Abstract
Formulas are presented for calculating the irradiance field, which is formed in a turbid medium with a narrow scattering phase function and homogeneous optical properties when an infinitely narrow light beam passes through it. The calculations are based on a new mathematical model of the stationary radiation field of an omnidirectional point source and relationships enabling one to represent the irradiance distribution in a continuous or modulated light beam through this field. The obtained formulas, in contrast to the previously known ones, permit taking into account the temporal spreading of a pulsed light beam in the sea without a significant decrease in the accuracy of describing its spatial structure.