Variable input lighting intensity device for light entrance surface of optical-waveguide or fibre

摘要

A lighting unit of a type suitable for illuminating specimens in a microscope or endoscope uses an optical conductor (4) that receives an input from a lighting source (2) that is set at the focal point of a reflector (3). The lighting intensity to be transmitted through the conductor is required to vary dependent upon the application and to this end an adjustable aperture stop (6) is positioned at entry to the conductor. This is in the form of a disc on a spindle (7) having six radial zones, each of which have a pattern of small apertures. The aperture cross sections are of different sizes for each of the zones and the disc may be indexed to a selected position.