Subnanosecond multi-gigawatt CO2 laser

A semiconductor switching technique has been utilized to produce 30-300 ps variable duration CO₂ laser pulses of 0.5-MW peak power. Eight passes through a 1.2-m long, UV-preionized, 3-atm TE CO₂ amplifier raise the output laser peak power to the 10¹⁰ W level. Sampling the amplifier gain in linear and saturated regimes using CO₂ laser radiation ranging from CW to 30 ps pulse length permits comparison with computer modeling of picosecond CO₂ pulse amplification. The potential for further peak power scaling of picosecond molecular lasers is discussed     

Application of a phase-conjugate Brillouin mirror to generation ofhigh-quality variable-duration KrF pulses

Phase conjugation by Brillouin scattering in SF₆ gas has been implemented on a two-pass KrF amplifier to provide near-diffraction-limited output pulses having a very low background level of amplified spontaneous emission. The pulse duration is variable between 1 and 10 ns by simply attenuating the input pulse. These pulses have also been used for the generation of much shorter duration pulses by truncated Brillouin scattering at the surface of cyclohexane     

A comparison between microsatellite and quantitative PCR analyses to detect frequent p16 copy number changes in primary bladder tumors

We tested 70 primary bladder tumors for altered copy number of p16 (D9S1752) by microsatellite analysis and by a quantitative PCR (QPCR) assay. These two approaches were fully concordant for 53 tumors, including all 39 tumors in which microsatellite analysis detected loss. In addition, the QPCR method detected useful anomalies in 17 additional cases, including those in which D9S1752 was uninformative. QPCR was abnormal in 56 of 70 (80%) cases, whereas microsatellite analysis was abnormal in 39 of 70 (56%) cases. Although QPCR uses more DNA than microsatellite analysis, it represents a rapid, informative technique that can readily detect both chromosome 9p21 deletions and amplifications in primary bladder tumors without the need for electrophoretic separation.     

A tilted mirror unstable resonator laser cavity

A simple unstable resonator cavity using flat optics which provides a nonannular low-divergence output beam from a large mode volume is described. The resonator uses as output the "spillover" from a walkoff mode established between a pair of tilted flat mirrors; this also allows continuous adjustability of the output coupling. An extra pass of this spillover output through the gain medium helps to provide a saturated output. Results obtained using this resonator on a CO2oscillator are described.     

Photopreionization of the 3371-Å pulsed N2laser

Photopreionization of the 3371-Å pulsed N2laser by use of a seed gas of low ionization threshold and flashlamp excitation is observed to result in increased laser output and reproducibility. Preionization also increases the range of permissible operating pressures, enabling operation with atmospheric-pressure mixtures of N2and He without reduced intensity.