Abstract: Light collectors formed by rolling one edge of a sheet of transparent thermoplastic material into an annular configuration, while keeping an opposite edge flat suffer from light collection inefficiency caused by local stretching and thus thinning of the sheet near the annular end, thereby increasing the number of internal reflections experienced by a light ray. This problem is solved by making a light collector that is uniform in thickness, or thicker toward the annular end.

Abstract: To prevent banding in a flat field exposed--by means of a linear array of photosources--upon a moving photosensitive web, the invention not only provides that the photosources be pulsed in correspondence with the movement of the photosensitive web, but that the lengths of the printing spots which are employed be equal (or approximately so) to the raster line spacing, whereby smear of any one exposure spot will blend into the smear from the next exposure spot to provide a perfectly flat field exposure.

Abstract: To provide high intensity, uniform and specular illumination over a relatively large area, the present invention provides a specially configured reflector and a radiation source so positioned within the reflector that an apparent source is produced comprising the true source plus a spherical array of virtual images of the source.

Abstract: Apparatus and method are disclosed for contact printing information from a master record carrier onto a replicate material of a type that emits gas during the contact print exposure (e.g., a diazo-film emulsion). It has been discovered that the emitted gas acts as an efficient lubricant of the master-replicate interface and contributes to relative movement between the master record carrier and the replicate material during the contact print exposure. In the case of videodisc replication, wherein video information is recorded in the form of billions of micron-sized apertures, such relative movement severely degrades the replicated imagery. To limit such relative movement, a preferred embodiment of the present invention provides contact printing apparatus, including a specially filtered exposing source, that substantially eliminates relative movement between the master record carrier and the replicate material.