Universal mode of operation of the APPLE II undulators at the MAX IV 1.5 GeV ring

At the MAX IV 1.5 GeV ring, two APPLE II undulators with period lengths of 84 mm (Bloch) and 95.2 mm (FinEstBeams) cover minimum photon energies of 7 eV and 4 eV, respectively. Operating below 80 eV, the polarization state is distorted significantly by the beamlines' optical elements. A combination of helical and linear inclined modes during undulator operation - the so-called universal mode - can compensate for the distortions. In this paper, we describe how we compensate for the effect of the undulators on the beam orbits and ring optics when operating in universal mode. Additionally, some of the achieved commissioning results at both beamlines will be shown.