Small optical magnetic-field sensor that uses rare-Earth iron garnet films based on the faraday effect.
Highly accurate optical magnetic-field probe sensors that use iron garnet films have been developed. New probe-type sensors were designed with a confocal optical system. A new garnet composition, Bi(0.98)Gd(0.92)La(0.03)Y(1.07)Fe(4.72)Ga(0.28)O(12), was found that shows high temperature stability for a sensitivity of less than 2.0% from -20 to +80 degrees C. The linearity error of the sensor output was within 1.0% for alternating magnetic fields from 0.3 to 42 mT. An optical current transformer that uses the proposed sensor has an ac linearity of 1.0% for input current up to nearly 300 A. The sensor realized high performance in actual use.
Itoh
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N
Multimedia Systems Research Laboratory, Matsushita Electric Industrial, 3-1-1 Yagumo-nakamachi, Moriguchi, Osaka 570-8501, Japan.
Minemoto
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H
Ishiko
D
D
Ishizuka
S
S