Response of very-fast-decay phosphors in image intensifier tubes for CCD readout devices

High repetition rate intensified cameras having interframe times in the microsecond(s) range are needed for flow analysis measurements such as Particle Imaging Velocimetry (PIV) or Molecular Tagging Velocimetry (MTV). For these applications, the lower efficiency, fast decay P46 and P47 phosphors must then be used instead of the higher efficiency P20 and P43 phosphors. Previous literature provides only the time-resolved phosphor response. For very short interframe time imaging applications, a significant fraction of the previous frame's intensity can appear as a 'ghost image' in the trailing frame. Fast phosphors minimize this energy transfer into a second frame. Previous data show a dependence of decay time on exposure time for the P46. The P47 has been reported to decay a factor of 3 to 30 faster than the P46. The transferred total intensity as a function of the shutter repetition rate is measured for these two fast phosphors. They are compared with data published in previous papers. Neither phosphor under investigation behaves fully in accordance with these prior characterizations.