Air Cooling of Motion Picture Film for Higher Screen Illumination<!-- * -->

Screen illumination in theater projection is limited by a maximum radiant-energy flux through the projector aperture. Excessive flux heats the film beyond its safe operating temperature, producing high-intensity effects in the film with loss of image quality on the screen and possible film damage. An increase of 30 to 60 per cent in permissible flux and in attainable screen illumination can be effected if film is cooled and its position controlled by high-velocity air jets directed at the film in the aperture. The high-intensity film effects are discussed and improvements in film behavior with air cooling are described.