ANGLE CONTROL METHOD

摘要

An angle control method has: a step wherein reproducing light (S) is taken out by applying reference light (R) to a hologram formed on an optical information recording medium (200), while rotating about a Y axis the optical information recording medium (200) having thereon the hologram generated due to interference between information light (I) and the reference light (R), by changing an rotating angle about the X axis or an angle at which the reference light (R) enters; a step wherein the reproducing light (S) is detected by using a photodetector (185) provided with two light receiving regions, which are formed by equally and symmetrically dividing a region with respect to the center of the optical axis, and error signals are taken out from the two light receiving regions detected by the photodetector (185); and a step wherein the angle is controlled by rotating the Y axis so that there is no error signal.