This paper describes two programs developed at Itek which are applicable to Laser Fusion focussing systems. The first program describes a diffraction based point spread function algorithm to calculate Irradiance profiles on spherical pellet surfaces. Classical aberrations, apodization functions, measured wavefronts and pellet adsorption factors can be specified to give accurate irradiance profiles. Thb second program describes the convolution algorithm for calculating multiple beam irradiance contours. Pellet decentration and random pointing errors for each beam channel can be input to specify tolerances using the RMS irradiance quality factor. Sample calculations are included to illustrate the flexibility of the programs to analyze Laser Fusion focussing systems.