| 摘要 |
PURPOSE:To detect an increase and a decrease in pressure variation by demultiplexing light and then multiplexing light waves passed through single-mode optical fibers which vary and do not vary in length with pressure, and photodetecting obtained interference fringes at two nearby points and deciding on the moving direction of the fringes. CONSTITUTION:When pressure is applied to a pressure admitting body 1, a pressure reception part 4 increases in diameter to cause an optical path difference between single- mode optical fibers 2 and 3 because the optical fiber 2 extends while the other optical fiber 3 of a reference light part 5 does not vary in length, and interference is caused in the output light of an optical multiplexer 9 to form interference fringes at a photodetection part 10. The interference fringes move from the center of photodetection to the circumference at the time of an increase in pressure or from the circumference to the photodetection center at the time of a decrease in pressure, so the interference fringes are photodetected by photodetectors 11 and 12 and converted into a pulse signal and outputs (a) and (b) of preamplifiers 13 and 14 are supplied to monostable multivibrators 15 and 16 to decide on the before-after relation of the timing. Further, a counter 17 counts up when the pressure increases and counts down when the pressure decreases. Thus, explosion resistance and digital signal output are secured. |
