| 摘要 |
PROBLEM TO BE SOLVED: To provide a writing optical device capable of obtaining much higher image quality by preventing intrusion of foreign matter without adopting a complicated configuration. SOLUTION: A writing optical device comprises a dustproof member 5 for closing an aperture 4 on a base surface of an optical housing 1. As material for the dustproof member, material having specific gravity higher than that of material for the optical housing is used. As material for the dustproof member, material having heat conductivity higher than that of the material for the optical housing is used. COPYRIGHT: (C)2005,JPO&NCIPI
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