Abstract: Control of speed and uniformity of the heating of the working zone of the preform in a glass drawing operation in which the softening heat is applied by forced convection (13), using a separate fluid heating zone to introduce temperature and velocity controlled fluid. The size of the working zone is further controlled by changing (18) the configuration of a movable exit sleeve. Uniformity and accuracy of temperature is enhanced by normalization (10) of the temperature of the preform close to a preselected value before the preform enters the furnace. A glass drawing apparatus embodies the preferred means to carry out the process, providing a two-chamber furnace having an air heating chamber (44) connected by air delivery channels (51) to a drawing chamber (43). The drawing chamber has preform inlet (41) and a drawn product outlet (56). Each of the latter preferably has an adjustable opening diameter. The inlet is provided with a pre-cooling collar (35).

Abstract: Control of speed and uniformity of the heating of the working zone of the preform in a glass drawing operation in which the softening heat is applied by forced convection (13), using a separate fluid heating zone to introduce temperature and velocity controlled fluid. The size of the working zone is further controlled by changing (18) the configuration of a movable exit sleeve. Uniformity and accuracy of temperature is enhanced by normalization (10) of the temperature of the preform close to a preselected value before the preform enters the furnace.A glass drawing apparatus embodies the preferred means to carry out the process, providing a two-chamber furnace having an air heating chamber (44) connected by air delivery channels (51) to a drawing chamber (43). The drawing chamber has preform inlet (41) and a drawn product outlet (56). Each of the latter preferably has an adjustable opening diameter. The inlet is provided with a pre-cooling collar (35).

Abstract: Apparatus for expanding a visual image consisting of a ribbon of clad optical fibers locked in closely-spaced, parallel relationship and cut across at a narrow acute angle at one end, the surface thus exposed being roughened in texture and the exterior of each fiber being provided in that area with a reflective material. Alternately to roughening the surface, the core of each fiber is partially etched out, and a plug of light-diffusing material inserted. A reflective layer is applied between this plug and the cladding of the fiber.

Abstract: A faceplate for a highly sensitive low-light level imaging device is provided with an off-axis light filter to reduce optical noise. A transparent optical conduit layer includes an absorbing region around the periphery to absorb off-axis light. A transparent front plate extends beyond the periphery of the conduit and forms a shoulder of easily polished glass to facilitate the sealing of the faceplate to the imaging device frame. A clear glass back plate extends so as to cover the entire inner surface of the conduit including the absorbing region, thereby providing an easily and consistently polishable surface upon which to bond a photosensitive semi-conductor wafer. This reduces the necessity for matching of glass compositions between the core and the absorbing region.

Abstract: Apparatus for expanding a visual image consisting of a ribbon of optical fibers locked in closely-spaced, parallel relationship and cut across at a narrow acute angle at one end, the surface thus exposed being roughened in texture and the exterior of each fiber being provided in that area with a reflective material.

Abstract: An optical display screen reduces image diffusion and extraneous images by the selective absorption of light rays oblique to the line of sight of an operator. Light-absorbing fibers such as black glass are embedded in the screen, parallel with the line of sight, and extending either completely through the screen, or through a thinner layer laminated to the screen. A conventional light emitting layer, such as a phosphor layer is provided. Oblique components of the phosphor emission are absorbed by the fibers. Sufficiently oblique external rays are also so absorbed, and prevented from creating extraneous images. The line of sight components of the phosphor emission are passed through the screen undiminished. Methods of forming the screen include the steps of forming a bundle of unclad clear fibers, including a small percentage of light-absorbing fibers, and fusing the bundle into a block containing parallel light-absorbing fibers.

Abstract: A contrast and resolution enhancing optical display screen has a plurality of straight, light-absorbing fibers embedded in at least a layer of the screen, the layer otherwise having uniform optical and physical properties. The fibers are so directed that the lines containing their axes converge toward the optical center of the first element of a lens system. Uniformity of image intensity is promoted. Sheets of material having fibers with the required arrangement are formed by: forming a thick slice having parallel fibers, bending the thick slice in a spheroidal mold or pattern at well below the working temperature until the fibers form the desired radial arrangement, and cutting the curved thick slice in at least two parallel chordal planes to form a thin sheet with fibers embedded in it. The fibers are disposed radially of a center outside the sheet.

Abstract: A radiation conducting conduit functions as an off-axis filter and contrast enhancer for an imaging device. A core of transparent glass has an axis aligned with the line of sight of the device. Cladding is provided which has the same index of refraction and co-efficient of thermal expansion as the core glass, except that a small percentage of the cladding glass is made of thin fibers or leaves of absorbing glass aligned substantially radially to the axis of the conduit and distributed randomly in the volume of the cladding. The interface between the core glass and the cladding glass of the same composition does not involve reflection or refraction, and non-axial light passes through the interface and is trapped among the absorbing black fibers. There, it is reflected and diminuated until it is totally absorbed.