Duplication process for video recording track - has coherent light projected through master track on to photosensitive track

• Main Author: CLAUDE BRICOT, JEAN-CLAUDE LEHUREAU ET GERARD ROBIN
• Format: Patent
• Language: English; French
• Published: 19.05.1978
• Subjects: AUXILIARY PROCESSES IN PHOTOGRAPHY; CINEMATOGRAPHY; ELECTROGRAPHY; HOLOGRAPHY; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR,STEREO-PHOTOGRAPHIC PROCESSES; PHOTOGRAPHY; PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHYSICS

A process is ued to duplicate information recorded on a track. The information of the track is stored in micro-elements providing variations of the track thickness. The process can use micro-densities of 105 points per square millimetre and is not sensitive to dust. The duplication is by means of a contactless method. The process consists of projecting a coherent light source (S) on a micro-element (P) of the track to be duplicated. It also uses a lens (L) to produce a beam on the phase modulated track (P). A photosensitive track (M) is placed parallel to the track (P). The photosensitive track (M) receives interference bands transmitted by the micro-elements (P). The photosensitive track (M) is then subjected to a chemical treatment to obtain local variations of light transmission. L'invention se rapporte à un procédé de reproduction de supports d'information ne nécessitant aucun contact entre le support à reproduire et le support mémoire. Elle a pour objet un procedé de reproduction consistant à éclairer le support d'information, sur lequel l'information est enregistrée sous forme de microéléments diffractants, par une onde plane, un support mémoire photosensible placé parallèlement au support d'information étant impressionné par une onde plane transmise sans déviation par le support d'information et par les ondes diffractées par les microeléments enregistrés. L'invention a également pour objet le support mémoire ainsi obtenu et le lecteur optique y associé. Un tel support mémoire est lisible par un rayonnement concentré et restitue une onde plane pour chaque microélément diffractant.