Nonlinearity and image persistence of P-20 phosphor-based intensified photodiode array detectors used in CARS...

Several self-scanning photodiode arrays (IPDA) used for CARS spectroscopy are shown to exhibit a greater image persistence than has generally been realized, and to exhibit a falloff in sensitivity that is logarithmic with decreasing output signal. These effects are attributed to the P-20 phosphor based intensifiers used in the IPDAs and are probably generic to all such detectors. A strategy for minimizing the image persistence in CARS spectroscopy is presented. A prototype detector incorporating a much faster rare earth phosphor is evaluated and shown to be more suited to single pulse CARS measurements in turbulent combustion than the IPDAs incorporating P-20 phosphors.