| 摘要 |
<p>PROBLEM TO BE SOLVED: To eliminate the influence of a shift caused by the temperature change of phase difference in aλ/4 plate in a photo-voltage sensor constituted in such a way as to detect system voltage from the change of transmitted light quantity in relation to applied voltage, of an electro-optical element formed of a Pockels element or the like. SOLUTION: The added value of a low band component DCS, outputted after photoelectric conversion by a photodiode 32 and passed through an LPF 36, of reflected light from a polarization analyzer 28, and a low band component DCP, outputted after photoelectric conversion by a photodiode 33 and passed through an LPF 37, of transmitted light of the polarization analyzer 28, is obtained by an adder 38, and a high band component ACS of the above-mentioned reflected light output through an HPF 35 is divided by the obtained added value by a divider 39. Accordingly, even though the light quantity of either one of the transmitted light and reflected light is increased by the shift of phase difference following temperature change, the light quantity of the other is decreased, so that the added value remains constant, and the change of the high band component where an applied voltage change appears can be detected with high accuracy.</p> |
