Summary form only given. Methane is an important greenhouse gas because it is a source gas that affects the lifetime of many other trace gases, its oxidation by OH produces peroxy radicals that are important for O3 production, and its... more
Summary form only given. Methane is an important greenhouse gas because it is a source gas that affects the lifetime of many other trace gases, its oxidation by OH produces peroxy radicals that are important for O3 production, and its oxidation is important for the production, destruction, and recycling of HOx radicals. The authors demonstrate a differential absorption lidar (DIAL)
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Materials Science, Laser, LiDAR, Methane, Greenhouse Gas, and 5 moreWavelength, Radical, Troposphere, trace gases, and Lambda
The development of a ground-based, eye-safe lidar system for differential absorption lidar measurements of trace gases such as methane in the mid-IR wavelength region and for aerosol measurements at 1.5 micrometers is described. This... more
The development of a ground-based, eye-safe lidar system for differential absorption lidar measurements of trace gases such as methane in the mid-IR wavelength region and for aerosol measurements at 1.5 micrometers is described. This prototype lidar system will be used for urban ambient trace gases and aerosol detection. An optical parametric oscillator pumped by an injection-seeded frequency-doubled Nd:YAG laser is employed as radiation source. The expected minimum detectable range of the system is about 1000 meters for range-resolved measurements of methane and several kilometers for aerosol measurements. The system performance is being tested through measurements of sources of atmospheric methane and aerosols.
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Laser Interrogation of Surface Agents (LISA) is a UV-Raman technique that provides short-range standoff detection and identification of surface-deposited chemical agents. ITT Industries, AdvancedEngineering and Sciences Division, is... more
Laser Interrogation of Surface Agents (LISA) is a UV-Raman technique that provides short-range standoff detection and identification of surface-deposited chemical agents. ITT Industries, AdvancedEngineering and Sciences Division, is currently developing and expanding the LISA technology under ...
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Cleanliness and damage measurements of optics in atmospheric-sensing high-energy lasers. [Proceedings of SPIE 2714, 696 (1996)]. Gale A. Harvey, Thomas H. Chyba, Marc C. Cimolino. Abstract. Langley Research Center ...
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Fielded surface detection systems rely on contact with either the liquid contamination itself or the associated chemical vapor above the contaminated surface and do not provide a standoff or remote detection capability. Conversely,... more
Fielded surface detection systems rely on contact with either the liquid contamination itself or the associated chemical vapor above the contaminated surface and do not provide a standoff or remote detection capability. Conversely, standoff chemical vapor sensing techniques have not shown efficacy in detecting those contaminants as liquids or solids on surfaces. There are a number of optical or spectroscopic
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ABSTRACT
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Jumps of + or - pi have been observed in the phase difference between the two counterpropagating modes of a HeNe ring laser whenever the complex backscattering coefficients satisfy a specified condition. The experiments made use of two... more
Jumps of + or - pi have been observed in the phase difference between the two counterpropagating modes of a HeNe ring laser whenever the complex backscattering coefficients satisfy a specified condition. The experiments made use of two retroreflectors that allowed light to be reflected back into the ring laser cavity with controllable amplitudes and phases. The phase jumps are
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Research Interests:
Physics, Optics, Laser, Medicine, Mathematical Sciences, and 15 morePhysical sciences, Colored Noise, Phase transition, Oscillations, Physical, CHEMICAL SCIENCES, Phase Transformation, Second Order, First Order Logic, Optical Pumping, Dye Lasers, Single Mode, Bandwidth, Monte Carlo Method, and Spectral Response
Preliminary results on a compact, visible barium nitrate Raman laser have been obtained. A total conversion efficiency greater than 65% at PRF of 30 Hz may make this a suitable laser for ozone DIAL when doubled to the UV region.
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Measurements of Raman gain in a Ba(NO3)2 crystal are reported at 532 nm using a Raman oscillator/amplifier arrangement for differential absorption lidar measurements of ozone. The experimentally determined gain coefficient will be... more
Measurements of Raman gain in a Ba(NO3)2 crystal are reported at 532 nm using a Raman oscillator/amplifier arrangement for differential absorption lidar measurements of ozone. The experimentally determined gain coefficient will be compared with theoretical results. The ...
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Aerosol extinction and backscatter coefficients have been measured with an eye-safe 1.53 μm lidar system with slant-path technique. The results compare favorably to values reported previously in the literature.
