The theoretical idea describing a new technical solution of a polarimeter designed for measurements of a rotation angle of light polarization plane is presented. The detecting part of a polarimeter consists of a linear phase shifter, an analyzer placed at suitable azimuth behind them and a detector. Phase shift between orthogonally polarized waves is controlled by a computer. A change of a detector signal is assigned to a change of a phase shift on linear phase shifter. In this way, a location of light polarization plane before linear phase shifter may be measured. Theoretical considerations have been corroborated by experimental results.