Disk laser
A disk laser (engl: disk laser ) is a form of solid-state laser in which the active medium (the laser crystal) the form of a disk (engl: disc ) has. The need for the development of the laser radiation energy (usually thickness between 80 microns and 200 microns ) generated by multiple passage of a pump radiation by the laser disc. This disc is vapor-deposited on its back with a highly reflective coating and serves as a resonator.
Advantage of the geometry of the disc laser medium is the better cooling of the laser crystal: This is secured by the mirror-coated surface of a heat sink. Due to the small thickness of the disc, as compared to its diameter of more than one centimeter in part, the dissipation of heat takes place almost exclusively through the bottom surface of the disk. Thus, a temperature gradient is almost exclusively found perpendicular to the disc surface, but not within the disc plane. This leads to a reduction of the mechanical stresses occurring during operation due to thermal expansion of the disc, which affects in many other high-performance solid-state lasers, the beam quality to a negative ( focusability ).
In contrast to the right-wing exemplary figure is the previously used in commercial applications crystal material ytterbium - doped yttrium aluminum garnet ( Yb: YAG) with an emission wavelength of 1030 nm Optical pumping is performed in this case with InGaAs laser diode at a wavelength of 940 nm, the efficiency of a Yb: YAG disc lasers of up to 70 % relative to the incident pump power.
The disk laser was developed by Adolf Giesen at the Institute of Laser Tools (University of Stuttgart ) and in Haas (now belonging to trump ) to the application stage (primarily cutting and welding of metals ) brought. The Trumpf now offers disk laser operating at a power of up to 16 kW electrical efficiency of about 25 % can be achieved (50 % electrical-to- optical efficiency of the diode laser and 50 % optical-to- optical efficiency of the disk ). The beam parameter product is in this case about 8 mm mrad.
(Also called semiconductor disk laser ) See also Optically pumped semiconductor laser.