Optical information storage device having phase compensating mechanism and polarization plane rotating mechanism

1. Field of the Invention An optical information storage device including a first photodetector for detecting a regenerative signal from reflected light from an optical recording medium, a second photodetector for detecting a tracking error signal and a focusing error signal from the reflected light, and a beam splitter for separating the reflected light into a first beam directed toward the first photodetector and a second beam directed toward the second photodetector. The optical information storage device further includes a phase compensating mechanism provided between the beam splitter and the first photodetector for compensating for a phase difference of the first beam, a Wollaston prism provided between the phase compensating mechanism and the first photodetector for separating the first beam into two beams having orthogonal polarization planes, and a polarization plane rotating mechanism for rotating the polarization plane of the first beam incident on the Wollaston prism.