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- K. Scheidt, G.A. Naylor
ESRF, The European Synchrotron Radiation Facility, Grenoble, France
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The development at the ESRF of a jitter-free, laser
triggered Streak Camera has now yielded time resolution
results as short as 460 fs while operating in accumulating
mode. The so-called jitter-free synchronisation between
the laser light and the Streak Camera is performed
through a GaAs photo-switch in a simple HV circuit that
connects directly to the Streak tubes deflection plates.
The novelty of this technique permits to obtain
excellent dynamic range measurements in a shot-to-shot
accumulation of ultra fast (laser stimulated) events at up
to 1kHz without degrading the time resolution.
Important insight was obtained on the quality of this
optical synchronisation and its dependence on the laser
characteristics, the switch circuit, and the structure of the
GaAs switch itself. This permitted to suppress the jitter
causes and today the 500 fs limitation is imposed by the
streak tubes intrinsic time resolution. This work was
done by measuring (with Au or Pd photo-cathodes) the
3rd harmonic (i.e. 267 nm) of a 100 fs Ti:Saph laser.
Also important progress was made with the reliability
of the photo-switch and problems of HV break-down and
structural degradation have been completely resolved.
Since the principal use of this system at the ESRF is in
ultra-fast X-ray diffraction experiments the
exchangeable photo-cathode structure of this tube covers
the entire UV-to-X-rays spectrum. The QE of various
photo-cathode materials was measured in the 8-30 keV
range.
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