Abstract: An endoscope is disclosed for examining minute details at an inaccessible location including an image transmitting conduit, a light guide for transmitting light from a source of ultraviolet and visible light to the remote end of the endoscope, and a conduit for delivering a substance which becomes fluorescent under the influence of ultraviolet light to that end of the endoscope. Preferably the endoscope includes a retractable filter for visible light which can be placed in the light guide to prevent visible light from passing through the light guide.