Abstract: An electrostatic precipitator is provided in a light valve of the Schlieren dark field type. The electrostatic precipitator comprises two conductive surfaces within the fluid reservoir of the light valve. One of these surfaces may be the filter housing (81), and the other may be a metal coating (105) which is applied to the inner glass surface of the rear housing (53) of the light valve. By applying a constant d.c. potential across these two conductive surfaces, a resinous or lacquer build-up occurs which is composed of the fine colloidal particulate wear material and a fluid related component which are produced as a result of the normal operation of the light valve. Both the wear material and the fluid related component are too fine to be filtered by mechanical means. Because the wear material and the fluid related component form an adherent resinous material which bonds to the negative electrode, these particulates are permanently removed from the fluid.

Abstract: A flushing system is provided for a light valve of the Schlieren dark field type. A small amount of filtered fluid is injected into the space between the rotating disc and the output window of the light valve. This is done by injecting the fluid through the center disc bearing, thereby providing a uniform radial flow outwardly from the center and flushing out any particles in the space and preventing any particles in the surrounding fluid from moving into the raster area. By properly regulating the flow of the center flush fluid, the disc can be floated off the support during rotation. This reduces wear generated particles which contribute to substrate buildup and subsequent loss of light throughput. In addition, erratic disc motion caused by a stick and slip frictional effect is reduced.

Abstract: A neutralizing electrode is provided in a light valve of the Schlieren dark field type. The purpose of this neutralizing electrode is to neutralize the large electrostatic forces which develop between the transparent conductive electrode on the rotating disc and the face plate of the light valve causing erratic rotational motion of the disk. The neutralizing electrode is connected to a source of potential which is of the same polarity and substantially the same the potential as that of the rotating disk electrode.

Abstract: A low cost tooling replication technique for producing glass pressing tools capable of producing precision complex optical surfaces is disclosed. A master glass pressing tool surface is first passivated and plated with nickel or other suitable material to a thickness sufficient to give the plated material some mechanical strength. The plated material is separated from the master glass pressing tool surface to reveal a negative of the master glass pressing tool surface. This negative surface is passivated and plated with nickel or other suitable material to a thickness sufficient to give the plated material some mechanical strength. The plated material is separated from the negative surface to reveal a replica of the master glass pressing tool surface. A plurality of platings may be made on the negative surface to produce a plurality of replicated master glass pressing surfaces. The replicated master glass pressing surfaces are provided with a backer.

Abstract: A light valve includes a rotatable disk, having a light modulating fluid layer on a writing surface of the disk, mounted for rotation on a cover plate assembly which combines the functions of a disk drive support plate and a baffle plate for hydrodynamically isolating the writing surface of the disk from contaminated fluid in a sump. The cover plate assembly is mounted on a light output window by engaging the window against a shoulder formed on a mounting rim projecting from the cover plate assembly and surrounding the disk. This structure protects the disk from particulate matter during assembly and permits the use of an assembly procedure which is more rapid and less likely to damage the disk. A modification of the device includes metal spacers mounted on a second shoulder formed on the rim for establishing a capillary distance between the light output window and the other surface of the disk.

Abstract: A light valve projection system in which information is impressed on a light modulating fluid overlaying a rotatable disk wherein incident light is modulated by said information and projected onto a viewing surface, said fluid including a raster upon which said information is written by the deposition of electric charge along scanning lines so as to form orthogonally related diffraction gratings which are parallel to a pair of coordinate axes in the plane of said disk. The raster is positioned on said disk offset from said coordinate axes so that movement of said fluid responsive to disk rotation is along paths that intersect said diffraction gratings, which is found to provide a more uniform fluid thickness and light transmission efficiency within the raster and to improve certain aspects of the projected information.