The orthogonal Michelson interferometer is used for homodyne laser vibration measurement system traditionally.However,it is difficult to remove error.A simple optical system was presentedin this paper.A quadrant detector(two pixels were used) was adopted.Since the two pixels of detector were in different parts of the interference fringe,the detector output two nonorthogonal Doppler signals.The signal processing method was researched:nonorthogonal Doppler signals were corrected into orthogonal signals firstl...