therefore, the capability of this SNSPD-based Lidar was close to the theoretical limit for sea fog measurements for extremely high signal-to-noise ratio of SNSPD.

Airborne 2-Micron Double-Pulsed Integrated Path Differential Absorption Lidar for Column CO2 Measurement

Science.gov (United States)

Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer F.; Remus, Ruben G.; Fay, James J.; Reithmaier, Karl

2014-01-01

Double-pulse 2-micron lasers have been demonstrated with energy as high as 600 millijouls and up to 10 Hz repetition rate. The two laser pulses are separated by 200 microseconds and can be tuned and locked separately. Applying double-pulse laser in DIAL system enhances the CO2 measurement capability by increasing the overlap of the sampled volume between the on-line and off-line. To avoid detection complicity, integrated path differential absorption (IPDA) lidar provides higher signal-to-noise ratio measurement compared to conventional range-resolved DIAL. Rather than weak atmospheric scattering returns, IPDA rely on the much stronger hard target returns that is best suited for airborne platforms. In addition, the IPDA technique measures the total integrated column content from the instrument to the hard target but with weighting that can be tuned by the transmitter. Therefore, the transmitter could be tuned to weight the column measurement to the surface for optimum CO2 interaction studies or up to the free troposphere for optimum transport studies. Currently, NASA LaRC is developing and integrating a double-Pulsed 2-micron direct detection IPDA lidar for CO2 column measurement from an airborne platform. The presentation will describe the development of the 2-micron IPDA lidar system and present the airborne measurement of column CO2 and will compare to in-situ measurement for various ground target of different reflectivity.

The use of lidar images in Costa Rica : case studies applied in geology, engineering, and archaeology

International Nuclear Information System (INIS)

Ruiz, Paulo; Garro, Jose F.; Soto, Gerardo J.

2014-01-01

A historical review is made about evolution of technology Lidar (Laser Imaging Detection and Ranging). The improvements of this technology and additions from other technologies are annotated in the last 15 years. The information of the aerial and terrestrial lidar operation, technical parameters for data acquisition and resolutions are presented. The results from four studies are presented in Costa Rica: 1) The discovery of pre-Columbian trails in the area of Volcan Arenal, 2) A case of geological mapping and discovery of new volcanic structures in the North area of the Volcan Poas, 3) The characterization of a landslide near Palmares that represents a hazard for the road network, 4) A detail survey of a pre-Columbian sphere. The results from new Lidar will become more frequent in the following years because its cost will be more affordable. The transference of data between institutions will generate new applications in different fields. (author) [es

Detectors for LIDAR type Thomson scattering diagnostics

International Nuclear Information System (INIS)

Hirsch, K.

1991-04-01

A report on the capability of the microchannel plate photomultiplier type (ITT F4128) presently used at the JET LIDAR Thomson Scattering System is given. Detailed investigation on time response, low noise amplification, shutter ratio, gating behaviour, linear mode of operation and saturation pulse recovery carried out during the design phase for LIDAR are presented. New investigation with respect to dc- and gated operation showed no measurable changes in sensitivity of this MCP photomultiplier. Comparing this type of detector with other MCP photomultipliers and with streak cameras some detection schemes for future LIDAR type diagnostic are proposed. (orig.)

Opo lidar sounding of trace atmospheric gases in the 3 – 4 μm spectral range

Directory of Open Access Journals (Sweden)

Romanovskii Oleg A.

2018-01-01

Full Text Available The applicability of a KTA crystal-based laser system with optical parametric oscillators (OPO generation to lidar sounding of the atmosphere in the spectral range 3–4 μm is studied in this work. A technique developed for lidar sounding of trace atmospheric gases (TAG is based on differential absorption lidar (DIAL method and differential optical absorption spectroscopy (DOAS. The DIAL-DOAS technique is tested to estimate its efficiency for lidar sounding of atmospheric trace gases. The numerical simulation performed shows that a KTA-based OPO laser is a promising source of radiation for remote DIAL-DOAS sounding of the TAGs under study along surface tropospheric paths. A possibility of using a PD38-03-PR photodiode for the DIAL gas analysis of the atmosphere is shown.

Mini-Uav LIDAR for Power Line Inspection

Science.gov (United States)

Teng, G. E.; Zhou, M.; Li, C. R.; Wu, H. H.; Li, W.; Meng, F. R.; Zhou, C. C.; Ma, L.

2017-09-01

Light detection and ranging (LIDAR) system based on unmanned aerial vehicles (UAVs) recently are in rapid advancement, meanwhile portable and flexible mini-UAV-borne laser scanners have been a hot research field, especially for the complex terrain survey in the mountains and other areas. This study proposes a power line inspection system solution based on mini-UAV-borne LIDAR system-AOEagle, developed by Academy of Opto-Electronics, Chinese Academy of Sciences, which mounted on a Multi-rotor unmanned aerial vehicle for complex terrain survey according to real test. Furthermore, the point cloud data was explored to validate its applicability for power line inspection, in terms of corridor and line laser point clouds; deformation detection of power towers, etc. The feasibility and advantages of AOEagle have been demonstrated by the promising results based on the real-measured data in the field of power line inspection.

Imaging doppler lidar for wind turbine wake profiling

Science.gov (United States)

Bossert, David J.

2015-11-19

An imaging Doppler lidar (IDL) enables the measurement of the velocity distribution of a large volume, in parallel, and at high spatial resolution in the wake of a wind turbine. Because the IDL is non-scanning, it can be orders of magnitude faster than conventional coherent lidar approaches. Scattering can be obtained from naturally occurring aerosol particles. Furthermore, the wind velocity can be measured directly from Doppler shifts of the laser light, so the measurement can be accomplished at large standoff and at wide fields-of-view.

NAMMA LIDAR ATMOSPHERIC SENSING EXPERIMENT (LASE) V1

Data.gov (United States)

National Aeronautics and Space Administration — NASA's Lidar Atmospheric Sensing Experiment (LASE) system using the DIAL (Differential Absorption Lidar) system was operated during the NASA African Monsoon...

Lasers in space

Science.gov (United States)

Michaelis, M. M.; Forbes, A.; Bingham, R.; Kellett, B. J.; Mathye, A.

2008-05-01

A variety of laser applications in space, past, present, future and far future are reviewed together with the contributions of some of the scientists and engineers involved, especially those that happen to have South African connections. Historically, two of the earliest laser applications in space, were atmospheric LIDAR and lunar ranging. These applications involved atmospheric physicists, several astronauts and many of the staff recruited into the Soviet and North American lunar exploration programmes. There is a strong interest in South Africa in both LIDAR and lunar ranging. Shortly after the birth of the laser (and even just prior) theoretical work on photonic propulsion and space propulsion by laser ablation was initiated by Georgii Marx, Arthur Kantrowitz and Eugen Saenger. Present or near future experimental programs are developing in the following fields: laser ablation propulsion, possibly coupled with rail gun or gas gun propulsion; interplanetary laser transmission; laser altimetry; gravity wave detection by space based Michelson interferometry; the de-orbiting of space debris by high power lasers; atom laser interferometry in space. Far future applications of laser-photonic space-propulsion were also pioneered by Carl Sagan and Robert Forward. They envisaged means of putting Saenger's ideas into practice. Forward also invented a laser based method for manufacturing solid antimatter or SANTIM, well before the ongoing experiments at CERN with anti-hydrogen production and laser-trapping. SANTIM would be an ideal propellant for interstellar missions if it could be manufactured in sufficient quantities. It would be equally useful as a power source for the transmission of information over light year distances. We briefly mention military lasers. Last but not least, we address naturally occurring lasers in space and pose the question: "did the Big Bang lase?"

Modulated Sine Waves for Differential Absorption Measurements Using a CW Laser System

Science.gov (United States)

Campbell, Joel F. (Inventor); Lin, Bing (Inventor); Nehrir, Amin R. (Inventor)

2015-01-01

A continuous wave Light Detection and Ranging (CW LiDAR) system utilizes two or more laser frequencies and time or range shifted pseudorandom noise (PN) codes to discriminate between the laser frequencies. The performance of these codes can be improved by subtracting out the bias before processing. The CW LiDAR system may be mounted to an artificial satellite orbiting the earth, and the relative strength of the return signal for each frequency can be utilized to determine the concentration of selected gases or other substances in the atmosphere.

18th International Laser Radar Conference

CERN Document Server

Neuber, Roland; Rairoux, Patrick; Wandinger, Ulla

1997-01-01

Lidar or laser radar, the depth-resolved remote measurement of atmospheric parameters with optical means, has become an important tool in the field of atmospheric and environmental remote sensing. In this volume the latest progress in the development of lidar methods, experiments, and applications is described. The content is based on selected and thoroughly refereed papers presented at the 18th International Laser Radar Conference, Berlin, 22-26 July 1996. The book is divided into six parts which cover the topics of tropospheric aerosols and clouds, lidar in space, wind, water vapor, troposheric trace gases and plumes, and stratospheric and mesospheric profiling. As a supplement to fundamental lidar textbooks this volume may serve as a guide for scientists, engineers, and graduate students through the blossoming field of modern lidar techniques and their contribution to atmospheric and environmental research.

LIDAR COMBINED SCANNING UNIT

Directory of Open Access Journals (Sweden)

V. V. Elizarov

2016-11-01

Full Text Available Subject of Research. The results of lidar combined scanning unit development for locating leaks of hydrocarbons are presented The unit enables to perform high-speed scanning of the investigated space in wide and narrow angle fields. Method. Scanning in a wide angular field is produced by one-line scanning path by means of the movable aluminum mirror with a frequency of 20Hz and amplitude of 20 degrees of swing. Narrowband scanning is performed along a spiral path by the deflector. The deflection of the beam is done by rotation of the optical wedges forming part of the deflector at an angle of ±50. The control function of the scanning node is performed by a specialized software product written in C# programming language. Main Results. This scanning unit allows scanning the investigated area at a distance of 50-100 m with spatial resolution at the level of 3 cm. The positioning accuracy of the laser beam in space is 15'. The developed scanning unit gives the possibility to browse the entire investigated area for the time not more than 1 ms at a rotation frequency of each wedge from 50 to 200 Hz. The problem of unambiguous definition of the beam geographical coordinates in space is solved at the software level according to the rotation angles of the mirrors and optical wedges. Lidar system coordinates are determined by means of GPS. Practical Relevance. Development results open the possibility for increasing the spatial resolution of scanning systems of a wide range of lidars and can provide high positioning accuracy of the laser beam in space.

Airborne direct-detection and coherent wind lidar measurements over the North Atlantic in 2015 supporting ESA's aeolus mission

Science.gov (United States)

Marksteiner, Uwe; Reitebuch, Oliver; Lemmerz, Christian; Lux, Oliver; Rahm, Stephan; Witschas, Benjamin; Schäfler, Andreas; Emmitt, Dave; Greco, Steve; Kavaya, Michael J.; Gentry, Bruce; Neely, Ryan R.; Kendall, Emma; Schüttemeyer, Dirk

2018-04-01

The launch of the Aeolus mission by the European Space Agency (ESA) is planned for 2018. The satellite will carry the first wind lidar in space, ALADIN (Atmospheric Laser Doppler INstrument). Its prototype instrument, the ALADIN Airborne Demonstrator (A2D), was deployed during several airborne campaigns aiming at the validation of the measurement principle and optimization of algorithms. In 2015, flights of two aircraft from DLR & NASA provided the chance to compare parallel wind measurements from four airborne wind lidars for the first time.

Design of Laser Based Monitoring Systems for Compliance Management of Odorous and Hazardous Air Pollutants in Selected Chemical Industrial Estates at Hyderabad, India

Science.gov (United States)

Sudhakar, P.; Kalavathi, P.; Ramakrishna Rao, D.; Satyanarayna, M.

2014-12-01

Industrialization can no longer sustain without internalization of the concerns of the receiving environment and land-use. Increased awareness and public pressure, coupled with regulatory instruments and bodies exert constant pressure on industries to control their emissions to a level acceptable to the receiving environment. However, when a group of industries come-up together as an industrial estate, the cumulative impacts of all the industries together often challenges the expected/desired quality of receiving environment, requiring stringent pollution control and monitoring measures. Laser remote sensing techniques provide powerful tools for environmental monitoring. These methods provide range resolved measurements of concentrations of various gaseous pollutants and suspended particulate matter (SPM) not only in the path of the beam but over the entire area. A three dimensional mapping of the pollutants and their dispersal can be estimated using the laser remote sensing methods on a continuous basis. Laser Radar (Lidar) systems are the measurements technology used in the laser remote sensing methods. Differential absorption lidar (DIAL) and Raman Lidar technologies have proved to be very useful for remote sensing of air pollutants. DIAL and Raman lidar systems can be applied for range resolved measurements of molecules like SO2, NO2, O3 Hg, CO, C2H4, H2O, CH4, hydrocarbons etc. in real time on a continuous basis. This paper describes the design details of the DAIL and Raman lidar techniques for measurement of various hazardous air pollutants which are being released into the atmosphere by the chemical industries operating in the Bachupally industrial Estate area at Hyderabad, India. The relative merits of the two techniques have been studied and the minimum concentration of pollutants that can be measured using these systems are presented. A dispersion model of the air pollutants in the selected chemical industrial estates at Hyderabad has been developed.

Processing and evaluation of riverine waveforms acquired by an experimental bathymetric LiDAR

Science.gov (United States)

Kinzel, P. J.; Legleiter, C. J.; Nelson, J. M.

2010-12-01

Accurate mapping of fluvial environments with airborne bathymetric LiDAR is challenged not only by environmental characteristics but also the development and application of software routines to post-process the recorded laser waveforms. During a bathymetric LiDAR survey, the transmission of the green-wavelength laser pulses through the water column is influenced by a number of factors including turbidity, the presence of organic material, and the reflectivity of the streambed. For backscattered laser pulses returned from the river bottom and digitized by the LiDAR detector, post-processing software is needed to interpret and identify distinct inflections in the reflected waveform. Relevant features of this energy signal include the air-water interface, volume reflection from the water column itself, and, ideally, a strong return from the bottom. We discuss our efforts to acquire, analyze, and interpret riverine surveys using the USGS Experimental Advanced Airborne Research LiDAR (EAARL) in a variety of fluvial environments. Initial processing of data collected in the Trinity River, California, using the EAARL Airborne Lidar Processing Software (ALPS) highlighted the difficulty of retrieving a distinct bottom signal in deep pools. Examination of laser waveforms from these pools indicated that weak bottom reflections were often neglected by a trailing edge algorithm used by ALPS to process shallow riverine waveforms. For the Trinity waveforms, this algorithm had a tendency to identify earlier inflections as the bottom, resulting in a shallow bias. Similarly, an EAARL survey along the upper Colorado River, Colorado, also revealed the inadequacy of the trailing edge algorithm for detecting weak bottom reflections. We developed an alternative waveform processing routine by exporting digitized laser waveforms from ALPS, computing the local extrema, and fitting Gaussian curves to the convolved backscatter. Our field data indicate that these techniques improved the

Measurements of stratospheric Pinatubo aerosol extinction profiles by a Raman lidar

International Nuclear Information System (INIS)

Abo, Makoto; Nagasawa, Chikao.

1992-01-01

The Raman lidar has been used for remote measurements of water vapor, ozone and atmospheric temperature in the lower troposphere because the Raman cross section is three orders smaller than the Rayleigh cross section. The authors estimated the extinction coefficients of the Pinatubo volcanic aerosol in the stratosphere using a Raman lidar. If the precise aerosol extinction coefficients are derived, the backscatter coefficient of a Mie scattering lidar will be more accurately estimated. The Raman lidar has performed to measure density profiles of some species using Raman scattering. Here the authors used a frequency-doubled Nd:YAG laser for transmitter and received nitrogen vibrational Q-branch Raman scattering signal. Ansmann et al. (1990) derived tropospherical aerosol extinction profiles with a Raman lidar. The authors think that this method can apply to dense stratospheric aerosols such as Pinatubo volcanic aerosols. As dense aerosols are now accumulated in the stratosphere by Pinatubo volcanic eruption, the error of Ramen lidar signal regarding the fluctuation of air density can be ignored

LIDAR Thomson scattering for ITER core plasma revisited

International Nuclear Information System (INIS)

Gowers, C.; Nielsen, P.; Salzmann, H.

2016-01-01

The authors have become aware that the development of the hitherto planned time-of-flight Thomson scattering system for the ITER core plasma is not proceeding and that conventional Thomson scattering set-ups are being discussed as an alternative. In this paper, we want to point out the advantages of LIDAR and show how criticized details of the original design can be improved. We present a design of the front optics, which in neutronics terms closely resembles a layout already previously accepted. The presented design does not require Raman scattering calibration for the density measurement. Comparison with the JET Core LIDAR system and simulations at higher temperatures both show that with the new design the specified accuracy can be met with a 1–2 J laser. Current laser and detector technology is reviewed. A strategy for how to proceed is presented

Advances and perspectives in bathymetry by airborne lidar

Science.gov (United States)

Zhou, Guoqing; Wang, Chenxi; Li, Mingyan; Wang, Yuefeng; Ye, Siqi; Han, Caiyun

2015-12-01

In this paper, the history of the airborne lidar and the development stages of the technology are reviewed. The basic principle of airborne lidar and the method of processing point-cloud data were discussed. At present, single point laser scanning method is widely used in bathymetric survey. Although the method has high ranging accuracy, the data processing and hardware system is too much complicated and expensive. For this reason, this paper present a kind of improved dual-frequency method for bathymetric and sea surface survey, in this method 176 units of 1064nm wavelength laser has been used by push-broom scanning and due to the airborne power limits still use 532nm wavelength single point for bathymetric survey by zigzag scanning. We establish a spatial coordinates for obtaining the WGS-84 of point cloud by using airborne POS system.

