| 摘要 |
A photosensitive device, for use in controlling the illumination intensity in an endoscope in response to the image light emerging from a fiber optical bundle in the tube of the endoscope, is positioned so as to provide only minimum interference with the image light emerging from the fibre optical bundle. A viewing lens and the photosensitive element are positioned relative to each other so that the viewing angle of incidence of the viewing lens is less than the aperture angle of the emerging light, and the photosensitive element is positioned so as to be within the aperture angle but outside of the viewing angle.
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