This PDF file contains the front matter associated with SPIE Proceedings Volume 6708, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

The probability distribution of aperture averaged signal intensity from free-space laser optical systems depends on the optical turbulence along the optical path. For most current free-space laser systems, random fluctuations of signal intensity are assumed to be statistically homogeneous and isotropic. Moreover, it is assumed that probability distributions are generally log-normal and that Kolmogorov -5/3 wave number turbulence power law represents the signal intensity data. In this paper, the Kolmogorov model is investigated for an optical path that traverses a complex non-uniform topography. Experimental research is conducted to determine the characteristic behavior of high frequency (2000 Hz) signal intensity data collected over a 2.33 km optical path at the Army Research Laboratory (ARL) Atmospheric Laser Optics Testbed (A_LOT) Facility. Results focus mainly on calculated power spectra and frequency distributions. In addition, a model is developed to calculate optical turbulence intensity (C2/n) as a function of receiving (and transmitting) aperture diameter, log-amplitude variance, and path length. Here, initial comparisons of calculated to measured C2/n data are favorable. It is anticipated that this kind of signal data analysis will benefit laser communication systems development and testing at the ARL.

It is well known that free space laser system performance is limited by atmospheric turbulence. Most theoretical treatments have been described for many years by Kolmogorov's power spectral density model because of its simplicity. Unfortunately several experiments have been reported recently that show the Kolmogorov theory is sometimes incomplete to describe atmospheric statistics properly, in particular, in portions of the troposphere and stratosphere. In this paper, using a non Kolmogorov spectrum and following same procedure already used for horizontal path analysis, we extend free space optical system performance analysis to uplink and downlink paths. Our non Kolmogorov spectrum uses a generalized exponent instead of constant standard exponent value 11/3 and a generalized amplitude factor instead of constant value 0.033. Therefore, in non-Kolmogorov weak turbulence, we carry out, for a uplink and a downlink paths, analysis of Long Term Beam Spread, Scintillation index, Probability of fade, mean SNR and mean BER as variation of the spectrum exponent.

Our objective is to determine the fraction of a propagated laser beam that will arrive at a receiver after traversing a 7.1 kilometer near-ocean-surface path. A multi-year experiment has been conducted in 2005 and 2006 to study near-surface propagation over water at Zuniga Shoal in San Diego. To quantify the effects of turbulence, we used a saturation-resistant scintillometer to measure the refractivity structure parameter C2/n. A meteorological buoy located near the mid-path point collected meteorological data which was used as input data for an optical turbulence model NSLOT. In addition for some of the test period there was also laser propagation data collected from a 1.064μm laser on the same path. We compare model predictions with the incoherent scintillometer data and the coherent laser propagation data.

In Perez et al. [J. Opt. Soc. Am. A 21 (10), 2004] we have given a general formalism to model the turbulent wave-front phase by using fractional Brownian motion processes. Moreover, it extends classical results to non- Kolmogorov turbulence: the Strehl ratio and the angle-of-arrival variance are shown to be dependent on the dynamic state of the turbulence. Nevertheless, this model has its drawbacks as it is unable of handling the stationarity of the phase increments over the full inertial range. The Levy fractional Brownian motion (LfBm) family is then introduced here in order to overcome this problem.

The performance of imaging and laser systems can be severely degraded by atmospheric turbulence, especially for near-horizon propagation paths. Having the ability to predict turbulence effects from relatively easily obtained measurements can be useful for system design and feasibility studies, and for real-time optimization of optical systems for the current environment. For this reason, so-called 'bulk' models have been developed that can estimate turbulence effects through the refractive index structure parameter (C_n²) from mean near-surface meteorological and sea surface temperature measurements. Bulk C_n² models are directly dependent upon empirically determined dimensionless functions, known as the dimensionless structure parameter functions for temperature and humidity. In this paper we attempt to improve bulk optical turbulence model performance by determining new over-ocean forms for the dimensionless temperature structure parameter (ƒ_T). During 2005-2006 atmospheric propagation experiments were conducted in the Zuniga Shoals area near San Diego to examine the impact of environmental conditions on low-altitude electro-optical propagation above the ocean surface. As part of this experiment the Naval Postgraduate School (NPS) deployed its flux research buoy along the propagation path. The measurements obtained on the NPS buoy enabled ƒ_T values to be obtained and new functions to be determined. These new functions differ greatly from those presented in the past, in that the new ƒ_T values asymptote towards very high values as the stability approaches neutrality. The dependence of the new ƒ_T function on the stability parameter in stable conditions was also different from that previously proposed. When these new functions were inserted into the NPS bulk C_n² model, the resulting values agreed much better with directly measured turbulent C_n² values in unstable conditions, but in stable conditions the new function actually made the agreement worse.

