Abstract
IT is natural to expect that the continuous operation of a public television broadcasting service in Great Britain will be accompanied by steady improvement in technique and equipment. An outstanding advance in the latter has recently been achieved by the production of the Super-Emitron camera in the laboratories of the Marconi-E.M.I. Television Co., Ltd. This new camera has already reached the stage of practical application, since it was used recently by the B.B.C. in television broadcasts of the Lord Mayor's Show, and of the Cenotaph ceremony on November 11. A brief technical description of the new camera, published in the Wireless World of November 18, shows that the major improvement depends upon the separation of the photo-electric screen and the mosaic screen which is scanned by the cathode ray beam. As a result of this separation, the photo-electric surface, upon which the visual image of the scene being transmitted is focused, may be made transparent. In this way, certain limitations placed upon the optical projection system of the present Emitron cameras have been removed ; lenses of shorter focal length and wider angle may be used, and even tele-photo lenses when required. Further, the separate mosaic screen may be made from substances having high secondary emission, and consequently considerable electron multiplication may be obtained in the tube itself, thus giving additional overall sensitivity. With the new camera, therefore, less illumination of the subject is necessary for the attainment of a good picture if the normal aperture lens system is retained. This is a valuable feature in outdoor broadcasts on dull days, or when using a telephoto lens for the reproduction of distant scenes. If the normal illumination is retained, however, as in studio work, the aperture of the lens can be reduced with a consequent gain in depth of focus.
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Improvements in Television Equipment. Nature 140, 962 (1937). https://doi.org/10.1038/140962b0
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DOI: https://doi.org/10.1038/140962b0