Fiber optic endoscopes exposed to X-ray or .gamma.-ray irradiation suffer discoloration of the optical fiber bundles with a reduction in light transmittance. This makes observation or examination using these devices difficult or impossible. The irradiation-induced reduction in light transmittance of...http://www.google.com/patents/US4569334?utm_source=gb-gplus-sharePatent US4569334 - Apparatus for restoring the light transmittance of an image-transmitting optical fiber bundle used in a fiber optic endoscope
