PHOTO DETECTOR

PURPOSE:To eliminate the need for cleaning by alcohol, etc., by using an optical connector whose socket is not a receptacle and opening part is movable and by including an electric circuit consisting of a photoelectric conversion circuit, an amplifier circuit, a discrimination circuit and a display circuit, and a battery for driving the electric circuit. CONSTITUTION:An optical connector inlet part 18 has a structure to widen just to allow an optical connector 18 to pass through and to close to approximately a diameter of an optical fiber 17 after the optical connector 16 passed through; a structure such as a diaphragm of a camera will do. Since received light is confined inside a photo receiving chamber 15 due to such a structure, most of it falls on a photo detector 11. Light is converted to an electric signal by the photo detector 11, treated by an electric circuit on a circuit substrate 12 and the presence or absence of light is displayed by display IEDs 13, 19. Detected light is received by an photo electric converting circuit 31 and converted to an electric signal. The signal is amplified by an amplifier circuit 32 and input to a discrimination circuit 33.