Film-Based Videodisc System

Abstract

This paper summarizes the current results of an effort to develop a video-disc system of reasonable simplicity and low cost with adequate video storage capability. The system uses silver halide films or their equivalent as the basic storage medium for the video signals. These film media offer numerous well-known advantages such as archival image quality, ease of duplication and low cost. A prime advantage of the film media is the possibility of storing video information on numerous layers of one disc, increasing the capacity of a disc. The video data on any given layer may be less densely packed, easing the requirements of the retrieval process; the total video information store and hence the playing time can be increased in direct proportion to the number of layers bonded into one disc. Film has other advantages in the recording and playback operations. Recording can be carried out in real time and subsequent processing of the master disc utilizes standard darkroom techniques with duplication accomplished by standard contact print techniques. Playback of the recorded information involves no material contact with the film surface; only a light beam, from a lasing or a normal light source, touches the disc. In the simplest playback configuration, a white light source illuminates the region of interest on the film. This region is projected by a lens system that presents an optical image which is directly accessible to detection and processing by well-known electronic means. The alignment of the light source, the objective, and the detector is noncritical, allowing the use of mechanical components of reasonable tolerance.