Sterilizable focusing lens assembly

This is provided a sealed adjustable lens focusing assembly including a lens barrel having a substantially tubular body and oppositely spaced barrel ends. The barrel is preferably sealed adjacent its opposite ends by optical windows, and a focusing lens is reciprocably mounted within the barrel for selective adjustment along a predetermined longitudinal focal axis. A longitudinally reciprocable drive member is provided which extends inwardly into the tubular body of the lens barrel for selectively moving the lens along the focal axis. An expandable tubular sealing member having a longitudinally expandable tubular wall with oppositely disposed retainer ends is concentrically telescoped over the lens barrel. The retainer ends are preferrably sealed in spaced relationship along the barrel, and the reciprocable drive member is connected to the focusing lens through the wall member intermediate the retainer ends. The sealing member provides an effective static seal about the lens barrel while permitting longitudinal adjustment of the focusing lens therewithin.