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.

Sandia National Laboratories has developed high-energy all-solid-state UV sources for use in laboratory tests of the feasibility of satellite-based ozone DIAL. These sources generate 320 nm light by sum-frequency mixing the 532 nm second harmonic of an Nd:YAG laser with the 803 nm signal light derived from a self-injection-seeded image-rotating optical parametric oscillator (OPO). The OPO cavity utilizes the RISTRA geometry, denoting rotated-image singly-resonant twisted rectangle. Two configurations were developed, one using extra-cavity sum-frequency mixing, where the sum-frequency-generation (SFG) crystal is outside the OPO cavity, and the other intra-cavity mixing, where the SFG crystal is placed inside the OPO cavity. Our goal was to obtain 200 mJ, 10 ns duration, 320 nm pulses at 10 Hz with near-IR to UV (1064 nm to 320 nm) optical conversion efficiency of 25%. To date we've obtained 190 mJ at 320 nm using extra-cavity SFG with 21% efficiency, and >140 mJ by intra-cavity SFG with efficiency approaching 24%. While these results are encouraging, we've determined our conversion efficiency can be enhanced by replacing self-seeding at the signal wavelength of 803 nm with pulsed idler seeding at 1576 nm. By switching to idler seeding and increasing the OPO cavity dimensions to accommodate flat-top beams with diameters up to 10 mm, we expect to generate UV energies approaching 300 mJ with optical conversion efficiency approaching 25%. While our technology was originally designed to obtain high pulse energies, it can also be used to generate low-energy UV pulses with high efficiency. Numerical simulations using an idler-seeded intra-cavity SFG RISTRA OPO scaled to half its nominal dimensions yielded 560 μJ of 320 nm light from 2 mJ of 532 nm pump using an idler-seed energy of 100 μJ.

We demonstrate a single transverse mode Yb-doped fiber laser that can be operated in a wide range of pulse lengths and repetition rates. The pulsed 1064nm beam of a single mode diode laser is amplified by a three stage fiber amplifier. It consists of two stages that incorporate single-mode fibers and a third stage using LMA fiber. A monolithic setup is achieved by an adiabatic taper between the second and the third stage exciting only the fundamental mode in the LMA fiber. Variable pulse regimes were investigated in the range from 10kHz to 1MHz and CW. A maximum output energy of 0.5mJ and maximum peak power of 66kW were measured. Pulse trains consisting of four pulses with pulse spacing of 200, 500 and 1000ns and a pulse length of 10ns were also evaluated. The repetition rate of the train was set to 1kHz.

Profiling of atmospheric carbon dioxide (CO₂) is important for understanding the natural carbon cycle on Earth and its influence on global warming and climate change. Differential absorption lidar is a powerful remote sensing technique used for profiling and monitoring atmospheric constituents. Recently there has been an interest to apply this technique, at the 2 μm wavelength, for investigating atmospheric CO₂. This drives the need for high quality detectors at this wavelength. Although 2 μm detectors are commercially available, the quest for a better detector is still on. The detector performance, regarding quantum efficiency, gain and associated noise, affects the DIAL signal-to-noise ratio and background signal, thereby influencing the instrument sensitivity and dynamic range. Detectors based on the III-V based compound materials shows a strong potential for such application. In this paper the detector requirements for a long range CO₂ DIAL profiles will be discussed. These requirements were compared to newly developed III-V compound infrared detectors. The performance of ternary InGaSb pn junction devices will be presented using different substrates, as well as quaternary InGaAsSb npn structure. The performance study was based on experimental characterization of the devices dark current, spectral response, gain and noise. The final results are compared to the current state-of-the-art InGaAs technology. Npn phototransistor structure showed the best performance, regarding the internal gain and therefore the device signal-to-noise ratio. 2-μm detectivity as high as 3.9x10¹¹ cmHz^1/2/W was obtained at a temperature of -20°C and 4 V bias voltage. This corresponds to a responsivity of 2650 A/W with about 60% quantum efficiency.

