Movable blinds to protect optical systems

摘要

To protect an optical system which can be used out of doors or in a hostile environment wherein a lens or covering window of the system is exposed to the elements or other obscuring medium which can impair the efficiency of the optical system, a blind of optically transparent film (17) mounted on rollers (18, 19) so that a section thereof covers the said lens or window (12), and movable selectively and/or automatically when the said section has water, dirt or other medium thereon to bring a fresh section of blind into the lens or window covering portion. Specified systems are cameras, telescopes and car headlamps. The blind and rollers may be in a disposable cartridge which is clipped on the optical system.