Multiple hologram bulk optical storage device

Claim 1

A multiple bulk optical holographic storage device, comprising: a thick photosensitive electro-optical material capable of storing information by the photovoltaic effect, and having reference and object faces forming a right angle; a source of monochromatic light; means for splitting the monochromatic light into first and second beams; means for forming the first beam into a collimated reference beam impinging onto the reference face with a variable optical axis with respect thereto; a convergent optical element; means for passing the second beam through the convergent optical element to form an object beam impinging on the object face without any zero-order stop; means interposed between the convergent optical element and the object face for modulating the object beam with information to be recorded within the electro-optical material, the modulated object and reference beams interfering within the material so as to be recorded as variations in refractive index within the material; and transparent electrodes attached to all of the faces of said material and electrically short circuited to one another so as to maintain a zero electrical potential difference therebetween to prevent elementary storage zones of said material from tending toward saturation after several successive storage operations.