Abstract: The invention relates to a process and circuitry for controlling a laser diode. To compensate for the temperature-dependent drop in the light intensity produced by the laser diode, the laser diode is controlled by a voltage generator with an adjustable internal resistance. A rise in the driver current of the laser diode as the temperature rises is set by the adjustable internal resistance in such a way that the rise in the light intensity produced determined by the rise in the driver current compensates for the temperature-dependent fall in the light intensity.

Abstract: The invention is directed to a method and to an apparatus for the correction of the positioning errors of a light ray deflected across a surface by a deflection system comprising at least one mirror face, said light ray moving transversely vis-a-vis the line direction relative to the deflection system. The light ray is generated with a laser diode that is displaceable transversely relative to the direction of the emerging light ray dependent on correction values. Before the actual operation, a plurality of positioning errors of the light ray are measured for every mirror face of the deflection system in the line direction (X-positioning error) and perpendicularly thereto (Y-positioning errors), measurements are made at measuring points orientated in the line direction on the surface. At least one X-correction value and one Y-correction value is generated for every mirror face.

Abstract: An apparatus for scanning a transparency image original wherein scattered light emerging from the original is guided through lens or diffraction gratings onto a diffusion screen attached to a light mixer. In the light mixer, the light is mixed by multiple reflection and, at a light exit of the mixer, is guided to a cross-sectional transducer formed of a plurality of optical fibers. These fibers conduct the light onto a photoelectric transducer. The apparatus works with high efficiency and reduces an image falsifying influence of the Callier effect to such a degree that it no longer has a disturbing appearance in reproduction.

Abstract: A novel apparatus and method for point-to-point and line-by-line opto-electronic scanning of masters mounted on a transparent master carrier and wherein simultaneous opaque and transparency scanning is accomplished to generate opaque and transparency scanning signals for each point of the master with one of the scanning signals being the actual image signal and the other scanning signal being a recognition signal for those points of the master where amplitude errors in the image signal occur due to scattered light and/or shadowing. The disruptive amplitude errors are eliminated by combining the recognition signal with the actual image signal to obtain a substantially error-free signal.

Abstract: Positional errors are corrected for a light beam which is deflected point and line-wise across a scanning surface by a polyhedral rotating mirror. For each mirror surface, the positional errors are measured in the line direction and perpendicular thereto at a plurality of measuring points oriented in the line direction in the area of the scanning surface. Correction values are generated which, during simultaneous error measurement, are changed until the positional errors are compensated by means of correction elements. The determined correction values are stored and are read out for continuous correction during the actual operation synchronously with the mirror surfaces simultaneously located in the beam path. Light deflectors are employed as correction elements.