SPECTRAL FILTERING OF LIGHT POSSESSING NON-GAUSSIAN STATISTICS

We have used a heterodyne detection technique to observe the intensity fluctuations and statistics of non-Gaussian scattered light, formed by illuminating a rotating ground-glass screen with a tightly focused laser beam. This type of light field contains the characteristic 'glints' commonly observed with laser radar systems. It is demonstrated both theoretically and experimentally that the statistics of the fluctuating intensity are significantly altered by spectral filtering of the light. In the limit, when the filter bandwidth becomes much narrower than the overall spectral linewidth of the scattered light, the distribution of intensities tends to that expected for complex Gaussian field statistics (i.e. a negative exponential). We compare this behaviour with that obtained by other workers for spectral filtering within the linewidth of light from a single-mode laser.