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Q: Fachverband Quantenoptik und Photonik

Q 54: Poster 3

Q 54.29: Poster

Donnerstag, 15. März 2012, 16:30–19:00, Poster.I+II

Laser feedback System for X-ray pump-probe experiments — •Dennis Goeries, Benjamin Dicke, Edgar Weckert, and Alke Meents — Deutsches Elektronen Synchrotron (Desy) - Hasylab, Notkestrasse 85, D-22607 Hamburg, Germany

The research in organic light emitting devices (OLEDs) is becoming more and more important nowadays. We plan to determine the excited state structures of different metal-organic compounds with time-resolved microcrystallography. Here the sample is probed by an X-ray a few microns in size only. This also requires the excitation of a much smaller volume than in conventional time-resolved experiments. This introduces less heat to the system and therefore allows higher repetition rates of the laser system.

A challenge for such kind of experiments is to provide a spatial and temporal overlap of both, the small laser and X-ray beam, over several hours with deviations below two microns. On this background we developed a PID controlled optical feedback system. It consists of two piezo actuator-driven mirrors (full stroke 23*m) and two position detecting devices (lateral effect sensors or cameras) with a high resolution. This system is divided into two loops, the first one for the positional and the second one for the angular stability. The second loop requires an additional lens focusing the light onto the detector and is highly dependent from the first loop, which defines a point source.Therefore a written complex algorithm ensures a smooth interplay between both loops. This configuration is built at beamline P11 at Petra III and we present results on the meeting.