High-Rate Data-Capture for an Airborne Lidar System

Science.gov (United States)

Valett, Susan; Hicks, Edward; Dabney, Philip; Harding, David

2012-01-01

A high-rate data system was required to capture the data for an airborne lidar system. A data system was developed that achieved up to 22 million (64-bit) events per second sustained data rate (1408 million bits per second), as well as short bursts (less than 4 s) at higher rates. All hardware used for the system was off the shelf, but carefully selected to achieve these rates. The system was used to capture laser fire, single-photon detection, and GPS data for the Slope Imaging Multi-polarization Photo-counting Lidar (SIMPL). However, the system has applications for other laser altimeter systems (waveform-recording), mass spectroscopy, xray radiometry imaging, high-background- rate ranging lidar, and other similar areas where very high-speed data capture is needed. The data capture software was used for the SIMPL instrument that employs a micropulse, single-photon ranging measurement approach and has 16 data channels. The detected single photons are from two sources those reflected from the target and solar background photons. The instrument is non-gated, so background photons are acquired for a range window of 13 km and can comprise many times the number of target photons. The highest background rate occurs when the atmosphere is clear, the Sun is high, and the target is a highly reflective surface such as snow. Under these conditions, the total data rate for the 16 channels combined is expected to be approximately 22 million events per second. For each photon detection event, the data capture software reads the relative time of receipt, with respect to a one-per-second absolute time pulse from a GPS receiver, from an event timer card with 0.1-ns precision, and records that information to a RAID (Redundant Array of Independent Disks) storage device. The relative time of laser pulse firings must also be read and recorded with the same precision. Each of the four event timer cards handles the throughput from four of the channels. For each detection event, a flag is

Single-Photon Avalanche Diode with Enhanced NIR-Sensitivity for Automotive LIDAR Systems

Directory of Open Access Journals (Sweden)

Isamu Takai

2016-03-01

Full Text Available A single-photon avalanche diode (SPAD with enhanced near-infrared (NIR sensitivity has been developed, based on 0.18 μm CMOS technology, for use in future automotive light detection and ranging (LIDAR systems. The newly proposed SPAD operating in Geiger mode achieves a high NIR photon detection efficiency (PDE without compromising the fill factor (FF and a low breakdown voltage of approximately 20.5 V. These properties are obtained by employing two custom layers that are designed to provide a full-depletion layer with a high electric field profile. Experimental evaluation of the proposed SPAD reveals an FF of 33.1% and a PDE of 19.4% at 870 nm, which is the laser wavelength of our LIDAR system. The dark count rate (DCR measurements shows that DCR levels of the proposed SPAD have a small effect on the ranging performance, even if the worst DCR (12.7 kcps SPAD among the test samples is used. Furthermore, with an eye toward vehicle installations, the DCR is measured over a wide temperature range of 25–132 °C. The ranging experiment demonstrates that target distances are successfully measured in the distance range of 50–180 cm.

Development and Deployment of a Compact Eye-Safe Scanning Differential absorption Lidar (DIAL) for Spatial Mapping of Carbon Dioxide for Monitoring/Verification/Accounting at Geologic Sequestration Sites

Energy Technology Data Exchange (ETDEWEB)

Repasky, Kevin

2014-03-31

A scanning differential absorption lidar (DIAL) instrument for monitoring carbon dioxide has been developed. The laser transmitter uses two tunable discrete mode laser diodes (DMLD) operating in the continuous wave (cw) mode with one locked to the online absorption wavelength and the other operating at the offline wavelength. Two in-line fiber optic switches are used to switch between online and offline operation. After the fiber optic switch, an acousto- optic modulator (AOM) is used to generate a pulse train used to injection seed an erbium doped fiber amplifier (EDFA) to produce eye-safe laser pulses with maximum pulse energies of 66 {micro}J, a pulse repetition frequency of 15 kHz, and an operating wavelength of 1.571 {micro}m. The DIAL receiver uses a 28 cm diameter Schmidt-Cassegrain telescope to collect that backscattered light, which is then monitored using a photo-multiplier tube (PMT) module operating in the photon counting mode. The DIAL instrument has been operated from a laboratory environment on the campus of Montana State University, at the Zero Emission Research Technology (ZERT) field site located in the agricultural research area on the western end of the Montana State University campus, and at the Big Sky Carbon Sequestration Partnership site located in north-central Montana. DIAL data has been collected and profiles have been validated using a co-located Licor LI-820 Gas Analyzer point sensor.

NAMMA LIDAR ATMOSPHERIC SENSING EXPERIMENT (LASE) V1

Data.gov (United States)

National Aeronautics and Space Administration — The NAMMA Lidar Atmospheric Sensing Experiment (LASE) dataset used the LASE system using the Differential Absorption Lidar (DIAL) system was operated during the NASA...

HiRes camera and LIDAR ranging system for the Clementine mission

Energy Technology Data Exchange (ETDEWEB)

Ledebuhr, A.G.; Kordas, J.F.; Lewis, I.T. [and others

1995-04-01

Lawrence Livermore National Laboratory developed a space-qualified High Resolution (HiRes) imaging LIDAR (Light Detection And Ranging) system for use on the DoD Clementine mission. The Clementine mission provided more than 1.7 million images of the moon, earth, and stars, including the first ever complete systematic surface mapping of the moon from the ultra-violet to near-infrared spectral regions. This article describes the Clementine HiRes/LIDAR system, discusses design goals and preliminary estimates of on-orbit performance, and summarizes lessons learned in building and using the sensor. The LIDAR receiver system consists of a High Resolution (HiRes) imaging channel which incorporates an intensified multi-spectral visible camera combined with a Laser ranging channel which uses an avalanche photo-diode for laser pulse detection and timing. The receiver was bore sighted to a light-weight McDonnell-Douglas diode-pumped ND:YAG laser transmitter that emmitted 1.06 {micro}m wavelength pulses of 200 mJ/pulse and 10 ns pulse-width, The LIDAR receiver uses a common F/9.5 Cassegrain telescope assembly. The optical path of the telescope is split using a color-separating beamsplitter. The imaging channel incorporates a filter wheel assembly which spectrally selects the light which is imaged onto a custom 12 mm gated image intensifier fiber-optically-coupled into a 384 x 276 pixel frame transfer CCD FPA. The image intensifier was spectrally sensitive over the 0.4 to 0.8 {micro}m wavelength region. The six-position filter wheel contained 4 narrow spectral filters, one broadband and one blocking filter. At periselene (400 km) the HiRes/LIDAR imaged a 2.8 km swath width at 20-meter resolution. The LIDAR function detected differential signal return with a 40-meter range accuracy, with a maximum range capability of 640 km, limited by the bit counter in the range return counting clock.

Early laser operations at the Large Binocular Telescope Observatory

Science.gov (United States)

Rahmer, Gustavo; Lefebvre, Michael; Christou, Julian; Raab, Walfried; Rabien, Sebastian; Ziegleder, Julian; Borelli, José L.; Gässler, Wolfgang

2014-08-01

ARGOS is the GLAO (Ground-Layer Adaptive Optics) Rayleigh-based LGS (Laser Guide Star) facility for the Large Binocular Telescope Observatory (LBTO). It is dedicated for observations with LUCI1 and LUCI2, LBTO's pair of NIR imagers and multi-object spectrographs. The system projects three laser beams from the back of each of the two secondary mirror units, which create two constellations circumscribed on circles of 2 arcmin radius with 120 degree spacing. Each of the six Nd:YAG lasers provides a beam of green (532nm) pulses at a rate of 10kHz with a power of 14W to 18W. We achieved first on-sky propagation on the night of November 5, 2013, and commissioning of the full system will take place during 2014. We present the initial results of laser operations at the observatory, including safety procedures and the required coordination with external agencies (FAA, Space Command, and Military Airspace Manager). We also describe our operational procedures and report on our experiences with aircraft spotters. Future plans for safer and more efficient aircraft monitoring and detection are discussed.

2007 FEMA New Jersey Flood Mitigation Lidar: Gloucester County

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. By positioning laser range finding with the use of 1...

2006 FEMA New Jersey Flood Mitigation Lidar: Middlesex County

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. By positioning laser range finding with the use of 1...

LIDAR AND INS FUSION IN PERIODS OF GPS OUTAGES FOR MOBILE LASER SCANNING MAPPING SYSTEMS

Directory of Open Access Journals (Sweden)

I. Klein

2012-09-01

Full Text Available Mobile laser scanning systems are becoming an increasingly popular means to obtain 3D coverage on a large scale. To perform the mapping, the exact position of the vehicle must be known throughout the trajectory. Exact position is achieved via integration of Global Positioning Systems (GPS and Inertial Navigation Systems (INS. Yet, in urban environments, cases of complete or even partial GPS outages may occur leaving the navigation solution to rely only on the INS. The INS navigation solution degrades with time as the Inertial Measurement Unit (IMU measurements contains noise, which permeates into the navigation equations. Degradation of the position determination leads to loss of data in such segments. To circumvent such drift and its effects, we propose fusing INS with lidar data by using building edges. This detection of edges is then translated into position data, which is used as an aiding to the INS. It thereby enables the determination of the vehicle position with a satisfactory level accuracy, sufficient to perform the laser-scanning based mapping in those outage periods.

Assessing LiDAR elevation data for KDOT applications.

Science.gov (United States)

2013-02-01

LiDAR-based elevation surveys are a cost-effective means for mapping topography over large areas. LiDAR : surveys use an airplane-mounted or ground-based laser radar unit to scan terrain. Post-processing techniques are : applied to remove vegetation ...

Spectral dependence of backscattering coefficient of mixed phase clouds over West Africa measured with two-wavelength Raman polarization lidar: Features attributed to ice-crystals corner reflection

Science.gov (United States)

Veselovskii, I.; Goloub, P.; Podvin, T.; Tanre, D.; Ansmann, A.; Korenskiy, M.; Borovoi, A.; Hu, Q.; Whiteman, D. N.

2017-11-01

The existing models predict that corner reflection (CR) of laser radiation by simple ice crystals of perfect shape, such as hexagonal columns or plates, can provide a significant contribution to the ice cloud backscattering. However in real clouds the CR effect may be suppressed due to crystal deformation and surface roughness. In contrast to the extinction coefficient, which is spectrally independent, consideration of diffraction associated with CR results in a spectral dependence of the backscattering coefficient. Thus measuring the spectral dependence of the cloud backscattering coefficient, the contribution of CR can be identified. The paper presents the results of profiling of backscattering coefficient (β) and particle depolarization ratio (δ) of ice and mixed-phase clouds over West Africa by means of a two-wavelength polarization Mie-Raman lidar operated at 355 nm and 532 nm during the SHADOW field campaign. The lidar observations were performed at a slant angle of 43 degree off zenith, thus CR from both randomly oriented crystals and oriented plates could be analyzed. For the most of the observations the cloud backscatter color ratio β355/β532 was close to 1.0, and no spectral features that might indicate the presence of CR of randomly oriented crystals were revealed. Still, in two measurement sessions we observed an increase of backscatter color ratio to a value of nearly 1.3 simultaneously with a decrease of the spectral depolarization ratio δ355/δ532 ratio from 1.0 to 0.8 inside the layers containing precipitating ice crystals. We attribute these changes in optical properties to corner reflections by horizontally oriented ice plates.

Laser Scanning in Forests

Directory of Open Access Journals (Sweden)

Håkan Olsson

2012-09-01

Full Text Available The introduction of Airborne Laser Scanning (ALS to forests has been revolutionary during the last decade. This development was facilitated by combining earlier ranging lidar discoveries [1–5], with experience obtained from full-waveform ranging radar [6,7] to new airborne laser scanning systems which had components such as a GNSS receiver (Global Navigation Satellite System, IMU (Inertial Measurement Unit and a scanning mechanism. Since the first commercial ALS in 1994, new ALS-based forest inventory approaches have been reported feasible for operational activities [8–12]. ALS is currently operationally applied for stand level forest inventories, for example, in Nordic countries. In Finland alone, the adoption of ALS for forest data collection has led to an annual savings of around 20 M€/year, and the work is mainly done by companies instead of governmental organizations. In spite of the long implementation times and there being a limited tradition of making changes in the forest sector, laser scanning was commercially and operationally applied after about only one decade of research. When analyzing high-ranked journal papers from ISI Web of Science, the topic of laser scanning of forests has been the driving force for the whole laser scanning research society over the last decade. Thus, the topic “laser scanning in forests” has provided a significant industrial, societal and scientific impact. [...

High-Speed Operation of Interband Cascade Lasers

Science.gov (United States)

Soibel, Alexander; Hill, Cory J.; Keo, Sam A.; Wright, Malcom W.; Farr, William H.; Yang, Rui Q.; Liu, H. C.

2010-01-01

Optical sources operating in the atmospheric window of 3-5 microns are of particular interest for the development of free-space optical communication link. It is more advantageous to operate the free-space optical communication link in 3-5-microns atmospheric transmission window than at the telecom wavelength of 1.5 m due to lower optical scattering, scintillation, and background radiation. However, the realization of optical communications at the longer wavelength has encountered significant difficulties due to lack of adequate optical sources and detectors operating in the desirable wavelength regions. Interband Cascade (IC) lasers are novel semiconductor lasers that have a great potential for the realization of high-power, room-temperature optical sources in the 3-5-microns wavelength region, yet no experimental work, until this one, was done on high-speed direct modulation of IC lasers. Here, highspeed interband cascade laser, operating at wavelength 3.0 m, has been developed and the first direct measurement of the laser modulation bandwidth has been performed using a unique, highspeed quantum well infrared photodetector (QWIP). The developed laser has modulation bandwidth exceeding 3 GHz. This constitutes a significant increase of the IC laser modulation bandwidth over currently existing devices. This result has demonstrated suitability of IC lasers as a mid-IR light source for multi-GHz free-space optical communications links

Monte Carlo analysis of radiative transport in oceanographic lidar measurements

Energy Technology Data Exchange (ETDEWEB)

Cupini, E.; Ferro, G. [ENEA, Divisione Fisica Applicata, Centro Ricerche Ezio Clementel, Bologna (Italy); Ferrari, N. [Bologna Univ., Bologna (Italy). Dipt. Ingegneria Energetica, Nucleare e del Controllo Ambientale

2001-07-01

The analysis of oceanographic lidar systems measurements is often carried out with semi-empirical methods, since there is only a rough understanding of the effects of many environmental variables. The development of techniques for interpreting the accuracy of lidar measurements is needed to evaluate the effects of various environmental situations, as well as of different experimental geometric configurations and boundary conditions. A Monte Carlo simulation model represents a tool that is particularly well suited for answering these important questions. The PREMAR-2F Monte Carlo code has been developed taking into account the main molecular and non-molecular components of the marine environment. The laser radiation interaction processes of diffusion, re-emission, refraction and absorption are treated. In particular are considered: the Rayleigh elastic scattering, produced by atoms and molecules with small dimensions with respect to the laser emission wavelength (i.e. water molecules), the Mie elastic scattering, arising from atoms or molecules with dimensions comparable to the laser wavelength (hydrosols), the Raman inelastic scattering, typical of water, the absorption of water, inorganic (sediments) and organic (phytoplankton and CDOM) hydrosols, the fluorescence re-emission of chlorophyll and yellow substances. PREMAR-2F is an extension of a code for the simulation of the radiative transport in atmospheric environments (PREMAR-2). The approach followed in PREMAR-2 was to combine conventional Monte Carlo techniques with analytical estimates of the probability of the receiver to have a contribution from photons coming back after an interaction in the field of view of the lidar fluorosensor collecting apparatus. This offers an effective mean for modelling a lidar system with realistic geometric constraints. The retrieved semianalytic Monte Carlo radiative transfer model has been developed in the frame of the Italian Research Program for Antarctica (PNRA) and it is

Landslides Mapped from LIDAR Imagery, Kitsap County, Washington

Science.gov (United States)

McKenna, Jonathan P.; Lidke, David J.; Coe, Jeffrey A.

2008-01-01

Landslides are a recurring problem on hillslopes throughout the Puget Lowland, Washington, but can be difficult to identify in the densely forested terrain. However, digital terrain models of the bare-earth surface derived from LIght Detection And Ranging (LIDAR) data express topographic details sufficiently well to identify landslides. Landslides and escarpments were mapped using LIDAR imagery and field checked (when permissible and accessible) throughout Kitsap County. We relied almost entirely on derivatives of LIDAR data for our mapping, including topographic-contour, slope, and hill-shaded relief maps. Each mapped landslide was assigned a level of 'high' or 'moderate' confidence based on the LIDAR characteristics and on field observations. A total of 231 landslides were identified representing 0.8 percent of the land area of Kitsap County. Shallow debris topples along the coastal bluffs and large (>10,000 m2) landslide complexes are the most common types of landslides. The smallest deposit mapped covers an area of 252 m2, while the largest covers 0.5 km2. Previous mapping efforts that relied solely on field and photogrammetric methods identified only 57 percent of the landslides mapped by LIDAR (61 percent high confidence and 39 percent moderate confidence), although nine landslides previously identified were not mapped during this study. The remaining 43 percent identified using LIDAR have 13 percent high confidence and 87 percent moderate confidence. Coastal areas are especially susceptible to landsliding; 67 percent of the landslide area that we mapped lies within 500 meters of the present coastline. The remaining 33 percent are located along drainages farther inland. The LIDAR data we used for mapping have some limitations including (1) rounding of the interface area between low slope surfaces and vertical faces (that is, along the edges of steep escarpments) which results in scarps being mapped too far headward (one or two meters), (2) incorrect laser

Lightweight Inexpensive Ozone Lidar Telescope Using a Plastic Fresnel Lens

Science.gov (United States)

DeYoung, Russell J.; Notari, Anthony; Carrion, William; Pliutau, Denis

2014-01-01

An inexpensive lightweight ozone lidar telescope was designed, constructed and operated during an ozone lidar field campaign. This report summarizes the design parameters and performance of the plastic Fresnel lens telescope and shows the ozone lidar performance compared to Zemax calculations.

Influence of index contrast in two dimensional photonic crystal lasers

DEFF Research Database (Denmark)

Jørgensen, Mette Marie; Petersen, Sidsel Rübner; Christiansen, Mads Brøkner

2010-01-01

The influence of index contrast variations for obtaining single-mode operation and low threshold in dye doped polymer two dimensional photonic crystal (PhC) lasers is investigated. We consider lasers made from Pyrromethene 597 doped Ormocore imprinted with a rectangular lattice PhC having a cavity...

Evaluation of the Wind Flow Variability Using Scanning Doppler Lidar Measurements

Science.gov (United States)

Sand, S. C.; Pichugina, Y. L.; Brewer, A.

