| A Compact, Pi-Mode Extraction Scheme for the Axial B-Field Recirculating Planar Magnetron |
23 Jul 2012 |
20 pages |
| Authors:
Brad W Hoff; M Franzi; D M French; G Greening; R M Gilgenbach; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
 | A recirculating planar magnetron (RPM), operating in the pi-mode and utilizing a compact, waveguide-based extraction scheme was simulated using ICEPIC. At an applied voltage of 300 kV and B-field of 0.140T, output power of the six-module RPM was 565 MW with 33% efficiency. The oscillator was found to operate at frequency of 2.245 GHz. Increasing the number of extracted modules in the RPM was found to result a linear increase ... |
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| Dielectric Nonlinear Transmission Line (Postprint) |
01 Dec 2011 |
6 pages |
| Authors:
David M French; Brad W Hoff; Susan Heidger; Don Shiffler; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| A parallel plate nonlinear transmission line (NLTL) was constructed. Periodic loading of nonlinear dielectric slabs provides the nonlinear capacitance and the gaps between provide linear inductive interconnects, this is essentially the same design used by Ikezi [1],[2]. The NLTL was modeled in a circuit simulation code using the experimentally measured form of the nonlinear capacitance. Dielectric loss included in the model as an equivalent series resistance derived from the measured ... |
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| Calibration Binaries |
Sep 2011 |
6 pages |
| Authors:
Jack D Drummond; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| Two Excel Spreadsheet files are offered to help calibrate telescope or camera image scale and orientation with binary stars for any time. One is a personally selected list of fixed position binaries and binaries with well-determined orbits and the other contains all binaries with published orbits. Both are derived from the web site of the Washington Double Star Library. The spreadsheets give the position angle and separation of the binaries ... |
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| Achievability of Cramer-Rao Lower Bounds by Multi-Frame Blind Deconvolution Algorithms, Part 2: PSF Estimation |
Sep 2011 |
10 pages |
| Authors:
Charles L Matson; Jr Beckner Charles C; Michael Flanagan; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| Cramer-Rao lower bound (CRB) theory can be used to calculate an algorithm-independent lower bound to the variance of any unbiased estimate of an unknown parameter. The theory also applies to joint estimation of multiple unknown parameters, to functions of estimates, and to estimates that have known bias gradients. CRBs are guaranteed to be lower bounds, but may not be achievable in practice. In particular, it is well known that algorithms ... |
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| Propagation of 3-D Beams Using a Finite-Difference Algorithm: Practical Considerations |
22 May 2011 |
12 pages |
| Authors:
Alan H Paxton; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| We discuss practical aspects of the use of the finite-difference, alternating-direction implicit (ADI), numerical solution of the paraxial wave equation, for the free-space propagation of light beams. Results of calculations solving the finite-difference equations are compared with fresnal-integral solutions. Calculations are for round beams, but the field is represented in cartesian coordinates. Modes for empty unstable resonators are also obtained using the finite-difference algorithm and are compared with fresnal-difference. |
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| Coherent Beam Combining of Fiber Amplifiers in a kW Regime |
21 APR 2011 |
8 pages |
| Authors:
Anthony D. Sanchez; Angel Flores; Thomas M. Shay; Chunte A. Lu; Craig Robin; Benjamin Pulford; Dane W. Hult; Ken B. Rowland; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| We report kW scale coherent beam combination (CBC) of both conventional silica fiber and photonic crystal fiber (PCF) amplifiers via LOCSET phase locking technology. Single-frequency CBC of 16 100W fiber lasers with 1.4 kW total output power is presented. In addition, kW scale CBC of novel SBS suppressive PCF amplifiers is presented. Three 350W PCF amplifiers arranged in a filled aperture configuration were combined into a single kW level laser ... |
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| Experimental and Computational Investigation of a Gas Laser Pressure Recovery System Diffuser |
08 Feb 2011 |
16 pages |
| Authors:
