US 11,885,841 B2
Electric field sensor
Yoshinori Matsumoto, Tokyo (JP); Hiroaki Tanaka, Tokyo (JP); Jun Katsuyama, Tokyo (JP); and Mitsuru Shinagawa, Tokyo (JP)
Assigned to Yokogawa Electric Corporation, Musashino (JP); and Hosei University, Tokyo (JP)
Appl. No. 17/275,464
Filed by Yokogawa Electric Corporation, Tokyo (JP); and Hosei University, Tokyo (JP)
PCT Filed Sep. 19, 2019, PCT No. PCT/JP2019/036677
§ 371(c)(1), (2) Date Mar. 11, 2021,
PCT Pub. No. WO2020/066816, PCT Pub. Date Apr. 2, 2020.
Claims priority of application No. 2018-180875 (JP), filed on Sep. 26, 2018.
Prior Publication US 2022/0050132 A1, Feb. 17, 2022
Int. Cl. G02F 1/035 (2006.01); G02F 1/295 (2006.01); G02B 6/12 (2006.01); G01R 29/08 (2006.01); G02F 1/03 (2006.01); G02F 1/225 (2006.01)
CPC G01R 29/0885 (2013.01) [G02F 1/0305 (2013.01); G02F 1/225 (2013.01)] 9 Claims
OG exemplary drawing
 
1. An electric field sensor which measures an electric field generated by a target utilizing an electro-optic effect, the electric field sensor comprising:
a light source;
an electro-optic crystal on which light in a predetermined polarization state emitted from the light source is incident and which is subjected to the electric field generated by the target;
a reference electric field applicator configured to apply an electric field based on a reference signal with a known signal level to the electro-optic crystal;
a light receiver configured to receive light emitted from the electro-optic crystal and to convert the received light into an electric signal; and
a separation corrector configured to separate the electric signal into a measurement signal based on the electric field generated by the target and the reference signal and to correct a signal level of the measurement signal on the basis of the signal level of the separated reference signal,
wherein the light receiver comprises:
a polarization beam splitter configured to separate circularly polarized light emitted from the electro-optic crystal into P-polarized light and S-polarized light; and
a differential amplifier configured to amplify a differential component of electric signals of the P-polarized light and the S-polarized light separated by the polarization beam splitter and to output the amplified electric signal to the separation corrector, and
wherein the separation corrector comprises:
a filter configured to remove a signal component of the electric field based on the reference signal in the electric signal output from the differential amplifier;
an amplifier configured to extract a signal component of the electric field based on the reference signal in the electric signal output from the differential amplifier using the reference signal;
a gain controller configured to generate a control signal that controls an amplification factor according to the signal component of the electric field based on the reference signal output from the amplifier; and
a variable gain amplifier configured to vary an amplification factor of the electric signal output from the filter in which the signal component of the electric field based on the reference signal is removed according to the control signal output from the gain controller, and to output the electric signal.