| 摘要 |
PURPOSE:To eliminate the influence execised resulting from changes in transmission path loss, by a method wherein an amount to be measured is measured through the conversion of the amount into a change in frequency. CONSTITUTION:Light, emitted from a light source 21, is supplied to a temperature detecting part 25 via an optical fiber 22, a photo branch element 23, and an optical fiber 24. The temperature detecting part 25 consists of a rod lens 26, a liquid crystal 27, a reflection mirror 28, and a variable frequency oscillator 29 for driving the liquid crystal 27, and modulates light, passing through the liquid crystal 27, by means of frequency corresponding to a measurement temperature. Light, reflected by the reflection mirror 28 and being incident into the optical fiber 24 again, is branched into an optical fiber 30 by means of the photo branch element 23, and is received by a light-receiving meter 31. The light-receiving meter 31 converts the photo signal into a pulse-shaped electric signal, and computes the number of pulses. This permits the measurement of the temperature at the temperature detecting part 25. |
