PURPOSE: To provide a valve opening detector of high reliability that can deal with fluctuations in laser beams due to the temperature nonuniformity of ambient air resulting from trace amounts of steam leakage and changes in the flow rate of steam.
CONSTITUTION: An optical detecting head 40A, from and on which laser beams B are emitted and incident, is mounted in a driving unit driving a steam governor via a shaft, and an optical fiber is coupled between the optical detecting head 40A and a signal processor. The optical detecting head 40A comprises a projecting lens which projects the laser beams B onto a regressive reflector and an incident optical system 20A. The incident optical system 20A has a jig 23 mounted in the focal position of a condensing lens 22, and the end of an incident optical fiber 21 is inserted, together with a sleeve 25, into a slit 24 provided in the focal position. A spacer 26 is interposed between the flange 25a of the sleeve 25 and the jig 23 to defocus the light incident on the incident optical fiber 21. The quantity of light decreased by defocusing is compensated by a limiter amplifier.
MAEDA MUNEAKI
IEDA HARUO
YAMAMOTO KENJI
NAGAHASHI KAZUAKI
IIDA YASUHISA
KONISHI MASAYOSHI
SHONO MICHIYUKI
HIRATA DAISAKU
FUKUNAGA HIRONOBU
KANSAI ELECTRIC POWER CO
SHIKOKU ELEC POWER
KYUSHU ELECTRIC POWER
JAPAN ATOMIC POWER
MITSUBISHI HEAVY IND LTD
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