Manifestation of changes in the morphology of thin island films in fluctuations of the absorption of focused beams

The relation between the morphology of a thin island film with fluctuations of the absorption of a laser beam scanned over the film is described. An expression for the spectrum of absorption fluctuations, which are determined by the statistics of mutual arrangement of islands in the field and of their sizes, is obtained. It is shown that, as films thicken, absorption fluctuations can decrease and their spectrum narrow. Both phenomena are explained by the correlation between the arrangement and island sizes in films.