Entity

Time filter

Source Type


Schellhorn M.,French German Research Institute of Saint Louis
Applied Physics B: Lasers and Optics | Year: 2011

Singly 0.5 at.% Ho doped crystals of YLiF4 (YLF) and LuLiF 4 (LLF) are studied under identical pump conditions in continuous-wave (CW) and Q-switched operation. Longitudinal end-pumped CW laser performance shows Ho:LLF to have a slightly lower threshold and a slightly higher slope efficiency with respect to absorbed pump power than Ho:YLF. Both lasers were operated on π-polarization. At a cavity output coupling of 20% and a crystal length of 30 mm, the Ho:LLF (Ho:YLF) laser yielded 18.8 W (18 W) of CW output at a wavelength of 2067.8 nm (2064.0 nm) for 41.4 W (42.2 W) of absorbed pump power with a slope efficiency of 67.1% (65.6%) and an optical-to-optical efficiency of 45.4% (42.6%) with respect to absorbed pump power. With the same output coupling and a crystal length of 40 mm, the Ho:LLF (Ho:YLF) laser yielded 20.5 W (18.1 W) of CW output at a wavelength of 2067.7 nm (2064.3 nm) for 51.5 W (50.0 W) of absorbed pump power with a slope efficiency of 58.4% (55.4%) and an optical-to-optical efficiency of 39.8 (36.1%) with respect to absorbed pump power. The influence of the temperature of the cooling mount on CW laser performance was studied and showed very similar results for both laser materials. At full pump power, a slope of-155 mW/°C (-149 mW/°C) was observed for the Ho:LLF (Ho:YLF) laser with a crystal length of 30 mm. In Q-switched operation, the Ho:LLF (Ho:YLF) laser produced 37 mJ (38.5 mJ) at a repetition rate of 100 Hz with a pulse duration of 38 ns (35 ns) at a wavelength of 2053.1 nm (2050.2 nm) with a slope efficiency of 30.3% (31%) and an optical-to-optical efficiency of 14.2% (13.9%) with respect to absorbed pump power. The beam quality was nearly diffraction limited (M2 < 1.1). © Springer-Verlag 2011. Source


Schellhorn M.,French German Research Institute of Saint Louis
Optics Letters | Year: 2010

A Q-switched Trn:fiber-laser-pumped Ho : LuLiF4 laser is reported that has been optimized for high-energy pulses at low repetition rates. Operating at 100 Hz, a pulse energy of 24.8 mJ with pulse widths of 47 ns at a wavelength of 2052 nm was achieved. The beam propagation factor (M2) was measured to be ∼1.04 at the maximum pump power, confirming fundamental transverse mode (TEM00) operation. Starting the pump laser at maximum power, the pulse energies of each of the first 10 pulses are >47 mJ. This strong influence of crystal temperature on laser performance is discussed with the prospect for further improvement of the laser efficiency. © 2010 Optical Society of America. Source


Patent
French German Research Institute of Saint Louis | Date: 2010-06-17

The invention concerns a process for the representation of a scanning function by means of a neuronal network and a device for the implementation of the process, whereby measurement values associated with a turbulent wave front, which contain phase information, are compared with reference values, with the result that the intermediate values thus obtained can be compared with comparison functions, in order, in the best case, to describe the measured pattern with a selection of comparison functions, whereby a neuronal network is trained in the comparison functions, so that the processing of the measured pattern can take place in near-real time.


Patent
French German Research Institute of Saint Louis | Date: 2010-03-08

The invention concerns the field of devices for improving the piloting of projectiles More specifically, the object of the invention is a piloting device for a missile or a projectile, for example, of small caliber, especially on the order of 40 mm, which has a lateral main surface with a nose at the level of one of its extremities, whereby said device includes at least one cavity consisting of a combustion chamber and filled, at least partially, by an explosive powder, and means of initiation of this explosive powder, and thereby the explosive powder includes nanothermites or gas-generating nanothermites.


Patent
French German Research Institute of Saint Louis | Date: 2011-05-17

The present invention especially concerns the field of lasers. Specifically, the object of the invention is a process for the emission of pulsed laser radiation generated by at least one laser crystal which is located in a cavity containing a first and a second mirror and pumped by des pumping means, wherein said process includes a first stage which consists of generating a first pumping laser radiation with an intensity of J

Discover hidden collaborations