No abstract available

No abstract available

[en] OAK-B135 Self-interference patterns and their application to inertial-fusion target characterization

[en] This Letter is a rebuttal of Kopeika's criticsm of our paper. To summarize the important points: We claimed that the magnitude of the optogalvanic effect (OGE) in U, Na, Eu, and Zr was independent of the ionization potential of the atom and depended on only the number of photons absorbed. Both mechanisms, increased electron temperature and direct ionization, undoubtably proceed simultaneously and the relative importance of one or the other probably depend on the experimental conditions. Our experiment has not demonstrated an increase in the electron temperature, rather our data appear to contradict the direct ionization mechanism in a hollow cathode discharge. More experimental evidence is necessary to determine the relative importance of the two mechanisms and their dependence on experimental conditions

[en] An easy formula for calculating both the approximate and (by iteration) the exact sagittal depth of a chord is presented

[en] This letter gives a theroetical justification for the method presented for detecting eccentricities in laser fusion targets. The problem is to detect nonconcentricites (eccentricities) of the inner and outer walls of the microspheres (called Type I defects). An algorithm for the detection is described

[en] The requirements and techniques for time- and space-resolved picosecond probing of laser-produced plasmas are reviewed. The design and limitations of a holographic microinterferometer are discussed, and optical pulse techniques are presented. This technique can provide significant data for understanding the absorption of energy within laser-produced plasmas. The primary requirements are to measure the electron densities in the 10²⁰--10²¹-e/cc range, with density contour velocities of 10⁶ to 10⁷ cm/sec and spatial resolution of 1 μm or better. For these velocities one requires a probe pulse duration of 3--30 psec, an UV wavelength as short as feasible, and large numerical aperture optics corrected for spherical aberration. Interferograms of laser-produced plasma obtained at 2660 A with a combined resolution of 1 μm and 15 psec are presented

[en] Two reprocessing techniques have been investigated that are capable of correcting the effects of nonoptimum optical density of photographic amplitude holograms recorded on Agfa-Gevaert type 10E75 plates. In some cases a reprocessed hologram will exhibit a diffraction efficiency even higher than that obtainable from a hologram exposed and processed to the optimum density. The SNR of the reprocessed holograms is much higher than that of the same holograms belached with cupric bromide. In some cases the SNR approaches the optimum value for a properly exposed amplitude hologram. Subjective image quality and resolution of reprocessed hologram reconstructins appear to be no different than for normal single-development holograms. Repeated reprocessing is feasible and in some cases desirable as a means of increasing diffraction efficiency

[en] A fringe visibility method for sizing particles 10 mm and larger has been developed. As the image of a particle scans across a variable frequency grid, the transmitted light signal oscillates with varying visibility. The visibility goes through a null at a well-defined point where the particle diameter approximates the local grid spacing. Several optical arrangements implementing the variable frequency grid technique have been tested. Using classified alumina and pulverized coal particles we obtained good agreement between size distributions measured by this technique and those from a commercial off-line analyzer. However, our optical arrangement and signal processing techniques require further development to reduce them to practice

[en] Reported here for the first time is the use of simultaneous airborne laser-induced fye fluorescence and the 3400-cm^-1 OH-stretch water Raman backscatter spectra to yield the absolute concentration of an ocean-dispersed tracer dye. Using a straightforward theoretical model, the concentration is calculated by numerically comparing the airborne laser-induced fluorescence and Raman backscatter spectra to similar laboratory data for a known dye concentration measured under comparable environmental and instrumental conditions. The dye is assumed to be uniformly mixed throughout the water column together with other interfering, fluorescent, organic matter. A minimum, detectable integrated water column dye concentration of approx.2 ppb by weight as limited by background and instrument noise is obtained. A dye concentration contour map produced from the conical scan lidar data is given