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An optical parametric oscillator (OPO) ground-based lidar system in the wavelength region of 1.45 - 4 pm for the remote measurement of methane will be described. The laser transmitter consists of an injection-seeded ND:YAG laser which... more
An optical parametric oscillator (OPO) ground-based lidar system in the wavelength region of 1.45 - 4 pm for the remote measurement of methane will be described. The laser transmitter consists of an injection-seeded ND:YAG laser which pumps an OPO. The OPO output is tunable from 1.45 - 4 pm, with a bandwidth less than 500 MHz, and a pulse energy of 1 to 3 mJ at 3.29 microns. The receiver is cart-mounted and consists of a 14" telescope with 1.57 and 3.29 micron detector channels. A fast oscilloscope is used for data acquisition. The system performance will be tested through measurements of sources of atmospheric methane.
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Without Abstract
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By using a Michelson interferometer arrangement, we have measured the phase shift (the Pancharatnam phase) experienced by a light beam whose state of polarization is made to follow, by successive unitary transformations, a closed circuit... more
By using a Michelson interferometer arrangement, we have measured the phase shift (the Pancharatnam phase) experienced by a light beam whose state of polarization is made to follow, by successive unitary transformations, a closed circuit on the Poincaré sphere. We ...
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Abstract The third order equations of motion for a rotating, bidirectional, inhomogeneously broadened ring laser at line center with backscattering and asymmetry are solved exactly when the additive noise terms are negligible. The... more
Abstract The third order equations of motion for a rotating, bidirectional, inhomogeneously broadened ring laser at line center with backscattering and asymmetry are solved exactly when the additive noise terms are negligible. The resulting solution for the relative phase of the two counterpropagating modes may exhibit steady state or transient oscillations. For certain initial conditions and operating parameters the phase solution is unstable. This gives rise to deterministic phase jumps in both the transient and steady state behavior. A series of phase jumps occurs if the system repeatedly crosses its unstable boundary. The jumps are multiples of π radians in magnitude, except for the case in which the phase discontinuity is caused by slowly varying operating parameters. Conditions are derived under which the frequency difference between the two modes (i) exhibits the well-known frequency lock-in effect at low rotation rates, or (ii) remains sensitive to cavity rotation regardless of rotation rate (lock-in suppression). Difficulties in achieving the latter result in a practical device are discussed.
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Abstract : A tunable UV and IR laser source was purchased through this grant utilized in lidar experiments and evaluated for potential DoD applications. The laser technology was incorporated into the Hampton University(HU) ozone... more
Abstract : A tunable UV and IR laser source was purchased through this grant utilized in lidar experiments and evaluated for potential DoD applications. The laser technology was incorporated into the Hampton University(HU) ozone differential absorption lidar system and lidar measurements of ozone were made. This same technology approach was utilized in the design of the laser for the HU scanning eyesafe aerosol lidar system. This effort resulted in a second research proposal being submitted jointly by HU and ITT Industries with AFRL support to apply this technology to the problem of laser induced fluorescence detection of bioaerosols for airbase defense.
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An application of the scalar product to first-year kinematics is presented as an instructive means to reinforce the concept of vector multiplication early in the semester.
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ABSTRACT
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Laser diodes are being utilized with increasing frequency in optical remote sensing applications. Their attractive features include small size, low cost, low power consumption, good output power, high modulation speed, good reliability,... more
Laser diodes are being utilized with increasing frequency in optical remote sensing applications. Their attractive features include small size, low cost, low power consumption, good output power, high modulation speed, good reliability, and good wavelength tunability. However, their optical properties vary significantly even during the same manufacturing run. Therefore, when the application places stringent requirements on their optical properties, diodes need to be individually characterized and evaluated. This paper discusses our present efforts to characterize laser diodes for use in a Differential Absorption Lidar (DIAL) instrument which imposes very tight requirements on diode behavior.
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Physics, Laser, Medicine, Instability, Mathematical Sciences, and 15 morePhysical sciences, FOkker Planck Equation, Oscillations, Physical, PARTIAL DIFFERENTIAL EQUATION, CHEMICAL SCIENCES, Spontaneous Emission, Jump, Equations of Motion, Equation of Motion, Differential equation, Initial Condition, Backscattering, Probability Distribution Function, and Probability Distribution Functions
Summary form only given.We report on the first experimental demonstration of high-order Stokes and antiStokes generation in triclinic /spl gamma/-KIO/sub 3/ crystals by cascading SRS and Raman-induced four-wave mixing (RFWM) under... more
Summary form only given.We report on the first experimental demonstration of high-order Stokes and antiStokes generation in triclinic /spl gamma/-KIO/sub 3/ crystals by cascading SRS and Raman-induced four-wave mixing (RFWM) under picosecond laser excitation at room temperature (RT) in the visible and near infrared (NIR).