Different statistical properties of laser illumination through atmospheric turbulence have already been derived either in the small or strong perturbation regimes. However, modeling the instantaneous illumination remains useful for the estimation of optical system performances. using an end-to-end propagation model based on a split step algorithm leads up to heavy calculations. We propose a simplified model to provide instantaneous laser illuminations according to the C2/n profile. This simplified method has been implemented. Hypothesis taken into account and cross check with a numerical end-to-end model developed at Onera are presented.

In recent years several extensive data sets have been collected to characterize horizontal laser propagation in a maritime environment. We report on data collected on a 1.35-km range over an arm of San Diego Bay. We analyze various atmospheric turbulence features of the optical propagation data, and we compare the experimental results with numerical wave-optics simulations. The goals are (a) to extract atmospheric turbulence strength descriptors for the period of record, and (b) to assess the ability of wave-optics simulation to reproduce the experimental results. We comment on the degrees of freedom available when comparing simulation and measurement, due to the lack of completely comprehensive measurement data.

We present a post-processing technique for mitigating the effect of turbulence on holographically recorded short-exposure images that consists of the two following sequential steps. First, the coherent field scattered from the viewed object propagates through a turbulence layer and is used to record a short-exposure Fourier hologram by interference with a know reference beam. Information about the instantaneous distorted optical field is hence stored permanently in the hologram. Secondly, the recorded hologram is read a posteriori using the reference beam with its wavefront modulated using adaptive optics. The resulting intensity image is used to compute a sharpness metric. Optimization of the metric is performed using a stochastic parallel gradient descent (SPGD) algorithm. Experimental and numerical results show an improvement of the image quality after convergence of the SPGD algorithm.

Effective compensation of phase noise in laser communication calls for fast, real-time, adaptive wavefront control. We present an analog, continuous-time, high-speed VLSI (Very Large Scale Integration) controller implementing multi-dithering perturbative gradient descent optimization of a direct measure of optical performance. The system applies parallel sinusoidal perturbations to the wavefront over a range of frequencies, and performs parallel synchronous detection of the metric signal to derive the gradient components over each frequency band. The system operates over a wide range of frequencies, supporting applications of model-free adaptive optics extending from compensation of slow atmospheric turbulence to compensation of fast random phase fluctuations in the actuators and laser amplifiers. The system has been tested as a phase controller for a multiple laser beam wavefront propagating through a highly turbulent medium. The results indicate a compensation bandwidth exceeding 300 kHz matching the turbulence bandwidth.

A newly developed adaptive optical transceiver telescope is used to investigate the possibility of correcting wavefront aberrations under strong atmospheric turbulence conditions over a distance of several kilometers. A fiber laser is connected to a fiber positioner within the telescope, which acts as a transmitter by sending laser light at wavelength 1550 nm through the turbulent air to a retro reflector mounted on the top of a water tower at a distance of 2.33 km. The reflected laser light is received by the telescope -(acting this time as a receiver) and focused onto the fiber tip. The light picked up by the fiber is - guided to a photo detector by means of a fiber splitter. The signal from the photo detector is recorded by a PC and used as feedback signal for the adaptive optics controller, which controls the fiber-tip positioner as well as an six-channel adaptive mirror using a stochastic parallel gradient descent optimization algorithm. Experimental results are reported in this paper.

We demonstrate the coherent combining of three beams with a phase-locking controller using VLSI multi-dithering technique. Three fiber-coupled phase shifters are used to compensate phase distortions in the beam propagation path. The highest dither frequency in our system is ~70MHz. The achieved closed-loop compensation bandwidth of three beamlets is up to 100KHz.

We present the development of a novel technique for numerical simulation and analysis of wide field-of-view (FOV) incoherent and anisoplanatic imaging of an object through volume turbulence. This technique is based on the recently developed brightness function method [J. Opt. Soc. Am. A, v. 22, p. 126 (2005)]. We present computer simulation results demonstrating the anisoplanatic turbulence effects on an object image quality.

