A Study of Partial Coherence and Its Application to the Collimation of Pulsed Multimode Laser Radiation
Classical coherence theory as presented by Wolf with the modification proposed by Neugebauer is used to describe mathematically and experimentally the collimation and focusing of the time-averaged intensity of pulsed multimode laser radiation. Measurements of the double-slit Fraunhofer pattern and the near and far zone intensity patterns were made on two pulsed ruby lasers by both still and streak photography to examine the spatial coherence and the collimation of the beam. Our result showed that the time-averaged collimation and focusing characteristics of the beam can be treated as the superposition of noncoupled spatially coherent modes.