Carrie Noren; Theordore Ortiz; Michael Wilkinson; Wade Klennert; Timothy Madden; Richard Chan; H W Behrens; Robert Watler; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| A diffuser, with the purpose of efficiently recovering pressure from a gas laser system, was designed and studied. A diffuser, as part of a pressure recovery system, is used in a gas laser system to transition the laser cavity's low pressure to the ambient pressure outside the device. The diffuser studied here is made up of constant-area supersonic section and a diverging subconic section. The diffuser is studied experimentally with ... |
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| Thermal Management Investigations in Ceramic Thin Disk Lasers |
14 Jan 2011 |
12 pages |
| Authors:
William P Latham; N Vretenar; T Carson; A Lobad; P Peterson; T C Newell; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| Directed Energy Applications for thin disk lasers demand improvements in materials, efficiency, thermal management, and most importantly beam quality. At the Air Force Research Laboratory ceramic Yb:YAG materials are being investigated along with various cooling techniques. 10-14mm diameter 0.2mm thick disks are mounted on silicon carbide (SiC), sapphire, and diamond submounts. From a larger platform, more than 6kW power is obtained from unmounted and submounted 35mm diameter disks. In conjunction ... |
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| 6.5 kW, Yb:YAG Ceramic Thin Disk Laser |
14 Jan 2011 |
12 pages |
| Authors:
William P Latham; Ahmed Lobad; Tim Newell; Don Stalnaker; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| The operation of a 1030 nm, single, thin disk laser which produced 6.5 kW of laser output power with 57 percent slope efficiency is reported. The Yb:YAG ceramic gain element is 200 micrometer thick, bonded to a 1 mm, undoped, ceramic YAG cap. The gain element is pumped by diodes at 940 nm. The maximum incident pump intensity was 5 kW/cm2, which yielded an output intensity of 2.6 kW/cm2 of ... |
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| Measurements of Tilt and Focus for Sodium Beacon Adaptive Optics on the Starfire 3.5 Meter Telescope |
Sep 2010 |
9 pages |
| Authors:
ROBERT JOHNSON; James Brown; James Spinhirne; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| Telescopes with adaptive optics systems can measure high-order aberrations using an artificial laser beacon without the need for a relatively bright object near the object being imaged. Unfortunately, tilt and focus measurements are difficult to obtain from a laser beacon. One solution is to use light from the object being imaged to measure tilt and focus. We characterize the performance of a Shack-Hartmann wavefront sensor with 2x2 sub-apertures for measuring ... |
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| The Long Wavelength Array (LWA): A Large HF/VHF Array for Solar Physics, Ionospheric Science, and Solar Radar |
Sep 2010 |
12 pages |
| Authors:
Namir E Kassim; Stephen M White; Paul Rodriguez; Jacob M Hartman; Brian C Hicks; Joseph Lazio; Kenneth P Stewart; Joseph Craig; Gregory B Taylor; Charles Cormier; Van Romero; Fredrick Jenet; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
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| The Long Wavelength Array (LWA), currently under construction in New Mexico, will be an imaging HF/VHF interferometer providing a new approach for studying the Sun-Earth environment from the surface of the sun to the Earth's ionosphere. The LWA will be a powerful tool for solar physics and space weather investigations, through its ability to characterize a diverse range of low-frequency, solar-related emissions, thereby increasing our understanding of particle acceleration and ... |
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| First Resolved Images of a Spacecraft in Geostationary Orbit with the Keck-II 10 m Telescope |
Sep 2010 |
7 pages |
| Authors:
Jack D Drummond; Richard H Rast; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| Resolved images of a geostationary satellite were obtained on October 30 2009, with the adaptive optics on the largest telescope on the planet, the 10 m Keck-II on the 14000 foot summit of Mauna Kea. As part of an engineering run at the Keck-II 10 m telescope on Mauna Kea, several adaptive optics images were obtained of geostationary satellite GE-23, a Spacebus 4000C3 built by Alenia Space, with solar panels ... |
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| An Experimental Study Showing the Effects on a Standard PI Controller Using a Segmented MEMS DM Acting as a MOD(lambdal) Device: Postprint |
01 Jul 2010 |
16 pages |
| Authors:
Julie C Smith; James Brown; Darryl J Sanchez; Denis W Oesch; Patrick Kelly; Katia Shtyrkova; Carolyn M Tewksbury-Christle; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| The ASALT lab has been investigating the use of a segmented MEMS DM in adaptive optics systems. One of the anticipated benefits of a segmented device is that in monochromatic light the throw is essentially infinite due to the modulo 2Pi nature of the device. Earlier work demonstrated how this modulo 2Pi behavior interacts unexpectedly with a standard proportional integral controller. Here we present experimental data on this effect to ... |
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| The Aggregate Behavior of Branch Points - A Proposal for an Atmospheric Turbulence Layer Sensor: Postprint |
01 Jul 2010 |
20 pages |
| Authors:
Darryl J Sanchez; Denis W Oesch; Carolyn M Tewksbury-Christle; Patrick R Kelly; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| We propose a sensor that measures the number, strength, altitude and velocity of atmospheric turbulence layers. Recent research has shown that pupil plane branch points contain four independent and measureable parameters and that these four parameters can be used to estimate four independent turbulence layer parameters--number, strength, altitude and velocity--for each atmospheric turbulence layer. Here, we summarized previous results and then demonstrate how these results allow for construction of a ... |
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| Simulation of High Power Lasers (Preprint) |
01 Jun 2010 |
20 pages |
| Authors:
Timothy J Madden; Robert K Decker; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| The time-dependent, chemically reacting, viscous fluid dynamics within gas laser mixing systems and pressure recovery systems are simulated using the unsteady, laminar and turbulent multi-component Navier-Stokes equations. The solutions of these equations are generated within simulations of the relevant laser sub-systems at standard operating conditions. The simulations are performed to provide greater insight regarding the physical processes underlying these sub-systems so that these physics may be exploited to improve performance. ... |
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| Experimental Demonstration of Real Time Gradient Gain Correction for Sodium Beacon Laser Guide Star: Postprint |
01 Jun 2010 |
20 pages |
| Authors:
Katia Shtyrkova; Michael D Oliker; Kevin P Vitayaudom; Denis W Oesch; Darryl J Sanchez; Patrick R Kelly; Carolyn M Tewksbury-Christle; Julie C Smith; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| One of the problems associated with the use of the sodium laser guide star as a beacon for an adaptive optics system is the changes in the sensitivity of the wavefront sensor caused by the extended nature of the sodium layer. Shack-Hartmann wavefront sensors use quad cell detectors to estimate the amount of x- and y- gradients in each sub-aperture. The gradients are multiplied by a constant gain factor that ... |
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| The Aggregate Behavior of Branch Points - Altitude and Strength of Atmospheric Tubulence Layers: Postprint |
01 Jun 2010 |
18 pages |
| Authors:
Denis W Oesch; Darryl J Sanchez; Carolyn M Tewksbury-Christle; Patrick R Kelly; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| In earlier work we have shown that pupil plane branch points carry information about the conditions of the atmospheric turbulence. Experiments in the Atmospheric Simulation and Adaptive-optic Laboratory Test-bed (ASALT) at the Air Force Research Laboratory. Directed Energy Directorate's Starfire Optical Range have shown that branch points can provide the number and velocity of turbulence layers. Here we demonstrate that these measurements can further be used to estimate the turbulence ... |
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| Experimental Analysis of Diffraction Effects from a Segmented MEMS Deformable Mirror for a Closed Loop Adaptive Optics System |
01 Jun 2010 |
18 pages |
| Authors:
Katia Shtyrkova; Loretta Arguello; Denis Oesch; Darryl J Sanchez; Patrick Kelly; Carylon Tewksbury-Christle; Julie Smith; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| Micro-Electro-Machined Systems (MEMS) have been increasingly used as mirrors in place of conventional continuous face sheet deformable mirrors (DM) in adaptive optics (AO) systems. Here we study the diffraction effects introduced into the optical path when a segmented MEMS DM is used to correct for the wavefront aberrations. Diffraction effects are monitored through the intermediate focus plane prior to the wavefront sensor. Low pass spatial filter is used at the ... |
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| SNR Limits to Achieving the Cramer-Rao Lower Bounds with PCID |
