Manufacturing method for hologram which can prevent the formation of ghant holograms due to noise light 



A manufacturing method for a hologram which can control the formation of a ghost hologram due to a surface reflected light caused on an interface with the atmosphere is disclosed. In the first manufacturing method for a hologram by a two-beam method or a one-beam method, on an interface between a substrate having a hologram photosensitive layer and the atmosphere is disposed a quarter-wave plate, and an incident light is converted from a circularly polarized light to a P-polarized light (or an S-polarized light) through the quarter-wave plate. On the other hand, in the second manufacturing method for a hologram, a substrate, which has a hologram photosensitive layer, is fittingly held by prisms on both sides thereof. A reference light is a P-polarized light, and an angle of the reference light to a surface reflected light on an interface of the reference light is set to be approximate to a right angle. It is appropriate that a reproduced hologram is manufactured by the one-beam method by using a hologram manufactured by the above method as a master hologram. 

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. 

Optical relay for pixel-based holographic storage and retrieval 



A holographic storage and retrieval system for use in co-propagating or counter-propagating geometries having a common optical relay for guiding a signal beam and a reference beam along a common optical axis to a holographic medium to write a hologram therein. The optical relay has an object region imaging quality such that at least 65% and preferably at least 80% of the nominal luminous energy from object pixels is encompassed or "ensquared" by the corresponding image pixels. Additionally, the optical relay has a high total numerical aperture (N.A.) of about 0.83, a pixel N.A. of approximately 0.04 for the signal beam. The system of the invention can be used with holographic storage media in the form of disks, tapes or bulk holographic crystals.