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Priority to JP9871481UpriorityCriticalpatent/JPS587228U/ja
Publication of JPS587228UpublicationCriticalpatent/JPS587228U/ja
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Publication of JPS6215866Y2publicationCriticalpatent/JPS6215866Y2/ja
Beam irradiation apparatus, optical apparatus having beam irradiation apparatus for information recording medium, method for manufacturing original disk for information recording medium, and method for manufacturing information recording medium