Abstract: Light transmitted by an electro-optically variable cell on application of a voltage actuates a photoconductor which controls the voltage. Voltage is, for example, applied across both a liquid crystal and a photoconductor, control then deriving from a relative change in impedance of the liquid crystal and photoconductor. High contrast and a hysteresis effect permit multi-cell adaptation using a high order of multiplexed addressing.

Abstract: A scanning device for use in a facsimile system is formed on a semiconductor substrate. The substrate has an array of apertures, the boundary of each aperture presenting a pn junction which functions as a photodetector when appropriate bias is applied through sensing and addressing circuits. A light is directed through the apertures from one side of the substrate to be incident on a document located against the other side. The boundaries of the apertures are contoured so that the photodetectors intercept light reflected from the document but are shielded from direct light. In use, the document and the scanning device are slid past one another at a rate commensurate with the rate of operation of the addressing circuit.

Abstract: An optical system provides a multiple image of a linear object, the images focussed on an image array, with the images displaced both laterally and longitudinally relative to each other, a different section of each image in a contiguous, side-by-side position. The multiple imaging is obtained by a plurality of mirrors in a stacked array, the mirrors each tilted about a first axis and rotated about a second axis, the tilt and rotation increasing progressively from the front mirror. The mirrors each have a predetermined optical transmission characteristic, being a maximum for the front mirror and decreasing progressively to the rearmost mirror.

Abstract: An optical system for imaging an elongate object comprises at least two prisms back to back and means for laterally displacing light rays from part of the image prior to passage through the prisms, so that a series of images are formed in side-by-side arrangement. The images will be displaced relative to each other in the direction of the longitudinal axis of the object but are still overlapping so that a section across the images will include all of the object. By increasing the number of prism pairs, further apparent subdivision of the object can be obtained.