Systems utilizing target-in-the-loop (TIL) techniques for adaptive optics phase compensation rely on a metric sensor to perform a hill climbing algorithm that maximizes the far-field Strehl ratio. In uncooperative TIL, the metric signal is derived from the light backscattered from a target. In cases where the target is illuminated with a laser with suffciently long coherence length, the potential exists for the validity of the metric sensor to be compromised by speckle-field effects. We report experimental results from a scaled laboratory designed to evaluate TIL performance in atmospheric turbulence and thermal blooming conditions where the metric sensors are influenced by varying degrees of backscatter speckle. We compare performance of several TIL configurations and metrics for cases with static speckle, and for cases with speckle fluctuations within the frequency range that the TIL system operates. The roles of metric sensor filtering and system bandwidth are discussed.

Real environmental conditions, such as atmospheric turbulence and aero-optics effects, make practical implementation of the object-in-the-loop (TIL) algorithm a very difficult task, especially when the system is set to operate with a signal from the diffuse surface image-resolved object. The problem becomes even more complex since for the remote object the intensity of the returned signal is extremely low. This presentation discusses the results of an analysis and experimental verification of a thresholdless coherent signal receiving system, capable not only in high-sensitivity detection of an ultra weak object-scattered light, but also in its high-gain amplification and phase conjugation. The process of coherent detection by using the Brillouin Enhanced Four Wave Mixing (BEFWM) enables retrieval of complete information on the received signal, including accurate measurement of its wavefront. This information can be used for direct real-time control of the adaptive mirror.

Efficient laser beam delivery on a distant target remains a key problem for practical implementation of tactical laser systems. Since the conventional target-in-the-loop (TIL) concept is generally not effective in such operational environments, new solutions are needed. In this report we discuss an innovative approach for effective compensation of laser beam aberrations in TIL systems. It is based on a recently devised technique that combines optical phase conjugation (OPC) with a TIL system for effective hot-spot formation. The proposed method should enable delivery of enhanced density laser energy to a target within a finite number of iteration cycles. Using the model based on an analogy between the TIL system and laser resonator, pointing of the laser beam on the target is performed at the image plane, resulting in reduced hot-spot formation time.

A laboratory demonstration of two novel tactical beam control methods for correcting the effects of strong turbulence including Beacon Anisoplanatism, and the combined effects of Beacon Anisoplanatism and Thermal Blooming, respectively, were performed in SAIC's Tactical Beam Control Test-Bed. Both systems were tested with ratio of aperture diameter to Fried parameter, D/r₀, of up to 7, and ratio of beam spot size at the target to isoplanatic angle, θ_B/θ_o, of up to 10. The first method was implemented in a Wavefront-based Stochastic Parallel Gradient Decent (WSPGD) adaptive optics (AO) system, which uses an off-axis wavefront sensor (WFS) to provide feedback for a multi-dithering beam control algorithm. The second method was implemented in a Hybrid WSPGD AO system, which incorporates the WSPGD AO system with a conventional Phase Conjugate (PC) AO system. The Hybrid system uses an on-axis WFS to generate initial deformable mirror commands and an off-axis WFS to generate additional commands that account for the high frequency phase components removed from the wavefront of a laser return by Beacon Anisoplanatism. We developed a low speed PC-based WSPGD controller, implemented designs of the WSPGD and Hybrid WSPGD AO systems in SAIC's Test-Bed, and tested both AO systems in static and dynamic turbulence over a wide range of turbulence conditions. A target-plane tracker was used to stabilize the line-of-sight in the AO corrected beam. Test results show that the WSPGD AO system efficiently compensates the effects of Beacon Anisoplanatism for both static and dynamic turbulence, providing a mean performance gain of 1.8 averaged over multiple turbulent realizations. We also found in testing that the Hybrid WSPGD system efficiently compensates for Beacon Anisoplanatism in the presence of Thermal Blooming - providing improved compensation for both Thermal Blooming and turbulence. In the presence of strong Beacon Anisoplanatism with θ_B/θ_o of up to 10, the maximum performance gain is 4.9 and the mean performance gain for multiple turbulence realizations is 2.1.

