RESUMEN
Based on long-term monitoring data of the blazar, a new model for determining the parameters of this close binary supermassive black hole (SMBH) is proposed. The model uses the laws of celestial mechanics and results of harmonic analysis of observational data obtained mainly in the radio and optical wavelength ranges. Within the framework of the proposed model, the masses of SMBH companions, the values of their orbital elements, the parameters of the accretion disk, and its dimensions and thickness were determined. The structure and dynamics of SMBHs and their interaction with the accretion disk are considered. It is shown that OJ 287 may be the most massive close binary SMBH with comparable masses. The obtained characteristics of the SMBH are used to estimate the level of gravitational wave radiation, the lifetime of the system before the merger, as well as the magnitude of changes in the orbits of the companions.
RESUMEN
We report a 3-kW thin-disk laser with 80% optical efficiency employing zero-phonon line pumping at 970 nm. A detailed comparison to conventional pumping at 940 nm is provided, which shows almost twice the pump power density handling capability.
RESUMEN
We describe a specially designed diode pumped solid state laser system based on the disk laser architecture for combustion diagnostics under microgravity (µg) conditions at the drop tower in Bremen. The two-stage oscillator-amplifier-system provides an excellent beam profile (TEM00) at narrowband operation (Δλ < 1 pm) and is tunable from 1018 nm to 1052 nm. The laser repetition rate of up to 4 kHz at pulse durations of 10 ns enables the tracking of processes on a millisecond time scale. Depending on the specific issue it is possible to convert the output radiation up to the fourth harmonic around 257 nm. The very compact laser system is integrated in a slightly modified drop capsule and withstands decelerations of up to 50 g (>11 ms). At first the concept of the two-stage disk laser is briefly explained, followed by a detailed description of the disk laser adaption to the drop tower requirements with special focus on the intended use under µg conditions. In order to demonstrate the capabilities of the capsule laser as a tool for µg combustion diagnostics, we finally present an investigation of the precursor-reactions before the droplet ignition using 2D imaging of the Laser Induced Fluorescence of formaldehyde.
RESUMEN
A thin-disk regenerative amplifier based on Yb-doped potassium yttrium tungstate is operated at 40 kHz with an output pulse energy of 116 microJ and a pulse duration of 250 fs. Dispersive stretching of the pulse during amplification instead of an external stretcher is used to avoid high peak intensities. The small amount of the laser active material in the amplifier inherent for the thin-disk laser design and a large beam radius in the Pockels cell reduce nonlinear effects further. Consequently the output pulses can be compressed to 250 fs using a pair of diffraction gratings.