2016-12-01

Better understanding of the wind flow variability at the heights of the modern turbines is essential to accurately assess of generated wind power and efficient turbine operations. Nowadays the wind energy industry often utilizes scanning Doppler lidar to measure wind-speed profiles at high spatial and temporal resolution.The study presents wind flow features captured by scanning Doppler lidars during the second Wind Forecast and Improvement Project (WFIP 2) sponsored by the Department of Energy (DOE) and National Oceanic and Atmospheric Administration (NOAA). This 18-month long experiment in the Columbia River Basin aims to improve model wind forecasts complicated by mountain terrain, coastal effects, and numerous wind farms.To provide a comprehensive dataset to use for characterizing and predicting meteorological phenomena important to Wind Energy, NOAA deployed scanning, pulsed Doppler lidars to two sites in Oregon, one at Wasco, located upstream of all wind farms relative to the predominant westerly flow in the region, and one at Arlington, located in the middle of several wind farms.In this presentation we will describe lidar scanning patterns capable of providing data in conical, or vertical-slice modes. These individual scans were processed to obtain 15-min averaged profiles of wind speed and direction in real time. Visualization of these profiles as time-height cross sections allows us to analyze variability of these parameters with height, time and location, and reveal periods of rapid changes (ramp events). Examples of wind flow variability between two sites of lidar measurements along with examples of reduced wind velocity downwind of operating turbines (wakes) will be presented.

Development of an EMCCD for LIDAR applications

Science.gov (United States)

De Monte, B.; Bell, R. T.

2017-11-01

A novel detector, incorporating e2v's EMCCD (L3VisionTM) [1] technology for use in LIDAR (Light Detection And Ranging) applications has been designed, manufactured and characterised. The most critical performance aspect was the requirement to collect charge from a 120μm square detection area for a 667ns temporal sampling window, with low crosstalk between successive samples, followed by signal readout with sub-electron effective noise. Additional requirements included low dark signal, high quantum efficiency at the 355nm laser wavelength and the ability to handle bright laser echoes, without corruption of the much fainter useful signals. The detector architecture used high speed charge binning to combine signal from each sampling window into a single charge packet. This was then passed through a multiplication register (EMCCD) operating with a typical gain of 100X to a conventional charge detection circuit. The detector achieved a typical quantum efficiency of 80% and a total noise in darkness of < 0.5 electrons rms. Development of the detector was supported by ESA.

New semiconductor laser technology for gas sensing applications in the 1650nm range

Science.gov (United States)

Morrison, Gordon B.; Sherman, Jes; Estrella, Steven; Moreira, Renan L.; Leisher, Paul O.; Mashanovitch, Milan L.; Stephen, Mark; Numata, Kenji; Wu, Stewart; Riris, Haris

2017-08-01

Atmospheric methane (CH4) is the second most important anthropogenic greenhouse gas with approximately 25 times the radiative forcing of carbon dioxide (CO2) per molecule. CH4 also contributes to pollution in the lower atmosphere through chemical reactions leading to ozone production. Recent developments of LIDAR measurement technology for CH4 have been previously reported by Goddard Space Flight Center (GSFC). In this paper, we report on a novel, high-performance tunable semiconductor laser technology developed by Freedom Photonics for the 1650nm wavelength range operation, and for LIDAR detection of CH4. Devices described are monolithic, with simple control, and compatible with low-cost fabrication techniques. We present 3 different types of tunable lasers implemented for this application.

Re-Normalization Method of Doppler Lidar Signal for Error Reduction

Energy Technology Data Exchange (ETDEWEB)

Park, Nakgyu; Baik, Sunghoon; Park, Seungkyu; Kim, Donglyul [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Dukhyeon [Hanbat National Univ., Daejeon (Korea, Republic of)

2014-05-15

In this paper, we presented a re-normalization method for the fluctuations of Doppler signals from the various noises mainly due to the frequency locking error for a Doppler lidar system. For the Doppler lidar system, we used an injection-seeded pulsed Nd:YAG laser as the transmitter and an iodine filter as the Doppler frequency discriminator. For the Doppler frequency shift measurement, the transmission ratio using the injection-seeded laser is locked to stabilize the frequency. If the frequency locking system is not perfect, the Doppler signal has some error due to the frequency locking error. The re-normalization process of the Doppler signals was performed to reduce this error using an additional laser beam to an Iodine cell. We confirmed that the renormalized Doppler signal shows the stable experimental data much more than that of the averaged Doppler signal using our calibration method, the reduced standard deviation was 4.838 Χ 10{sup -3}.

GRIP DOPPLER AEROSOL WIND LIDAR (DAWN) V1

Data.gov (United States)

National Aeronautics and Space Administration — The GRIP Doppler Aerosol WiNd Lidar (DAWN) Dataset was collected by the Doppler Aerosol WiNd (DAWN), a pulsed lidar, which operated aboard a NASA DC-8 aircraft...

Non-Topographic Space-Based Laser Remote Sensing

Science.gov (United States)

Yu, Anthony W.; Abshire, James B.; Riris, Haris; Purucker, Michael; Janches, Diego; Getty, Stephanie; Krainak, Michael A.; Stephen, Mark A.; Chen, Jeffrey R.; Li, Steve X.;

Detection of Wind Evolution and Lidar Trajectory Optimization for Lidar-Assisted Wind Turbine Control

Directory of Open Access Journals (Sweden)

David Schlipf

2015-11-01

Full Text Available Recent developments in remote sensing are offering a promising opportunity to rethink conventional control strategies of wind turbines. With technologies such as lidar, the information about the incoming wind field - the main disturbance to the system - can be made available ahead of time. Initial field testing of collective pitch feedforward control shows, that lidar measurements are only beneficial if they are filtered properly to avoid harmful control action. However, commercial lidar systems developed for site assessment are usually unable to provide a usable signal for real time control. Recent research shows, that the correlation between the measurement of rotor effective wind speed and the turbine reaction can be modeled and that the model can be used to optimize a scan pattern. This correlation depends on several criteria such as turbine size, position of the measurements, measurement volume, and how the wind evolves on its way towards the rotor. In this work the longitudinal wind evolution is identified with the line-of-sight measurements of a pulsed lidar system installed on a large commercial wind turbine. This is done by staring directly into the inflowing wind during operation of the turbine and fitting the coherence between the wind at different measurement distances to an exponential model taking into account the yaw misalignment, limitation to line-of-sight measurements and the pulse volume. The identified wind evolution is then used to optimize the scan trajectory of a scanning lidar for lidar-assisted feedforward control in order to get the best correlation possible within the constraints of the system. Further, an adaptive filer is fitted to the modeled correlation to avoid negative impact of feedforward control because of uncorrelated frequencies of the wind measurement. The main results of the presented work are a first estimate of the wind evolution in front of operating wind turbines and an approach which manufacturers of

Demonstration of coherent Doppler lidar for navigation in GPS-denied environments

Science.gov (United States)

Amzajerdian, Farzin; Hines, Glenn D.; Pierrottet, Diego F.; Barnes, Bruce W.; Petway, Larry B.; Carson, John M.

2017-05-01

A coherent Doppler lidar has been developed to address NASA's need for a high-performance, compact, and cost-effective velocity and altitude sensor onboard its landing vehicles. Future robotic and manned missions to solar system bodies require precise ground-relative velocity vector and altitude data to execute complex descent maneuvers and safe, soft landing at a pre-designated site. This lidar sensor, referred to as a Navigation Doppler Lidar (NDL), meets the required performance of the landing missions while complying with vehicle size, mass, and power constraints. Operating from up to four kilometers altitude, the NDL obtains velocity and range precision measurements reaching 2 cm/sec and 2 meters, respectively, dominated by the vehicle motion. Terrestrial aerial vehicles will also benefit from NDL data products as enhancement or replacement to GPS systems when GPS is unavailable or redundancy is needed. The NDL offers a viable option to aircraft navigation in areas where the GPS signal can be blocked or jammed by intentional or unintentional interference. The NDL transmits three laser beams at different pointing angles toward the ground to measure range and velocity along each beam using a frequency modulated continuous wave (FMCW) technique. The three line-of-sight measurements are then combined in order to determine the three components of the vehicle velocity vector and its altitude relative to the ground. This paper describes the performance and capabilities that the NDL demonstrated through extensive ground tests, helicopter flight tests, and onboard an autonomous rocket-powered test vehicle while operating in closedloop with a guidance, navigation, and control (GN and C) system.

The LIDAR Thomson Scattering Diagnostic on JET

DEFF Research Database (Denmark)

Salzmann, H.; Bundgaard, J.; Gadd, A.

1988-01-01

By combining the time‐of‐flight or LIDAR principle with a Thomson backscatter diagnostic, spatial profiles of the electron temperature and density are measured in a magnetically confined fusion plasma. This technique was realized for the first time on the JET tokamak. A ruby laser (3‐J pulse ener...

Evaluating a small footprint, waveform-resolving lidar over coastal vegetation communities

Science.gov (United States)

Nayegandhl, A.; Brock, J.C.; Wright, C.W.; O'Connell, M. J.

2006-01-01

NASA's Experimental Advanced Airborne Research Lidar (EAARL) is a raster-scanning, waveform-resolving, green-wavelength (532 nm) lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor records the time history of the return waveform within a small footprint (20 cm diameter) for each laser pulse, enabling characterization of vegetation canopy structure and "bare earth" topography under a variety of vegetation types. A collection of individual waveforms combined within a synthesized large footprint was used to define three metrics: canopy height (CH), canopy reflection ratio (CRR), and height of median energy (HOME). Bare Earth Elevation (BEE) metric was derived using the individual small-footprint waveforms. All four metrics were tested for reproducibility, which resulted in an average of 95 percent correspondence within two standard deviations of the mean. CH and BEE values were also tested for accuracy using ground-truth data. The results presented in this paper show that combining several individual small-footprint laser pulses to define a composite "large-footprint" waveform is a possible method to depict the vertical structure of a vegetation canopy. ?? 2006 American Society for Photogrammetry and Remote Sensing.

Typical Applications of Airborne LIDAR Technolagy in Geological Investigation

Science.gov (United States)

Zheng, X.; Xiao, C.

2018-05-01

The technology of airborne light detection and ranging (LiDAR), also referred to as Airborne Laser Scanning, is widely used for high-resolution topographic data acquisition (even under forest cover) with sub-meter planimetric and vertical accuracy. This contribution constructs the real digital terrain model to provide the direct observation data for the landscape analysis in geological domains. Based on the advantage of LiDAR, the authors mainly deal with the applications of LiDAR data to such fields as surface land collapse, landslide and fault structure extraction. The review conclusion shows that airborne LiDAR technology is becoming an indispensable tool for above mentioned issues, especially in the local and large scale investigations of micro-topography. The technology not only can identify the surface collapse, landslide boundary and subtle faulted landform, but also be able to extract the filling parameters of collapsed surface, the geomorphic parameters of landslide stability evaluation and cracks. This technology has extensive prospect of applications in geological investigation.

TYPICAL APPLICATIONS OF AIRBORNE LIDAR TECHNOLAGY IN GEOLOGICAL INVESTIGATION

Directory of Open Access Journals (Sweden)

X. Zheng

2018-05-01

Full Text Available The technology of airborne light detection and ranging (LiDAR, also referred to as Airborne Laser Scanning, is widely used for high-resolution topographic data acquisition (even under forest cover with sub-meter planimetric and vertical accuracy. This contribution constructs the real digital terrain model to provide the direct observation data for the landscape analysis in geological domains. Based on the advantage of LiDAR, the authors mainly deal with the applications of LiDAR data to such fields as surface land collapse, landslide and fault structure extraction. The review conclusion shows that airborne LiDAR technology is becoming an indispensable tool for above mentioned issues, especially in the local and large scale investigations of micro-topography. The technology not only can identify the surface collapse, landslide boundary and subtle faulted landform, but also be able to extract the filling parameters of collapsed surface, the geomorphic parameters of landslide stability evaluation and cracks. This technology has extensive prospect of applications in geological investigation.

Comparisons of Simultaneously Acquired Airborne Sfm Photogrammetry and Lidar

Science.gov (United States)

Larsen, C. F.

2014-12-01

Digital elevation models (DEMs) created using images from a consumer DSLR camera are compared against simultaneously acquired LiDAR on a number of airborne mapping projects across Alaska, California and Utah. The aircraft used is a Cessna 180, and is equipped with the University of Alaska Geophysical Institute (UAF-GI) scanning airborne LiDAR system. This LiDAR is the same as described in Johnson et al, 2013, and is the principal instrument used for NASA's Operation IceBridge flights in Alaska. The system has been in extensive use since 2009, and is particularly well characterized with dozens of calibration flights and a careful program of boresight angle determination and monitoring. The UAF-GI LiDAR has a precision of +/- 8 cm and accuracy of +/- 15 cm. The photogrammetry DEM simultaneously acquired with the LiDAR relies on precise shutter timing using an event marker input to the IMU associated with the LiDAR system. The photo positions are derived from the fully coupled GPS/IMU processing, which samples at 100 Hz and is able to directly calculate the antenna to image plane offset displacements from the full orientation data. This use of the GPS/IMU solution means that both the LiDAR and Cessna 180 photogrammetry DEM share trajectory input data, however no orientation data nor ground control is used for the photorammetry processing. The photogrammetry DEMs are overlaid on the LiDAR point cloud and analyzed for horizontal shifts or warps relative to the LiDAR. No warping or horizontal shifts have been detectable for a number of photogrammetry DEMs. Vertical offsets range from +/- 30 cm, with a typical standard deviation about that mean of 10 cm or better. LiDAR and photogrammetry function inherently differently over trees and brush, and direct comparisons between the two methods show much larger differences over vegetated areas. Finally, the differences in flight patterns associated with the two methods will be discussed, highlighting the photogrammetry

A New Framework for Quantifying Lidar Uncertainty

Energy Technology Data Exchange (ETDEWEB)

Newman, Jennifer, F.; Clifton, Andrew; Bonin, Timothy A.; Churchfield, Matthew J.

2017-03-24

As wind turbine sizes increase and wind energy expands to more complex and remote sites, remote sensing devices such as lidars are expected to play a key role in wind resource assessment and power performance testing. The switch to remote sensing devices represents a paradigm shift in the way the wind industry typically obtains and interprets measurement data for wind energy. For example, the measurement techniques and sources of uncertainty for a remote sensing device are vastly different from those associated with a cup anemometer on a meteorological tower. Current IEC standards discuss uncertainty due to mounting, calibration, and classification of the remote sensing device, among other parameters. Values of the uncertainty are typically given as a function of the mean wind speed measured by a reference device. However, real-world experience has shown that lidar performance is highly dependent on atmospheric conditions, such as wind shear, turbulence, and aerosol content. At present, these conditions are not directly incorporated into the estimated uncertainty of a lidar device. In this presentation, we propose the development of a new lidar uncertainty framework that adapts to current flow conditions and more accurately represents the actual uncertainty inherent in lidar measurements under different conditions. In this new framework, sources of uncertainty are identified for estimation of the line-of-sight wind speed and reconstruction of the three-dimensional wind field. These sources are then related to physical processes caused by the atmosphere and lidar operating conditions. The framework is applied to lidar data from an operational wind farm to assess the ability of the framework to predict errors in lidar-measured wind speed.

Design validation of an eye-safe scanning aerosol lidar with the Center for Lidar and Atmospheric Sciences Students (CLASS) at Hampton University

Science.gov (United States)

Richter, Dale A.; Higdon, N. S.; Ponsardin, Patrick L.; Sanchez, David; Chyba, Thomas H.; Temple, Doyle A.; Gong, Wei; Battle, Russell; Edmondson, Mika; Futrell, Anne; Harper, David; Haughton, Lincoln; Johnson, Demetra; Lewis, Kyle; Payne-Baggott, Renee S.

2002-01-01

ITTs Advanced Engineering and Sciences Division and the Hampton University Center for Lidar and Atmospheric Sciences Students (CLASS) team have worked closely to design, fabricate and test an eye-safe, scanning aerosol-lidar system that can be safely deployed and used by students form a variety of disciplines. CLASS is a 5-year undergraduate- research training program funded by NASA to provide hands-on atmospheric-science and lidar-technology education. The system is based on a 1.5 micron, 125 mJ, 20 Hz eye-safe optical parametric oscillator (OPO) and will be used by the HU researchers and students to evaluate the biological impact of aerosols, clouds, and pollution a variety of systems issues. The system design tasks we addressed include the development of software to calculate eye-safety levels and to model lidar performance, implementation of eye-safety features in the lidar transmitter, optimization of the receiver using optical ray tracing software, evaluation of detectors and amplifiers in the near RI, test of OPO and receiver technology, development of hardware and software for laser and scanner control and video display of the scan region.

Application of short-range dual-Doppler lidars to evaluate the coherence of turbulence

Science.gov (United States)

Cheynet, Etienne; Jakobsen, Jasna Bogunović; Snæbjörnsson, Jónas; Mikkelsen, Torben; Sjöholm, Mikael; Mann, Jakob; Hansen, Per; Angelou, Nikolas; Svardal, Benny

2016-12-01

Two synchronized continuous wave scanning lidars are used to study the coherence of the along-wind and across-wind velocity components. The goal is to evaluate the potential of the lidar technology for application in wind engineering. The wind lidars were installed on the Lysefjord Bridge during four days in May 2014 to monitor the wind field in the horizontal plane upstream of the bridge deck. Wind records obtained by five sonic anemometers mounted on the West side of the bridge are used as reference data. Single- and two-point statistics of wind turbulence are studied, with special emphasis on the root-coherence and the co-coherence of turbulence. A four-parameter decaying exponential function has been fitted to the measured co-coherence, and a good agreement is observed between data obtained by the sonic anemometers and the lidars. The root-coherence of turbulence is compared to theoretical models. The analytical predictions agree rather well with the measured coherence for the along-wind component. For increasing wavenumbers, larger discrepancies are, however, noticeable between the measured coherence and the theoretical predictions. The WindScanners are observed to slightly overestimate the integral length scales, which could not be explained by the laser beam averaging effect alone. On the other hand, the spatial averaging effect does not seem to have any significant effect on the coherence.

U.S. Coast Guard oil spill remote sensing : preliminary laser fluorosensor studies

International Nuclear Information System (INIS)

Fant, J.W.; Hansen, K.A.

