NASA Scientific and Technical Aerospace Reports

used to generate a Ne-like Fe transient gain x-ray laser that is recorded simultaneously. A spherically-curved crystal
spectrometer gives high resolution x-ray spectra of the n= 3-2 and n= 4-2 resonance lines with 1-D spatial resolution along
the line focus. Spectra are presented for different laser pulse conditions. In addition, a variety of x-ray imaging techniques are
described. We discuss imaging results from a double-slit x-ray camera with a spherically-curved crystal spectrometer. We
show a high resolution Fe K-(alpha) spectrum from the x-ray laser target that indicates the presence of hot electrons in the
x-ray laser plasma.
NTIS
X Ray Lasers; Spectroscopy
20040071097 Lawrence Livermore National Lab., Livermore, CA
Influence of Subsurface Cracks on Laser Induced Surface Damage
Feit, M. D.; Rubenchik, A. M.; Nov. 07, 2003; In English
Report No.(s): DE2004-15005753; UCRL-CONF-153481; No Copyright; Avail: National Technical Information Service
(NTIS)
Cracks can affect laser damage susceptibility in three ways. These are field intensification due to interference, enhanced
absorption due to trapped material in the cracks, and increased mechanical weakness. Enhanced absorption is the most
important effect. The purpose of this report is to describe the ways in which near surface cracks can affect laser-induced
damage susceptibility. It is organized according to the three necessary conditions for macroscopic damage listed above. Laser
beam intensification due to either electromagnetic boundary conditions at crack walls or to total internal reflection at cracks
and free surfaces along with interference increases the available light energy density. Particulate matter, especially that derived
from polishing, can be trapped in cracks. Together with chemical bond changes at crack walls, such trapping adds absorbing
centers near the surface. Finally, the presence of cracks mechanically weakens the material making it easier to cause
macroscopic damage for given energy input. We consider both intrinsic (dielectric breakdown) and extrinsic (absorption by
small particles) mechanisms. We find that enhanced absorption due to either particulate matter trapped in cracks or clusters
of oxygen deficient chips formed during crack formation are the most likely source of the crack related damage enhancement
in fused silica surface damage.
NTIS
Laser Damage; Cracks
20040073598 Naval Command, Control and Ocean Surveillance Center, San Diego, CA
Underwater Docking of Autonomous Undersea Vehicles Using Optical Terminal Guidance
Cowen, Steve; Briest, Susan; Dombrowski, James; Oct. 1997; 6 pp.; In English
Report No.(s): AD-A422445; No Copyright; Avail: CASI; A02, Hardcopy
Missions in which an autonomous undersea vehicle docks with an underwater node for the purpose of battery recharging
and/or data transfer greatly increase the scope of potential applications possible with UUV’s. Robust and accurate vehicle
guidance to a small, simple and reliable docking structure is a critical capability which must be developed in order to achieve
this end. This paper describes a simple but highly effective underwater vehicle guidance scheme which is based upon an
optical quadrant tracker which locks onto a visible light source located at the dock in the same manner as a Sidewinder
air-to-air missile tracks its target in air. An optical terminal guidance system based upon this concept was developed by NRaD.
Optical guidance and docking was demonstrated using two autonomous underwater vehicles: a SeaGrant Odyssey IIB and the
NRaD flying Plug. The optical docking system was demonstrated to be accurate and robust for vehicle terminal guidance
during field operations and provided targeting accuracy on the order of 1 centimeter under real- world conditions, even in
turbid bay water. Such a system is projected to provide reliable terminal vehicle guidance to an underwater dock from a
maximum acquisition range of approximately 100 meters in typical continental shelf ocean water.
DTIC
Autonomy; Spacecraft Docking; Terminal Guidance; Underwater Vehicles
20040073731 Oregon Univ., Eugene, OR
Optical Processes in High-Q Semiconductor Microcavities
Wang, Hailin; Mar. 22, 2004; 15 pp.; In English; Original contains color illustrations
Contract(s)/Grant(s): DAAD19-00-01-0393
Report No.(s): AD-A422647; ARO-40671.1-PH-QC; No Copyright; Avail: CASI; A03, Hardcopy
This final progress report summarizes research efforts in two areas: cavity QED of quantum dots and electromagnetically
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