DIFFRACTION OF A HERMITE-GAUSSIAN LASER-BEAM ON A THIN SINUSOIDAL PHASE GRATING

A solution to the problem of the transformation of the beam parameters and mode structure of a general order Hermite-Gaussian simple astigma tic laser beam caused by a thin sinusoidal phase grating, is given. Th e analysis is based on the results obtained from the scalar Fresnel-Ki rchhoff approximation. The theory of Fresnel diffraction of an inciden t Hermite-Gaussian beam by a phase grating predicts its splitting in t wo series of Hermite-Gaussian beams of the same mode order as that of the incident beam. The irradiance distribution in the observation plan e and its verification by computer calculation is also given. It is sh own that the intensity of the diffracted spots depends upon the square of Bessel functions, the argument of which is the phase amplitude mod ulation of the grating.