2005-01-01

Maritime oil spill events are costly and damaging to the environment. Nearly 40 per cent of ship sourced spills occurring in the last 25 years have involved medium to heavy grade fuel oils. There is, therefore, an immediate need to detect and track subsurface oil spills, particularly as heavy and weathered oil can sink below the surface during a spill and often becomes problematic to detect, track and recover. The United States Coast Guard has limited capabilities to detect and track an oil spill, especially in poor weather. This paper discussed research and assessment efforts focused on laser fluorosensor technology. Testing of 3 independent laser fluorosensing systems was conducted to determine sensing depth capabilities and sensor shortcomings in ideal conditions. Studies included the detection and collection of laser induced fluorescence spectra at the surface as well as at various depths down to 5 metres in both daylight and night-time environments. The sensors were tested to assess their capabilities to meet the Coast Guard's oil sensor and operational requirements. Three sensors were tested by the Coast Guard at the Ohmsett National Oil Response Test Facility: the Airborne Oceanographic Lidar (AOL-3), a light detection and ranging system (lidar) to measure biological and physical oceanographic features developed by the National Aeronautics and Space Administration (NASA); the Fluorescent Lidar Spectrometer (FLS) lidar, developed by Laser Diagnostic Instruments International Inc. of Canada; and the Ultraviolet Biological Trigger Lidar, developed by Science and Engineering Services, Inc. (SESI) to detect and discriminate bio-warfare agent aerosols for the United States Army. The 3 fluorometers exhibited the ability to detect oil both on and below the water's surface. There were differences in the peak locations in the spectrum for the same oils among the lasers tested. It was also noted that all the systems had the capability of detecting oil in a night

Blue Laser for Ice and Melt Pond Lidar Applications

Data.gov (United States)

National Aeronautics and Space Administration — Lidar has been utilized for decades to study the cryosphere and its study is a core science product of several national organizations, including NASA, NOAA, and many...

Waveform LiDAR across forest biomass gradients

Science.gov (United States)

Montesano, P. M.; Nelson, R. F.; Dubayah, R.; Sun, G.; Ranson, J.

2011-12-01

Detailed information on the quantity and distribution of aboveground biomass (AGB) is needed to understand how it varies across space and changes over time. Waveform LiDAR data is routinely used to derive the heights of scattering elements in each illuminated footprint, and the vertical structure of vegetation is related to AGB. Changes in LiDAR waveforms across vegetation structure gradients can demonstrate instrument sensitivity to land cover transitions. A close examination of LiDAR waveforms in footprints across a forest gradient can provide new insight into the relationship of vegetation structure and forest AGB. In this study we use field measurements of individual trees within Laser Vegetation Imaging Sensor (LVIS) footprints along transects crossing forest to non-forest gradients to examine changes in LVIS waveform characteristics at sites with low (field AGB measurements to original and adjusted LVIS waveforms to detect the forest AGB interval along a forest - non-forest transition in which the LVIS waveform lose the ability to discern differences in AGB. Our results help identify the lower end the forest biomass range that a ~20m footprint waveform LiDAR can detect, which can help infer accumulation of biomass after disturbances and during forest expansion, and which can guide the use of LiDAR within a multi-sensor fusion biomass mapping approach.

Detection of preferential particle orientation in the atmosphere: Development of an alternative polarization lidar system

International Nuclear Information System (INIS)

Geier, Manfred; Arienti, Marco

2014-01-01

Increasing interest in polarimetric characterization of atmospheric aerosols has led to the development of complete sample-measuring (Mueller) polarimeters that are capable of measuring the entire backscattering phase matrix of a probed volume. These Mueller polarimeters consist of several moving parts, which limit measurement rates and complicate data analysis. In this paper, we present the concept of a less complex polarization lidar setup for detection of preferential orientation of atmospheric particulates. On the basis of theoretical considerations of data inversion stability and propagation of measurement uncertainties, an optimum optical configuration is established for two modes of operation (with either a linear or a circular polarized incident laser beam). The conceptualized setup falls in the category of incomplete sample-measuring polarimeters and uses four detection channels for simultaneous measurement of the backscattered light. The expected performance characteristics are discussed through an example of a typical aerosol with a small fraction of particles oriented in a preferred direction. The theoretical analysis suggests that achievable accuracies in backscatter cross-sections and depolarization ratios are similar to those with conventional two-channel configurations, while in addition preferential orientation can be detected with the proposed four-channel system for a wide range of conditions. - Highlights: • A theoretical study of a new four-channel lidar concept is offered. • Preferential particle orientation detection could be realized with minor device modifications. • The proposed configuration is optimized to balance inversion uncertainties. • Circular polarized beam is demonstrated to provide the best noise performance. • Operation with ultra-short pulses is proposed to quantify particle number density

Balloonborne lidar experiment

Science.gov (United States)

Shepherd, O.; Aurilio, G.; Bucknam, R. D.; Brooke, R. W.; Hurd, A. G.

1980-12-01

The object of this contract was to design a balloonborne lidar experiment capable of performing nightime atmospheric density measurements in the 10 to 40 km altitude domain with a resolution of 100 meters. The payload includes a frequency-tripled Nd:YAG laser with outputs at 353 and 1064 nm, a telescoped receiver with PMT detectors, a command-controlled optical pointing system, and support systems, including thermal control, telemetry, command, and power. Density measurements would be made using the back-scattered 353 nm radiation data with aerosol corrections obtained from 1064 nm radiation scatterings.

Lidar observations of stratospheric aerosol layer after the Mt. Pinatubo volcanic eruption

International Nuclear Information System (INIS)

Nagai, Tomohiro; Uchino, Osamu; Fujimoto, Toshifumi.

1992-01-01

The volcano Mt. Pinatubo located on the Luzon Island, Philippines, had explosively erupted on June 15, 1991. The volcanic eruptions such as volcanic ash, SO2 and H2O reached into the stratosphere over 30 km altitude by the NOAA-11 satellite observation and this is considered one of the biggest volcanic eruptions in this century. A grandiose volcanic eruption influences the atmosphere seriously and causes many climatic effects globally. There had been many impacts on radiation, atmospheric temperature and stratospheric ozone after some past volcanic eruptions. The main cause of volcanic influence depends on stratospheric aerosol, that stay long enough to change climate and other meteorological conditions. Therefore it is very important to watch stratospheric aerosol layers carefully and continuously. Standing on this respect, we do not only continue stratospheric aerosol observation at Tsukuba but also have urgently developed another lidar observational point at Naha in Okinawa Island. This observational station could be thought valuable since there is no lidar observational station in this latitudinal zone and it is much nearer to Mt. Pinatubo. Especially, there is advantage to link up these two stations on studying the transportation mechanism in the stratosphere. In this paper, we present the results of lidar observations at Tsukuba and Naha by lidar systems with Nd:YAG laser

Lidar Observations of Stratospheric Aerosol Layer After the Mt. Pinatubo Volcanic Eruption

Science.gov (United States)

Nagai, Tomohiro; Uchino, Osamu; Fujimoto, Toshifumi

1992-01-01

The volcano Mt. Pinatubo located on the Luzon Island, Philippines, had explosively erupted on June 15, 1991. The volcanic eruptions such as volcanic ash, SO2 and H2O reached into the stratosphere over 30 km altitude by the NOAA-11 satellite observation and this is considered one of the biggest volcanic eruptions in this century. A grandiose volcanic eruption influences the atmosphere seriously and causes many climatic effects globally. There had been many impacts on radiation, atmospheric temperature and stratospheric ozone after some past volcanic eruptions. The main cause of volcanic influence depends on stratospheric aerosol, that stay long enough to change climate and other meteorological conditions. Therefore it is very important to watch stratospheric aerosol layers carefully and continuously. Standing on this respect, we do not only continue stratospheric aerosol observation at Tsukuba but also have urgently developed another lidar observational point at Naha in Okinawa Island. This observational station could be thought valuable since there is no lidar observational station in this latitudinal zone and it is much nearer to Mt. Pinatubo. Especially, there is advantage to link up these two stations on studying the transportation mechanism in the stratosphere. In this paper, we present the results of lidar observations at Tsukuba and Naha by lidar systems with Nd:YAG laser.

Stable CW Single Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

Science.gov (United States)

Duerksen, Gary L.; Krainak, Michael A.

1999-01-01

Previously, single-frequency semiconductor laser operation using fiber Bragg gratings has been achieved by tWo methods: 1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element'; 2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback'. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback.

Detecting Multi-layered Forest Stands Using High Density Airborne LiDAR Data. GI_Forum|GI_Forum 2015 – Geospatial Minds for Society|

OpenAIRE

Schultz, Alfred; Mund, Jan-Peter; Körner, Michael; Wilke, Robert

2016-01-01

Since two decades, the use of terrestrial laser scanning (TLS) and Airborne Light Detection and Ranging (LIDAR) has become very prominent in analysing 3D forest structures (AKAY et al. 2009). The potential of full waveform analysis of high density Airborne LiDAR data (ALS) for the detection and structural analysis of multi-layered forest stands is not yet well investigated (JASKIERNIAK et al. 2011), although ALS data provide exact information on tree heights of multi-layered forest stands usi...

Photon counting altimeter and lidar for air and spaceborne applications

Science.gov (United States)

Vacek, Michael; Michalek, Vojtech; Peca, Marek; Prochazka, Ivan; Blazej, Josef; Kodet, Jan

2011-06-01

We are presenting the concept and preliminary design of modular multipurpose device for space segment: single photon counting laser altimeter, atmospheric lidar, laser transponder and one way laser ranging receiver. For all the mentioned purposes, the same compact configuration of the device is appropriate. Overall estimated device weight should not exceed 5 kg with the power consumption below 10 W. The device will consists of three main parts, namely, receiver, transmitter and control and processing unit. As a transmitter a commercial solid state laser at 532 nm wavelength with 10 mW power will be used. The transmitter optics will have a diameter at most of 50 mm. The laser pulse width will be of hundreds of picoseconds order. For the laser altimeter and atmospheric lidar application, the repetition rate of 10 kHz is planned in order to obtain sufficient number of data for a distance value computing. The receiver device will be composed of active quenched Single Photon Avalanche Diode module, tiny optics, and narrow-band optical filter. The core part of the control and processing unit including high precision timing unit is implemented using single FPGA chip. The preliminary device concept includes considerations on energy balance, and statistical algorithms to meet all the mentioned purposes. Recently, the bread board version of the device is under construction in our labs. The concept, construction, and timing results will be presented.

Performance analysis and technical assessment of coherent lidar systems for airborne wind shear detection

Science.gov (United States)

Huffaker, R. Milton; Targ, Russell

1988-01-01

Detailed computer simulations of the lidar wind-measuring process have been conducted to evaluate the use of pulsed coherent lidar for airborne windshear monitoring. NASA data fields for an actual microburst event were used in the simulation. Both CO2 and Ho:YAG laser lidar systems performed well in the microburst test case, and were able to measure wind shear in the severe weather of this wet microburst to ranges in excess of 1.4 km. The consequent warning time gained was about 15 sec.

Laser Heterodyning

CERN Document Server

Protopopov, Vladimir V

2009-01-01

Laser heterodyning is now a widespread optical technique, based on interference of two waves with slightly different frequencies within the sensitive area of a photo-detector. Its unique feature – preserving phase information about optical wave in the electrical signal of the photo-detector – finds numerous applications in various domains of applied optics and optoelectronics: in spectroscopy, polarimetry, radiometry, laser radars and Lidars, microscopy and other areas. The reader may be surprised by a variety of disciplines that this book covers and satisfied by detailed explanation of the phenomena. Very well illustrated, this book will be helpful for researches, postgraduates and students, working in applied optics.

Wild fire aerosol optical properties measured by lidar at Haifa, Israel

Science.gov (United States)

Heese, Birgit; Hofer, Julian; Baars, Holger; Engelmann, Ronny; Althausen, Dietrich; Schechner, Yoav Y.

2018-04-01

Optical properties of fresh biomass burning aerosol were measured by lidar during the wild fires in Israel in November 2016. A single-wavelength lidar Polly was operated at the Technion Campus at Haifa. The detector with originally two channels at 532 and 607 nm was recently upgraded with a cross- and a co-polarised channel at 532 nm, and a rotational Raman channel at 530.2 nm. Preliminary results show high particle depolarisation ratios probably caused by soil dust and large fly-ash particles.

Lidar instruments for ESA Earth observation missions

Science.gov (United States)

Hélière, Arnaud; Armandillo, Errico; Durand, Yannig; Culoma, Alain; Meynart, Roland

2017-11-01

The idea of deploying a lidar system on an Earthorbiting satellite stems from the need for continuously providing profiles of our atmospheric structure with high accuracy and resolution and global coverage. Interest in this information for climatology, meteorology and the atmospheric sciences in general is huge. Areas of application range from the determination of global warming and greenhouse effects, to monitoring the transport and accumulation of pollutants in the different atmospheric regions (such as the recent fires in Southeast Asia), to the assessment of the largely unknown microphysical properties and the structural dynamics of the atmosphere itself. Spaceborne lidar systems have been the subject of extensive investigations by the European Space Agency since mid 1970's, resulting in mission and instrument concepts, such as ATLID, the cloud backscatter lidar payload of the EarthCARE mission, ALADIN, the Doppler wind lidar of the Atmospheric Dynamics Mission (ADM) and more recently a water vapour Differential Absorption Lidar considered for the WALES mission. These studies have shown the basic scientific and technical feasibility of spaceborne lidars, but they have also demonstrated their complexity from the instrument viewpoint. As a result, the Agency undertook technology development in order to strengthen the instrument maturity. This is the case for ATLID, which benefited from a decade of technology development and supporting studies and is now studied in the frame of the EarthCARE mission. ALADIN, a Direct Detection Doppler Wind Lidar operating in the Ultra -Violet, will be the 1st European lidar to fly in 2007 as payload of the Earth Explorer Core Mission ADM. WALES currently studied at the level of a phase A, is based upon a lidar operating at 4 wavelengths in near infrared and aims to profile the water vapour in the lower part of the atmosphere with high accuracy and low bias. Lastly, the European Space Agency is extending the lidar instrument field

Filtering Photogrammetric Point Clouds Using Standard LIDAR Filters Towards DTM Generation

Science.gov (United States)

Zhang, Z.; Gerke, M.; Vosselman, G.; Yang, M. Y.

2018-05-01

Digital Terrain Models (DTMs) can be generated from point clouds acquired by laser scanning or photogrammetric dense matching. During the last two decades, much effort has been paid to developing robust filtering algorithms for the airborne laser scanning (ALS) data. With the point cloud quality from dense image matching (DIM) getting better and better, the research question that arises is whether those standard Lidar filters can be used to filter photogrammetric point clouds as well. Experiments are implemented to filter two dense matching point clouds with different noise levels. Results show that the standard Lidar filter is robust to random noise. However, artefacts and blunders in the DIM points often appear due to low contrast or poor texture in the images. Filtering will be erroneous in these locations. Filtering the DIM points pre-processed by a ranking filter will bring higher Type II error (i.e. non-ground points actually labelled as ground points) but much lower Type I error (i.e. bare ground points labelled as non-ground points). Finally, the potential DTM accuracy that can be achieved by DIM points is evaluated. Two DIM point clouds derived by Pix4Dmapper and SURE are compared. On grassland dense matching generates points higher than the true terrain surface, which will result in incorrectly elevated DTMs. The application of the ranking filter leads to a reduced bias in the DTM height, but a slightly increased noise level.

Atmospheric CO2 Column Measurements with an Airborne Intensity-Modulated Continuous-Wave 1.57-micron Fiber Laser Lidar

Science.gov (United States)

Dobler, Jeremy T.; Harrison, F. Wallace; Browell, Edward V.; Lin, Bing; McGregor, Doug; Kooi, Susan; Choi, Yonghoon; Ismail, Syed

2013-01-01

The 2007 National Research Council (NRC) Decadal Survey on Earth Science and Applications from Space recommended Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) as a mid-term, Tier II, NASA space mission. ITT Exelis, formerly ITT Corp., and NASA Langley Research Center have been working together since 2004 to develop and demonstrate a prototype Laser Absorption Spectrometer for making high-precision, column CO2 mixing ratio measurements needed for the ASCENDS mission. This instrument, called the Multifunctional Fiber Laser Lidar (MFLL), operates in an intensity-modulated, continuous-wave mode in the 1.57- micron CO2 absorption band. Flight experiments have been conducted with the MFLL on a Lear-25, UC-12, and DC-8 aircraft over a variety of different surfaces and under a wide range of atmospheric conditions. Very high-precision CO2 column measurements resulting from high signal-to-noise (great than 1300) column optical depth measurements for a 10-s (approximately 1 km) averaging interval have been achieved. In situ measurements of atmospheric CO2 profiles were used to derive the expected CO2 column values, and when compared to the MFLL measurements over desert and vegetated surfaces, the MFLL measurements were found to agree with the in situ-derived CO2 columns to within an average of 0.17% or approximately 0.65 ppmv with a standard deviation of 0.44% or approximately 1.7 ppmv. Initial results demonstrating ranging capability using a swept modulation technique are also presented.

Diode-pumped two micron solid-state lasers

International Nuclear Information System (INIS)

Elder, I.F.