We demonstrate the feasibility of applying the emerging technology of internal discrete amplification to create an efficient, ultra low noise, universal analog and counting photodetector for LIDAR remote sensing. Photodetectors with internal discrete amplification can operate in the linear detection mode with a gain-bandwidth product of up to 10¹⁵ and in the photon counting mode with count rates of up to 10⁹ counts/sec. Detectors based on this mechanism could have performance parameters superior to those of conventional avalanche photodiodes and photomultiplier tubes. For silicon photodetector prototypes, measured excess noise factor is as low as 1.02 at gains greater than 100,000. This gives the photodetectors and, consequently, the LIDAR systems new capabilities that could lead to important advances in LIDAR remote sensing.

NASA's requirements for high reliability, high performance satellite laser instruments have driven the investigation of many critical components; specifically, 808 nm laser diode array (LDA) pump devices. Performance and comprehensive characterization data of Quasi-CW, High-power, laser diode arrays is presented.

Advances in high power semiconductor lasers such as increased spectral brightness, increased spatial brightness, and reduced cost architectures at wavelengths from the near infrared to the eye-safe regime have the potential to dramatically improve diode pumped systems and enable new direct diode applications. Data are presented which demonstrate both edge emitter devices and high power surface emitting 2-dimensional arrays with internal gratings to narrow and stabilize the spectrum. Diodes with multimode high spatial brightness and high power single mode performance in the 808 and 976nm regime are described, and advances in high power arrays at eye-safe wavelengths are presented.

Laser diode packaging affects reliability, power level and weight (mass). Traditional thermal management materials - copper, copper/tungsten, copper/molybdenum, etc. - all have serious deficiencies. In the last few years there have been revolutionary thermal management material advances. There are now over 15 low-CTE, low-density materials having thermal conductivities that range from that of copper (400 W/m-K) to four times that of copper (1600 W/m-K). They are being used in an increasing number of commercial and aerospace applications. Some are low cost. Others have low cost potential in high volumes. Several are space qualified. This paper discusses the large and increasing number of advanced thermal management materials, including properties, applications, space qualification, cost, lessons learned, how to use composites to fix manufacturing problems, and future directions, including nanocomposites.

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.

Raman lidar has provided a remarkable tool for characterizing the various properties of the lower atmosphere. The research of the Penn State University Lidar Laboratory is focused on development of Raman lidar techniques and research using five Raman lidar instruments prepared since the mid-1970's. The LAPS instrument was demonstrated in 1996 as the first prototype for an operational shipboard lidar sensor. It is the most advanced lidar instrument developed to date for profiling properties of the lower atmosphere. The LAPS sensor measures profiles with eight data channels to determine several atmospheric properties simultaneously. The single most important property for understanding the meteorological state in the lower atmosphere is the water vapor profile. The specific humidity and temperature profiles are measured directly using the vibrational and rotational Raman scattered signals. The electromagnetic parameter of most interest is the gradient in the refractive index profile, because of the influence it has on RF-propagation of radar and radio communications signals. The electro-optical parameter of most interest is the optical extinction profile at various wavelengths, because optical propagation affects aircraft operations, visual aesthetics, and optical sensor performance. Profiles of water vapor, temperature and multiwavelength optical extinction are measured simultaneously to describe the meteorological, electromagnetic, electro-optical and air quality environmental conditions. Measurements are key in forecasting atmospheric conditions and are of major importance because of their influence on the performance of various systems. Current techniques and capabilities are described in this paper, and examples are used to indicate how well the Raman lidar performs in characterizing the atmosphere.