Conventional tracking systems measure time-space-position data and collect imagery to quantify the flight dynamics of tracked targets. One of the major obstacles that severely impacts the accuracy and fidelity of the target characterization is atmospheric turbulence induced distortions of the tracking laser beam at the target surface and imagery degradations. Tracking occurs in a continuously changing atmosphere resulting in rapid variations in the tracking laser beam and distorted imagery. These atmospheric effects, in combination with other sources of degradation, such as measurement system motions (e.g. vibration/jitter), defocus blur, and spatially varying noise, severely limit the useful and accuracy of many tracking and analysis methods. This paper discusses the viability of employing stereo image correlation methods for high speed moving target characterization through atmospheric turbulence. Stereo imaging methods have proven effective in the laboratory for quantifying temporally and spatially resolved 3D motions across a target surface. This technique acquires stereo views (two or more) of a test article that has an applied random speckled (dot) pattern painted on the surface to provide trackable features on the entire target surface. The stereo views are reconciled via coordinate transformations and correlation of the transformed images. The principle limitations of this method have been the need for clean imagery and fixed camera positions and orientations. However, recent field tests have demonstrated that these limitations can be overcome to provide a new method for quantifying flight dynamics with stereo laser tracking and multi-video imagery in the presence of atmospheric turbulence.

In this paper, we present the recent development of a conformal optical system with three adaptive phase-locked fiber elements. The coherent beam combining based on stochastic parallel gradient descent (SPGD) algorithm is investigated. We implement both phase-locking control and wavefront phase tip-tilt control in our conformal optical system. The phase-locking control is performed with fiber-coupled lithium niobate phase shifters which are modulated by an AVR micro-processor based SPGD controller. The perturbation rate of this SPGD controller is ~95,000 iterations per second. Phase-locking compensation bandwidth for phase distortion amplitude of 2π-radian phase shift is >100Hz. The tip-tilt control is realized with piezoelectric fiber positioners which are modulated by a computer-based software SPGD controller. The perturbation rate of the tip-tilt SPGD controller is up to ~950 iterations per second. The tip-tilt compensation bandwidth using fiber positioners is ~10Hz at 60-μrad. jitter swing angle.

The knowledge of the atmospheric aerosol characteristics is of great importance for the range performance of Infrared and Electro-Optical sensor systems. The composition, the concentration and the size distribution of aerosols determine their scattering behavior as function of wavelength and thus their attenuation of light beams. When studies are made on this attenuation, it is considered to be very useful to incorporate the spatial variation of the aerosol characteristics along the measurement path, such as found during a previous campaign, carried out over the San Diego Bay (August 2005). In a more recent experiment (November 2006) a trial was set-up at Scripps pier of the Institute of Oceanography near La Jolla (US-West Coast). This place is known for the high frequency of occurrence of hazy conditions, not only variable with location, but also in time. TNO did participate in this experiment with two Particle Measurement Systems (PMS), one on the shore and one at the end of the pier, a weather station and the Multi Spectral Radiometer Transmissometer (MSRT), used in previous trials. It was shown before, that the use of multi-band transmission data allows a more detailed analysis of the aerosol characteristics in the measurement path. The advantage of the MSRT concerns a larger measurement volume, thus providing a higher signal to noise (S/N) ratio and a shorter response time, compared to the in-situ PMS systems. A similar method, based on the spectral dependence of the scattering coefficient, has been used during the analysis of the data, collected in November 2006. In this paper representative data samples are presented, showing the variability of the transmission in each of the spectral bands. By using the weather data, a separation has been made between extinction by molecules and aerosols. A brief description is given of the retrieval method, just mentioned. The retrieved particle characteristics are compared to the data from the PMS systems, taking into account the fact, that part of the measurement path, having a length of 6.68 km, was grazing the shore-line. In general the particle density, as found by the PMS systems was less than the retrieved value, especially when the wind was from off-shore directions. At certain occasions, sinusoidal variations in the transmission level, with a period of about 5 minutes, were found, probably due to oscillatory motions of the air mass in the measurement path. It was found, that the value of the Junge exponent of the Particle Size Distribution (PSD) was rather frequently of the order of -3, showing that the concentration of bigger particles (> 3 μm) compared to the smaller particles (< 0.5 μm), was greater than the value, found in experiments at other locations. It is investigated how accurate the transmission levels of the IR bands can be predicted by using the retrieved PSD's and the absolute humidity, obtained from the weather data. Due to the low wind speed during the trial (< 4 m/s), it was not possible to find any particular effect from aerosols, potentially created in the surf zone at higher wind speeds.

Results from a quantitative model for the prediction of the sea-salt mass flux produced in the surf zone are presented in this paper. The model relates the surf zone sea salt mass flux to the amount of wave energy dissipated in the surf zone. In order to apply this aerosol emission model, a wave numerical model is required to obtain estimates for the total wave energy dissipated in the surf zone, as well as for the width of the surf zone. In the present work, we show using different wave models that the aerosol emission model is not sensitive to the details of the formulation of the wave model, provided a clear definition for the width of surf zone is adopted and the calibration of the numerical models is properly done.