1997-01-01

This thesis presents an investigation of diode-pumped two micron solid-state lasers, concentrating on a comparison of the cw room temperature operation of Tm:YAP, Tm,Ho:YAP and Tm,Ho:YLF. Dopant concentrations in YAP were 4.2% thulium and 0.28% holmium; in YLF they were 6% thulium and 0.4% holmium. Thermal modelling was carried out in order to provide an insight into the thermal lensing and population distributions in these materials. Laser operation was achieved utilising an end-pumping geometry with a simple two mirror standing wave resonator. The pump source for these experiments was a 3 W laser diode. Maximum output power was achieved with Tm:YAP, generating 730 mW of laser output, representing 42% conversion efficiency in terms of absorbed pump power. Upper bounds on the conversion efficiency of Tm,Ho:YAP and Tm,Ho:YLF laser crystal of 14% and 30% were obtained, with corresponding output powers of 270 and 660 mW. In all three cases, the output beam was TEM 00 in nature. Visible upconversion fluorescence bands in the green and red were identified in Tm,Ho:YAP and Tm,Ho:YLF, with additional blue emission from the latter, all assigned to transitions on holmium. The principal upconversion mechanisms in these materials all involved the holmium first excited state. Upconversion in Tm:YAP was negligible. The spectral output of Tm:YAP consisted of a comb of lines in the range 1.965 to 2.020 μm. For both the double-doped crystals, the laser output was multilongitudinal mode on a single transition, wavelength 2.120 μm in YAP, 2.065 μm in YLF. In the time domain the output of Tm:YAP was dominated by large amplitude spiking, unlike both of the double-doped laser crystals. The long lifetime of the thulium upper laser level (4.4 ms) provided very weak damping of the spiking. Excitation sharing between thulium and holmium, with a measured characteristic lifetime in YAP of 11.9 μs and YLF of 14.8 μs, provided strong damping of any spiking behaviour. (author)

Dual-beam operation of the Astra Gemini laser facility

International Nuclear Information System (INIS)

Bryan Parry; Nicola Booth; Oleg Chekhlov; John Collier; Edwin Divall; Klaus Ertel; Peta Foster; Steve Hawkes; Chris Hooker; Victoria Marshall

2010-01-01

Complete text of publication follows. Gemini is a Petawatt class Ti:Sapphire laser system at the Rutherford Appleton Laboratory, UK. It was designed as a dual beam laser, with two independently configurable 800 nm beams delivering 15 J to target in 30 fs pulse duration, giving 0.5 PW peak power per beam. It is capable of reaching intensities over 10 22 W/cm 2 . Gemini can achieve a maximum repetition rate of one shot every 20 seconds, allowing it to deliver hundreds of shots per day; a feature which makes it unique among PW lasers. Already this has proved valuable in experiments involving electron acceleration in gas jets. The first Gemini beamline became operational in 2008. Commissioning of the second beam was deferred to allow earlier access to the facility by experimental scientists, and to develop operational experience. In this mode, Gemini has already produced significant results from a number of advanced plasma physics experiments. The second beam of Gemini is now coming online, with the first dual beam experiment starting in June 2010. The flexibility offered by two short pulse, ultra high intensity beams is another aspect that makes this laser system unique. The dual beams enable versatile configurations and illumination geometries, facilitating a wider range of experiments than is possible with only a single beam. Operationally however, it introduces additional factors which must be monitored and controlled in order to achieve experimental success. The beams must be timed with respect to each other with accuracy less than the pulse duration. The beam foci must also be overlapped spatially, and the stability of both these factors maintained over extended periods. We report on the second beam commissioning process, including the latest results on the characteristics, stability and spatio-temporal overlap of the two beams. We present details of amplifier performance, along with measurements of beam quality, focal spot, pulse duration and contrast, to give a

LIDAR optical rugosity of coral reefs in Biscayne National Park, Florida

Science.gov (United States)

Brock, J.C.; Wright, C.W.; Clayton, T.D.; Nayegandhi, A.

2004-01-01

The NASA Experimental Advanced Airborne Research Lidar (EAARL), a temporal waveform-resolving, airborne, green wavelength LIDAR (light detection and ranging), is designed to measure the submeter-scale topography of shallow reef substrates. Topographic variability is a prime component of habitat complexity, an ecological factor that both expresses and controls the abundance and distribution of many reef organisms. Following the acquisition of EAARL coverage over both mid-platform patch reefs and shelf-margin bank reefs within Biscayne National Park in August 2002, EAARL-based optical indices of topographic variability were evaluated at 15 patch reef and bank reef sites. Several sites were selected to match reefs previously evaluated in situ along underwater video and belt transects. The analysis used large populations of submarine topographic transects derived from the examination of closely spaced laser spot reflections along LIDAR raster scans. At all 15 sites, each LIDAR transect was evaluated separately to determine optical rugosity (Rotran), and the average elevation difference between adjacent points (Av(??E ap)). Further, the whole-site mean and maximum values of Ro tran and Av(??Eap) for the entire population of transects at each analysis site, along with their standard deviations, were calculated. This study revealed that the greater habitat complexity of inshore patch reefs versus outer bank reefs results in relative differences in topographic complexity that can be discerned in the laser returns. Accordingly, LIDAR sensing of optical rugosity is proposed as a complementary new technique for the rapid assessment of shallow coral reefs. ?? Springer-Verlag 2004.

Airborne Lidar for Simultaneous Measurement of Column CO2 and Water Vapor in the Atmosphere

Science.gov (United States)

Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Antill, Charles W.; Remus, Ruben; Yu, Jirong

2016-01-01

The 2-micron wavelength region is suitable for atmospheric carbon dioxide (CO2) measurements due to the existence of distinct absorption feathers for the gas at this particular wavelength. For more than 20 years, researchers at NASA Langley Research Center (LaRC) have developed several high-energy and high repetition rate 2-micron pulsed lasers. This paper will provide status and details of an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar. The development of this active optical remote sensing IPDA instrument is targeted for measuring both CO2 and water vapor (H2O) in the atmosphere from an airborne platform. This presentation will focus on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver telescope, detection system and data acquisition. Future plans for the IPDA lidar system for ground integration, testing and flight validation will also be presented.

2007 Northwest Florida Water Management District (NWFWMD) Lidar: North Jefferson County

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. Using a combination of laser range finding, GPS...

Lidars for oceanological research: criteria for comparison, main limitations, perspectives

Science.gov (United States)

Feigels, Victor I.

1992-12-01

The paper contains a comparative analysis and discussion of resultant recommendations for the optimization of an airborne lidar's parameters, with application to modern lidar systems as employed in various countries for the ocean and continental shelf research. As criteria for the systems comparison in different remote sensing conditions (aircraft altitude, depth, day/night, zenithal sun angle, sea-water attenuation coefficient, receiver optical system's field of view (FOV), laser wavelength, etc.,) Sakitt's D-index of discriminability is used. We demonstrate the optical signal, as determined by the following process: reflecting from boundary -- backscattering in the atmosphere -- secondary reflecting from boundary, to be the cause for limiting the distance of underwater measurements. Some estimates for the bottom depth values to be achieved by a `super-lidar' are presented.

Study on two-color planar laser induced fluorescence thermometry

International Nuclear Information System (INIS)

Li Shaodan; Tan Sichao; Gao Puzhen; Lin Yuansheng

2014-01-01

Many of the convection heat transfer process are involved in the research of nuclear reactor thermal hydraulics. To experimentally determine the variation of the temperature field in those processes is important for the design and safety operation of the nuclear reactor. The application of the two-color planar laser induced fluorescence (PLIF) in the measurements of fluid temperature distribution is discussed in the paper. The laser dyes used here is rhodamine B (RhB) with negative temperature coefficient and fluorescein 27 (F127) with positive temperature coefficient. The beam of the laser light is adjusted to laser sheet by using the lens group. The fluid with dyes is excited by this laser sheet in a specific plane and temperature dependent fluorescence is released. The temperature field of the plane can be determined through the intensity information. Some technical aspects encountered in the application of the two-laser PLIF are discussed in the paper, such as the spectra characteristic of the dyes and the separation of the spectra. The calibration temperature is higher than the water saturation temperature (at atmosphere pressure). (authors)

European Space Agency lidar development programs for remote sensing of the atmosphere

Science.gov (United States)

Armandillo, Errico

1992-12-01

Active laser remote sensing from space is considered an important step forward in the understanding of the processes which regulate weather and climate changes. The planned launching into polar orbit in the late 1990s of a series of dedicated Earth observation satellites offer new possibilities for flying lidar in space. Among the various lidar candidates, ESA has recognized in the backscattering lidar and Doppler wind lidar the instruments which can most contribute to the Earth observation program. To meet the schedule of the on-coming flight opportunities, ESA has been engaged over the past years in a preparatory program aimed to define the instruments and ensure timely availability of the critical components. This paper reviews the status of the ongoing developments and highlights the critical issues addressed.

Water-Vapor Raman Lidar System Reaches Higher Altitude

Science.gov (United States)

Leblanc, Thierry; McDermid, I. Stewart

2010-01-01

A Raman lidar system for measuring the vertical distribution of water vapor in the atmosphere is located at the Table Mountain Facility (TMF) in California. Raman lidar systems for obtaining vertical water-vapor profiles in the troposphere have been in use for some time. The TMF system incorporates a number of improvements over prior such systems that enable extension of the altitude range of measurements through the tropopause into the lower stratosphere. One major obstacle to extension of the altitude range is the fact that the mixing ratio of water vapor in the tropopause and the lower stratosphere is so low that Raman lidar measurements in this region are limited by noise. Therefore, the design of the TMF system incorporates several features intended to maximize the signal-to-noise ratio. These features include (1) the use of 355-nm-wavelength laser pulses having an energy (0.9 J per pulse) that is high relative to the laser-pulse energy levels of prior such systems, (2) a telescope having a large aperture (91 cm in diameter) and a narrow field of view (angular width .0.6 mrad), and (3) narrow-bandpass (wavelength bandwidth 0.6 nm) filters for the water-vapor Raman spectral channels. In addition to the large-aperture telescope, three telescopes having apertures 7.5 cm in diameter are used to collect returns from low altitudes.

A Dual Wavelength Echidna® Lidar (DWEL) for Forest Structure Retrieval

Science.gov (United States)

Strahler, A. H.; Douglas, E. S.; Martel, J.; Cook, T.; Mendillo, C.; Marshall, R. A.; Chakrabarti, S.; Schaaf, C.; Woodcock, C. E.; Li, Z.; Yang, X.; Culvenor, D.; Jupp, D.; Newnham, G.; Lovell, J.

2012-12-01

A newly-constructed, ground-based lidar scanner designed for automated retrieval of forest structure, the Dual Wavelength Echidna Lidar (DWEL), separates laser "hits" of leaves from hits of trunks and branches using simultaneous laser pulses at 1548 nm, where leaf water content produces strong absorption, and at 1064 nm, where leaves and branches have similar reflectances. The DWEL uses a rotating mirror scan mechanism on a revolving mount, coupled with full digitization of return waveforms, to identify, locate, and parameterize scattering events in the three-dimensional space around the scanner. In the DWEL instrument, the two measurement lasers are triggered simultaneously. Laser pulses are sharply peaked; full-width half-max pulse length of the lasers is 5.1 ns, corresponding to 1.53 m in distance. The laser pulses are expanded and collimated to a 6-mm beam diameter (1/e2), then shaped into a top-hat cross section using a diffraction apparatus. Interchangeable optics provide a beam divergence of 1.25-, 2.5-, or 5-mrad. A mirror and two dichroic filters combine the beams and join them with a visible green continuous-wave marker laser. The combined beam is guided along an optical path to the 10-cm rotating scan mirror. Scan encoders in zenith and azimuth directions resolve the pointing of the instrument to 215 units per 2π radians. Scan resolution has three settings: 1-, 2-, and 4-mrad. Scan time varies with resolution: 11 min at 4 mrad; 41 min at 2 mrad; and 2.7 hr at 1 mrad. The return beam enters the 10-cm diameter Newtonian-Nasmyth telescope and is directed to the receiver assembly, which splits the return beam using a dichroic filter and narrowband pass filters. Two 0.5 mm InGaAs photodiodes measure the return signal, which is sampled by two digitizers at 2 gigasamples per second with 10-bit precision. This provides a 7.5-cm sampling of the 1.53 m pulse, allowing very good reconstruction of the return waveform. The designed signal-to-noise ratio is 10:1 (8

Cotton phenotyping with lidar from a track-mounted platform

Science.gov (United States)

French, Andrew N.; Gore, Michael A.; Thompson, Alison

2016-05-01

High-Throughput Phenotyping (HTP) is a discipline for rapidly identifying plant architectural and physiological responses to environmental factors such as heat and water stress. Experiments conducted since 2010 at Maricopa, Arizona with a three-fold sensor group, including thermal infrared radiometers, active visible/near infrared reflectance sensors, and acoustic plant height sensors, have shown the validity of HTP with a tractor-based system. However, results from these experiments also show that accuracy of plant phenotyping is limited by the system's inability to discriminate plant components and their local environmental conditions. This limitation may be overcome with plant imaging and laser scanning which can help map details in plant architecture and sunlit/shaded leaves. To test the capability for mapping cotton plants with a laser system, a track-mounted platform was deployed in 2015 over a full canopy and defoliated cotton crop consisting of a scanning LIDAR driven by Arduinocontrolled stepper motors. Using custom Python and Tkinter code, the platform moved autonomously along a pipe-track at 0.1 m/s while collecting LIDAR scans at 25 Hz (0.1667 deg. beam). These tests showed that an autonomous LIDAR platform can reduce HTP logistical problems and provide the capability to accurately map cotton plants and cotton bolls. A prototype track-mounted platform was developed to test the use of LIDAR scanning for High- Throughput Phenotyping (HTP). The platform was deployed in 2015 at Maricopa, Arizona over a senescent cotton crop. Using custom Python and Tkinter code, the platform moved autonomously along a pipe-track at cotton bolls.

Aerosol backscatter measurements at 10.6 microns with airborne and ground-based CO2 Doppler lidars over the Colorado High Plains. I - Lidar intercomparison

Science.gov (United States)

Bowdle, David A.; Rothermel, Jeffry; Vaughan, J. Michael; Brown, Derek W.; Post, Madison J.

1991-01-01

An airborne continuous-wave (CW) focused CO2 Doppler lidar and a ground-based pulsed CO2 Doppler lidar were to obtain seven pairs of comparative measurements of tropospheric aerosol backscatter profiles at 10.6-micron wavelength, near Denver, Colorado, during a 20-day period in July 1982. In regions of uniform backscatter, the two lidars show good agreement, with differences usually less than about 50 percent near 8-km altitude and less than a factor of 2 or 3 elsewhere but with the pulsed lidar often lower than the CW lidar. Near sharp backscatter gradients, the two lidars show poorer agreement, with the pulsed lidar usually higher than the CW lidar. Most discrepancies arise from a combination of atmospheric factors and instrument factors, particularly small-scale areal and temporal backscatter heterogeneity above the planetary boundary layer, unusual large-scale vertical backscatter structure in the upper troposphere and lower stratosphere, and differences in the spatial resolution, detection threshold, and noise estimation for the two lidars.

Janus neodymium glass laser operations manual

International Nuclear Information System (INIS)

Auerbach, J.M.; Holmes, N.C.; Trainor, R.J.

1978-01-01

A manual, prepared to guide personnel in operating and maintaining the Janus glass laser system, is presented. System components are described in detail. Step-by-step procedures are presented for firing the laser and for performing routine maintenance and calibration procedures

Hub Height Ocean Winds over the North Sea Observed by the NORSEWInD Lidar Array: Measuring Techniques, Quality Control and Data Management

DEFF Research Database (Denmark)

Hasager, Charlotte Bay; Stein, Detlef; Courtney, Michael

2013-01-01

performed excellently, two slightly failed the first criterion and one failed both. The lidars were operated offshore from six months to more than two years and observed in total 107 months of 10-min mean wind profile observations. Four lidars were re-evaluated post deployment with excellent results...

Tunable solid-state laser technology for applications to scientific and technological experiments from space

Science.gov (United States)

Allario, F.; Taylor, L. V.

1986-01-01

Current plans for the Earth Observing System (EOS) include development of a lidar facility to conduct scientific experiments from a polar orbiting platforms. A recommended set of experiments were scoped, which includes techniques of atmospheric backscatter (Lidar), Differential Absorption Lidar (DIAL), altimetry, and retroranging. Preliminary assessments of the resources (power, weight, volume) required by the Eos Lidar Facility were conducted. A research program in tunable solid state laser technology was developed, which includes laser materials development, modeling and experiments on the physics of solid state laser materials, and development of solid state laser transmitters with a strong focus on Eos scientific investigations. Some of the system studies that were conducted which highlight the payoff of solid state laser technology for the Eos scientific investigations will be discussed. Additionally, a summary of some promising research results which have recently emerged from the research program will be presented.

Operational characteristics of dual gain single cavity Nd:YVO 4 laser

Indian Academy of Sciences (India)

Operational characteristics of a dual gain single cavity Nd:YVO4 laser have been investigated. With semiconductor diode laser pump power of 2 W, 800 mW output was obtained with a slope efficiency of 49%. Further, by changing the relative orientation of the two crystals the polarization characteristics of the output could be ...

Surface detection performance evaluation of pseudo-random noise continuous wave laser radar

Science.gov (United States)

Mitev, Valentin; Matthey, Renaud; Pereira do Carmo, Joao

2017-11-01

A number of space missions (including in the ESA Exploration Programme) foreseen a use of laser radar sensor (or lidar) for determination of range between spacecrafts or between spacecraft and ground surface (altimetry). Such sensors need to be compact, robust and power efficient, at the same time with high detection performance. These requirements can be achieved with a Pseudo-Random Noise continuous wave lidar (PRN cw lidar). Previous studies have pointed to the advantages of this lidar with respect to space missions, but they also identified its limitations in high optical background. The progress of the lasers and the detectors in the near IR spectral range requires a re-evaluation of the PRN cw lidar potential. Here we address the performances of this lidar for surface detection (altimetry) in planetary missions. The evaluation is based on the following system configuration: (i) A cw fiber amplifier as lidar transmitter. The seeding laser exhibits a single-frequency spectral line, with subsequent amplitude modulation. The fiber amplifier allows high output power level, keeping the spectral characteristics and the modulation of the seeding light input. (ii) An avalanche photodiode in photon counting detection; (iii) Measurement scenarios representative for Earth, Mercury and Mars.

Full-Scale Field Test of a Blade-Integrated Dual-Telescope Wind Lidar

DEFF Research Database (Denmark)

Pedersen, Anders Tegtmeier; Sjöholm, Mikael; Angelou, Nikolas

. Simultaneously, data regarding wind speed, rotational speed, and pitch angle recorded by the turbine was logged as well as data from a nearby met mast. The encouraging results of this first campaign include wind speed measurements at 20 Hz data rate along the rotor plane, acquired during the co...... in the top and bottom of the rotor plane. Conclusion We present here what we believe is the first successful wind speed measurements from a dual-telescope lidar installed on the blade of an operating wind turbine. The full-scale field test performed in the summer of 2012 has clearly demonstrated...... the possibility of integrating lidar telescopes into turbine blades as well as the capability of the lidar to measure the required wind speeds and to operate in the challenging environment of a rotating spinner and vibrating blade. The use of two separate telescopes allows a direct measurement of the blade’s AOA...

Multicascade X-Ray Free-Electron Laser with Harmonic Multiplier and Two-Frequency Undulator

Science.gov (United States)

Zhukovsky, K. V.

2018-06-01

The feasibility of generation of powerful x-ray radiation by a cascade free-electron laser (FEL) with amplification of higher harmonics using a two-frequency undulator is studied. To analyze the FEL operation, a complex phenomenological single-pass FEL model is developed and used. It describes linear and nonlinear generation of harmonics in the FEL with seed laser that takes into account initial electron beam noise and describes all main losses of each harmonic in each FEL cascade. The model is also calibrated against and approved by the experimental FEL data and available results of three-dimensional numerical simulation. The electron beam in the undulator is assumed to be matched and focused, and the dynamics of power in the singlepass FEL with cascade harmonic multipliers is investigated to obtain x-ray laser radiation in the FEL having the shortest length, beam energy, and frequency of the seed laser as low as possible. In this context, the advantages of the two-frequency undulator used for generation of harmonics are demonstrated. The evolution of harmonics in a multicascade FEL with multiplication of harmonics is investigated. The operation of the cascade FEL at the wavelength λ = 1.14 nm, generating 30 MW already on 38 m with the seed laser operating at a wavelength of 11.43 nm corresponding to the maximal reflectivity of the multilayered mirror MoRu/Be coating is investigated. In addition, the operation of the multicascade FEL with accessible seed UVlaser operating at a wavelength of 157 nm (F2 excimer UV-laser) and electron beam with energy of 0.5 GeV is investigated. X-ray radiation simulated in it at the wavelength λ 3.9 nm reaches power of 50 MW already at 27 m, which is by two orders of magnitude shorter than 3.4 km of the x-ray FEL recently put into operation in Europe.