01 Jan 2010 |
46 pages |
| Authors:
Chuck Matson; Mike Flanagan; Tony Vincent; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| We conducted this research to better understand how Cramer-Rao lower bounds can be used to understand the performance of multi-frame blind deconvolution algorithms such used to understand the performance of multi-frame blind deconvolution algorithms such as PCID. It was clear from previous results that we generated that the image-domain sample variances from PCID deviated from the CRBs significantly more than was expected given the signal-to-noise ratios of the data. It ... |
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| Power Enhancement of a Rubidium Vapor Laser With a Master Oscillator Power Amplifier (Postprint) |
15-Sep-2009 |
6 pages |
| Authors:
David A Hostutler; Wade L Klennert; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| A master oscillator power amplifier (MOPA) with variable amplifier gain lengths was built to demonstrate power enhancement of an alkali vapor laser. A small signal gain of 0.91 / cm for two different gain lengths was observed. For a 2 cm long amplifier gain length an amplification of 7.9 dB was observed. |
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| Comparing Speckle Imaging Methods |
Sep 2009 |
11 pages |
| Authors:
Gregory C Dente; Michael L Tilton; Andrew P Ongstad; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| We will compare speckle imaging reconstruction results for several speckle imaging approaches. In particular, we will compare and contrast four methods: 1) Knox-Thompson, using a hidden phase-finder in the object spectrum phase reconstruction; 2) Knox-Thompson, using a phasor-based phase reconstruction; 3) Bispectrum, using only two bispectrum planes; Bispectrum, using four bispectrum planes. In each application of the four approaches we first calculate the modulus of the object spectrum using a ... |
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| The Balloon Ring: A High-Performance Low-Cost Instrumentation Platform for Measuring Atmospheric Turbulence Profiles (Postprint) |
22 Jun 2009 |
16 pages |
| Authors:
Demos T Kyrazis; Frank D Eaton; Don G Black; Wiley Black; Alastair Black; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| Balloons, similar to those used for meteorological observations, are commonly used to carry a small instrumentation package for measuring optical turbulence in the atmosphere as a function of altitude. Two temperature sensors, one meter apart, measure a single point of the temperature structure function. The raw data is processed to provide the value of cr2, and the results transmitted to a ground receiving site. These data are converted to the ... |
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| The Aggregate Behavior of Branch Points I - The Creation and Evolution of Branch Points (Postprint) |
19-Jun-2009 |
18 pages |
| Authors:
Darryl J Sanchez; Denis W Oesch; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| It has long been known that branch points cause degradation in adaptive optic performance. Here, we begin a study on the aggregate nature of branch points, specifically beginning the process to relate branch points measured in the pupil to the upstream turbulence that created them. As such, we study not only the wave as measured in the telescope's pupil, but also the wave in the intervening region between the turbulence ... |
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| Experimental Analysis of Perspective Elongation Effects Using a Laser Guide Star in an Adaptive-Optics System (POSTPRINT) |
01 Jun 2009 |
14 pages |
| Authors:
Kevin P Vitayaudom; Darryl J Sanchez; Denis W Oesch; Patrick R Kelly; Carolyn M Tewksbury-Christle; Julie C Smith; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| The use of a laser guidestar (LGS) for the purpose of a beacon in an adaptive-optics (AO) system is prone to perspective elongation effects on the spots of a Shack-Hartmann wavefront sensor. The elongated spots can vary in size over the subapertures and affect the gradient sensitivity of the sensor. The Air Force Research Laboratory (AFRL) has developed a LGS model that outputs gradient gains which represent the effects of ... |
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| The Aggregate Behavior of Branch Points - Branch Point Density as a Characteristic of an Atmospheric Turbulence Simulator (postprint) |
01 Jun 2009 |
14 pages |
| Authors:
Denis W Oesch; Darryl J Sanchez; Carolyn M Tewksbury-Christle; Patrick R Kelly; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| The atmospheric turbulence simulator used in testing in the atmospheric simulation and adaptive-optic laboratory test-bed at Starfire Optical Range is configured based on three characteristics: Fried's parameter, the Rytov number and the Greenwood Frequency. All three may be estimated from open loop data as a means of verifying the simulated turbulence conditions for a given test configuration. However, unlike Fried's parameter and the Greenwood Frequency the Rytov number isn't directly ... |
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| Misregistration in Adaptive Optics Systems |
01 Jun 2009 |
16 pages |
| Authors:
Nathan Engstrom; D; Jason D Schmidt; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| An adaptive optics (AO) system is most effective when there is a known alignment between the wave front sensor (WFS) and the deformable mirror (DM). Misregistration is the term for the unknown alignment between the WFS and DM. Misregistration degrades system performance and can make the system unstable. An AO system uses a reconstruction matrix that to transform WFS measurements into DM commands. A standard AO system uses a model ... |
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| A New Sodium Guidestar Adaptive Optics System for the Starfire Optical Range 3.5 m Telescope (Postprint) |
18-May-2009 |
6 pages |
| Authors:
ROBERT JOHNSON; Dennis Montera; Timothy Schneeberger; James Spinhirne; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| A new adaptive optics is being installed on the Starfire 3.5 m telescope. Its uses the existing 50 watt pump to create a sodium guidestar. Transmission to the wavefront sensor is improved from 0.16 to 0.75. |
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| Materials Characteristics and Surface Morphology of a Cesium Iodide Coated Carbon Velvet Cathode (POSTPRINT) |
31 Mar 2009 |
26 pages |
| Authors:
Don Shiffler; Susan Heidger; Keith Cartwright; Rich Vaia; David Kiptak; Gary Price; Matthew Lacour; Ken Golby; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| Cesium Iodide (CsI) coated carbon fiber cathodes have shown promise as a cold cathode for microwave and x-ray devices. In particular, the cathodes have demonstrated over 1 million shots lifetime at operating voltages at or in excess of 165 kV and current densities greater than 25 A/cm2. While the vacuum emission characteristics have been well studied, the materials characteristics of the cathodes themselves, particularly after operation have received little attention. ... |
|
| An Investigation of a Gas Laser Pressure Recovery System Diffuser |
19-Dec-2008 |
10 pages |
| Authors:
Carrie A Noren; Theodore Ortiz; Michael Wilkinson; Wade Klennert; Timothy J Madden; Richard W Chan; H W Behrens; Robert Walter; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| A diffuser, with the purpose of efficiently recovering pressure from a gas laser system, was designed and studied. A diffuser, as part of a pressure recovery system, is used in a gas laser system to transition the laser cavity's low pressure to the ambient pressure outside the device. The diffuser studied here is made up of a constant-area supersonic section and a diverging subsonic section. The diffuser is studied experimentally ... |
|
| A Comparison of Multi-Frame Blind Deconvolution and Speckle Imaging Energy Spectrum Signal-to-Noise Ratios (Preprint) |
11-Sep-2008 |
14 pages |
| Authors:
Charles L Matson; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| An analytical signal-to-noise ratio (SNR) expression is derived for unbiased estimates of energy spectra obtained using multi-frame blind deconvolution (MFBD) algorithms. Because an analytical variance expression cannot, in general, be derived, Cramer-Rao lower bounds are used in place of the variances. As a result, the SNR expression provides upper bounds to the achievable SNRs that are independent of the MFBD algorithm implementation. The SNR expression is evaluated for the scenario ... |
|
| Measuring Tilt and Focus for Sodium Beacon Adaptive Optics on the Starfile 3.5 Meter Telescope -- Conference Proceedings (Preprint) |
01-Sep-2008 |
10 pages |
| Authors:
ROBERT JOHNSON; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| Adaptive optics systems can measure high-order aberrations using an artificial laser beacon without the need for a relatively bright object near the object being imaged. Unfortunately, tilt and focus measurements are difficult to obtain from a laser beacon. One solution is to use light from the object being imaged to measure tilt and focus. Through analysis, I estimate the performance of using a Shack-Hartmann wavefront sensor with 2 by 2 ... |
|
| AO Images of Asteroids, Inverting their Lightcurves, and SSA |
