Triple-correlation values are obtained as a combination of second-order factorial moments of the triggered photocount distribution. The signal-to-noise ratio obtained from this kind of measurement is smaller than that obtained from direct calculation of the triple correlation for small time-delay values.
The theoretical expression of the first-order factorial moment of a triggered delayed photocount distribution and a description of its SNR have been developed. We explain the adventages of this thecnique, in comparison with the second-order correlation function, when we measured a temporal signal under low light level. We derived the theoretical errors involved in determining a parameter by measuring both functions for a signal with a periodically modulated intensity, since this kind of signals usually appear in spectroscopy. We conclude that the first-order factorial moment of a triggered delayed photocount distribution is a useful tool for characterizing a signal at low; light level conditions.
The expression corresponding to the normalized first-order factorial moment (NFOFM) of a double triggered photocount distribution (DTPCD) has been developed. It is found that the NFOFM of a DTCPD has the spectral information of incident light corresponding to the third-order autocorrelation function. A theoretical error model was developed and checked by using a computer simulation method. We also compare the results obtained from the measurement of the NFOFM of a DTPCD with those obtained from the second- and third-order correlation functions.