This PDF file contains the front matter associated with SPIE Proceedings Volume XXXX, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

We describe a new lidar system for CO2 that uses a Fabry-Perot based system as the detector portion of the instrument and replaces the narrow band laser commonly used in lidars with the newly available superluminescent light emitting diode (SLED) as the source. This approach reduces the number of individual lasers used in the system from three or more to one-considerably reducing the risk of failure. It also tremendously reduces the requirement for wavelength stability in the source putting this responsibility on the Fabry-Perot. &128;

We report results on a single-end pumped waveguide laser for sensing applications Output power in excess of 20 mW with 17% slope efficiency in robust single-frequency operation at 1533.5 nm is demonstrated. The overall laser cavity laser was 60-mm long but the active medium, an Er:Yb-doped phosphate glass, was only 9-mm long. The waveguide was fabricated by two-step Ag-Na ion-exchange technique. The overall cavity length including butt-coupled fiber- Bragg-grating mirrors was <60 mm. We also reports on recent work to reach 100-mW single-frequency output power. To extend the operation wavelength to 2-micron wavelength region we also developed new tellurite glasses. Preliminary results on glass investigation are also reported.

NASA Langley Research Center has been developing 2-micron lidar technologies over a decade for wind measurements, utilizing coherent Doppler wind lidar technique and carbon dioxide measurements, utilizing Differential Absorption Lidar (DIAL) technique. Significant advancements have been made towards developing state-of-the-art technologies towards laser transmitters, detectors, and receiver systems. These efforts have led to the development of solid-state lasers with high pulse energy, tunablility, wavelength-stability, and double-pulsed operation. This paper will present a review of these technological developments along with examples of high resolution wind and high precision CO₂ measurements in the atmosphere. Plans for the development of compact high power lasers for applications in airborne and future space platforms for wind and regional to global scale measurement of atmospheric CO₂ will also be discussed.

We present efficient CW lasing Tm³⁺/Ho³⁺/Yb³⁺-triply-doped tellurite fibre at ~2.1 μm. Two different pump schemes have been demonstrated for this laser: a 1.088 μm Yb³⁺-doped silica fibre laser simultaneously pumping the Tm³⁺: ³H₅, Ho³⁺: ⁵I₆ and Yb³⁺: ²F_5/2 levels, and a 1.6 μm Er³⁺/Yb³⁺-doped silica fibre laser directly pumping the Tm³⁺: ³F₄ level. For the 1.6 μm pumping, a slope efficiency of 62% has been achieved in a 76 cm long fibre which is close to the Stokes efficiency limit of ~75%. An output power of 160 mW has also been achieved, but with no signs of saturation or fibre damage suggesting that higher output powers should be possible. For the 1.088 μm pumping there is very strong pump ESA resulting in bright blue (480 nm) and near-IR (800 nm) fluorescence due to the ¹G₄ → ³H₆ and ³H₄ → ³H₆ transitions of Tm³⁺, respectively, and this limits the achievable slope efficiency, which in this case was a maximum of 25% for a 17 cm long fibre. With this pump scheme, the highest observed output power was 60 mW, and further power scaling was limited due to the intense ESA and thermal damage to the pump end of the fibre. We also present results on the active Q-switching of the 1.6 μm pumped fibre laser using a mechanical chopper operating at 19.4 kHz. Average powers of 26 mW and pulse energies of 0.65 μJ were measured with pulse widths in the range 100-160 ns.

Lidar has in recent years matured into a reliable and versatile technology for remotely measuring wind speeds at all heights across the rotor diameter. A laser beam is used to acquire the radial wind velocity in a number of directions at a given height from the Doppler shift of the backscattered light. From this the wind velocity at that height can be derived. Lidar allows wind flow model validation. Deployment of a Lidar to sites where different runs of modeling have produced divergent results can help select which input parameter set is most useful for characterizing wind flow, by taking measurements that allow differentiation between models. The cost of data acquisition for offshore wind resource assessment can be reduced by adopting Lidar methods. Less stringent specifications are imposed for platform installation, and approaches that dispense with the need for a platform are being developed. Operational turbine performance monitoring can be helpfully augmented by using Lidar to obtain data describing the wind flow impinging upon a turbine or in its wake. Lidar is also useful in obtaining details of wind shear, turbulence, vertical inflow and wind veer at proposed and operational turbine locations. Some of the uses Lidar has been applied to, some of its limitations, and the developing role Lidar will grow into in the future of wind resource assessment, are reviewed here.

