Photocount statistic and correlation for a single Lorentzian

The mean count rate has been treated as an independent parameter in the investigation to avoid a biasing of the data. Measurements were conducted concerning the photocount statistic and the second order correlation function. Difficulties which had to be overcome are related to the effects of dust in the sample, dead-time effects, and the influence of stray light. The test results show that it is possible to measure the coherence time of a diffusive process with a comparable accuracy by either a correlation approach or with the aid of a count-statistic method.