Dr. Ing. Rudolf Hell Gmbh

Thomas Zelenka

Heinrich Juergensen

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.

Scan device with light mixer and diffusing means for half-tone

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.

Method and apparatus for scanning masters

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. Employing the rotating mirror in a recording arrangement, transit time elements controlled by the correction values are disposed as correction elements in the signal path of the image signal for the correction of the positional errors in the line direction. If the image signal is stored, the frequency of the read clock can alternately be changed as a function of the correction values. The method is very accurate so that, in particular, errors caused by uneven mirror surfaces are corrected.

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Kiel, Germany

Thomas Zelenka