Active remote sensing using lidar appears to be very attractive for the measurement of atmospheric greenhouse gases like carbon dioxide from spaceborne platforms. Feasibility studies are currently being performed to demonstrate the required measurement performance. Due to the high precision required (less than 0.3 %) for climate studies, space-borne IPDA (Integrating Path Differential Absorption) Lidar is preferred over the range resolving DIAL technique which uses atmospheric backscatter. This is due to the larger Lidar echoes from hard target when using systems of comparable size. Applying the IPDA Lidar method, magnitude and variability of the ground reflectance becomes an important issue in terms of instrument sizing and pointing requirements of space-borne systems. Because of the stringent sensitivity requirements, even small gradients of the ground reflectance could introduce noticeable retrieval errors in the CO2 column content, when the laser transmitter does not point on the same ground spot for the on- and off-line measurement. However, the current knowledge on the variability of the ground reflectance both in the appropriate wavelength range and on small spatial scales is insufficient for an accurate error assessment. In order to address these deficiencies, airborne lidar measurements at 1.6 µm wavelength were performed. The wavelength range around 1.6 µm provides suitable absorption lines for the measurement of carbon dioxide. A pulsed optical parametric oscillator (OPO) system (5 mJ at 1573 nm, 10 Hz pulse rate) was deployed on the DLR Cessna Caravan aircraft to measure the variations of the ground return. In order to simulate a satellite system, statistical analyses on the data including upscaling to a larger ground spot size of a space-borne system and different averaging ranges are being performed. The focus of this study is on the investigation of the characteristics of typical surface types including the open sea.

The Planetary Science Division (PSD) within NASA Headquarters' Science Mission Directorate (SMD) has several Research & Analysis (R&A) programs that support the definition and development of instrumentation for science investigations of all bodies in the solar system. These programs are part of the Research Opportunities in Space and Earth Sciences (ROSES) - 2008 and can be found at http://nspires.nasaprs.com com. Science instrumentation of interest to the Planetary Science Division includes remote sensors as well as in situ sensors and laser-based instruments are well suited for both scenarios. The programs that support hardware development include the Planetary Instrument Definition & Development Program (PIDDP), the Astrobiology Science & Technology Instrument Development (ASTID) program, the Astrobiology Science & Technology for exploring Planets (ASTEP) program, and the Mars Technology Project/Mars Instrument Development Program (MIDP). PIDDP has been expanding over the last two years to cover advanced instrument development with Technology Readiness Levels up to TRL 6. Beyond these R&A elements, a new Announcement of Opportunity (AO) for Stand Alone Missions of Opportunity Notice (SALMON) will provide resources to further develop science instrumentation for flights of opportunity aboard non-NASA missions.

The CALIPSO Level II data are analyzed to assess the veracity of the CALIPSO aerosol type identification algorithm and generate distributions of aerosol types and their respective optical characteristics. The distributions show that the classification algorithm has no surface type or diurnal dependencies. For this initial assessment of algorithm performance, we analyze global distributions of the CALIPSO aerosol types, along with distributions of integrated attenuated backscatter, backscatter color ratio, and volume depolarization ratio for each type. The aerosol type distributions are further partitioned according to various geophysical discriminators (e.g., geographic region, land vs. ocean, and day vs. night). The algorithm generates the expected results in most scenes. The total color ratio distributions show significant overlap between the aerosol types. Since the aerosol typing algorithm uses a logical decision tree based on fixed thresholds, we test the sensitivity of the typing algorithm to perturbations in these threshold values. To test the CALIPSO extinction to backscatter ratio estimates, we compare extinction-to-backscatter ratios derived using the transmittance method to the values in the look up tables.

The height of cloud and aerosol layers in the atmosphere is believed to affect climate change and air pollution because both of them have important direct effects on the radiation balance of the earth. In this paper, we study the ability of Cloud Aerosol LIDAR and Infrared Pathfinder Satellite Observation (CALIPSO) data to detect, locate and distinguish between cloud and aerosol layers in the atmosphere over Peninsula Malaysia. We also used image processing technique to differentiate between cloud and aerosol layers from the CALIPSO images. The cloud and aerosol layers mostly are seen at troposphere (>10 km) and lower stratosphere (>15km). The results shows that CALIPSO can be used to determine cloud and aerosol layers and image processing technique has successfully distinguished them in the atmosphere.

