INTENSITY CORRELATION FUNCTIONS FOR `THERMALISED` TEM_n0LASER BEAMS

A well-stabilised, single mode laser beam will give zero intensity correlation. However, a laser beam may be 'thermalised' by shining it on a rotating ground glass disc, and then intensity correlation experiments will give nonzero results. We present here calculations of the intensity correlation functions of the TEM//1//0, TEM//2//0, TEM//3//0 and TEM//4//0 Gaussian-Hermite beams. We were led to perform these calculations by the results of intensity correlation measurements on a laser with 'butted-on' mirrors nearing the end of its useful life.