We present an ultrafast thin-disk based multipass amplifier operating at a wavelength of 1030 nm, designed for atmospheric research in the framework of the Laser Lightning Rod project. The CPA system delivers a pulse energy of 720 mJ and a pulse duration of 920 fs at a repetition rate of 1 kHz. The 240 mJ seed pulses generated by a regenerative amplifier are amplified to the final energy in a multipass amplifier via four industrial thin-disk laser heads. The beam quality factor remains ∼ 2.1 at the output. First results on horizontal long-range filament generation are presented.
Picosecond infrared laser ablation results in negligible heat generation, considerably less than Er:YAG laser ablation, which confirms the potential of this novel technology in minimizing undesirable thermal injury associated with lasers currently in clinical use.
Lightning is highly destructive due to its high power density and unpredictable character. Directing lightning away would allow to protect sensitive sites from its direct and indirect impacts (electromagnetic perturbations). Up to now, lasers have been unable to guide lightning efficiently since they were not offering simultaneously terawatt peak powers and kHz repetition rates. In the framework of the Laser Lightning Rod project, we develop a laser system for lightning control, with J-range pulses of 1 ps duration at 1 kHz. The project aims at investigate its propagation in the multiple filamentation regime and its ability to control high-voltage discharges. In particular, a field campaign at the Säntis mountain will assess the laser ability to trigger upward lightning.
Objectives/Hypothesis: Conventional lasers ablate tissue through photothermal, photomechanical, and/or photoionizing effects, which may result in collateral tissue damage. The novel nonionizing picosecond infrared laser (PIRL) selectively energizes tissue water molecules using ultrafast pulses to drive ablation on timescales faster than energy transport to minimize collateral damage to adjacent cells. Study Design: Animal cadaver study. Methods: Cuts in porcine laryngeal epithelium, lamina propria, and cartilage were made using PIRL and carbon dioxide (CO2) laser. Lateral damage zones and cutting gaps were histologically compared. Results: The mean widths of epithelial (8.5 μm), subepithelial (10.9 μm), and cartilage damage zones (8.1 μm) were significantly lower for cuts made by PIRL compared with CO2 laser (p < 0.001). Mean cutting gaps in vocal fold (174.7 μm) and epiglottic cartilage (56.3 μm) were significantly narrower for cuts made by PIRL compared with CO2 laser (P < 0.01, P < 0.05). Conclusion: PIRL ablation demonstrates superiority over CO2 laser in cutting precision with less collateral tissue damage
The authors report on an InP based photovoltaic quantum cascade detector operating at 16.5μm and using miniband-based vertical transport. This concept allowed the construction of a longitudinal optical phonon extraction stair with two rungs without touching on a high device resistance. At 10K, they observed a responsivity of 1.72mA∕W and a Johnson noise limited detectivity of 2.2×109 Jones. Altogether, this design resulted in detection at temperatures of up to 90K with a lower bandwidth limit of 200MHz imposed by the measurement setup.
The carbon dioxide (CO2) laser is routinely used in glottic microsurgery for the treatment of benign and malignant disease, despite significant collateral thermal damage secondary to photothermal vaporization without thermal confinement. Subsequent tissue response to thermal injury involves excess collagen deposition resulting in scarring and functional impairment. To minimize collateral thermal injury, short-pulse laser systems such as the microsecond pulsed erbium:yttrium-aluminium-garnet (Er:YAG) laser and picosecond infrared laser (PIRL) have been developed. This study compares incisions made in ex vivo human laryngeal tissues by CO2 and Er:YAG lasers versus PIRL using light microscopy, environmental scanning electron microscopy (ESEM), and infrared thermography (IRT). In comparison to the CO2 and Er:YAG lasers, PIRL incisions showed significantly decreased mean epithelial (59.70 µm) and subepithelial (22.15 µm) damage zones (p < 0.05). Cutting gaps were significantly narrower for PIRL (133.70 µm) compared to Er:YAG and CO2 lasers (p < 0.05), which were more than 5 times larger. ESEM revealed intact collagen fibers along PIRL cutting edges without obvious carbonization, in comparison to diffuse carbonization and tissue melting seen for CO2 and Er:YAG laser incisions. IRT demonstrated median temperature rise of 4.1 K in PIRL vocal fold incisions, significantly less than for Er:YAG laser cuts (171.85 K; p < 0.001). This study has shown increased cutting precision and reduced lateral thermal damage zones for PIRL ablation in comparison to conventional CO2 and Er:YAG lasers in human glottis and supraglottic tissues.
[1] We present Mars zonal wind measurements by means of infrared heterodyne spectroscopy of CO 2 features at 959.3917 cm À1 (10.423 m). Observations were carried out using the Cologne Tuneable Heterodyne Infrared Spectrometer (THIS) from 5-8 December 2005 shortly after Mars opposition at the McMath-Pierce Solar Telescope of the National Solar Observatory on Kitt Peak in Arizona with an unprecedented spatial resolution of $1.7 arcsec on a $16 arcsec Martian disk. Mars was observed at six different latitudes close to the west (evening) limb and zonal winds were retrieved from Doppler shifts between CO 2 nonthermal emission from the mesosphere and absorption features from low atmospheric regions. The season on Mars was late northern winter (L S % 337°). We retrieved retrograde winds at latitude 45°N (À27 ± 17 m/s) that were particularly strong at the equator (up to À80 ± 13 m/s) and prograde winds at high southern latitudes (75°S) up to 51 ± 29 m/s. Citation: Sonnabend, G., M. Sornig, P. J. Krötz, R. T. Schieder, and K. E. Fast (2006), High spatial resolution mapping of Mars mesospheric zonal winds by infrared heterodyne spectroscopy of CO 2 , Geophys.
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