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ABSTRACT The need for high resolution spatial and temporal measurements of tropospheric ozone is discussed. Tropospheric ozone is globally increasing due to anthropogenic sources such as industrialization and biomass burning. In addition... more
ABSTRACT The need for high resolution spatial and temporal measurements of tropospheric ozone is discussed. Tropospheric ozone is globally increasing due to anthropogenic sources such as industrialization and biomass burning. In addition to its hazardous effects during pollution episodes, elevated levels of tropospheric ozone may have additional detrimental environmental effects due to ozone's crucial role in tropospheric chemistry and in global climate. Ground-based lidar instruments can play an important role in meeting this measurement need. We present test results for a prototype compact, minimal-cost ozone lidar. The instrument is designed to be as reliable and simple as possible but still be capable of routinely measuring ozone profiles with less than 10% relative error from the ground up into the lower stratosphere. In addition to local pollution monitoring, this lidar satisfies the basic requirements necessary for future global monitoring projects requiring multi-instrument networks, such as that proposed for the Global Tropospheric Ozone Project (GTOP). GTOP is currently being formulated by a scientific panel of the International Global Atmospheric Chemistry Project to meet its goal to better understand the processes that control the global sources, sinks, and transformation mechanisms of tropospheric ozone.
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... AA Kaminskii*, HJ Eichler**, J. Hulliger***, S. Haussühl****, T. Chyba***** D. Temple***** JC Barnes***** VN Dolbinina ... 3012 Switzerland **** Institute Crystallography, Cologne University, Cologne, D-50674 Germany ***** Department... more
... AA Kaminskii*, HJ Eichler**, J. Hulliger***, S. Haussühl****, T. Chyba***** D. Temple***** JC Barnes***** VN Dolbinina ... 3012 Switzerland **** Institute Crystallography, Cologne University, Cologne, D-50674 Germany ***** Department of Physics, Hampton University, Hampton ...
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We are investigating pulsed barium nitrate (Ba(NO3)2) lasers and amplifiers for an ozone lidar system. Previously, we reported that the visible output of a Raman laser, pumped by a Q-switched, frequency-doubled Nd:YAG laser at 532 nm, is... more
We are investigating pulsed barium nitrate (Ba(NO3)2) lasers and amplifiers for an ozone lidar system. Previously, we reported that the visible output of a Raman laser, pumped by a Q-switched, frequency-doubled Nd:YAG laser at 532 nm, is slightly depolarized. In this paper, we present quantitative depolarization measurements and demonstrate a simple technique to compensate for the crystal birefringence
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Materials Science, Optics, Laser, Raman Spectroscopy, Neodymium, and 3 moreOzone, Barium, and Birefringence
When a ring laser is oscillating in two counterpropagating modes, and light is reflected or scattered from one mode back into the other, it is found that the behavior of the laser can be drastically modified. In particular, certain... more
When a ring laser is oscillating in two counterpropagating modes, and light is reflected or scattered from one mode back into the other, it is found that the behavior of the laser can be drastically modified. In particular, certain instabilities have been encountered in which the two mode intensities oscillate in antiphase, and the phase difference between the two complex mode amplitudes exhibits jumps of ±π.1-11 These phase jumps are always connected with zero crossings of one or the other mode amplitude. The time intervals observed between successive phase jumps show substantial variations in one of the experiments7 and in some computer simulations, whereas other computer solutions of the equations of motion indicate greater regularity.5 This discrepancy provided part of the motivation for the present work. We were also interested to see how the laser behaves when the instability condition5-7, 10-11 \( {\tilde R_1} + \tilde R_2^* = 0, \), in which \( {\tilde R_1},{\tilde R_2} \) are complex backscattering coefficients, is not satisfied exactly.
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High resolution spectral measurements of the first, second, and third Stokes shifts in barium nitrate are reported. The laser source for the experiment is a frequency-doubled, injection-seeded Nd:YAG laser. Spectra for both single-pass... more
High resolution spectral measurements of the first, second, and third Stokes shifts in barium nitrate are reported. The laser source for the experiment is a frequency-doubled, injection-seeded Nd:YAG laser. Spectra for both single-pass conversion and for a Raman oscillator are compared. Significant gain narrowing of the spectrum is observed.
