  We have made the first observation of a charged particle beam by means of its
electro-optical effect on the propagation of laser light in a birefringent
crystal at the Brookhaven National Laboratory Accelerator Test Facility.
Polarized infrared light was coupled to a LiNbO3 crystal through a polarization
maintaining fiber of 4 micron diameter. An electron beam in 10ps bunches of 1mm
diameter was scanned across the crystal. The modulation of the laser light
during passage of the electron beam was observed using a photodiode with 45GHz
bandwidth. The fastest rise time measured, 120ps, was made in the single shot
mode and was limited by the bandwidth of the oscilloscope and the associated
electronics. Both polarization dependent and polarization independent effects
were observed. This technology holds promise of greatly improved spatial and
temporal resolution of charged particle beams.
