| 摘要 |
PURPOSE:To provide a temp. measuring method of high accuracy which is of an explosionproof type, has a wide temp. measuring range and is not affected by the environmental change during the course of transmission by using an optical directional coupler of a distribution coupling type as a temp. detecting sensor. CONSTITUTION:Respective waveguides 8, 9a, 9b are formed of a flush planar type of quarts (5mumphi core diameter) in the optical directional coupler 1. Fibers 2 of 6/125mum are welded and connected to the waveguides 8, 9a, 9b. Input light is fed from a light emitting device 3 such as light emitting diode and output light is received from light receiving devices 4a, 4b such as photodiodes, both of which light are processed by a processor 5 such as microcomputer. The results of the processing, etc., are displayed on a display part 6. The input light lambdain from the light emitting device 3 passes the waveguides 8, 9a, 9b, is subjected to distribution coupling at that time and is outputted as two rays of the output light lambdaout1, lambdaout2. The ratio of the two rays of the output light has a specific correlative relation with a temp. change when the ambient temp. changes. The temp. measurement is thus made with high accuracy.
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