Intensity Fluctuations in Closed and Open Systems
  We consider the intensity pattern, generated by a monochromatic source, in a disordered cavity coupled to the environment. For weak coupling, and when the source frequency is tuned to a resonance, the intensity distribution is close to Porter-Thomas distribution. When the coupling increases, gradually crosses over to the Rayleigh distribution. The joint probability distribution for intensities at two different points is also discussed. 
R. Pnini, B. Shapiro (Phys. Dep. Technion, Haifa, Israel)