Study of Photon Correlation in the 100-Nanosecond Range with Photoelectron Time-of-Arrival Technique
Among the many advantages of studying photon correlation with the photoelectron time-of-arrival technique, one of the apparent unsurpassing capabilities is the measurement of the correlation time in the range around 10−6 to 10−7 seconds. This is the region for which both the conventional light beating and the interferometric (Fabry-Perot) techniques are likely to become unreliable. We present in this paper such a study encountered in Rayleigh scattering experiments. We first review briefly the historical development, ranging from single-stop to multi-stop measurements, of this time-of-arrival technique. This is followed by an examination on the dead-time effect of the photomultiplier in general counting experiments. The analysis is based upon the single time-interval counting statistics developed by Glauber. Some close-form analytical expressions are derived for the case of intensity-stabilized laser light. This consideration of the dead-time effect is of crucial importance for correlation time measurements in the time scale mentioned above. It indicates that in this particular case a single-stop measurement is the only appropriate approach. We also discuss for this technique the effect due to the imperfection of spatial coherence, which is of practical interest but has not been mentioned before.