LiDAR utility for natural resource managers

Science.gov (United States)

Andrew Thomas Hudak; Jeffrey Scott Evans; Alistair Mattthew Stuart. Smith

2009-01-01

Applications of LiDAR remote sensing are exploding, while moving from the research to the operational realm. Increasingly, natural resource managers are recognizing the tremendous utility of LiDAR-derived information to make improved decisions. This review provides a cross-section of studies, many recent, that demonstrate the relevance of LiDAR across a suite of...

Capability of Raman lidar for monitoring the variation of atmospheric CO2 profile

International Nuclear Information System (INIS)

Zhao Peitao; Hu Shunxing; Su Jia; Cao Kaifa; Hu Huanling; Zhang Yinchao; Wang Lian; Zhao Yuefeng

2008-01-01

Lidar (Light detection and ranging) has special capabilities for remote sensing of many different behaviours of the atmosphere. One of the techniques which show a great deal of promise for several applications is Raman scattering. The detecting capability, including maximum operation range and minimum detectable gas concentration is one of the most significant parameters for lidar remote sensing of pollutants. In this paper, based on the new method for evaluating the capabilities of a Raman lidar system, we present an evaluation of detecting capability of Raman lidar for monitoring atmospheric CO 2 in Hefei. Numerical simulations about the influence of atmospheric conditions on lidar detecting capability were carried out, and a conclusion can be drawn that the maximum difference of the operation ranges caused by the weather conditions alone can reach about 0.4 to 0.5km with a measuring precision within 30ppmv. The range of minimum detectable concentration caused by the weather conditions alone can reach about 20 to 35 ppmv in vertical direction for 20000 shots at a distance of 1 km on the assumption that other parameters are kept constant. The other corresponding parameters under different conditions are also given. The capability of Raman lidar operated in vertical direction was found to be superior to that operated in horizontal direction. During practical measurement with the Raman lidar whose hardware components were fixed, aerosol scattering extinction effect would be a significant factor that influenced the capability of Raman lidar. This work may be a valuable reference for lidar system designing, measurement accuracy improving and data processing

Broadband multi-wavelength Brillouin lasers with an operating wavelength range of 1500–1600 nm generated by four-wave mixing in a dual wavelength Brillouin fiber laser cavity

Science.gov (United States)

Li, Q.; Jia, Z. X.; Weng, H. Z.; Li, Z. R.; Yang, Y. D.; Xiao, J. L.; Chen, S. W.; Huang, Y. Z.; Qin, W. P.; Qin, G. S.

2018-05-01

We demonstrate broadband multi-wavelength Brillouin lasers with an operating wavelength range of 1500–1600 nm and a frequency separation of ~9.28 GHz generated by four-wave mixing in a dual wavelength Brillouin fiber laser cavity. By using one continuous-wave laser as the pump source, multi-wavelength Brillouin lasers with an operating wavelength range of 1554–1574 nm were generated via cascaded Brillouin scattering and four-wave mixing. Interestingly, when pumped by two continuous-wave lasers with an appropriate frequency separation, the operating wavelength range of the multi-wavelength Brillouin lasers was increased to 1500–1600 nm due to cavity-enhanced cascaded four-wave mixing among the frequency components generated by two pump lasers in the dual wavelength Brillouin laser cavity.

Evaluation of short-term geomorphic changes along the Tagliamento river using LiDAR and terrestrial laser scanner surveys

Directory of Open Access Journals (Sweden)

R. Rainato

2013-09-01

Full Text Available In the recent years a change in the predominant morphology of several river environments has taken place, consisting in a reduction of the braided pattern in favor to wandering or straight configurations. This evolution seems to be due, according to the scientific community, to anthropic causes and, in particular, to the alteration of flow regimes as well as the reduction of sediment transport. Braided rivers are characterized by two or more active channels, separated by bars and fluvial islands and normally feature a high morphological dynamism. This dynamism is the result of the interaction among different elements as sediment supply, flow regime and in-channel and perifluvial vegetation. These factors have a fundamental role in the erosion and deposition processes which are the basis of the morphological changes. The aims of this study are the assessment of the short period geomorphic and volumetric changes occurred along a reach of the Tagliamento River and the comparison between the results obtained from LiDAR (Light Detection and Ranging and TLS (Terrestrial Laser Scanner data. The Tagliamento river is a natural gravel-bed river located in the NE of Italy, characterized by a relatively low degree of human disturbances. The analyses were carried out considering two different scales (a reach of about 430 ha and a sub-reach of about 25 ha and were based on two subsequent datasets in order to investigate the shortterm geomorphic changes due to eight significant floods. The surveys were performed using two different datasets derived from LiDAR and TLS technologies and used to analyze the reach and sub-reach respectively. The short-term estimates of geomorphic and volumetric changes were performed using DEMs of Difference (DoD based on a Fuzzy Inference System. The results have confirmed the high dynamism of the Tagliamento river, estimating a prevalent deposition at reach and a predominant erosion at sub-reach levels. Finally, a comparative

Experimental study of a quantum random-number generator based on two independent lasers

Science.gov (United States)

Sun, Shi-Hai; Xu, Feihu

2017-12-01

A quantum random-number generator (QRNG) can produce true randomness by utilizing the inherent probabilistic nature of quantum mechanics. Recently, the spontaneous-emission quantum phase noise of the laser has been widely deployed for quantum random-number generation, due to its high rate, its low cost, and the feasibility of chip-scale integration. Here, we perform a comprehensive experimental study of a phase-noise-based QRNG with two independent lasers, each of which operates in either continuous-wave (CW) or pulsed mode. We implement the QRNG by operating the two lasers in three configurations, namely, CW + CW, CW + pulsed, and pulsed + pulsed, and demonstrate their trade-offs, strengths, and weaknesses.

LiDAR Vegetation Investigation and Signature Analysis System (LVISA)

Science.gov (United States)

Höfle, Bernhard; Koenig, Kristina; Griesbaum, Luisa; Kiefer, Andreas; Hämmerle, Martin; Eitel, Jan; Koma, Zsófia

2015-04-01

Our physical environment undergoes constant changes in space and time with strongly varying triggers, frequencies, and magnitudes. Monitoring these environmental changes is crucial to improve our scientific understanding of complex human-environmental interactions and helps us to respond to environmental change by adaptation or mitigation. The three-dimensional (3D) description of the Earth surface features and the detailed monitoring of surface processes using 3D spatial data have gained increasing attention within the last decades, such as in climate change research (e.g., glacier retreat), carbon sequestration (e.g., forest biomass monitoring), precision agriculture and natural hazard management. In all those areas, 3D data have helped to improve our process understanding by allowing quantifying the structural properties of earth surface features and their changes over time. This advancement has been fostered by technological developments and increased availability of 3D sensing systems. In particular, LiDAR (light detection and ranging) technology, also referred to as laser scanning, has made significant progress and has evolved into an operational tool in environmental research and geosciences. The main result of LiDAR measurements is a highly spatially resolved 3D point cloud. Each point within the LiDAR point cloud has a XYZ coordinate associated with it and often additional information such as the strength of the returned backscatter. The point cloud provided by LiDAR contains rich geospatial, structural, and potentially biochemical information about the surveyed objects. To deal with the inherently unorganized datasets and the large data volume (frequently millions of XYZ coordinates) of LiDAR datasets, a multitude of algorithms for automatic 3D object detection (e.g., of single trees) and physical surface description (e.g., biomass) have been developed. However, so far the exchange of datasets and approaches (i.e., extraction algorithms) among LiDAR users

Stable CW Single-Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

Science.gov (United States)

Duerksen, Gary L.; Krainak, Michael A.

1999-01-01

Previously, single-frequency semiconductor laser operation using fiber Bragg gratings has been achieved by two methods: 1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element'; 2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback. We coupled a nominal 935 run-wavelength Fabry-Perot laser diode to an ultra narrow band (18 pm) FBG. When tuned by varying its temperature, the laser wavelength is pulled toward the centerline of the Bragg grating, and the spectrum of the laser output is seen to fall into three discrete stability regimes as measured by the side-mode suppression ratio.

Overview of Lidar Contributions to the Atmospheric Carbon and Transport - America (ACT-America) Program

Science.gov (United States)

Davis, K. J.; Meadows, B.; Barrick, J. D. W.; Bell, E.; Browell, E. V.; Campbell, J. F.; DiGangi, J. P.; Chen, G.; Dobler, J. T.; Fan, T. F.; Feng, S.; Fried, A.; Kooi, S. A.; Lauvaux, T.; Lin, B.; McGill, M. J.; Miles, N.; Nehrir, A. R.; Obland, M. D.; O'Dell, C.; Pal, S.; Pauly, R.; Sweeney, C.; Yang, M. Y.

2017-12-01

The Atmospheric Carbon and Transport - America (ACT-America) is an Earth Venture Suborbital -2 (EVS-2) mission sponsored by the Earth Science Division of NASA's Science Mission Directorate. A major objective is to enhance our knowledge of the sources/sinks and transport of atmospheric CO2 through the application of remote and in situ airborne measurements of CO2 and other atmospheric properties on spatial and temporal scales not previously available to the science community. ACT-America consists of five campaigns to measure regional carbon and evaluate transport under various meteorological conditions in three regional areas of the Continental United States. Three of the five campaigns, summer 2016, winter 2017, and fall 2017, have taken place. Data have been collected during these campaigns using 2 airborne platforms (NASA Wallops' C-130 and NASA Langley's B-200) with in-situ instruments on both aircraft and three lidar systems on the C-130, along with instrumented towers and coordinated under flights with the Orbiting Carbon Observatory (OCO-2) satellite. The lidar systems include the Harris Corp. Multi-Frequency Fiber Laser Lidar (MFLL), the NASA Langley ASCENDS CarbonHawk Experiment Simulator (ACES) and the Goddard Cloud Physics Laboratory (CPL). The airborne lidars provide unique data that complement the more traditional in situ sensors. Lidar CO2 measurements provide integrated views of spatial variations of partial columns of atmospheric CO2 which can be adjusted to the column of scientific interest by changing flight altitudes. Lidar backscatter data provide detailed views of atmospheric layers, including the atmospheric boundary layer, residual layers, and cloud layers. The combination of these two lidars provide a far more comprehensive view of atmospheric structure and CO2 content than can be achieved with in situ measurements alone. This presentation provides an overview of the application of these three lidar systems toward achieving ACT

Using the Rapid-Scanning, Ultra-Portable, Canopy Biomass Lidar (CBL) Alone and In Tandem with the Full-Waveform Dual-Wavelength Echidna® Lidar (DWEL) to Establish Forest Structure and Biomass Estimates in a Variety of Ecosystems

Science.gov (United States)

Schaaf, C.; Paynter, I.; Saenz, E. J.; Li, Z.; Strahler, A. H.; Peri, F.; Erb, A.; Raumonen, P.; Muir, J.; Howe, G.; Hewawasam, K.; Martel, J.; Douglas, E. S.; Chakrabarti, S.; Cook, T.; Schaefer, M.; Newnham, G.; Jupp, D. L. B.; van Aardt, J. A.; Kelbe, D.; Romanczyk, P.; Faulring, J.

2014-12-01

Terrestrial lidars are increasingly being deployed in a variety of ecosystems to calibrate and validate large scale airborne and spaceborne estimates of forest structure and biomass. While these lidars provide a wealth of high resolution information on canopy structure and understory vegetation, they tend to be expensive, slow scanning and somewhat ponderous to deploy. Therefore, frequent deployments and characterization of larger areas of a hectare or more can still be challenging. This suggests a role for low cost, ultra-portable, rapid scanning (but lower resolution) instruments -- particularly in scanning extreme environments and as a way to augment and extend strategically placed scans from the more highly capable lidars. The Canopy Biomass Lidar (CBL) is an inexpensive, highly portable, fast-scanning (33 seconds), time-of-flight, terrestrial laser scanning (TLS) instrument, built in collaboration with RIT, by U Mass Boston. The instrument uses a 905nm SICK time of flight laser with a 0.25o resolution and 30m range. The higher resolution, full-waveform Dual Wavelength Echidna® Lidar (DWEL), developed by Boston University, U Mass Lowell and U Mass Boston, builds on the Australian CSIRO single wavelength, full-waveform Echidna® Validation Instrument (EVI), but utilizes two simultaneous laser pulses at 1064 and 1548 nm to separate woody returns from those of foliage at a range of up to 100m range. The UMass Boston CBL has been deployed in rangelands (San Joaquin Experimental Range, CA), high altitude conifers (Sierra National Forest, CA), mixed forests (Harvard Forest LTER MA), tropical forests (La Selva and Sirena Biological Stations, Costa Rica), eucalypts (Karawatha, Brisbane TERN, Australia), and woodlands (Alice Holt Forest, UK), frequently along-side the DWEL, as well as in more challenging environments such as mangrove forests (Corcovado National Park, Costa Rica) and Massachusetts salt marshes and eroding bluffs (Plum Island LTER, and UMass Boston

Coherent Lidar Turbulence Measurement for Gust Load Alleviation

Science.gov (United States)

Bogue, Rodney K.; Ehernberger, L. J.; Soreide, David; Bagley, Hal

1996-01-01

Atmospheric turbulence adversely affects operation of commercial and military aircraft and is a design constraint. The airplane structure must be designed to survive the loads imposed by turbulence. Reducing these loads allows the airplane structure to be lighter, a substantial advantage for a commercial airplane. Gust alleviation systems based on accelerometers mounted in the airplane can reduce the maximum gust loads by a small fraction. These systems still represent an economic advantage. The ability to reduce the gust load increases tremendously if the turbulent gust can be measured before the airplane encounters it. A lidar system can make measurements of turbulent gusts ahead of the airplane, and the NASA Airborne Coherent Lidar for Advanced In-Flight Measurements (ACLAIM) program is developing such a lidar. The ACLAIM program is intended to develop a prototype lidar system for use in feasibility testing of gust load alleviation systems and other airborne lidar applications, to define applications of lidar with the potential for improving airplane performance, and to determine the feasibility and benefits of these applications. This paper gives an overview of the ACLAIM program, describes the lidar architecture for a gust alleviation system, and describes the prototype ACLAIM lidar system.

Cloud Physics Lidar Measurements During the SAFARI-2000 Field Campaign

Science.gov (United States)

McGill, Matthew; Hlavka, Dennis; Hart, William; Spinhirne, James; Scott, Stan; Starr, David OC. (Technical Monitor)

2001-01-01

A new remote sensing instrument, the Cloud Physics Lidar (CPL) has been built for use on the ER-2 aircraft. The first deployment for CPL was the SAFARI-2000 field campaign during August-September 2000. The CPL is a three-wavelength lidar designed for studies of cirrus, subvisual cirrus, and boundary layer aerosols. The CPL utilizes a high repetition rate, low pulse energy laser with photon counting detectors. A brief description of the CPL instrument will be given, followed by examples of CPL data products. In particular, examples of aerosol backscatter, including boundary layer smoke and cirrus clouds will be shown. Resulting optical depth estimates derived from the aerosol measurements will be shown. Comparisons of the CPL optical depth and optical depth derived from microPulse Lidar and the AATS-14 sunphotomer will be shown.

Airborne 3D Imaging Lidar for Contiguous Decimeter Resolution Terrain Mapping and Shallow Water Bathymetry

Science.gov (United States)

Degnan, J. J.; Wells, D. N.; Huet, H.; Chauvet, N.; Lawrence, D. W.; Mitchell, S. E.; Eklund, W. D.

2005-12-01

A 3D imaging lidar system, developed for the University of Florida at Gainesville and operating at the water transmissive wavelength of 532 nm, is designed to contiguously map underlying terrain and/or perform shallow water bathymetry on a single overflight from an altitude of 600 m with a swath width of 225 m and a horizontal spatial resolution of 20 cm. Each 600 psec pulse from a frequency-doubled, low power (~3 microjoules @ 8 kHz = 24 mW), passively Q-switched Nd:YAG microchip laser is passed through a holographic element which projects a 10x10 array of spots onto a 2m x 2m target area. The individual ground spots are then imaged onto individual anodes within a 10x10 segmented anode photomultiplier. The latter is followed by a 100 channel multistop ranging receiver with a range resolution of about 4 cm. The multistop feature permits single photon detection in daylight with wide range gates as well as multiple single photon returns per pixel per laser fire from volumetric scatterers such as tree canopies or turbid water columns. The individual single pulse 3D images are contiguously mosaiced together through the combined action of the platform velocity and a counter-rotating dual wedge optical scanner whose rotations are synchronized to the laser pulse train. The paper provides an overview of the lidar opto-mechanical design, the synchronized dual wedge scanner and servo controller, and the experimental results obtained to date.

Calibration of scanning Lidar

DEFF Research Database (Denmark)

Gómez Arranz, Paula; Courtney, Michael

This report describes the tests carried out on a scanning lidar at the DTU Test Station for large wind turbines, Høvsøre. The tests were divided in two parts. In the first part, the purpose was to obtain wind speed calibrations at two heights against two cup anemometers mounted on a mast. Additio......This report describes the tests carried out on a scanning lidar at the DTU Test Station for large wind turbines, Høvsøre. The tests were divided in two parts. In the first part, the purpose was to obtain wind speed calibrations at two heights against two cup anemometers mounted on a mast...

