Abstract: The invention relates to a flat plate X-ray detector. In one example a back plate of a flat xenon detector has coaxial cables in a conducting solid matrix connected to the power supply. Each cable center conductor is a small capacitor which charges in response to ion collection. The signals are derived via a commutator.In another embodiment the back plate is an anisotropic plate discharged in a spiral pattern similar to a gramophone record groove.

Abstract: To make a gravure cylinder, a metal cylinder is formed with recesses in its surface in a regular pattern and all of substantially the same depth, the recesses constituting gravure cells separated by cell walls. A different material, generally a plastics material, is then used to overfill the cells and the filled cylinder is subjected to the action of a surfacing tool, the operation of which is controlled not with reference to the axis of the cylinder but with reference to the cylindrical surface formed by the tops of the metal cell walls.

Abstract: In apparatus for excavating material from a gravure cylinder surface, for example, by means of a laser beam, the polarization of the laser beam is modulated and the modulated beam is then passed through a polarization analyzer system to a focusing lens which focuses light on to the surface to be excavated. The polarization analyzing system includes an aperture through which a central portion of the laser beam passes, regardless of its polarization the extent to which the remainder of the beam is transmitted by the analyzer depending upon its polarization modulation. The effect of the aperture is to reduce variation in excavation width with the intensity of the beam.

Abstract: In a laser scanning apparatus, in which a laser and a focusing lens are moved in a direction parallel to the cylinder axis during rotation of the cylinder so that the focused laser beam traces out a helical path on the cylindrical surface, the laser and focusing lens are mounted to permit relative movement in the said direction parallel to the cylinder axis and are separately driven, the driving means for the focusing lens being such as to permit a rate of movement of the focusing lens in the said direction more uniform than can be achieved with the laser driving means, the size of the lens aperture and the extent of the said relative movement during operation of the driving means being such that the laser beam always passes through the lens aperture; the uniformity of the movement of the focused laser beam along the cylindrical surface is then governed by the uniformity of the movement of the focusing lens, the lens head being lighter in weight than the laser head.