CALIPSO is a satellite mission designed to measure the vertical structure and optical properties of aerosol and clouds over the globe. The Science Team for the mission has organized an international program, named quid pro quo (QPQ), to obtain correlative measurements to support validation of its retrieved products. EARLINET, a network of 25 European lidar stations, joined the QPQ program and have been performing correlative measurements at all stations within 80 km from the overpasses ("mandatory" measurements) and additionally at the lidar station which is closest to the actually overpassed site ("suggested" measurements). In this work, we present the results obtained during the primary validation phase for the #21 EARLINET station (CIEMAT-Madrid) correlative measurements. Two different data products have been compared: The "Total Backscatter_Coefficient_532" from level 2 files (released on Jan/2008) and the version 2 (released on Dec/2007) Level 1 data product called "Total_Attenuated_Backscatter_532", that must be compared with a simulated lidar profile calculated from the 532-nm extinction and backscattering coefficients profiles independently measured by the unpolarized elastic channel and Raman channel of the ground system. Several cases with a reasonable agreement in terms of backscattering coefficient magnitude have been found (7 cases, 26% of the total cases analyzed: 27 cases), while cases with bad agreement amounts to 38%. The rest correspond to cases with clouds (18%) and bad assignment of aerosol layer as clouds (18%).

LIDAR backscatter signal analysis can establish surface elevation at the LIDAR footprint, in kilometers above local mean sea level. Since aberrations in the signal caused by a non-ideal transient response in the 532 nm detectors, the geometric thickness associated with the LIDAR surface elevation can be utmost misleading. In this place, the provisional LIDAR surface elevation should treated all signal beneath the reported LIDAR surface elevation top as being pure instrument artifact introduced by the non-ideal transient response of the detectors. Apparently, no geophysical significance should be ascribed to the subsurface portion of the LIDAR return. This study will present the comparison between the LIDAR Surface Elevation and Digital Elevation Map (DEM) using CALIPSO LIDAR data over Peninsular Malaysia.

An algorithm using N-way analysis for the detection of multiple clouds in multi-wavelength lidar data is presented. Nway analysis is a tool for algebraic manipulation of N-dimensional (ND) data arrays, and it allows for spatial (range), temporal (time), and spectral (wavelength) information to be extracted simultaneously from 3D lidar data. The algorithm tracks the spectral signal strength and location of each of the multiple clouds through time within the lidar measurements via a method that is shown to be similar to multivariate anomaly detection. The method is data driven and can be applied to arrays of any number of dimensions (e.g., polarization as the 4th dimension). Results of the algorithm for CO2 lidar simulations of aerosol clouds are shown and discussed.

Lidar investigation of temporal and vertical optical atmospheric properties will play a key role in the future for a continuous monitoring over the whole planet through world ground based networks. The EZ Lidar^TM, manufactured by LEOSPHERE, has been validated in several campaigns as that one in Southern Great Plains (ARM) or at Goddard Space Flight Center (NASA). An EZ LIDAR^TM with cross-polarization capabilities was deployed in Kanpur, India in the frame of TIGER-Z campaign organized by NASA/AERONET in order to measure aerosol microphysical and optical properties in the Gange basin. In addition, 12 sun-photometers were deployed during this campaign and CALIPSO (The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) data were also acquired. In this work we present the results in retrieving aerosol extinction and backscattering from EZ Lidar^TM measurements, and the validation of the space borne instrument CALIPSO under the satellite track. EZ Lidar^TM is also coupled with the photometers to provide the measurements of the Aerosol Optical Depth over the selected region.

In this paper, a scheme of a subpicosecond dispersion range-finder is proposed and an estimate of the precision of rangefinding for large distances in open atmosphere using this device is performed. Using subpicosecond pulses allows us not only to improve range-finding precision, but also to eliminate the effect of air refractive index indeterminacy on the path of propagation quite effectively.

A number of vector and volume averaging considerations arise in relation to remote sensing, and in particular, Lidar. 1) Remote sensing devices obtain vector averages. These values are often compared to the scalar averages associated with cup anemometry. The magnitude of a vector average is less than or equal to the scalar average obtained over the same period. The use of Lidars in wind power applications has entailed the estimation of scalar averages by vector averages and vice versa. The relationship between the two kinds of average must therefore be understood. It is found that the ratio of the averages depends upon wind direction variability according to a Bessel function of the standard deviation of the wind direction during the averaging interval. 2) The finite probe length of remote sensing devices also incurs a volume averaging bias when wind shear is non-linear. The sensitivity of the devices to signals from a range of heights produces volume averages which will be representative of wind speeds at heights within that range. One can distinguish between the effective or apparent height the measured wind speeds represent as a result of volume averaging bias, and the configuration height at which the device has been set to measure wind speeds. If the wind shear is described by a logarithmic wind profile the apparent height is found to depend mainly on simple geometrical arguments concerning configuration height and probe length and is largely independent of the degree of wind shear. 3) The restriction of the locus of points at which radial velocity measurements are made to the circumference of a horizontally oriented disc at a particular height is seen to introduce ambiguity into results when dealing with wind vector fields which are not irrotational.