FOREST STEM VOLUME CALCULATION USING AIRBORNE LIDAR DATA

Directory of Open Access Journals (Sweden)

I. Büyüksalih

2017-05-01

Full Text Available Airborne LiDAR data have been collected for the city of Istanbul using Riegl laser scanner Q680i with 400 kHz and an average flight height of 600 m. The flight campaign was performed by a helicopter and covers an area of 5400 km2. According to a flight speed of 80 knot a point density of more than 16 points/m2 and a laser footprint size of 30 cm could be achieved. As a result of bundle adjustment, in total, approximately 17,000 LAS files with the file size of 500 m by 700 m have been generated for the whole city. The main object classes Ground, Building, Vegetation (medium, high were derived from these LAS files using the macros in Terrasolid software. The forest area under investigation is located northwest of the city of Istanbul, main tree species occurring in the test site are pine (pinus pinaster, oak (quercus and beech (fagus. In total, 120 LAS tiles covering the investigation area have been analysed using the software IMPACT of Joanneum Research Forschungsgesellschaft, Graz, Austria. First of all, the digital terrain model (DTM and the digital surface models (DSM were imported and converted into a raster file from the original laser point clouds with a spatial resolution of 50 cm. Then, a normalized digital surface model (nDSM was derived as the difference between DSM and the DTM. Tree top detection was performed by multi – resolution filter operations and tree crowns were segmented by a region growing algorithms develop specifically for this purpose. Breast Height Diameter (BHD was calculated on the base of tree height and crown areas derived from image segmentation applying allometric functions found in literature. The assessment of stem volume was then calculated as a function of tree height and BHD. A comparison of timber volume estimated from the LiDAR data and field plots measured by the Forest Department of Istanbul showed R2 of 0.46. The low correlation might arise either from the low quality of the field plots or

Calibrating nacelle lidars

Energy Technology Data Exchange (ETDEWEB)

Courtney, M.

2013-01-15

Nacelle mounted, forward looking wind lidars are beginning to be used to provide reference wind speed measurements for the power performance testing of wind turbines. In such applications, a formal calibration procedure with a corresponding uncertainty assessment will be necessary. This report presents four concepts for performing such a nacelle lidar calibration. Of the four methods, two are found to be immediately relevant and are pursued in some detail. The first of these is a line of sight calibration method in which both lines of sight (for a two beam lidar) are individually calibrated by accurately aligning the beam to pass close to a reference wind speed sensor. A testing procedure is presented, reporting requirements outlined and the uncertainty of the method analysed. It is seen that the main limitation of the line of sight calibration method is the time required to obtain a representative distribution of radial wind speeds. An alternative method is to place the nacelle lidar on the ground and incline the beams upwards to bisect a mast equipped with reference instrumentation at a known height and range. This method will be easier and faster to implement and execute but the beam inclination introduces extra uncertainties. A procedure for conducting such a calibration is presented and initial indications of the uncertainties given. A discussion of the merits and weaknesses of the two methods is given together with some proposals for the next important steps to be taken in this work. (Author)

Development of wavelength locking circuit for 1.53 micron water vapor monitoring coherent differential absorption LIDAR

Science.gov (United States)

Imaki, Masaharu; Kojima, Ryota; Kameyama, Shumpei

2018-04-01

We have studied a ground based coherent differential absorption LIDAR (DIAL) for vertical profiling of water vapor density using a 1.5μm laser wavelength. A coherent LIDAR has an advantage in daytime measurement compared with incoherent LIDAR because the influence of background light is greatly suppressed. In addition, the LIDAR can simultaneously measure wind speed and water vapor density. We had developed a wavelength locking circuit using the phase modulation technique and offset locking technique, and wavelength stabilities of 0.123 pm which corresponds to 16 MHz are realized. In this paper, we report the wavelength locking circuits for the 1.5 um wavelength.

Continuous-Integration Laser Energy Lidar Monitor

Science.gov (United States)

Karsh, Jeremy

2011-01-01

This circuit design implements an integrator intended to allow digitization of the energy output of a pulsed laser, or the energy of a received pulse of laser light. It integrates the output of a detector upon which the laser light is incident. The integration is performed constantly, either by means of an active integrator, or by passive components.

Compact lidar system using laser diode, binary continuous wave power modulation, and an avalanche photodiode-based receiver controlled by a digital signal processor

Science.gov (United States)

Ardanuy, Antoni; Comerón, Adolfo

2018-04-01

We analyze the practical limits of a lidar system based on the use of a laser diode, random binary continuous wave power modulation, and an avalanche photodiode (APD)-based photereceiver, combined with the control and computing power of the digital signal processors (DSP) currently available. The target is to design a compact portable lidar system made all in semiconductor technology, with a low-power demand and an easy configuration of the system, allowing change in some of its features through software. Unlike many prior works, we emphasize the use of APDs instead of photomultiplier tubes to detect the return signal and the application of the system to measure not only hard targets, but also medium-range aerosols and clouds. We have developed an experimental prototype to evaluate the behavior of the system under different environmental conditions. Experimental results provided by the prototype are presented and discussed.

A lidar study of atmospheric aerosols during two contrasting monsoon seasons

Energy Technology Data Exchange (ETDEWEB)

Devara, P.C.S.; Raj, P.E. [Indian Institute of Tropical Meteorology (India)

1998-10-01

The vertical profiles of the boundary-layer aerosols obtained with a bistatic argon ion lidar system at the Indian Institute of Tropical Meteorology (IITM), Pune, India, during two contrasting, successive south-west (summer) monsoon seasons of 1987 (weak monsoon year) and 1988 (active monsoon year) have been examined. The concurrent meteorological parameters such as temperature, relative humidity and rainfall over Pune have also been studied. It is noticed that the aerosol columnar content (integration of vertical profile throughout the height range) is greater during the active monsoon months and less during the weak monsoon months. Thus the monsoon season total rainfall during 1987 and 1988, apart from other meteorological parameters, shows close correspondence with the aerosol columnar content over the experimental station. A brief description of the lidar experimental setup and the database is given. The observed association between the aerosol columnar content and the monsoon activity is explained in terms of the environmental and meteorological conditions prevailing over Pune. [Spanish] Los perfiles verticales de los aerosoles de la capa fronteriza obtenidos mediante un sistema de Lidar biestatico de iones de argon en el Instituto de Meteorologia Tropical (IITM) en Pune, India, durante dos estaciones contrastantes y suscesivas del monzon del SW (verano) de 1987 (ano de monzon debil) y 1988 (ano activo de monzon) han sido estudiados. Los parametros meteorologicos concurrentes tales como temperatura, humedad relativa y lluvia en Pune, han sido tambien estudiados. Se observa que el contenido columnar de aerosoles (integracion del perfil vertical en toda la gama de alturas) es mayor durante los meses del monzon activo y menor en los meses del monzon debil. De manera que, el total de la lluvia monzonica durante 1987 y 1988, aparte de otros parametros meteorologicos, muestran una correspondencia intima con el contenido columnar de a erosoles sobre la estacion

Volumetric visualization of multiple-return LIDAR data: Using voxels

Science.gov (United States)

Stoker, Jason M.

2009-01-01

Elevation data are an important component in the visualization and analysis of geographic information. The creation and display of 3D models representing bare earth, vegetation, and surface structures have become a major focus of light detection and ranging (lidar) remote sensing research in the past few years. Lidar is an active sensor that records the distance, or range, of a laser usually fi red from an airplane, helicopter, or satellite. By converting the millions of 3D lidar returns from a system into bare ground, vegetation, or structural elevation information, extremely accurate, high-resolution elevation models can be derived and produced to visualize and quantify scenes in three dimensions. These data can be used to produce high-resolution bare-earth digital elevation models; quantitative estimates of vegetative features such as canopy height, canopy closure, and biomass; and models of urban areas such as building footprints and 3D city models.

Development of an Airborne Triple-Pulse 2-Micron Integrated Path Differential Absorption Lidar (IPDA) for Simultaneous Airborne Column Measurements of Carbon Dioxide and Water Vapor in the Atmosphere

Science.gov (United States)

Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Yu, Jirong; Antill, Charles W.; Remus, Ruben

2016-01-01

This presentation will provide status and details of an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar being developed at NASA Langley Research Center with support from NASA ESTO Instrument Incubator Program. The development of this active optical remote sensing IPDA instrument is targeted for measuring both atmospheric carbon dioxide and water vapor in the atmosphere from an airborne platform. This presentation will focus on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver and detector upgrades, laser packaging and lidar integration. Future plan for IPDA lidar system for ground integration, testing and flight validation will also be presented.

Rayleigh lidar observation of tropical mesospheric inversion layer: a comparison between dynamics and chemistry

Directory of Open Access Journals (Sweden)

Ramesh K.

2018-01-01

Full Text Available The Rayleigh lidar at National Atmospheric Research Laboratory, Gadanki (13.5°N, 79.2°E, India operates at 532 nm green laser with ~600 mJ/pulse since 2007. The vertical temperature profiles are derived above ~30 km by assuming the atmosphere is in hydrostatic equilibrium and obeys ideal gas law. A large mesospheric inversion layer (MIL is observed at ~77.4-84.6 km on the night of 22 March 2007 over Gadanki. Although dynamics and chemistry play vital role, both the mechanisms are compared for the occurrence of the MIL in the present study.

Rayleigh lidar observation of tropical mesospheric inversion layer: a comparison between dynamics and chemistry

Science.gov (United States)

Ramesh, K.; Sridharan, S.; Raghunath, K.

2018-04-01

The Rayleigh lidar at National Atmospheric Research Laboratory, Gadanki (13.5°N, 79.2°E), India operates at 532 nm green laser with 600 mJ/pulse since 2007. The vertical temperature profiles are derived above 30 km by assuming the atmosphere is in hydrostatic equilibrium and obeys ideal gas law. A large mesospheric inversion layer (MIL) is observed at 77.4-84.6 km on the night of 22 March 2007 over Gadanki. Although dynamics and chemistry play vital role, both the mechanisms are compared for the occurrence of the MIL in the present study.

2006 Federal Emergency Management Agency (FEMA) Topographic LiDAR: Connecticut Coastline Survey

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. By positioning laser range finding with the use of 1...

Mid-Infrared Lasers

Data.gov (United States)

National Aeronautics and Space Administration — Mid infrared solid state lasers for Differential Absorption Lidar (DIAL) systems required for understanding atmospheric chemistry are not available. This program...

Hardware in the Loop Performance Assessment of LIDAR-Based Spacecraft Pose Determination.

Science.gov (United States)

Opromolla, Roberto; Fasano, Giancarmine; Rufino, Giancarlo; Grassi, Michele

2017-09-24

In this paper an original, easy to reproduce, semi-analytic calibration approach is developed for hardware-in-the-loop performance assessment of pose determination algorithms processing point cloud data, collected by imaging a non-cooperative target with LIDARs. The laboratory setup includes a scanning LIDAR, a monocular camera, a scaled-replica of a satellite-like target, and a set of calibration tools. The point clouds are processed by uncooperative model-based algorithms to estimate the target relative position and attitude with respect to the LIDAR. Target images, acquired by a monocular camera operated simultaneously with the LIDAR, are processed applying standard solutions to the Perspective- n -Points problem to get high-accuracy pose estimates which can be used as a benchmark to evaluate the accuracy attained by the LIDAR-based techniques. To this aim, a precise knowledge of the extrinsic relative calibration between the camera and the LIDAR is essential, and it is obtained by implementing an original calibration approach which does not need ad-hoc homologous targets (e.g., retro-reflectors) easily recognizable by the two sensors. The pose determination techniques investigated by this work are of interest to space applications involving close-proximity maneuvers between non-cooperative platforms, e.g., on-orbit servicing and active debris removal.

Precision operation of the Nova laser for fusion experiments

International Nuclear Information System (INIS)

Caird, J.A.; Ehrlich, R.B.; Hermes, G.L.; Landen, O.L.; Laumann, C.W.; Lerche, R.A.; Miller, J.L.; Murray, J.E.; Nielsen, N.D.; Powell, H.T.; Rushford, M.C.; Saunders, R.L.; Thompson, C.E.; VanArsdall, P.J.; Vann, C.S.; Weiland, T.L.

1994-01-01

The operation of a Neodymium glass laser of a special design for fusion experiments is improved by a better pulse synchronization, the gain stabilization, and the laser diagnostics. We used sensor upgrading and antifriction coating of focusing lenses. The pointing accuracy of the Nova laser meets now our goal for precision operation. (AIP) copyright 1994 American Institute of Physics

Design and Demonstration of a Miniature Lidar System for Rover Applications

Science.gov (United States)

Robinson, Benjamin

2010-01-01

A basic small and portable lidar system for rover applications has been designed. It uses a 20 Hz Nd:YAG pulsed laser, a 4-inch diameter telescope receiver, a custom-built power distribution unit (PDU), and a custom-built 532 nm photomultiplier tube (PMT) to measure the lidar signal. The receiving optics have been designed, but not constructed yet. LabVIEW and MATLAB programs have also been written to control the system, acquire data, and analyze data. The proposed system design, along with some measurements, is described. Future work to be completed is also discussed.

Army Solid State Laser Program: Design, Operation, and Mission Analysis for a Heat-Capacity Laser

International Nuclear Information System (INIS)

Dane, C B; Flath, L; Rotter, M; Fochs, S; Brase, J; Bretney, K

2001-01-01

scenario including a dense attack of rockets, mortars, and artillery has indicated that multiple HEL weapon systems, based on the solid state, heat capacity laser concept, can provide significantly improved protection of high value battlefield assets. We will present EADSIM results for two government-supplied scenarios, one with temporally high threat density over a fairly large defended area, and one with fewer threats concentrating on a single defended asset. Implications for weapon system requirements will be presented. In order to demonstrate the operation of a high average power heat-capacity laser system, we have developed a flashlamp-pumped Nd:glass laser with output energies in the range of 500-1000J/pulse in a 10 x 10cm 2 beam. With a repetition frequency of 20Hz, an average power of 13kW has been demonstrated for operational periods of up to 10s using a stable optical resonator (see enclosed figure). Using an M=1.4 unstable resonator, a beam divergence of 5X diffraction-limited has been measured with no active wavefront correction. An adaptively corrected unstable resonator that incorporates an intracavity deformable mirror controlled by feedback from an external wavefront sensor will provide <2X diffraction-limited output integrated over an entire 10s run at an average power of 10kW. A very similar laser architecture in which the Nd:glass is replaced by Nd:GGG and the flashlamps are replaced by large diode-laser arrays will enable the scaling of the output average power from the demonstrated 10kW to 100kW (500J/pulse at 200Hz). Risk reduction experiments for diode-pumped Nd:GGG, the fabrication of large Nd:GGG amplifier slabs, as well as the progress toward a sub-scale amplifier testbed pumped by diode arrays with total of 1MW peak power will also be presented

Operator-machine interface at a large laser-fusion facility

International Nuclear Information System (INIS)

Sutton, J.G.; Howell, J.A.

1982-01-01

The operator-machine interface at the Antares Laser Facility provides the operator with a means of controlling the laser system and obtaining operational and performance information. The goal of this interface is to provide an operator with access to the control system in a comfortable way, and to facilitate meeting operational requirements. We describe the philosophy and requirements behind this interface, the hardware used in building it, and the software environment

Elevation - LIDAR Survey - Roseau County, Minnesota

Data.gov (United States)

Army Corps of Engineers, Department of the Army, Department of Defense — LIDAR Data for Roseau County Minnesota. This project consists of approximately 87 square miles of LIDAR mapping in Roseau County, Minnesota at two sites: area 1,...

Atmospheric Boundary Layer temperature and humidity from new-generation Raman lidar

Science.gov (United States)

Froidevaux, Martin; Higgins, Chad; Simeonov, Valentin; Pardyjak, Eric R.; Parlange, Marc B.

2010-05-01

Mixing ratio and temperature data, obtained with EPFL Raman lidar during the TABLE-08 experiment are presented. The processing methods will be discussed along with fundamental physics. An independent calibration is performed at different distances along the laser beam, demonstrating that the multi-telescopes design of the lidar system is reliable for field application. The maximum achievable distance as a function of time and/or space averaging will also be discussed. During the TABLE-08 experiment, different type of lidar measurements have been obtained including: horizontal and vertical time series, as well as boundary layer "cuts", during day and night. The high resolution data, 1s in time and 1.25 m in space, are used to understand the response of the atmosphere to variations in surface variability.

On mean wind and turbulence profile measurements from ground-based wind lidars

DEFF Research Database (Denmark)

Mikkelsen, Torben

2009-01-01

Two types of wind lidar?s have become available for ground-based vertical mean wind and turbulence profiling. A continuous wave (CW) wind lidar, and a pulsed wind lidar. Although they both are build upon the same recent 1.55 μ telecom fibre technology, they possess fundamental differences between...... their temporal and spatial resolution capabilities. A literature review of the two lidar systems spatial and temporal resolution characteristics will be presented, and the implication for the two lidar types vertical profile measurements of mean wind and turbulence in the lower atmospheric boundary layer...

Assessing the Temperature Dependence of Narrow-Band Raman Water Vapor Lidar Measurements: A Practical Approach

Science.gov (United States)

Whiteman, David N.; Venable, Demetrius D.; Walker, Monique; Cardirola, Martin; Sakai, Tetsu; Veselovskii, Igor

2013-01-01

Narrow-band detection of the Raman water vapor spectrum using the lidar technique introduces a concern over the temperature dependence of the Raman spectrum. Various groups have addressed this issue either by trying to minimize the temperature dependence to the point where it can be ignored or by correcting for whatever degree of temperature dependence exists. The traditional technique for performing either of these entails accurately measuring both the laser output wavelength and the water vapor spectral passband with combined uncertainty of approximately 0.01 nm. However, uncertainty in interference filter center wavelengths and laser output wavelengths can be this large or larger. These combined uncertainties translate into uncertainties in the magnitude of the temperature dependence of the Raman lidar water vapor measurement of 3% or more. We present here an alternate approach for accurately determining the temperature dependence of the Raman lidar water vapor measurement. This alternate approach entails acquiring sequential atmospheric profiles using the lidar while scanning the channel passband across portions of the Raman water vapor Q-branch. This scanning is accomplished either by tilt-tuning an interference filter or by scanning the output of a spectrometer. Through this process a peak in the transmitted intensity can be discerned in a manner that defines the spectral location of the channel passband with respect to the laser output wavelength to much higher accuracy than that achieved with standard laboratory techniques. Given the peak of the water vapor signal intensity curve, determined using the techniques described here, and an approximate knowledge of atmospheric temperature, the temperature dependence of a given Raman lidar profile can be determined with accuracy of 0.5% or better. A Mathematica notebook that demonstrates the calculations used here is available from the lead author.

Sixteenth International Laser Radar Conference, Part 1

International Nuclear Information System (INIS)

Mccormick, M.P.