Sep 2008 |
11 pages |
| Authors:
Jack Drummond; Julian Christou; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| In a program to study asteroids with large telescopes, we have recently obtained images of Main- Belt asteroids with adaptive optics (AO) on the Keck-II 10 meter telescope, the world's largest. Although generally featureless as expected, these images show irregular asteroid outlines, and by following the changing size and orientation we have been able to deduce their full triaxial ellipsoid dimensions and spin axis direction in less than one night. ... |
|
| Iao: The New Adaptive Optics Visible Imaging and Photometric System for AEOS |
Sep 2008 |
11 pages |
| Authors:
Mark A Skinner; Fred Anast; John Mooney; Daryn Kono; Lewis C Roberts; Arthur Hassall; Scott Hunt; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| The Iao camera is a totally new camera system that will be replacing the existing visible imager (VisIM) camera. It functions as the science camera, and is capable of collecting uncompensated, as well as adaptive-optics compensated images. Iao offers a number of improvements over the existing system, including higher speed, greater sensitivity, as well as improved flexibility in control of the imaging system. We describe the Iao camera system, the ... |
|
| A Modular Control Platform for a Diode Pumped Alkali Laser |
Sep 2008 |
10 pages |
| Authors:
Joshua Shapiro; Scott W Teare; David A Hostutler; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| Many of the difficulties of creating compact, high power laser systems can be overcome if the heat dissipating properties of chemical lasers can be combined with the efficiency of diode lasers. Recently, the novel idea of using solid state diode lasers to pump gaseous gain media, such as is done in diode pumped alkali lasers (DPALs), has been proposed and early experiments have shown promising results. However, a number of ... |
|
| Autonomous Global Sky Surveillance with Real-Time Robotic Follow-up: Night Sky Awareness through Thinking Telescopes Technology |
Sep 2008 |
10 pages |
| Authors:
W T Vestrand; Heath Davis; James Wren; Przemek Wozniak; Ben Norman; Robert R White; Jeff Bloch; Edward Fenimore; Barry Hogge; Moriba Jah; Richard Rast; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| We discuss the development of prototypes for a global grid of advanced thinking sky sentinels and robotic follow-up telescopes that observe the full night sky to provide real-time monitoring of the night sky by autonomously recognizing anomalous behavior, selecting targets for detailed investigation, and making real-time, follow-up observations. The layered, fault-tolerant, network uses relatively inexpensive robotic EO sensors to provide persistent autonomous monitoring and real-time anomaly detection to enable rapid ... |
|
| Investigation of Closed Loop Adaptive Optics with the Deformable Mirror not in Pupil- Part 2: Theory (POSTPRINT) |
01 Jul 2008 |
17 pages |
| Authors:
Darryl J Sanchez; Katherine Lilevjen; Troy Rhoadarmer; Mala Mateen; Denis Oesh; Charles Beckner; Deborah Fung; Patrick Kelly; R A Vincent; Roger Petty; Loretta Arguello; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| This is the second of two papers discussing aspects of placing the deformable mirror in a location not conjugate to the pupil plane telescope. The Starfire Optical Range, Air Force Research Laboratory is in the process of developing a high efficiency adaptive optics (AO) system for its 3.5m telescope. The objective is to achieve maximum optical throughput while maintaining diffraction limited performance. This can be achieved by minimizing the number ... |
|
| Broadening of the I2P1/2 P3/2 Transition Lineshape by Unsteady Vortex Motion (Postprint) |
24 Jun 2008 |
20 pages |
| Authors:
Timothy J Madden; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| The spectroscopically measured lineshape of an atomic transition provides a wealth of useful information relative to diagnosing The use of atomic transition lineshapes to ascertain the temperature of a gas stems to the 1920s, particularly within the astronomical community. Indeed, this community was the first to recognize the potential contribution of large scale bulk motion of the gas to the breadth of the spectroscopic measurement of transition lineshapes beyond that ... |
|
| Quantitative Mixing Measurements of a Supersonic Injection COIL Nozzle with Trip Jets |
13-Jun-2008 |
170 pages |
| Authors:
Carrie A Noren; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| A supersonic nozzle with supersonic iodine injection was designed and studied with Planar Laser-Induced Fluorescence (PLIF). The nozzle simulates Chemical Oxygen Iodine Laser (COIL) flow conditions with non-reacting, cold flows. A laser sheet near 565 nm excited the iodine, and the fluorescence was imaged with an intensified and gated CCD camera. Streamwise and semi-spanwise (oblique-view) images were taken, where the presence of injected flow was highlighted. With these images, the ... |
|
| A Fast and Optimal Multi-Frame Blind Deconvolution Algorithm for High-Resolution Ground-Based Imaging of Space Objects--Journal Article (Preprint) |
01-Apr-2008 |
47 pages |
| Authors:
Charles L Matson; Kathy Borelli; Stuart Jefferies; Beckner; Charles C Jr; E K Hege; Michael Lloyd-Hart; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| We report on a multi-frame blind deconvolution algorithm that we have developed for imaging through the atmosphere. The algorithm has been parallelized to a significant degree for execution on high-peformance computer, with an emphasis on distributed-memory systems so that it can be hosted on commodity clusters. As a result, image restorations can be obtained in seconds to minutes. We have compared the quality of its output to the associated Crammer-Rao ... |
|
| Energy Losses in Simulated Relativistic Michigan A6 Magnetron with Shaped Cathode |
Apr-2008 |
2 pages |
| Authors:
Peter Mardahl; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| Recently there has been much research interest in improving magnetron performance by employing various priming techniques, such as shaped cathodes and nonuniform magnetic fields. These priming techniques have been successfully applied to reduce magnetron noise and improve mode-locking and efficiency. Inserting a shaped cathode into the simulated Michigan magnetron yields a maximum efficiency (the radiofrequency (RF) output power for a cycle divided by the current times voltage input for that ... |
|
| Development of Numerical Simulation Methods for Analysis of Laser Guided Arc Discharge |
29-Feb-2008 |
46 pages |
| Authors:
William Page; William Zimmerman; Brian Fisk; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| Modeling of the Use of USP laser pre-ionization as a guide path for a high voltage discharge in air was addressed. The physical processes involved are complex and span many orders of magnitude in the temporal and spatial resolution that must be considered. A two dimensional simulation model was produced that treats the problem in different time regimes with suitable approximations. The theoretical models and numerical models developed are described ... |
|
| An Algorithm-Independent Analysis of the Quality of Images Produced Using Multi-Frame Blind Deconvolution Algorithms--Conference Proceedings (Postprint) |
01-Sep-2007 |
10 pages |
| Authors:
Charles Matson; Alim Haji; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| Multi-frame blind deconvolution (MFBD) algorithms can be used to generate a deblurred image of an object from a sequence of short-exposure and atmospherically-blurred images of the object by jointly estimating the common object and all the blurring functions. In this paper we present fundamental limits (Cramer-Rao lower bounds) to the quality of restored images generated with MFBD algorithms. We show that image restorations are less noisy when using a Zemike-based ... |
|
| Stimulated Brillouin Scattering (SBS) Suppression Techniques |
31 JUL 2007 |
28 pages |
| Authors:
Michael W. Zmuda; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| In an effort to increase SBS threshold for future high power fiber amplifier applications, several mitigation techniques have been evaluated and modeled. Among these techniques include novel modulation schemes, core material modifications, and utilization of the core thermal differential during amplification. The most promising techniques were combined to provide an estimated increase in SBS threshold by over a decade. |
|
| Mid-Infrared Optically Pumped, Unstable Resonator Lasers (Postprint) |
19 JUN 2007 |
5 pages |
| Authors:
A. P. Ongstad; R. Kaspi; G. C. Dente; M. L. Tilton; J. Chavez; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
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| The authors describe high-brightness, broad area midinfrared semiconductor lasers. These devices were fabricated in the authors laboratory using a commercial solid-source molecular beam epitaxial system. The laser structures incorporated 14 type-II quantum wells embedded in thick waveguide/ absorber regions composed of In0.2Ga0.8As0.18Sb0.82. The optically pumped devices achieved higher brightness operation as unstable resonators. Each unstable resonator was realized by polishing a diverging cylindrical mirror at one of the facets. For ... |