Measurements obtained by the PSU Lidar Atmospheric Profile Sensor (LAPS) Raman lidar, during different periods, provide a comprehensive dataset to characterize cloud properties and aerosol distributions. The PSU Raman lidar measures the profiles of molecular nitrogen, molecular oxygen and the rotational Raman scatter (the mixture of all molecular species) at both visible and ultraviolet wavelengths, which are then used to generate vertical aerosol extinction profiles from the incremental extinction. Since the optical extinction at different wavelengths is strongly dependent on the size distribution of aerosols, variations in the profile of the size distribution can be inferred over an interesting range corresponding to accumulation mode particles, 50 nm to 1μm. The variation in the extinction profiles at different wavelengths is also used along with the water vapor profiles to observe the formation, growth and dissipation of cloud structures. The water vapor concentrations have been seen to decrease in regions surrounding a growing cloud as the particles increase in size by absorbing the water. Also, the water vapor concentration is found to increase as clouds begin to dissipate. The change in the size of the cloud particles during the different stages can also be observed in the multi-wavelength aerosol extinction. Results obtained from different locations, and for a wide range of atmospheric conditions, are used to compare and contrast the aerosol distributions and also to study the physical properties of clouds.

Numerous coherent lidar systems have shown the ability to make measurements of atmospheric winds over the past three decades. During the past decade a 2-micron-wavelength coherent lidar system for remote wind and aerosol backscatter measurements has been advanced from initial breadboard demonstration units to a turnkey coherent lidar product, the WindTracer^"R" that can operate autonomously and reliably. In this paper, the instrument is described and recent examples of wind measurement capability are provided.

Observing System Simulation Experiments (OSSEs) are an important tool for evaluating the potential impact of proposed new observing systems, as well as for evaluating trade-offs in observing system design, and in developing and assessing improved methodology for assimilating new observations. OSSEs conducted at NASA GSFC and elsewhere have indicated significant potential for space-based lidar winds to improve numerical weather prediction. In this paper we summarize OSSE methodology and earlier OSSE results, and present methodology and new results from a Quick OSSE designed to assess the potential impact of lidar winds on the predicted track of a specific hurricane.

For space-based lidar applications, conductively cooled lasers have been identified as a critical technology for high energy, 2-micron laser transmitter. Effective thermal management is a challenge for high-energy, 2-micon lasers. In this paper, the design of a totally conductively cooled, diode pumped, 2-micron laser amplifier is presented. Based on the successful testing of a conductively cooled oscillator, concepts for a laser amplifier were developed. The newly designed amplifier consists of a 40 mm long Ho:Tm: LuLF rod being pumped by 4 banks of 5-radially arranged diode lasers totaling 80W pump power. Optical and thermal studies for the amplifier head are presented and discussed. Currently, the design of the amplifier head is being integrated into a complete amplifier subsystem for a conductive cooled Master Oscillator Power Amplifier (MOPA) laser.

Effective monitoring of the atmosphere for potentially hazardous aerosol plumes in urban areas requires a lidar that produces high signal-to-noise backscatter returns, fine spatial resolution, rapid updates, eye-safety at all ranges, and long-range operation. A scanning elastic backscatter lidar with high pulse energy that meets these requirements was recently developed at NCAR. The latest upgrades to the lidar system include the use of a new Raman cell for wavelength conversion and a two-channel receiver for backscatter depolarization ratio measurements. Highlights from recent field tests of the system are presented and plans to improve the prototype, as well as construct an unattended and continuously operating version, are discussed.

Recent experimental work has shown that passive systems such as hyperspectral FTIR and frequency-tunable IR cameras have application in detection of biological aerosols. This provided the motivation for a new detection technique, which we call Aerosol Ranging Spectroscopy (ARS), whereby a scattering LIDAR is used to augment passive spectrometer data to determine the location and optical depth of the aerosol plume. When the two systems are co-aligned or boresighted, the hybrid data product provides valuable enhancements for signal exploitation of the passive spectral data. This paper presents the motivation and theoretical basis for the ARS technique. A prototype implementation of an ARS system will also be described, along with preliminary results from recent outdoor field experiments.