We have been engaged in a long-term test to determine the beam extinction effects of aerosols. During four test periods of one month duration each, we propagated a beam over a 7-km path near the ocean surface, and measured the received intensity in two near-infrared wavebands (1.061 μm and at 1.622 μm). In each test period, meteorological measurements were obtained from a meteorological buoy located at the mid-point of the propagation path. These meteorological data were used as input for the Advanced Navy Aerosol Model (ANAM). In this paper we will describe the comparison between the ANAM predictions and the measured transmission. We found that there are significant and sustained discrepancies between the ANAM model predictions and the optical transmission data. We will focus on two particular problems that have emerged from our comparison: first, the ANAM dependence on local wind speed can cause errors, and second, the local relative humidity is not optimally coupled in the ANAM. We will present the analysis we used to support these claims, and we will present recommendations for modifications to the model.

The variation of the extinction coefficient with wavelength can be presented as a power law function with a constant (related to the power factor) known as the Ångström coefficient. When the particle size distribution is dominated by small particles, usually associated with pollution, the Ångström coefficients are high; in clear conditions they are usually low. Long residence time of air masses over land and in particular the passage over large urban areas cause high concentrations of fine particles and thus high values of the Ångström coefficients. The opposite effect can be observed over water. The longer the time that the air masses spent over water the more evident is a change in the aerosol size distribution caused by the deposition of continental aerosols. As a result of this process the measured Ångström coefficient values become much smaller. Therefore this parameter is a good tracer for the concentration of aerosols originated over land. The relation between the Ångström coefficient and TOS (time over sea) is demonstrated on three data sets. The first data set includes measurements collected at the Irish Atlantic coast in 1994 and 1995, the second one, data collected within the Rough Evaporation Duct (RED) experiment that took place off Oahu, Hawaii in 2001. The third one represents data collected at the Baltic Sea during cruises in 1997and 1998.

Sea basing operations in coastal environments require a rapid and accurate description of the physical conditions in the region. Battlespace characterization and sensor performance assist in optimizing the efficiency and safety of operations, of which the detection of targets at low level above the sea surface is all-important. The environmental conditions of the marine boundary layer (MBL) - due to weather and atmospheric effects - change continuously in space and time, which certainly holds for the aerosol make-up. Models have been developed to describe the electro-optical propagation in the boundary layer as a function of meteorological parameters. EOSTAR is such an end-to-end model suite for EO sensor performance in which the Advanced Navy Aerosol Model (ANAM) is embedded for computing the aerosol extinction. While ANAM provides favourable results in open ocean conditions, in coastal zones the model lacks accuracy due to the presence of aerosols from a variety of sources that need to be assessed. In offshore wind conditions continental aerosols of anthropogenic and natural origin mix with marine aerosols produced in the surf zone and by wave breaking further offshore. Radiometers on satellites can be used to retrieve the spatial variation over an extended area determined by the swath width, with a resolution determined by the radiometer pixel size. In this contribution we explore the potential of satellite measurements to provide information on the aerosol properties over the range of interest in order to correctly handle their influence on transmission characteristics in the coastal zone. Results from measurements of the multidisciplinary Maritime REA/Battlespace Preparation 2007 trial, held during 20 April and 5 May 2007 near the vicinity of the island Elba along the west coast of Italy, are presented in this analysis. For one particular day, the satellite retrieved aerosol optical thickness (AOT) is to be compared with hand-held sun photometer measurements for quality assessment. The AOT values are converted into aerosol extinction coefficients for a pre-defined path. For one visible wavelength channel the transmission loss is computed with these coefficients and is compared with the computed transmission loss for the path in case of a) a single extinction coefficient obtained from measurements and b) a modeled extinction coefficient obtained from ANAM.

We present the design and evaluation of compact adaptive optical antennas with apertures diameters of 16 mm and 100 mm for 5Gbit/s-class free-space optical communication systems. The antennas provide a bi-directional optically transparent link between fiber-optical wavelength-division multiplex systems and allow for mitigation of atmospheric-turbulence induced wavefront phase distortions with adaptive optics components. Beam steering is implemented in the antennas either with mirrors on novel tip/tilt platforms or a fiber-tip positioning system, both enabling operation bandwidths of more than 1 kHz. Bimorph piezoelectric actuated deformable mirrors are used for low-order phase-distortion compensation. An imaging system is integrated in the antennas for coarse pointing and tracking. Beam steering and wavefront control is based on blind maximization of the received signal level using a stochastic parallel gradient descent algorithm. The adaptive optics control architecture allowed the use of feedback signals provided locally within each transceiver system and remotely by the opposite transceiver system via an RF link. First atmospheric compensation results from communication experiments over a 250 m near-ground propagation path are presented.

