| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a photovoltage sensor capable of accurately measuring a voltage even in the presence of an intensity fluctuation caused by an external factor and an optical bias fluctuation caused by a temperature fluctuation. SOLUTION: This photovoltage sensor has a polarizer 11, a 1/4 wavelength plate 12, an electrooptical crystal 13 and a variable analyzer 14. The variable analyzer 14 switches a polarization direction between two directions orthogonal to each other according to a polarization control signal 130. Emission light 112 passing through the variable analyzer 14 is photoelectrically converted into a light intensity signal 131 in a light reception part 15. A sum of DC components of the light intensity signals 131 is constant even if an optical bias fluctuation occurs, while an AC component is either of two antiphase signals having equal amplitudes. A calculation part 17 executes correction calculation by use of the two signals having such characteristics, and calculates a voltage measurement result 102 from the result.</p> |
