Diffraction techniques are widely used especially as additional tools for analytical microprobe analysis.A supplementary device to a scanning electron microscope (SEM) allows taking of X-ray lattice source and wide angle interference patterns, now termed Kossel and Pseudo Kossel patterns, respectively, in transmission and back reflection arrangement as reported by DÄBRITZ et al. (1986, 1997a,b). The developed program KOPSKO simulates exactly the entire reflection system of Kossel and Pseudo Kossel diffraction patterns basing on the geometric diffraction theory. It permits phase, orientation, and structure determination. The present paper shows the wide range of possibilities using the computerized analysis in this field. Initially it deals with simulation of Kossel patterns, which are excellent suitable for a precise determination of lattice constants in the micro range for instance. A new way for simulation of Pseudo Kossel diffraction patterns using three dimensional vector algebra to calculate reflections in point by point procedure is presented in the second part. The attained precise coincidence of simulation and experimentally taken Pseudo Kossel patterns allows a relatively easy determination of crystallographic data of mono- and polycrystals.Particularly the program is designed to determine lattice constants precisely, for the complex divergent beam X-ray interferences, too. Through the three dimensional simulation it takes into account shade originated by the target holder. Moreover, the three dimensional point by point procedure enables the localization of lattice imperfections as well as the consideration of grain size effects in polycrystals, which lead to interruptions of Pseudo Kossel lines. By simulation of diffraction patterns of polycrystalline materials the study of such specimens is essentially simplified.