During the Dry Season (July-September) of 2007 aerosol profiling campaign was carried with an aerosol backscattering LIDAR system in Sao Paulo, Brazil. The main goal of this campaign was to observe the aerosol load in the lower troposphere (up to 10 km) and its daily behavior in order to check for air dispersion conditions, planetary boundary and mixed layer daily evolution, mid and long range transport. For the latter we used air mass trajectory analysis and satellite data. With the LIDAR analysis we can provide the aerosol optical properties in the visible range (532 nm) and quantities such as aerosol backscattering and extinction coefficients. Altogether we could measure during 60 days, since when there was the presence of precipitation no measurement was conducted. Collocated with the LIDAR was a AERONET Sunphotometer which help in characterizing the aerosol optical properties. Our data was correlated with the Environmental Air using Optical Sensors in the Remote Air Quality Assessment and cross-correlations were made with Aerosol Optical Thickness, Planetary Boundary Layer evolution and Air Quality Index.

In this paper, the properties of Low-level clouds are explored with a Raman-elastic lidar. In particular, we examine two complementary methods to measure thin cloud optical depth (COD). The first is direct integration of Raman Derived extinction while the second method utilizes a regression technique. We show that if we correct for aerosol influences the regression method for low cloud optical depth can be dramatically improved. Furthermore, estimates of extinction to backscatter ratio can be made within the cloud. We find that when the lidar ratio in cloud is averaged over the vertical extent, an S ratio on the order of 20 sr is found which is consistent with conventional water phase cloud droplet models.

Following article presents LIDAR for stand off detection of aerosols which was constructed in Institute of Optoelectronics in Military University of Technology. LIDAR is a DISC type system (DIfferential SCattering) and is based on analysis of backscattering signal for two wavelengths (λ₁ = 1064 nm and λ₂ = 532 nm) - the first and the second harmonic of Nd:YAG laser. Optical receiving system is consisted of aspherical mirror lens, two additional mirrors and a system of interference filters. In detection system of LIDAR a silicon avalanche photodiode and two different amplifiers were used. Whole system is mounted on a specialized platform designed for possibility of LIDAR scanning movements. LIDAR is computer controlled. The compiled software enables regulation of the scanning platform work, gain control, and control of data processing and acquisition system. In the article main functional elements of LIDAR are shown and typical parameters of system work and construction are presented. One presented also first results of research with use of LIDAR. The aim of research was to detect and characterize scattering aerosol, both natural and anthropogenic one. For analyses of natural aerosols, cumulus cloud was used. For analyses of anthropogenic aerosols one used three various pyrotechnic mixtures (DM11, M2, M16) which generate smoke of different parameters. All scattering centers were firstly well described and theoretical analyses were conducted. Results of LIDAR research were compared with theoretical analyses and general conclusions concerning correctness of LIDAR work and its application were drawn.

Petrochemical and oil refining facilities play an increasingly important role in the industrial context. The corresponding need for monitoring emissions from these facilities as well as in their neighborhood has raised in importance, leading to the present tendency of creating real time data acquisition and analysis systems. The use of LIDAR-based techniques, both for air quality and emissions monitoring purposes is currently being developed for the area of Cubatao, Sao Paulo, one of the largest petrochemical and industrial sites in Brazil. In a partnership with the University of São Paulo (USP) the Brazilian oil company PETROBRAS has implemented an Environmental Research Center - CEPEMA - located in the industrial site, in which the development of fieldwork will be carried out. The current joint R&D project focuses on the development of a real time acquisition system, together with automated multicomponent chemical analysis. Additionally, fugitive emissions from oil processing and storage sites will be measured, together with the main greenhouse gases (CO₂, CH₄), and aerosols. Our first effort is to assess the potential chemical species coming out of an oil refinery site and to verify which LIDAR technique, DIAL, Raman, fluorescence would be most efficient in detecting and quantifying the specific atmospheric emissions.