1992-07-01

This publication contains extended abstracts of papers presented at the 16th International Laser Radar Conference. One-hundred ninety-five papers were presented in both oral and poster sessions. The topics of the conference sessions were: (1) Mt. Pinatubo Volcanic Dust Layer Observations; (2) Global Change/Ozone Measurements; (3) GLOBE/LAWS/LITE; (4) Mesospheric Measurements and Measurement Systems; (5) Middle Atmosphere; (6) Wind Measurements and Measurement Systems; (7) Imaging and Ranging; (8) Water Vapor Measurements; (9) Systems and Facilities; and (10) Laser Devices and Technology. This conference reflects the breadth of research activities being conducted in the lidar field. These abstracts address subjects from lidar-based atmospheric investigations relating to global change to the development of new lidar systems and technology

Measurement of Spray Drift with a Specifically Designed Lidar System.

Science.gov (United States)

Gregorio, Eduard; Torrent, Xavier; Planas de Martí, Santiago; Solanelles, Francesc; Sanz, Ricardo; Rocadenbosch, Francesc; Masip, Joan; Ribes-Dasi, Manel; Rosell-Polo, Joan R

2016-04-08

Field measurements of spray drift are usually carried out by passive collectors and tracers. However, these methods are labour- and time-intensive and only provide point- and time-integrated measurements. Unlike these methods, the light detection and ranging (lidar) technique allows real-time measurements, obtaining information with temporal and spatial resolution. Recently, the authors have developed the first eye-safe lidar system specifically designed for spray drift monitoring. This prototype is based on a 1534 nm erbium-doped glass laser and an 80 mm diameter telescope, has scanning capability, and is easily transportable. This paper presents the results of the first experimental campaign carried out with this instrument. High coefficients of determination (R² > 0.85) were observed by comparing lidar measurements of the spray drift with those obtained by horizontal collectors. Furthermore, the lidar system allowed an assessment of the drift reduction potential (DRP) when comparing low-drift nozzles with standard ones, resulting in a DRP of 57% (preliminary result) for the tested nozzles. The lidar system was also used for monitoring the evolution of the spray flux over the canopy and to generate 2-D images of these plumes. The developed instrument is an advantageous alternative to passive collectors and opens the possibility of new methods for field measurement of spray drift.

LIDAR wind speed measurements from a rotating spinner (SpinnerEx 2009)

Energy Technology Data Exchange (ETDEWEB)

Angelou, N.; Mikkelsen, Torben; Hansen, Kasper H.; Sjoeholm, M.; Harris, M.

2010-08-15

In the context of the increasing application of remote sensing techniques in wind energy, the feasibility of upwind observations via a spinner-mounted wind lidar was tested during the SpinnerEx 2009 experiment. The objective was to install a QinetiQ (Natural Power) ZephIR lidar in the rotating spinner of a MW-sized wind turbine, and investigate the approaching wind fields from this vantage point. Time series of wind speed measurements from the lidar with 50 Hz sampling rate were successfully obtained for approximately 60 days, during the measurement campaign lasting from April to August 2009. In this report, information is given regarding the experimental setup and the lidar's operation parameters. The geometrical model used for the reconstruction of the scanning pattern of the lidar is described. This model takes into account the lidar's pointing direction, the spinner axis's vertical tilt and the wind turbine's yaw relative to the mean wind speed direction. The data analysis processes are documented. A methodology for the calculation of the yaw misalignment of the wind turbine relative to the wind direction, as a function of various averaging times, is proposed, using the lidar's instantaneous line-of-sight radial wind speed measurements. Two different setups have been investigated in which the approaching wind field was measured at distances of 0.58 OE and 1.24 OE rotor diameters upwind, respectively. For both setups, the instantaneous yaw misalignment of the turbine has been estimated from the lidar measurements. Data from an adjacent meteorological mast as well as data logged within the wind turbine's control system were used to evaluate the results. (author)

Nonlinear dynamic effects in a two-wave CO2 laser

International Nuclear Information System (INIS)

Gorobets, V A; Kozlov, K V; Kuntsevich, B F; Petukhov, V O

1999-01-01

Theoretical and experimental investigations were made of nonlinear dynamic regimes of the operation of a two-wave CO 2 laser with cw excitation in an electric discharge and loss modulation in one of the channels. Nonlinear amplitude - frequency characteristics of each of the laser channels have two low-frequency resonance spikes, associated with forced linear oscillations of two coupled oscillators, and high-frequency spikes, corresponding to doubling of the period of the output radiation oscillations. At low loss-modulation frequencies the intensity oscillations of the output radiation in the coupled channels are in antiphase, whereas at high modulation frequencies the dynamics is cophasal. Nonlinear dynamic effects, such as doubling of the period and of the repetition frequency of the pulses and chaotic oscillations of the output radiation intensity, are observed for certain system parameters. (control of laser radiation parameters)

Modeling of electro-statically actuated two-axis (tip-tilt) MEMS torsion micro-mirrors for laser beamsteering

Science.gov (United States)

Edwards, C. L.; Boone, B. G.; Levine, W. S.; Davis, C. C.

2007-04-01

The availability of recently developed MEMS micro-mirror technology provides an opportunity to replace macro-scale actuators for free-space laser beamsteering in lidar and communication systems. Such an approach is under investigation at the Johns Hopkins University Applied Physics Laboratory for use on space-based platforms. Precision modeling of mirror pointing and its dynamics are critical to optimal design and control of MEMS beamsteerers. Beginning with Hornbeck's torque approach, this paper presents a first-principle, analytically closed-form torque model for an electro-statically actuated two-axis (tip-tilt) MEMS structure. An Euler dynamic equation formulation describes the gimbaled motion as a coupled pair of damped harmonic oscillators with a common forcing function. Static physical parameters such as MEMS mirror dimensions, facet mass, and height are inputs to the model as well as dynamic harmonic oscillator parameters such as damping and restoring constants fitted from measurements. A Taylor series expansion of the torque function provides valuable insights into basic one dimensional as well as two dimensional MEMS behavior, including operational sensitivities near "pull-in." The model also permits the natural inclusion and analysis of pointing noise sources such as electrical drive noise, platform vibration, and molecular Brownian motion. MATLAB and SIMULINK simulations illustrate performance sensitivities, controllability, and physical limitations, important considerations in the design of optimal pointing systems.

LIDAR TS for ITER core plasma. Part I: layout & hardware

Science.gov (United States)

Salzmann, H.; Gowers, C.; Nielsen, P.

2017-12-01

The original time-of-flight design of the Thomson scattering diagnostic for the ITER core plasma has been shown up by ITER. This decision was justified by insufficiencies of some of the components. In this paper we show that with available, present day technology a LIDAR TS system is feasible which meets all the ITER specifications. As opposed to the conventional TS system the LIDAR TS also measures the high field side of the plasma. The optical layout of the front end has been changed only little in comparison with the latest one considered by ITER. The main change is that it offers an optical collection without any vignetting over the low field side. The throughput of the system is defined only by the size and the angle of acceptance of the detectors. This, in combination with the fact that the LIDAR system uses only one set of spectral channels for the whole line of sight, means that no absolute calibration using Raman or Rayleigh scattering from a non-hydrogen isotope gas fill of the vessel is needed. Alignment of the system is easy since the collection optics view the footprint of the laser on the inner wall. In the described design we use, simultaneously, two different wavelength pulses from a Nd:YAG laser system. Its fundamental wavelength ensures measurements of 2 keV up to more than 40 keV, whereas the injection of the second harmonic enables measurements of low temperatures. As it is the purpose of this paper to show the technological feasibility of the LIDAR system, the hardware is considered in Part I of the paper. In Part II we demonstrate by numerical simulations that the accuracy of the measurements as required by ITER is maintained throughout the given plasma parameter range. The effect of enhanced background radiation in the wavelength range 400 nm-500 nm is considered. In Part III the recovery of calibration in case of changing spectral transmission of the front end is treated. We also investigate how to improve the spatial resolution at the

APPLICABILITY ANALYSIS OF CLOTH SIMULATION FILTERING ALGORITHM FOR MOBILE LIDAR POINT CLOUD

Directory of Open Access Journals (Sweden)

S. Cai

2018-04-01

Full Text Available Classifying the original point clouds into ground and non-ground points is a key step in LiDAR (light detection and ranging data post-processing. Cloth simulation filtering (CSF algorithm, which based on a physical process, has been validated to be an accurate, automatic and easy-to-use algorithm for airborne LiDAR point cloud. As a new technique of three-dimensional data collection, the mobile laser scanning (MLS has been gradually applied in various fields, such as reconstruction of digital terrain models (DTM, 3D building modeling and forest inventory and management. Compared with airborne LiDAR point cloud, there are some different features (such as point density feature, distribution feature and complexity feature for mobile LiDAR point cloud. Some filtering algorithms for airborne LiDAR data were directly used in mobile LiDAR point cloud, but it did not give satisfactory results. In this paper, we explore the ability of the CSF algorithm for mobile LiDAR point cloud. Three samples with different shape of the terrain are selected to test the performance of this algorithm, which respectively yields total errors of 0.44 %, 0.77 % and1.20 %. Additionally, large area dataset is also tested to further validate the effectiveness of this algorithm, and results show that it can quickly and accurately separate point clouds into ground and non-ground points. In summary, this algorithm is efficient and reliable for mobile LiDAR point cloud.

Improvement on Timing Accuracy of LIDAR for Remote Sensing

Science.gov (United States)

Zhou, G.; Huang, W.; Zhou, X.; Huang, Y.; He, C.; Li, X.; Zhang, L.

2018-05-01

The traditional timing discrimination technique for laser rangefinding in remote sensing, which is lower in measurement performance and also has a larger error, has been unable to meet the high precision measurement and high definition lidar image. To solve this problem, an improvement of timing accuracy based on the improved leading-edge timing discrimination (LED) is proposed. Firstly, the method enables the corresponding timing point of the same threshold to move forward with the multiple amplifying of the received signal. Then, timing information is sampled, and fitted the timing points through algorithms in MATLAB software. Finally, the minimum timing error is calculated by the fitting function. Thereby, the timing error of the received signal from the lidar is compressed and the lidar data quality is improved. Experiments show that timing error can be significantly reduced by the multiple amplifying of the received signal and the algorithm of fitting the parameters, and a timing accuracy of 4.63 ps is achieved.

A cloud masking algorithm for EARLINET lidar systems

Science.gov (United States)

Binietoglou, Ioannis; Baars, Holger; D'Amico, Giuseppe; Nicolae, Doina

2015-04-01

Cloud masking is an important first step in any aerosol lidar processing chain as most data processing algorithms can only be applied on cloud free observations. Up to now, the selection of a cloud-free time interval for data processing is typically performed manually, and this is one of the outstanding problems for automatic processing of lidar data in networks such as EARLINET. In this contribution we present initial developments of a cloud masking algorithm that permits the selection of the appropriate time intervals for lidar data processing based on uncalibrated lidar signals. The algorithm is based on a signal normalization procedure using the range of observed values of lidar returns, designed to work with different lidar systems with minimal user input. This normalization procedure can be applied to measurement periods of only few hours, even if no suitable cloud-free interval exists, and thus can be used even when only a short period of lidar measurements is available. Clouds are detected based on a combination of criteria including the magnitude of the normalized lidar signal and time-space edge detection performed using the Sobel operator. In this way the algorithm avoids misclassification of strong aerosol layers as clouds. Cloud detection is performed using the highest available time and vertical resolution of the lidar signals, allowing the effective detection of low-level clouds (e.g. cumulus humilis). Special attention is given to suppress false cloud detection due to signal noise that can affect the algorithm's performance, especially during day-time. In this contribution we present the details of algorithm, the effect of lidar characteristics (space-time resolution, available wavelengths, signal-to-noise ratio) to detection performance, and highlight the current strengths and limitations of the algorithm using lidar scenes from different lidar systems in different locations across Europe.

A digital signal processing system for coherent laser radar

Science.gov (United States)

Hampton, Diana M.; Jones, William D.; Rothermel, Jeffry

1991-01-01

A data processing system for use with continuous-wave lidar is described in terms of its configuration and performance during the second survey mission of NASA'a Global Backscatter Experiment. The system is designed to estimate a complete lidar spectrum in real time, record the data from two lidars, and monitor variables related to the lidar operating environment. The PC-based system includes a transient capture board, a digital-signal processing (DSP) board, and a low-speed data-acquisition board. Both unprocessed and processed lidar spectrum data are monitored in real time, and the results are compared to those of a previous non-DSP-based system. Because the DSP-based system is digital it is slower than the surface-acoustic-wave signal processor and collects 2500 spectra/s. However, the DSP-based system provides complete data sets at two wavelengths from the continuous-wave lidars.

High Spectral Resolution Lidar Based on a Potassium Faraday Dispersive Filter for Daytime Temperature Measurement

Directory of Open Access Journals (Sweden)

Abo Makoto

2016-01-01

Full Text Available In this paper, a new high-spectral-resolution lidar technique is proposed for measuring the profiles of atmospheric temperature in daytime. Based on the theory of high resolution Rayleigh scattering, the feasibility and advantages of using potassium (K Faraday dispersive optical filters as blocking filters for measuring atmospheric temperature are demonstrated with a numerical simulation. It was found that temperature profiles could be measured within 1K error for the height of 9 km with a 500 m range resolution in 60 min by using laser pulses with 1mJ/pulse and 1 kHz, and a 50 cm diameter telescope. Furthermore, we are developing compact pulsed laser system for temperature lidar transmitter.

Utilizing LiDAR Datasets From Experimental Watersheds to Advance Ecohydrological Understanding in Seasonally Snow-Covered Forests

Science.gov (United States)

Harpold, A. A.; Broxton, P. D.; Guo, Q.; Barlage, M. J.; Gochis, D. J.

2014-12-01

The Western U.S. is strongly reliant on snowmelt from forested areas for ecosystem services and downstream populations. The ability to manage water resources from snow-covered forests faces major challenges from drought, disturbance, and regional changes in climate. An exciting avenue for improving ecohydrological process understanding is Light Detection and Ranging (LiDAR) because the technology simultaneously observes topography, forest properties, and snow/ice at high-resolution (100 km2). The availability and quality of LiDAR datasets is increasing rapidly, however they remain under-utilized for process-based ecohydrology investigations. This presentation will illustrate how LiDAR datasets from the Critical Zone Observatory (CZO) network have been applied to advance ecohydrological understanding through direct empirical analysis, as well as model parameterization and verification. Direct analysis of the datasets has proved fruitful for pre- and post-disturbance snow distribution estimates and interpreting in-situ snow depth measurements across sites. In addition, we illustrate the potential value of LiDAR to parameterize and verify of physical models with two examples. First, we use LiDAR to parameterize a land surface model, Noah multi-parameterization (Noah-MP), to investigate the sensitivity of modeled water and energy fluxes to high-resolution forest information. Second, we present a Snow Physics and Laser Mapping (SnowPALM) model that is parameterized with LiDAR information at its native 1-m scale. Both modeling studies demonstrate the value of LiDAR for representing processes with greater fidelity. More importantly, the increased model fidelity led to different estimates of water and energy fluxes at larger, watershed scales. Creating a network of experimental watersheds with LiDAR datasets offers the potential to test theories and models in previously unexplored ways.

Windscanner: 3-D wind and turbulence measurements from three steerable doppler lidars

International Nuclear Information System (INIS)

Mikkelsen, T; Mann, J; Courtney, M; Sjoeholm, M

2008-01-01

At RISOe DTU we has started to build a new-designed laser-based lidar scanning facility for detailed remote measurements of the wind fields engulfing the huge wind turbines of today. Our aim is to measure in real-time 3D wind vector data at several hundred points every second: 1) upstream of the turbine, 2) near the turbine, and 3) in the wakes of the turbine rotors. Our first proto-type Windscanner is now being built from three commercially available Continuous Wave (CW) wind lidars modified with fast adjustable focus length and equipped with 2-D prism-based scan heads, in conjunction with a commercially available pulsed wind lidar for extended vertical profiling range. Design, construction and initial testing of the new 3-D wind lidar scanning facility are described and the functionality of the Windscanner and its potential as a new research facility within the wind energy community is discussed

3D Lasers Increase Efficiency, Safety of Moving Machines

Science.gov (United States)

2015-01-01

Canadian company Neptec Design Group Ltd. developed its Laser Camera System, used by shuttles to render 3D maps of their hulls for assessing potential damage. Using NASA funding, the firm incorporated LiDAR technology and created the TriDAR 3D sensor. Its commercial arm, Neptec Technologies Corp., has sold the technology to Orbital Sciences, which uses it to guide its Cygnus spacecraft during rendezvous and dock operations at the International Space Station.

Theoretical and experimental study of two-frequency solid-state lasers in the GHz to THz ranges. Opto-microwave applications waves

International Nuclear Information System (INIS)

Lai, N.D.

2003-07-01

We explored some new features of single- and dual-frequency solid-state lasers oscillating in continuous-wave or pulsed regimes. First, we have developed some techniques to optimise the characteristics of pulsed lasers. A weak modulation of the pump power made it possible to obtain a stable repetition rate with a relative stability of 10 -6 . The pulse duration was continuously controlled from ten nanoseconds to a few hundreds nanoseconds by three different methods: adjustment of the laser beam diameter in the absorber, adjustment of the pump beam diameter in the active medium, and, in particular, the use of forked eigenstates in a two-axis laser. Moreover, the forked eigenstates allows to increase the pulse energy by coherent addition of the pulses. A compact two-frequency Nd:YAG-Cr:YAG laser with a beat note frequency continuously adjustable up to 2,7 GHz was demonstrated. The two-frequency pulses are ideal sources to meet various needs of applications such as the Doppler lidar-radar. Moreover, we show that two-frequency pulses at 1,55 μm can be obtained by using a new c-cut Co:ASL saturable absorber in an Er-Yb:glass laser. These pulses are perfectly adapted to free-space detection systems requiring eye safety. The coherence time of the beat note in these lasers was also studied: it is limited by the pulse duration. A new technique of modulating the pump power of a solid-state laser at frequencies close to its relaxation oscillation frequency was studied and made it possible to generate a beat note coherence from pulse to pulse. Frequency conversion techniques using the nonlinear optical effects make it possible to obtain tunable two-frequency sources in the visible spectrum. Green and red two-frequency pulses were obtained by using different conversion techniques, intra-cavity or extra-cavity. A two-frequency THz source in the red spectrum was also obtained by doubling the frequencies of a two-frequency THz Er-Yb:glass laser using a mixed fan-out PPLN crystal