OPTICAL FIBER ILLUMINANCE SENSOR

Japanese Patent JPH0194226

A

PURPOSE:To enhance illuminance measuring accuracy, by applying the electromotive force corresponding to the incidence intensity of light to be measured to a liquid crystal light modulation part and modulating the intensity of the probe light incident to the modulation part through an optical fiber to emit signal light as illuminance data. CONSTITUTION:When light to be measured is incident to the light receiving surface 7 of a photoelectromotive force generating part 3, the electromotive force corresponding to the incidence intensity of said light 6 is generated and, when said electromotive force is applied to a transparent electrode 9, the liquid crystal molecule of a liquid crystal layer 8 is oriented in an electrolytic direction by the angle corresponding to the intensity of an electric field. When the intensity of the electric field is sufficiently high, the long axis of the liquid crystal molecule becomes a molecular orientation state almost along the electrolytic direction. Therefore, the linear polarized light 16P incident to the liquid crystal layer 8 almost receives no rotary action and, as a result, the greater part of the linear polarized light 16S emitted from the liquid crystal layer 8 is blocked by a detector 12. When no light 6 to be measured arrives, the linear polarized light 16S becomes parallel to both vibration surfaces of the detector 12 and, therefore, said light 16S can pass through the detector 12 as modulated light 17. The light 17 is condensed to a SELFOC lens 13 and passes through an optical fiber 5 to be incident to a light receiver.

SHIODA TAKAO
HIDAKA HIROMI
TAKAHASHI KOICHI
SATO MASAHIRO
FUKUDA TAKERU

JP25296387A

April 12, 1989

October 07, 1987

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FUJIKURA LTD

G01J1/04; G01J1/02; G08C23/00; G08C23/04; (IPC1-7): G01J1/02; G01J1/04; G08C23/00

Masatake Shiga (2 outside)

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