ISR-2

RULLI (Remote Ultra-Low Light Imager) is a unique single photon imager with very high (microsecond) time resolution and continuous sensitivity, developed at Los Alamos National Laboratory. This technology allows a family of astrophysical and satellite observations that were not feasible in the past. We will describe the results of the analysis of recent observations of the LAGEOS II satellite and the opportunities expected for future observations of the Crab nebula. The LAGEOS/LARES experiments have measured the dynamical General Relativistic effects of the rotation of the earth, the Lense-Thirring effect. The major error source is photon thrust and a required knowledge of the orientation of the spin axis of LAGEOS. This information is required for the analysis of the observations to date, and for future observations to obtain more accurate measurements of the Lense-Thirring effect, of deviations from the inverse square law, and of other General Relativistic effects. The rotation of...

an affirmative actionlequal opportunity emptdyer, is operated by the University of California for the US. Department of Energy under contract W-7405-ENG-36. By acceptance of this article, the publisher recognizes that the US. Government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or to allow others to do so, for US. Government purposes. The Los Alarnos National Laboratory requests that the publisher identify this article as work performed under the auspices of the US. Department of Energy.

The remarkable temporal resolution of the Remote Ultra-Low Light Imaging (RULLI) sensor developed by Los Alamos.confEnal Laboratory has led to interest in exploiting this capability to perform 3-D imaging of satellites for improved Space Situational Awareness (SSA). Such a system would require a pulsed laser illuminator combined with an adaptive optics system. We have developed a simulation of such a

Remote Ultra-Low Light Imaging detectors are photon limited detectors developed at Los Alamos National Laboratories. RULLI detectors provide a very high degree of temporal resolution for the arrival times of detected photoevents, but saturate at a photo-detection rate of about 10 6 photo-events per second. Rather than recording a conventional image, such as output by a charged coupled device (CCD) camera, the RULLI detector outputs a data stream consisting of the two-dimensional location, and time of arrival of each detected photo-electron. Hence, there is no need to select a specific exposure time to accumulate photo-events prior to the data collection with a RULLI detector-this quantity can be optimized in post processing. RULLI detectors have lower peak quantum efficiency (from as low as 5% to perhaps as much as 40% with modern photocathode technology) than back-illuminated CCD's (80% or higher). As a result of these factors, and the associated analyses of signal and noise, we have found that RULLI detectors can play two key new roles in SSA: passive imaging of exceedingly dim objects, and three-dimensional imaging of objects illuminated with an appropriate pulsed laser. In this paper we describe the RULLI detection model, compare it to a conventional CCD detection model, and present analytic and simulation results to show the limits of performance of RULLI detectors used for SSA applications at AMOS field site.

We have developed a technique for laser tuning at rates of 100 kHz or more using a pair of acousto-optic modulators. In addition to all-electronic wavelength control, the same modulators also can provide electronically variable Q-switching, cavity length and power stabilization, chirp and linewidth control, and variable output coupling, all at rates far beyond what is possible with conventional mechanically tuned components. Tuning rates of 70 kHz have been demonstrated on a radio-frequency-pumped CO 2 laser, with random access to over 50 laser lines spanning a 17% range in wavelength and with wavelength discrimination better than 1 part in 1000. A compact tuner and Q-switch has been deployed in a 5-10-kHz pulsed lidar system. The modulators each operate at a fixed Bragg angle, with the acoustic frequency determining the selected wavelength. This arrangement doubles the wavelength resolution without introducing an undesirable frequency shift.

Feasibility of Microwave Interferometry and Fourier-Transform Spectrometry for High-Spectral-Resolution Sensing ... Sig Gerstl, NIS-DO Bradley Cooke, NIS-4 Abram Jacobson, NIS-1 Steven Love, NIS-2 Andrew Zardecki, NIS-7 ... DOE Office of Scientific ...

We survey recent developments in off-beam cloud lidar and especially the Wide Angle Imaging Lidar (WAIL) developed at Los Alamos National Laboratory (LANL). By abandoning the single backscattering assumption of standard (on-beam) lidar in favor of a multiple scattering model and with the appropriate modifications of the instrument, we enable detection robust detection of the cloud boundary opposite to the source, hence cloud thickness (as well as altitude). We can also determine a volumeaveraged extinction at 532 nm, hence mean cloud optical depth. Comparisons with Atmospheric Radiation Measurement (ARM) program instruments targeting the same cloud properties are already good and easily improvable. Finally, we describe several extensions of WAIL capability at various stages of planning and realization.

We describe a new type of lidar instrument, Wide-Angle Imaging Lidar (WAIL), designed to study and directly make use of multiple scattering in clouds. Providing time-resolved imagery over a 60°field of view, the new instrument captures returns at virtually all orders of scattering in a groundbased measurement. We report the first retrievals of cloud properties using this system, from measurements of a moderately opaque altostratus. Following insights from photon diffusion theory, we are able to infer the physical thickness and optical depth of the cloud layer, and, from there, obtain an estimate of the volume-averaged liquid water content. Performance of the new instrument is discussed and it is compared with other active techniques in cloud remote sensing.

The discovery of persistent spectral hole burning in the infrared vibrational modes of simple molecular impurities in the chalcogenide glasses, the first instances of non-electronic persistent hole burning in covalently bonded glasses, makes available a ...

The Wide-Angle Imaging Lidar (WAIL), a new instrument that measures cloud optical and geometrical properties by means of off-beam lidar returns, was deployed as part of a multi-instrument campaign to probe a cloud field at the Atmospheric Radiation Measurement (ARM) Southern Great Plain (SGP) site on 25 March 2002. WAIL is designed to determine physical and geometrical characteristics using the off-beam component of the lidar return that can be adequately modeled within the diffusion approximation. Using WAIL data, the extinction coefficient and geometrical thickness of a dense cloud layer is estimated, from which optical thickness is inferred. Results from the new methodology agree well with counterparts obtained from other instruments located permanently at the SGP ARM site and from the WAIL-like airborne instrument that flew over the site during our observation period.

This paper describes the design and characteristics of a scanning spectral polarimeter designed to measure spectral radiances and fluxes in the range between 0.4 and 4.0 m. The instrument characteristics are described, and the procedures to calibrate the unpolarized radiances and fluxes in the spectral range from 0.4 to 1.1 m are discussed along with detailed error analyses of this calibration. The accuracy of the radiance calibration was determined to be approximately 3%. The calibration of fluxes based on two different procedures is estimated to be accurate to 3%-6%. Detailed calibration of fluxes was performed using a standard lamp that is not an isotropic source. For this type of calibration the angular response of the flux channel deviates from a pure cosine function at wavelengths longer than 0.74 m, thus forming a frontal lobe. A less detailed calibration using a 40-in. integrated sphere was also performed. In that case the light source is isotropic and the frontal lobe does not appear. Calibration factors are derived by combining data from both calibration procedures. A comparison with spectral flux measurements obtained from different instruments with different angular response properties is presented with agreement that is within the quoted calibration accuracy. Measurements obtained from two different aircraft flights are presented to illustrate the types of application of the data. Data analyses shows that the reflected (unpolarized) fluxes measured above a cirrus cloud can be reasonably matched to modeled fluxes using optical properties retrieved from the measured (unpolarized) radiances.