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A ground-based lidar system for differential absorption lidar measurements of methane and trace gases in the 1.45 - 4 micrometer wavelength region is described. An optical parametric oscillator pumped by an injection-seeded... more
A ground-based lidar system for differential absorption lidar measurements of methane and trace gases in the 1.45 - 4 micrometer wavelength region is described. An optical parametric oscillator pumped by an injection-seeded frequency-doubled Nd:YAG laser is employed as a radiation source. The expected minimum detectable range of the system is about 1000 meters for range resolved measurements of methane. The system performance is being tested through measurements of sources of atmospheric methane and aerosols.
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ABSTRACT We are developing a portable, eye-safe, ground-based ozone lidar instrument specialized for ozone differential absorption lidar (DIAL) measurements in the troposphere. This prototype instrument is intended to operate at remote... more
ABSTRACT We are developing a portable, eye-safe, ground-based ozone lidar instrument specialized for ozone differential absorption lidar (DIAL) measurements in the troposphere. This prototype instrument is intended to operate at remote field sites and to serve as the basic unit for future monitoring projects requiring multi-instrument networks, such as that proposed for the Global Tropospheric Ozone Project (GTOP). GTOP is currently being formulated by a scientific panel of the International Global Atmospheric Chemistry Project to meet its goal to better understand the processes that control the global distribution of tropospheric ozone. In order for the lidar to be widely deployed in networks, it must be fairly easy to use and maintain as well as being cost-competitive with ground station launching ozone sondes which operate several times a day. To achieve these goals, emphasis is placed upon the incorporation of: (1) all-solid state transmitters which can reliably produce 20-40 mJ pulses; (2) a highly efficient, narrow-bandpass receiver; (3) dual analog and photon-counting detector channels; and (4) flexible, user-friendly control software.
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In order to measure atmospheric ozone with the DIAL technique, the laser transmitter must generate suitable on-line and off-line wavelength pulse pairs. Preliminary experiments1 at NASA LaRC suggested that the solid state Raman shifting... more
In order to measure atmospheric ozone with the DIAL technique, the laser transmitter must generate suitable on-line and off-line wavelength pulse pairs. Preliminary experiments1 at NASA LaRC suggested that the solid state Raman shifting material, Ba(NO3)2, could be utilized to produce these pulse pairs. A Raman oscillator pumped at 532 nm by a frequency-doubled Nd:YAG laser can create first Stokes laser output at 563 nm and second Stokes output at 599 nm. With a frequency doubler, UV output at 281 nm and 299 nm can be subsequently obtained. This all-solid state system can be very compact and has the potential to be very efficient and reliable. Such attributes are essential for the next generation of airborne or space-borne lidar systems.
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The Zemax® optical design program is being used to develop the Hampton University ozone and aerosol lidar systems. A macro developed for use within the Zemax® program enables the design to be optimized.
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In recent experimental studies of instabilities in single-mode lasers, power spectra of the intensity (photocurrent) have often shown period doublings, or doubly periodic behavior, which develop a broadband spectral component as the laser... more
In recent experimental studies of instabilities in single-mode lasers, power spectra of the intensity (photocurrent) have often shown period doublings, or doubly periodic behavior, which develop a broadband spectral component as the laser excitation is increased. This has been tentatively identified as the signature of dynamical chaos; but as the power spectrum represents only the Fourier transform of the two-time correlation function, it does not provide a conclusive distinction between dynamical and stochastic noise. Similarly, when the spectral peaks are broader than the instrumental resolution, the cause could be AM modulation by stochastic noise or one of the several types of nearly periodic deterministic chaos.
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ABSTRACT An eye-safe, ground-based differential absorption lidar for ozone measurements is currently being tested. Its novel features include an all-solid state OPO transmitter, a dual channel grating-based receiver and a fast membrane... more
ABSTRACT An eye-safe, ground-based differential absorption lidar for ozone measurements is currently being tested. Its novel features include an all-solid state OPO transmitter, a dual channel grating-based receiver and a fast membrane mirror light shutter.
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ABSTRACT Laser Interrogation of Surface Agents (LISA) is a new technique which exploits Raman scattering to provide standoff detection and identification of surface-deposited chemical agents. ITT Industries, Advanced Engineering and... more
ABSTRACT Laser Interrogation of Surface Agents (LISA) is a new technique which exploits Raman scattering to provide standoff detection and identification of surface-deposited chemical agents. ITT Industries, Advanced Engineering and Sciences Division is developing the LISA technology under a cost-sharing arrangement with the US Army Soldier and Biological Chemical Command for incorporation on the Army's future reconnaissance vehicles. A field-engineered prototype LISA-Recon system is being designed to demonstrate on-the- move measurements of chemical contaminants. In this article, we will describe the LISA technique, data form proof-of- concept measurements, the LISA-Recon design, and some of the future realizations envisioned for military sensing applications.
