| 摘要 |
PURPOSE:To uniform photodetection levels by making the length of optical fiber constant, by inputting light signals, proportional to measurement values from photosensors, to the optical fiber in time-division mode via optical switches. CONSTITUTION:Light from light source 1 enters a loop of optical fiber 2 having optical switches 4-1-4-4 arranged in series and is modulated as it is or in proportion to some measurement value before being inputted to measuring device 3 including a photodetector. Optical switches 4-1-4-4 are connected to individual corresponding photosensors 5-1-5-4 with short closed-loop optical fibers 6-1-6-4. Sensors 5-1- 5-4 output light signals having fluctuations of the quantity of light, frequency and wavelength in proportion to a process variable. Optical switches 4-1-4-4, selected through the operation of time-division controller 7, move down glass piece 31 along guide 33 as a voltage is applied to electromanget 32 constituting switches 4-1-4-4, forming a light transmission line. |
