| 摘要 |
PURPOSE:To emit an illuminating light in a wide angle without enlarging the outside diameter of the in-duct line observation device by emitting irregularly a light beam emitted as a wave front state from an emitting end face of a light guide into a duct line. CONSTITUTION:On the outside periphery of an in-duct line observation mirror 1 of a television camera, a fiberscope, etc., a light guide 2 are arranged in a ring, shape, and the inner wall D of a duct line B is observed by a light beam emitted from the emitting end face 3 of the light guide 2. Since the emitting end face 3 of the light guide 2 is in a wave front state, the light beam emitted from the emitting end face 3 is emitted irregularly, an emission angle becomes wider than a numerical aperture of an optical fiber used for the light guide 2, and a comparatively uniform illuminance is obtained in the inner wall D of the duct line B. Since the illuminating light is emitted in a wide angle, it is unnecessary to allow the tip of the light guide 2 to have an angle, and the outside diameter of the in-duct observation device does not become large. |
