| 摘要 |
<p>PURPOSE:To measure a DC electric field without using a member which is driven mechanically by giving a light beam to an electro-optical crystal, giving an emitted light from this electro-optical crystal to a measuring part and measuring an electric field from intensity of a photodetected light beam. CONSTITUTION:When a DC electric field E to be measured is given to a terminal 2, the electric field E is brought to DC - AC conversion by a bridge circuit 1 and given to an electro-optical crystal 5. Subsequently, as for a light beam which is made incident on the crystal 5 through an optical fiber 9 from a light source 10, intensity of an emitted light is controlled in accordance with intensity of the electric field E. Accordingly, the emitted light of this crystal 5 is inputted to a photoelectric converter 13 through an optical fiber 11 and converted to an electric signal. Next, a DC component of this electric signal is obtained by a DC amplifier 21, and an AC component thereof is obtained by an amplifier 20 and a low-pass filter 22. These DC component and AC component are converted to an effective value by an effective value converting circuit 24 and a DC signal corresponding to a modulation degree, namely, intensity of an impressed electric field is obtained. In such a way, the DC electric field is measured by using the electro-optical crystal.</p> |