Topographic backscatter lidar that uses solid surfaces to provide the return signals is a well known vapor estimation technique either though the two-wavelength DIAL (differential absorption lidar) paradigm or a multiple wavelength generalization. All algorithms known to the authors for estimating the path-integrated concentration, or CL, require prior knowledge of the wavelength dependence of the absorptivity of the vapor materials of interest for generating the CL estimates. However, for many applications it is not feasible to process the data in the traditional way. In addition, for some materials the absorptivity may be only approximately known. For these reasons it is often desirable to estimate the spectral structure of the absorptivity using the same data set used to estimate the vapor CL. This paper describes a method for simultaneously estimating the spectral dependence of the absorptivity of a set of Q materials in parallel with the timedependence of the corresponding CLs using a time series of topographic backscatter lidar data collected at M wavelengths. For processing efficiency we provide dynamic estimates of the CLs through a Kalman filter. The fluctuating transmitted energy is also included in the state vector. This inclusion automatically accomplishes transmitter energy normalization optimally. Absorptivity is estimated through a sequential least-squares method. The basic idea is to run two estimators in parallel: a Kalman filter for CL and transmitter energy, and a sequential least-squares estimator for absorptivity. These algorithms exchange information continuously over the data processing stream. The approach is illustrated on simulated and real topographic backscatter lidar data collected by ECBC.

Chemical and biological (Chem-Bio) sensors for detection and tracking of hazardous and toxic agents are primarily being developed for homeland security and defense applications at various government laboratories and research institutions. However, several groups at NASA and various universities are working on similar sensors for space-based applications. The quest for answers to questions on the origins of life on the Martian enironment is continuing at NASA. Recent studies on a Martian meteorite have kindled interest in the possibilities of past life on Mars. The existance of polycyclic aromatic hydrocarbons in fresh fracture surfaces have promoted further studies to examine the evidence for possibilities of the existenc of life on Martian surface soil in the past. Lignins and kerogens containing aromatic and polyaromatic components which are considered precursors of life on Mars. Likwise, tholins are considered possible precurors for life on some outerbodies in our Solar system. Laser induced Fluorescence (LIF) and Raman based techniques with emphasis in the deep ultraviolet (UV) (200-300 nm) spectral region are anticipated to play a significant role in characterizing these precursors. In this paper, previous stuides done on these precursors in the UV are examined for the development of a wavelength agile LIF system for in situ and remote sensing experiments in the deep-UV spectral region.

Q-switching techniques that modify the quality factor of a laser resonator are normally used to generate short pulses in a solid-state laser. The saturable absorber based technique, also known as passive Q-switching, is operationally attractive and simple when compared with mechanical or active optical techniques. Cr4+:YAG is a common saturable absorber material for many laser materials including Nd:YAG for operation around 1 μm wavelength. Recently, self-passive Qswitching using a Nd:YAG gain medium that is externally implanted with chromium ions through annealing process has been demonstrated. Pulsewidths up to 2μsecs and PRFs up to 100kHz have been demonstrated. In this paper, the improved annealing technique utilized to obtain chromium doped Nd:YAG crystals is discussed. Tailored dopant chromium ion profile inside a host laser material is shown to provide controlled temporal lasing characteristics. The current technique is applicable to several other laser gain media. The present technique simplifies laser cavity configuration, eliminates alignment issues that could exist between the gain medium and passive Q-switch crystal, and aids in the rugged packaging of a laser module.

The University of Illinois Fe (iron) Boltzmann temperature lidar was operated at the South Pole (90°S) from November 1999 to October 2001, and then at the Rothera Station (67.5°S, 68.0°W) from December 2002 to March 2005. This lidar transmits two UV wavelengths at 372 and 374 nm, and is able to measure the middle and upper atmosphere temperature, Fe density, polar mesospheric clouds (PMC), and polar stratospheric clouds (PSCs). In this paper, we analyze the PSC data collected in the winters and springs of 2003 and 2004 at Rothera, and compare them with the PSC data collected at the South Pole in the 2000 and 2001. PSCs were observed in the range of 15-28 km during the seasons from May/June to October at both locations. The PSC backscatter ratio, width, and altitude at Rothera are comparable to those at the South Pole. However, Rothera PSCs occur less frequently (~17.7%) and in shorter periods, compared to PSCs at the South Pole (~64.9%). At Rothera, PSC occurrence frequency in 2004 is only half of that in 2003, which is likely due to warmer stratospheric temperatures in 2004 associated with changes of the polar vortex. These are the first ground-based lidar observations of PSC at Rothera, and also the first in West Antarctica.