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In the DIAL technique, the water vapor concentration profile is determined by analyzing the lidar backscatter signals for laser wavelengths tuned "on" and "off" a water vapor absorption line. Desired characteristics of... more
In the DIAL technique, the water vapor concentration profile is determined by analyzing the lidar backscatter signals for laser wavelengths tuned "on" and "off" a water vapor absorption line. Desired characteristics of the on-line transmitted laser beam include: pulse energy ≥100 mJ, high-resolution, continuous tuning capability (uncertainty < 0.25 pm), good spectral stability (jitter <0.5 pm about the mean), and high spectral purity (>99%).1The off-line laser, whose spectral requirements are much less stringent, is generally detuned less than 100 pm away from the water vapor line.
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The two-mode dye ring laser when operated moderately far above threshold exhibits an instability that causes it to switch seemingly at random between clockwise and counterclockwise modes. The phenomenon has been explained in terms of... more
The two-mode dye ring laser when operated moderately far above threshold exhibits an instability that causes it to switch seemingly at random between clockwise and counterclockwise modes. The phenomenon has been explained in terms of spontaneous emission fluctuations,1-4 which cause the representative point in phase space to tunnel between two metastable states, and this interpretation has so far proved to be in good agreement with all experimental measurements. By implication the switching phenomenon is a macroscopic manifestation of quantum fluctuations in the laser, and it can be described by two coupled Langevin equations in the two mode amplitudes, with additive quantum noise.1 Although these equations account for the mode switching, better quantitative agreement with experiment is obtained when pumping fluctuations are also introduced.5
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Abstract: There is a growing need for standoff detection of nonvolatile threat contamination on surfaces. These threats include explosives in the form of improvised explosive devices (IEDs) as well as low volatility chemical agents and... more
Abstract: There is a growing need for standoff detection of nonvolatile threat contamination on surfaces. These threats include explosives in the form of improvised explosive devices (IEDs) as well as low volatility chemical agents and toxic industrial chemicals (TICs). The ability to assess surface hazards, even at standoff distances as short as 1 m, would provide an increased level of safety to those tasked with assessing sites with possible weapons of mass destruction (WMD). A number of optical spectroscopy techniques have been investigated to solve this problem. Laser-induced breakdown spectroscopy (LIBS), fluorescence, and Raman all show promise for meeting this challenge of surface detection, with each having both advantages and disadvantages. While most of the work to date has been on assessing these techniques individually, more emphasis is being placed on combining orthogonal detection techniques for improved probability of detection and the reduction in false positives.
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In a joint collaboration, QinetiQ North America (QNA), Idaho National Labs (INL) and ITT are developing a ground robotic platform that provides real time remote sensitive site assessment with sensor fused area mapping, dynamic obstacle... more
In a joint collaboration, QinetiQ North America (QNA), Idaho National Labs (INL) and ITT are developing a ground robotic platform that provides real time remote sensitive site assessment with sensor fused area mapping, dynamic obstacle detection and avoidance, and path planning that can be retrofitted to the over 3000 fielded TALONs to date. This platform is developed under Defense Threat Reduction Agency (DTRA) Rapid Area Sensitive-Site Reconnaissance (RASR) Advanced Technical Demonstration (ATD) in conjunction with the Edgewood Chemical Biological Center. The RASR platform provides Warfighters, Civil Support Teams and First Responders with marked improvements in enhanced situational awareness and remote assessment tools.
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Methane plays an important role as one of the greenhouse gases in the atmosphere. The differential absorption lidar (DIAL) technique is widely used for range-resolved measurements of the concentration of atmospheric constituents. This... more
Methane plays an important role as one of the greenhouse gases in the atmosphere. The differential absorption lidar (DIAL) technique is widely used for range-resolved measurements of the concentration of atmospheric constituents. This technique ...
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Hampton University Center for Lidar and Atmospheric Sciences Students (CLASS) team and... more
Hampton University Center for Lidar and Atmospheric Sciences Students (CLASS) team and ITT&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#x27;s Advanced Engineering &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Sciences Division have worked together to develop a portable, eyesafe and scanning aerosol lidar system, the system is based on a 1.5 micron, 125 mJ, 20 Hz eye-safe optical parametric oscillator (OPO). Its purpose is to remotely detect aerosols, clouds, and pollution in the