Optical scanning apparatus

摘要

An optical scanning apparatus includes: an optical deflector having a rotatable polygon mirror for reflecting a light beam projected thereon; an ftheta lens for transmitting the light beam reflected on a light reflecting surface of the polygon mirror; a cylindrical lens for transmitting the light beam passing through the ftheta lens; and a sound-insulating case for the ftheta lens having an opening or for the cylindrical lens having an opening, wherein the sound-insulating case houses the optical deflector and the opening of the sound-insulating case is sealed hermetically with the ftheta lens or the cylindrical lens.