[en] The first chapter presents the installation of the source at the MAMI accelerator and explains the conditions under which it became possible to transport practically all electrons produced in the source to the experiment and thereby although aim excellent emittance values and beam stability. The notoric problematics of the finite lifetime of the photocathode could be not only removed but the contributing processes clarified, so that at the today further development potentials are sketched. In the following chapter studies are presented, which concern the depolarization of the electron ensemble in the photoemission from the III/V heterostructures used at MAMI. The third chapter describes the control of the symmetry of the beam parameters at the helicity change of the electron beam