Mainz 2017 – scientific programme

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MO: Fachverband Molekülphysik

MO 16: Posters 3: Experimental Techniques and Theoretical Approaches

MO 16.10: Poster

Thursday, March 9, 2017, 17:00–19:00, P OG1

Implementation of a mechanical shutter into a He droplet apparatus using a hard disk drive actuator — •Katharina Schneider, Marcel Binz, Lukas Bruder, and Frank Stienkemeier — Institute of Physics, University of Freiburg, Germany

Controlled modulation or switching of light intensity is indispensable to many laser-based experiments. There are various ways to provide fast shuttering, varying in speed, reliability, expenses and extinction ratio.

Mechanical shutter excel in usability, expenses and transmission rate. Referring to [1], the voice-coil system of a computer hard disc drive can be modified to make a fast mechanical shutter, with switching times comparable to commercial devices. The voice-coil is driven by a custom circuit, using high-current pulses to ensure rapid shutter action. The direction of current is controlled by a TTL signal, enabling varying shutter frequencies and an asymmetric performance.

We setup such a shutter in a vacuum chamber to block a He droplet beam in front of a doping cell. This allows us to measure the remaining effusive signal in femtosecond HENDI (helium nanodroplet isolation) spectroscopy experiments. By subtracting this background from the measurement signal with the shutter open, the real doped droplet signal can be obtained.

[1] L. P. Maguire, S. Szilagyi, and R. E. Scholten, Rev. Sci. Instrum. 75, 3077 (2004)