We report a Compact Eye-Safe Backscatter Lidar (CESBL) system conceived for tropospheric aerosol research in the Arctic environment. The instrument will play an active role in the investigation of Arctic Haze and Ice Fog during winter time; intercontinental transport of Asian dust during springtime; and Aerosol plumes released from forest fires during summer time. In addition the system will perform systematic observations of Arctic Boundary Layer dynamics and Cirrus clouds. The lidar works at 1.574 μm and delivers 200 mJ maximum per pulse at 10 Hz prf. The output beam is conveniently expanded to yield an Eye-Safe factor greater than 250 suitable to operate in Urban Environments. The receiver is aimed with a Cassegrain telescope F/10, 20 cm primary diameter. The collimation and focusing were designed using commercial optics to holds approximately 1mrad field of view over a detector surface of 0.2 mm diameter. Signal detection is made by an InGaAs-APD followed by amplifiers. The Lidar system is mounted on an optical breadboard on a steerable platform and integrated into a PXI National Instrument data acquisition computer providing two acquisition channels at 200 MS/s maximum; 200 MHz of maximum bandwidth; and 12 bits vertical resolution. The acquisition code runs in a Lab-View platform with visualization interface and acquisition options optimized for field work. In this article the lidar system characteristics and the concept design are discussed. Initial geophysical results are shown.

We performed a calibration experiment on a Spectralon Target using a wavelength of 0.532 μm and a 60 cm lidar system coupled to a photon counter via a Triax 190 monochrometer. The complete system optics, including the telescope and monchromator, were modeled using a commercial ray-tracing program. Energy efficiency was calculated by generating large numbers of equal-area rays on the telescope input pupil from points in the plane of the target. The number of these rays received by the PMT cathode was then used to estimate the optical efficiency. Comparison of the calculated and observed signals gave agreement to within 30%. We discuss the possible sources of disagreement between the calculated and observed signals.

Water vapor is one of the most significant constituents of the atmosphere because of its role in cloud formation, precipitation, and interactions with electromagnetic radiation, especially its absorption of longwave infrared radiation. Some details of the role of water vapor and related feedback mechanisms in the Earth system need to be characterized better if local weather, global climate, and the water cycle are to be understood. A Differential Absorption LIDAR (DIAL) with a compact laser diode source may be able to provide boundary-layer water vapor profiles with improved vertical resolution relative to passive remote sensors. While the tradeoff with small DIAL systems is lower vertical resolution relative to large LIDARs, the advantage is that DIAL systems can be built much smaller and more robust at less cost, and consequently are the more ideal choice for creating a multi-point array or satellite-borne system. This paper highlights the progress made at Montana State University towards a water vapor DIAL using a widely tunable amplified external cavity diode laser (ECDL) transmitter. The ECDL is configured in a Littman-Metcalf configuration and was built at Montana State University. It has a continuous wave (cw) output power of 20 mW, a center wavelength of 832 nm, a coarse tuning range of 17 nm, and a continuous tuning range greater than 20 GHz. The ECDL is used to injection seed a tapered amplifier with a cw output power of 500 mW. The spectral characteristics of the ECDL are transferred to the output of the tapered amplifier. The rest of the LIDAR uses commercially available telescopes, filter optics, and detectors. Initial cw and pulsed absorption measurements are presented.

Laser induced fluorescence has been used for decades to classify and identify a variety of materials. The traditional fluorescence detection method involves the use of narrow band filters or a spectrometer combined with a telescope. We propose using a multi-aperture telescope operated in Fizeau imaging mode for the projection of a pump wavelength and the collection of the fluorescence photons. The phased array is operated such that the array is optically phased for the pump wavelength and de-phased at the fluorescent wavelength thereby spatially distributing the two wavelengths in the image plane. This allows single shot identification of fluorescent modes.

