Incident light blocking endoscope - has tube with front observation window contg. externally controlled turntable prism

摘要

The turntable prism is interposed in the tube between the window and an optical system lens for image observation, such that by turning the prism through a wire operable at the base end portion of the main tube a visual field extending from the front surface to the side surface can be observed. A shading plate is mounted in the tube and is movable with the turning of the prism to block passage of incident light to the optical system from the side surface at the time of front surface observation.