Optical-voltage sensor

Abstract

A measurement sensitivity of an electro-optical element higher is made highly sensitive, and an optical-voltage sensor having a simple structure capable of being formed by directly laminating the highly sensitive electro-optical elements is provided. The optical-voltage sensor comprises a light source 1 , a polarizer 2 , a ¼ wavelength plate 3 , an analyzer 5 , and an O/E converting part. In the optical-voltage sensor in accordance with the present invention, two electro-optical elements 4 a , 4 b are arranged adjacent to each other along a transmitting direction of light between the ¼ wavelength plate 3 and the analyzer 5. Transparent electrodes 7 are attached on both surfaces of each of the electro-optical elements 4 a , 4 b , and voltages having a magnitude equal to and a polarity opposite to each other are applied at a time to the electro-optical element 4 a in the polarizer 3 side and the electro-optical element 4 b in the analyzer 5 side from a power supply 8a and a power supply 8 b , respectively.

What is claimed is:  
     
         1 . An optical-voltage sensor comprising a polarizer for converting incident light into linearly polarized light; a ¼ wavelength plate for converting said linearly polarized light into circular polarized light; electro-optical elements to transmit said circular polarized light therethrough and to perform phase modulation of said light corresponding to a voltage applied to transparent electrodes in the both surfaces; and an analyzer for sensing light transmitted through said electro-optical elements, wherein 
 two of said electro-optical elements are arranged adjacently to each other along a transmitting direction of the light, and a voltage to be measured is applied to each of said two electro-optical elements at a time with polarities opposite to each other.  
 
     
     
         2 . An optical-voltage sensor comprising a polarizer for converting incident light into linearly polarized light; a ¼ wavelength plate for converting said linearly polarized light into circular polarized light; electro-optical elements to transmit said circular polarized light therethrough and to perform phase modulation of said light corresponding to a voltage applied to transparent electrodes in the both surfaces; and an analyzer for sensing light transmitted through said electro-optical elements, wherein 
 two of said electro-optical elements are arranged adjacently to each other along a transmitting direction of the light, and said two electro-optical elements are arranged so that an angle difference between crystal orientations of said electro-optical elements becomes 90 degrees in a plane perpendicular to the transmitting direction of said light, and a voltage to be measured is applied to each of said two electro-optical elements at a time with an equal polarity.  
 
     
     
         3 . An optical-voltage sensor comprising a polarizer for converting incident light into linearly polarized light; a ¼ wavelength plate for converting said linearly polarized light into circular polarized light; electro-optical elements to transmit said circular polarized light therethrough and to perform phase modulation of said light corresponding to a voltage applied to transparent electrodes in the both surfaces; and an analyzer for sensing light transmitted through said electro-optical elements, wherein 
 an even number of said electro-optical elements are arranged continuously along a transmitting direction of said light, and a voltage to be measured is applied to each of said even number of electro-optical elements at a time with polarities opposite to each other with respect to the adjacent electro-optical element.  
 
     
     
         4 . An optical-voltage sensor comprising a polarizer for converting incident light into linearly polarized light; a ¼ wavelength plate for converting said linearly polarized light into circular polarized light; electro-optical elements to transmit said circular polarized light therethrough and to perform phase modulation of said light corresponding to a voltage applied to transparent electrodes in the both surfaces; and an analyzer for sensing light transmitted through said electro-optical elements, wherein 
 an even number of said electro-optical elements are arranged continuously along a transmitting direction of said light, and said even number of electro-optical elements are arranged so that crystal orientations of said even number of electro-optical elements are rotated by 90 degrees in a plane perpendicular to the transmitting direction of said light, and a voltage to be measured is applied to each of said even number of electro-optical elements at a time with an equal polarity.  
 
     
     
         5 . An optical-voltage sensor according to any one of  claim 1  to  claim 4 , wherein said electro-optical element is formed so that a thickness of said electro-optical element in the transmitting direction of the light corresponds to an angle of natural optical rotatory power larger than 45 degrees.