Correlation between the degree of spatial coherence of the field and the variance of the wave vectors of laser radiation

It is shown that in lasers with an active medium optically inhomogeneous over the transverse cross section and an absorbing lateral boundary, amplitude fluctuations make a negligible contribution compared with phase fluctuations to the deterioration of the spatial coherence of the field. The correlation between the degree of spatial coherence of the field and the variance of the wave vectors of the radiation is obtained for such lasers. The conditions are found under which the main contribution to the variance of the wave vectors is made by the variance of their directions but the variance of the different mode frequencies can be neglected. Measurements of the degree of spatial coherence of the field may yield information on the width of the angular spectrum of the laser radiation in the near field.