| 摘要 |
PURPOSE:To detect light power with high accuracy by passing output light from a laser light source through a reference fiber and a sensor fiber and controlling the phase of the reference fiber according to interference light, and measuring its control voltage. CONSTITUTION:The output light of the laser light source 1 is branched by a fiber coupler 4 to the sensor optical fiber 5 and reference optical fiber 6. The light passed through the sensor part 7 and light on the reference fiber side which is passed through a phase compensator 9 are coupled by a fiber coupler 8 and a photodetector 12 detects the interference light between the both. The output of this detector 12 and a reference signal are compared by a differential amplifier 13 to obtain an error voltage proportional to the optical path difference between the sensor fiber 5 and reference fiber 6. A piezoelectric element 9c is driven with the error voltage to control the phase compensator 9, and the optical path length of the reference fiber 6 is varied corresponding to the optical path variation of the sensor fiber 5. A power meter 15 is connected to a driving circuit 14 which drives said piezoelectric element and the power of a light beam to be measured by this power meter is measured. |
