Nonstationary angular distribution of optical field radiance from an isotropic source in sea water

The spatial-angular and temporal characteristics of the radiance of the light field emitted by a nonstationary point isotropic source in sea water are studied. Using the Monte Carlo method, we calculated the pulse transfer functions and frequency responses of the angular radiance distributions at various distances from the source. Particular integral characteristics of the angular radiance distributions are estimated. It is shown that with an increase in the delay time, measured from the time of arrival of ballistic photons, the angular radiance distribution asymptotically tends to be isotropic. The frequency and phase responses of the alternating radiance component from a source modulated by power at a high frequency are studied. It is shown that with an increase in the modulation frequency, the angular distribution of the alternating radiance component is concentrated close to the direction to the source.