High power,single frequency operation of a Q-switched TEM00 Mode NdYAG laser

An actively Q-switched NdYAG laser, using a telescopic resonator configuration has produced single longitudinal mode, TEM₀₀ outputs of 100 mJ with output pulses free from any observable mode-beating.     

In-beam implantation of iron into germanium in an external magnetic field studied by the Mössbauer effect

In order to determine whether the doublet observed in the Mössbauer spectra of⁵⁷Fe after in-beam, recoil implantation into Ge is due to a quadrupole interaction or corresponds to two implantation sites, this implantation experiment was performed in the presence of a 35 kG external magnetic field. The resulting Mössbauer spectrum favors a dominant quadrupole interaction hypothesis.     

Performance of a Nd: YAG oscillator/ampflifier with phase-conjugation via stimulated Brillouin scattering

Phase conjugation via stimulated Brillouin scattering in CH₄ gas has been used to correct amplifier aberrations in a Nd: YAG oscillator/amplifier system. The single amplifier stage has been used in two-pass and four-pass arrangements. Using the four-pass arrangement incorporating compensation for thermal birefringence, a single-frequency diffraction-limited output of 350 mJ, in a compressed 6 ns pulse is achieved at 15 Hz repetition rate.     

Some electrical properties of wood pulp treated with sodium hydroxide

The effect of the degree of crystallinity and degree of polymerization on the electrical properties of soda-treated wood pulp has been investigated. The dielectric constant (E′) and the dielectric loss (E″) were measured for the treated samples over a frequency band 0.2–10 MHz at 20°C. Also, the electrical conductivity (σ) was calculated from the measured data of the dielectric constant. From the results obtained we found that the degree of crystallinity and the degree of polymerization decrease with time of oxidation while the number of carboxylic groups increased. E″,E′, and σ were found to increase with the decrease in the degree of crystallinity.     

Human efficiency for visual detection of targets on cathode ray tube displays using a two-level multiple-channel time history format.

Human observers were tested for their ability to detect targets on visual displays. The displays simulated the multiple-channel time history format, using two levels of intensity encoding. A target was presented on 50% of the trials at a constant bearing. Observers indicated their judgment as to whether a target was present by using a four-category rating scale. Receiver-operating characteristics (ROCs) were generated from the rating data and compared to ROCs for an optimal detector. In experiment I, data were collected for two signal-to-noise ratios and for 32, 64, and 128 lines of data. Results indicated that observers were 3-5 dB less sensitive than an optimal detector. Performance improved as the number of lines increased but not to the extent predicted by optimal integration of information across lines of the display. In experiment II, the bearing at which subjects judged whether a target was present, was clearly delineated from the background by encoding information presented at this bearing in red. The purpose of experiment II was to determine the degree to which human inefficiency in detecting targets is due to the inability to focus on a single column of data. Subject performance improved when the red encoding was utilized, but subjects still performed 2 dB below ideal. This suggests that subjects use a suboptimal decision rule for judging the presence of the target.     

Free-field attenuation of earmuffs and earplugs both singly and in combination

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Cost Comparisons for Out-of-Phase Inventory Models

Inventory costs for a fixed time period have traditionally been determined by allocating total costs per cycle uniformly throughout that cycle as well as any partial cycles. This procedure for cost allocation has led to the solution of numerous inventory problems, most notable of which is the anticipated price-increase model. When comparing two out-of-phase inventory models, if costs are accounted for when they occur over a fixed planning horizon, inventory policies should be changed to reflect the impact of this different cost-allocation procedure. For the anticipated price-increase model, the ‘optimal’ order quantity as well as the implied savings in inventory costs will be different when cost models are developed based on these different cost-allocation methods. If the objective is to maximize over a fixed planning horizon the actual savings in inventory costs as they occur, the cost models presented here should be used.     

Stable single-mode operation of a Q-switched laser by a simple resonator length control technique

A simple extension to the technique of “pre-lase” Q-switching ensures that a TEM₀₀ mode, Q-switched NdYAG laser produces single longitudinal mode oscillation on every shot.