| 摘要 |
PURPOSE:To eliminate the optical power loss and the effect of the reflected light pulse at the end surface of an optical fiber being measured, by using an optical chopper to alternately connect and screen the optical paths between a light source and the fiber being measured and between a light receiver and said fiber. CONSTITUTION:When an optical chopper 11 made of a totally reflecting mirror is located at a position where both an optical cord 3 and an optical fiber 7 can be viewed without any obstruction, a light source 1 is driven to make a light pulse incident on the optical fiber 7 through a lens 2, the optical cord 3 and lenses 4 and 6. Thereafter, the optical chopper 11 is moved in order to screen the optical path between the optical cord 3 and the optical fiber 7 as well as to make the optical chopper 11 reflect the reflected light pulse from the optical fiber 7, and said reflected light pulse is made incident on a light-receiving circuit 10 through a lens 8 and an optical cord 9 and converted into an electric pulse to perform measurement. The driving circuit 14 of the light source 1, the optical chopper driving part 12 and the light-receiving circuit 10 are synchronized with each other by a control circuit 13. The light from a light source 17 is detected by means of a light receiver 20 through optical cords 16 and 19, and the operating state of the optical chopper thus measured is fed back to the control circuit 13. |
