Apparatus and method for recording and/or playing back optical information and media for it apparatus and method for recording and/or playing back optical information and media for them 

An optical information recording/playback apparatus having a compact construction of a recording/playback optical system. A light beam emitted from a laser coupler is modulated by a spatial modulator according to difference in the polarizing direction. The modulated light enters an S-polarized light hologram which separates an information light and a recording reference light of different polarizing directions and having different focal positions. An optical rotation is effected by a split optical rotation plate such that the polarizing directions of the information light and the recording reference light coincide with each other in a region of a holographic layer of a recording medium where the information light and the recording reference light are superposed on each other. The light beam having undergone the optical rotation is applied to the holographic layer through an objective lens, whereby the information carried by the information light is recorded in the holographic layer in terms of an interference pattern produced as a result of an interference between the information light and the recording reference light.