| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an optical electric field sensor which enables its reliability increase and high-sensitivity electric field measurement as well. SOLUTION: A sensor head is fitted with a directional coupling type 3 dB coupler 22, and a photodetector 4 is composed of two photoelectric converters 5 and an arithmetic circuit 6. Two output lights of a directional coupling type 3 dB coupler 22 strike the two photoelectric converters 5, respectively. The output signal lights of the photoelectric converters 5 are insulted to the arithmetic circuit 6, and one output signal light of the photoelectric converters 5 by an output signal light of a smaller one out of the optical biases of the two output signal lights of the directional coupling type 3 dB coupler 22 is outputted selectively. Along with it, the intensity of emitted light of a light source 3 is controlled so that the intensity of the said optical bias may be constant.</p> |