Fast piezoelectric controlled adaptive optics elements are developed allowing one to design the adaptive optics system with compensation of optical phase aberrations in frequency range exceeding 10 kHz. Adaptive optic elements include: 13-channel deformable mirrors DM-13 with aperture 25 and 30mm, combine device formed with DM-13 attached to the tip/tilt platform, 49-channel deformable mirror PM-49 based on in-pockets piezoelectric multi-pixel actuators. The designs, fabrication and performances of the developed devices are described. The emphasis is made on the experimental investigation of resonance behavior of the devices and influence of the passive damping on the frequency bandwidth.

Within the marine atmospheric surface layer it is possible for a single camera to deduce passively the range to a point target. Although this range determination would appear impossible at first glance, such a measurement exploits the common occurrence of sub-refractive propagation conditions in the marine environment. A calculation of the range to an object utilizes a geometric optics determination of slight angular differences between two different ray trajectories to the object. This is most commonly done with the assumption of Euclidean or 'free-space' conditions. In this paper we utilize the phenomenon of inferior mirages to provide two different ray-paths to an imaging sensor. The primary assumption is that the environment containing the path from camera (or eye) to target is homogeneous (but not isotropic).

Optical free-space communications involving moving parties require precise beam pointing and mutual tracking of communicating transceivers. The existing variety of tracking techniques is still the major limiting factor in free-space laser communications. Here we propose a technique for optical beam tracking and shaping that utilize nonlinear optical properties of materials. In our proof-of-concept experiment a thin layer of a nematic liquid crystal (NLC) with high thermal nonlinearity was used to produce a thermal lens induced by the incoming optical beam. That beam modulated the NLC refractive index. As the transmitted optical beam passed through the same layer the beam intensity was modulated in the far field. A sharp intensity maximum was formed at the distant communicating party position proving the device's tracking capability. Numerical modeling showed very good agreement with the experiment. The technique offers - many advantages and is simple to implement.

Knowledge of optical properties of ice crystal particles of cirrus clouds is a challenging problem of atmospheric optics. Cirrus clouds cover, in average, 20%-30% of Earth's surface that leads to their essential impact of climate. Therefore these optical properties are needed for incorporation in up-to-date models of Earth's radiation budget and, consequently, they should be used in numerical models of climate prediction or climate change. The optical properties of ice crystal particles have been calculated for recent 20-30 years by a lot of authors under an assumption of 3-D orientation. However, the crystals often reveal a tendency to be oriented in the horizontal plane because of aerodynamic laws. Phase functions for light scattering by horizontally and preferably oriented hexagonal ice plates and columns are numerically calculated within the framework of geometric optics. The main quantitative properties of the halos (sundog, parhelion 120°, suncave Parry arc, sunvex Parry arc, and others) are obtained for a number of both incident light directions and aspect ratios of the plates and columns respectively. A parameterization of the phase functions in the parhelic, subparhelic and circumzenithal (circumhorizonthal) circles for the plates and all scattered energy for the columns are proposed based on the integral contributions of the narrow angular peaks (halos) that are tabulated as the weight coefficients. Our results can be used for atmospheric lidar observation for determining of size, shape distributions of the ice crystals particles in cirrus clouds. A method for retrieving aspect ratios of the plates by means of polarization measurements is discussed.

Commercial ranging systems (both beam modulation and pulsed time of flight systems) have an operating range and accuracy far below the needs for moving target system qualification testing and model validation. A new, eye-safe, long operating range, accurate (order of cm) ranging system must be developed. The most feasible approach to achieve this capability requires an ultrashort pulse laser system in conjunction with time-of-flight measurement methods. Accordingly, the Institute of Applied Physics and Sandia National Laboratories are developing an advanced ranging system for use in Sandia's mobile laser tracker for quantification of the flight dynamics of high speed moving targets. Key to this development is a new laser. This paper presents a new picosecond Raman laser capable of range measurements to 50 km with 1 cm accuracy in the presence of atmospheric turbulence.