An innovative, ground-based bistatic lidar receiver to measure aerosol scattering in the atmospheric boundary layer has been developed and tested for proof-of-concept. The raster-mirror designs have greater than two orders of magnitude light gathering capability, and higher altitude resolution than the design used in Barnes et. al., thus allowing the use of lower power eye safe lasers. The design is based on dividing the wide 100° vertical field of view into several sectors, using 1-D rastering of mirrors and parallel imaging of the laser light scattered from each sector onto one CCD while employing a single narrow angle-of-view objective. The system is applicable for simultaneous measurements of several laser beams to obtain spectral, spatial, and temporal information about the atmosphere. Using an off-axis parabolic mirror objective eliminates chromatic aberrations, making the system employable in a broad spectral range from IR to UV. The advantages of the proposed technology are: the ability to control the dynamic range of the registered signal, the superior height resolution of 14 mm/pixel at the ground level, and 175m/pixel at 20km altitude, low cost, and simplicity. The bistatic CLidar receiver will include automatic system feedback and self-calibration. The system will be developed to accommodate daytime operational conditions.

The aim of this project is the measurement of urban pollution in the Magurele platform (near Bucharest city where the pollutant sources are known) using LIDAR system operating at 532 and 1064 nm wavelengths. The application is based on the remote detection of aerosols in the atmosphere using a Smoke Analyzer by sending a short light pulse and receiving the radiation scattered in backward direction that provides backscattering signal as a function of distance. The observable backscattered signal is generated by air density fluctuations (Rayleigh scattering) and by small aerosol particles always present in the atmosphere. The presence of aerosol particles gives rise to an increase of the backscattered signal and thus the aerosol flow can be detected on the background surrounding clean atmosphere. In these applications, it is important the response time to be as shorter as possible, and the sensitivity to be very high, in correlation with an eventual alert when the pollutants exceeds a risk threshold. Therefore processing the lidar data constitutes an important factor in obtaining air quality information. This papers presents first results obtained in Romania by direct lidar measurements in the area of Bucharest and the original software developed by the Environmental group in INOE for lidar data processing and PBL height identification.

High wall-plug efficiency and a wide range of available wavelengths make laser diode arrays preferable for many high-power applications, including optical pumping of solid state lasers. Recently, we designed and fabricated InGaAsP/InP arrays operating at 1.5-μm and In(Al)GaAsSb/GaSb arrays operating at 2.3-μm. We have demonstrated a high continuous-wave (CW) output power of 25 W from a one dimensional laser array and a quasi-CW (q-CW) output power of 110 W from a two dimensional laser array both operating near 1.5-μm. We have obtained a CW output power of 10 W from the 2.3-μm laser array. The 1.5-μm arrays are suitable for resonant pumping of erbium doped solid-state lasers, which require high power optical sources emitting in the narrow erbium absorption bands. Long current-injection pulses produce a considerable temperature increase within the diode laser structure which induces a red-shift of the output wavelength. This thermal drift of the laser array emission spectrum can lead to misalignment with the erbium absorption bands, which decreases pumping efficiency. We have developed an experimental technique to measure the time dependence of the laser emission spectrum during a single current pulse. From the red-shift of the laser emission, we determine the temperature of the laser active region as a function of time. The spacing between the individual laser emitters has an effect on the array heating. In steady state operation, this spacing is a contributing factor in the non-uniformity of the thermal field within the bar, and thus to the overall thermal resistance of the laser bar. Under pulse operation, the transient heating process can be divided into three time periods; each with its own heat transport condition. It was shown that in the initial period of time the heat propagates within the laser bar structure and the laser bar design (fill factor) strongly affects the active region temperature rise. In the later periods the temperature kinetics is insensitive to the fill factor. This analysis has been verified in experimental studies using the 1.5-μm laser arrays.

The work described here reports on the improvement of a Raman lidar algorithm for measuring aerosol extinction. In order to calculate aerosol extinction from Raman lidar data it is necessary to perform the derivative of a molecular Raman signal with respect to altitude. The typical approach taken in the lidar community is to make an a priori assumption about the functional behavior of the data in order to calculate the derivative. Here a technique is shown that uses the chi-squared test to determine the most likely functional behavior of the data prior to actually calculating the derivative. A mathematical simulation is described that shows the capabilities of this technique and the possibility of reducing the extinction uncertainties with respect to traditional techniques.

