Abstract: An illumination system for illuminating an object includes a light source and a lens array system. The light source includes an illumination element emitting light rays and surrounded by a parabolic reflector. The lens array system includes a first lens array plate and a second lens array plate. The first lens array plate includes a matrix of lenslets where, in one embodiment, each lenslet has a shape matching the aspect ratio of the object to be illuminated. The second lens array plate includes a radial pattern of wedge shaped lenslets each corresponding to a lenslet in the first lens array plate. Each wedge shaped lenslet in the second lens array plate has dimensions that are selected to provide a radial and theta collection angles matching the maximum divergence angle of the light source and the maximum divergence angles of the corresponding lenslet in the first lens array plate.

Abstract: A liquid crystal light valve (10) includes compensation for wire shadow effects caused by the interception of writing beam primary electrons as they propagate through the collector electrode (66). The wire shadows stem from the lack of charge deposited on target surface regions ( 106) intended to be addressed by the writing electron beam (60a). The present invention applies to the collector electrode an appropriate voltage that diverts the paths (112) of nonintercepted writing beam electrons toward target surface regions directly below the collector electrode portions that intercepted the writing beam electrons. Diverting the paths of nonintercepted electrons provides a more uniform charge distribution on the target surface (45) and thereby fills the charge voids created by the electron intercepting portions of the collector electrode.

Abstract: An electron beam addressed liquid crystal light modulator or "valve" (10) includes a liquid crystasl cell (40) having a target surface (45) which a writing electron beam (60a) and an erasing electron beam (60b) address to provide a display image. The writing electron beam and the erasing electron beam sequentially strike preselected locations on the target surface to cause an emission of secondary electrons and, thereby, develop an electrostatic potential at such preselected locations. A secondary electron collector electrode (66) positioned over and above the target surface collects in a uniform manner the secondary electrons emitted by all regions of the target surface. A collector electrode controller circuit (81) sequentially applied first and second potential differences between the target surface and the collector electrode in synchronism with the striking of the preselected locations by the respective writing and erasing beams.

Abstract: An electron beam addressed liquid crystal light modulator or "valve" includes a liquid crystal cell having a target surface which a writing electron beam and an erasing electron beam address to provide a display image. The writing electron beam and the erasing electron beam sequentially strike preselected locations on the target surface to cause an emission of secondary electrons and, thereby, develop an electrostatic potential at such preselected locations. A secondary electron collector electrode positioned over and above the target surface collects in a uniform manner the secondary electrons emitted by all regions of the target surface. A collector electrode controller circuit sequentially applies first and second potential differences between the target surface and the collector electrode in synchronism with the striking of the preselected locations by the respective writing and erasing beams.

Abstract: A switchable color filter comprising a pair of twisted nematic liquid crystal devices (126 and 128) and a light polarizing system (108) which includes three color selective polarizing filters (102, 104, and 106) is incorporated as an optical subassembly in a field sequential color display system (100) to provide output states of white light and light of three different colors to form an image in full color and high brightness with strong color contrast.

Abstract: An electron beam-addressed liquid crystal cell for a light valve. The cell (40) includes liquid crystal material (42) sandwiched between two substrates (16, 44). One substrate (44) is addressed by the electron beam (60a, 60b) and includes a coating (51) having a rate of secondary electron emission greater than the characteristic rate of secondary electron emissions of the base layer (49) of the substrate (44). The enhanced secondary electron emission characteristics of the coated substrate (44) permit the cell to be modulated with relatively lower electron beam current for correspondingly higher image resolution.

Abstract: In connection with radiographic inspection of structural and industrial materials, method and apparatus are disclosed for automatically determining and displaying the time required to expose a radiographic film, positioned to receive radiation passed by a test specimen, so that the finished film is exposed to an optimum blackening (density) for maximum film contrast. A plot is made of the variations in a total exposure parameter (representing the product of detected radiation rate and time needed to cause optimum film blackening) as a function of the voltage level applied to an X-ray tube. An electronic function generator storing the shape of this plot is incorporated into an exposure monitoring apparatus, such that for a selected tube voltage setting, the function generator produces an electrical analog signal of the corresponding exposure parameter.