Means for preventing contamination of the surgical viewing instrument including a flexible bag mounted on the proximal end of a hollow double walled tubular elongated member concentrically mounted to a borescope or surgical viewing instrument where the space between the walls define a passage for flowing...http://www.google.de/patents/US5339800?utm_source=gb-gplus-sharePatent US5339800 - Lens cleaning means for invasive viewing medical instruments with anti-contamination means