As part of environmental studies of the southern atmosphere, the CEILAP Lidar Division in collaboration with the Service d'Aeronomie has developed a mobile differential absorption lidar capable of making precise and accurate measurements of the stratospheric ozone. The XeCl excimer laser emission at 308 nm is used as absorbed line in the DIAL technique and an Nd-YAG laser 355 nm third harmonic is employed as a reference wavelength. Six detected channels are used for stratospheric ozone retrieval, four of them in the high and low energy of the elastically backscattered signal of the emitted wavelengths and two corresponding to the first Stokes nitrogen Raman of the emitted wavelengths. Tropospheric Water Vapor profiles using Raman channels and Aerosol Backscatter profiles are also obtained. In this paper we present a detailed description of the instrument, a discussion of data analysis and the results of the first lidar-satellite inter-comparison of stratospheric ozone profiles measured with this instrument. We also present a description of the SOLAR campaign that will be held in the 2005 southern winter-spring period in Rio Gallegos (51° 55'S, 69° 14'W) with the objective of studying the ozone layer when the polar vortex crosses over the continental part of Argentina. This campaign will be supported by JICA (Japan International Cooperation Agency).

An intensive study of an aerosol intrusion episode in Buenos Aires is presented. We have combined back-trajectories calculations (HYSPLIT) and satellite images with the aim of revealing the origin of these air masses. The aerosol intensive properties were characterized using a collocated sun-photometer from the AERONET network. The corresponding pressure levels for each air mass were obtained by means of a LIDAR system, which was also used to calculate the aerosol extinction profiles for the available wavelengths.

High power solid state tunable lasers have played an important role in providing the technology necessary for active remote sensing and would be very useful for space exploration. Many recent studies on diode-pumped solid state lasers have focused on polycrystalline ceramic lasers. We present our initial results on the material, optical, and spectroscopic properties of a solid-state ceramic laser material using neodymium doped Yttria (Nd:Y2O3). Using a proprietary scalable production method, spherical non agglomerated and monodisperse ceramic powders of Nd:Y2O3 are made that can be used to fabricate polycrystalline ceramic material disks with sintered grain size in a suitable range. Initially, we produced translucent material with good emission properties. In further studies we have successfully prepared transparent Nd:Yttria ceramic material. Polycrystalline ceramic lasers have enormous potential commercial applications, which include remote sensing, chemical detection and space exploration research. Furthermore, the cost to produce ceramic laser materials is potentially much lower than that for single crystal materials because of the shorter time it takes to fabricate the material and also because of the possibility of mass production. The polycrystalline ceramic material that we have produced will be characterized for its suitability as a diode pumped solid state laser. Different laser designs will be discussed including end-pumping schemes and the thin-disk laser configuration.

Large footprint (15m-25m diameter) lidar records the full lidar energy return (lidar waveform), when laser energy penetrates into vegetation canopy. The full lidar waveforms are directly linked with the three-dimensional characterization of vegetation structure. Recently studies on vegetation structure parameter retrievals from large foot-print lidar found direct relationships between vegetation structure parameters such as tree height, stem diameter, above ground biomass and full lidar waveforms. But these studies are mainly limited to empirical studies and these relationships vary for different sites. To better understand the link between large foot print lidar waveforms and vegetation structure parameters, we applied a vegetation Geometric-Optical and Radiative Transfer (GORT) model to simulate vegetation lidar waveforms with 3-D vegetation structure parameters as inputs. We evaluated the performance of the GORT model in conifer forests using the data collected by Scanning Lidar Imager of Canopies by Echo Recovery (SLICER) and found that GORT simulates large-footprint vegetation lidar waveforms well. To better retrieve 3-D vegetation structure parameters, we investigate the sensitivity of waveforms to GORT input parameters. Our analysis shows that lidar waveforms is most sensitive to the tree density, then to the foliage density and the least to the tree size. A stochastic inversion method will be implemented for inversion.