Rotary optical filter apparatus integrated with cooling fan and illumination optical system

摘要

A rotary optical filter apparatus containing an optical filter is integrated with a sirocco type cooling fan having a plurality of fan blades. The cooling fan is supported by a rotary holder of the optical filter apparatus so as to be integrally rotatable with the optical filter. The cooling fan inhales an air from its center part and discharges thus inhaled air from its outer peripheral part due to an action of the fan blades upon rotating, so as to make an airflow along the filter face and cool the optical filter.