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| Noise Reduction in Support-Constrained Multi-Frame Blind-Deconvolution Restoration as a Function of the Number of Data Frames and the Support Constraint Sizes |
01 Jun 2007 |
5 pages |
| Authors:
Charles L Matson; Alim Haji; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
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| We show that the amount of relative noise reduction in multi-frame blind deconvolution image restorations is greatest for just a few data frames and is a more complicated function of the support constraint sizes. |
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| Chemical Oxygen-Iodine Laser Device Simulation Using the 3D, Unsteady Navier-Stokes Equations |
Jun 2007 |
9 pages |
| Authors:
Timothy J Madden; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
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| The time-dependent, chemically reacting, viscous fluid dynamics within the chemical oxygen-iodine laser (COIL) flow field are simulated using the unsteady, laminar, multi-component Navier-Stokes equations. The solutions of these equations are generated within simulations of COIL hardware at standard operating conditions; conditions predicted in previous simulations to be unsteady. These current simulations ascertain the effect of the flow unsteadiness upon the laser gain through Doppler broadening of the spectral lineshape induced ... |
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| Mid-Infrared Optically Pumped, Unstable Resonator Lasers (Preprint) |
31 MAY 2007 |
13 pages |
| Authors:
A. P. Ongstad; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
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| The authors describe high-brightness, broad area midinfrared semiconductor lasers. These devices were fabricated in the authors laboratory using a commercial solid-source molecular beam epitaxial system. The laser structures incorporated 14 type-II quantum wells embedded in thick waveguide/ absorber regions composed of In0.2 Ga0.8 As0.18 Sb0.82. The optically pumped devices achieved higher brightness operation as unstable resonators. Each unstable resonator was realized by polishing a diverging cylindrical mirror at one of ... |
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| High-Efficiency Diode-Pumped Rubidium Laser: Experimental Results (Preprint) |
29 JAN 2007 |
8 pages |
| Authors:
Ty A. Perschbacher; David A. Hostutler; Thomas M. Shay; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
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| A diode-pumped rubidium laser with an optical slope efficiency of 69% has been constructed. This study utilized a narrow-line diode laser pump source for the experiments. The trade space study included optimization of various parameters such as lasing cell composition, temperature, and output coupler reflectivities. The results of the experimental study are given. |
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| Noise Reduction in Support-Constrained Multi-Frame Blind-Deconvolution Restorations as a Function of the Number of Data Frames and the Support Constraint Sizes (Preprint) |
06 DEC 2006 |
6 pages |
| Authors:
Charles Matson; Alim Haji; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
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| Multi-frame blind deconvolution (MFBD) algorithms seek to estimate jointly an object being imaged along with all the system point spread functions (PSFs) present in the measured data frames. It is well known that the quality of an object restoration improves as the number of data frames included in the restoration process is increased and as the sizes of the support constraints used in the algorithm decrease in size (while still ... |
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| Temperature Effects on the Emission Properties of Yb-Doped Fiber (Postprint) |
29 Nov 2006 |
9 pages |
| Authors:
T C Newell; P Peterson; A Gavrielides; M P Sharma; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
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| Ytterbium-doped fiber lasers are making impressive leaps in power production. Yet in spite of fibers large surface area to volume ratio which is beneficial for cooling, such power inevitably leads to high core temperatures that in turn affect the laser performance. In this letter, the temperature effects on the emission and fluorescence lifetime of ytterbium doped optical fibers are investigated. From these the temperature dependent emission and absorption cross sections ... |
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