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Nippon Telegraph and Telephone Corp
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Nippon Telegraph and Telephone Corp
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Filing date
Publication date
Application filed by Nippon Telegraph and Telephone CorpfiledCriticalNippon Telegraph and Telephone Corp
Priority to JP7074575ApriorityCriticalpatent/JPS51147319A/en
Publication of JPS51147319ApublicationCriticalpatent/JPS51147319A/en
PURPOSE: By combining an optical system which makes a parallel flux-of-light to define the focus position of a lens ysstem on a microfilm position and a large aperture lens system, to get a mechansm whereby no compensation against the change of light-pass length is necessary.