Jahresbericht 2005 - IPHT Jena

86
Fig. 4.6: EFISH signal development (cf. text) at
Si/SiO 2 surfaces with oxidized silicon of low
(upper part) and high p-type doping (lower part).
across the Si/SiO 2 interface is steadily compensated
and overwhelmed by laser induced electron
injection into the SiO 2 layer building up an
electric field of opposite direction. In addition the
SSHG method was successfully applied to detect
the damage of monomolecular surface layers
induced by excimer laser irradiation.
Further investigations of optical materials and
components in 2005 refer to the laser durability of
fused silica (undesired microchannel formation),
CaF 2 (HELD = high energy laser durability project),
optical layers (impurity and defect detection)
as well as the performance of optical functional
elements.
Combustion processes
(Dirk Müller, Wolfgang Paa, Wolfgang Triebel)
Laser diagnostics is applied to investigate steady
state and dynamic flames up to pulse repetition
rates of 1 kHz. The well-established detection of
OH radicals by LIF now has – in cooperation with
the Optics division – also successfully been
applied to flames of industrial burners containing
particles (loaded flames) and used to determine
local gas temperatures. On the other hand, the LIF
method is capable of characterising very small
flames created by microburners which were prepared
in the division for Microsystems (Fig. 4.7).
The breadboard model of the advanced disk
laser system (ADL) at IPHT Jena was further
LASERTECHNIK / LASER TECHNOLOGY
Fig. 4.7: 2D-LIF image of OH in small flame on
top of microburner with 380 µm channel width.
improved and tested to generate 2D-LIF images
of OH in flames. This required generating the
third harmonic of the ADL pulses efficiently with
sufficiently high pulse energy. Furthermore, some
preliminary work has been performed towards
fast wavelength switching of the ADL system
using the available tuning components at the high
laser pulse repetition rate.
Moreover the ADL-FT (Fallturm) system was tested
in several drops with maximum deceleration of
about 35 g in polystyrene granulate: Evidently the
laser system survives these procedures. Convection,
however, is still present in front of the laser
disk and changes when microgravity conditions
start. These changes are small but sufficient to
influence the laser operation so that some revisions
of the laser system and operation are required.
4.3 Appendix
Partners (in alphabetical sequence)
in Jena and Thuringia:
• CiS Institut für Mikrosensorik, Erfurt
• Ersol Solar Energy AG, Erfurt
• Fachhochschule (University of Applied Sciences)
Jena
• Fraunhofer-Institut für Angewandte Optik und
Feinmechanik (IOF), Jena
• Friedrich-Schiller-Universität, Jena
Institut für Festkörperphysik und Astrophysikalisches
Labor
• Institut für Fügetechnik und Werkstoffprüfung
(IFW), Jena
• ITP GmbH, Weimar
• Jenoptik Laser.Optik.Systeme GmbH, Jena
• Jenoptik Laserdiode GmbH, Jena
• Layertec GmbH, Mellingen
• LLT Applikation GmbH, Ilmenau
• MWS Schneidwerkzeuge GmbH&Co. KG,
Schmalkalden