| 摘要 |
PURPOSE:To detect an electrical signal to be measured faithfully, by light modulation of an electrical signal detected with a probe electrode with an electro- optic effect crystal member within a probe. CONSTITUTION:Light from a laser diode 61 is made incident into an electro-optic effect crystal member 3 within a probe 1 via a polarizer 62 and an optical fiber 4. An electrical signal to be measured is inputted into one electrode of the member 3 from a probe electrode 2 while the other electrode thereof 3 is connected to a case 11. Consequently, an electric field corresponding to the electrical signal is generated between both the electrodes of the member 3, optical characteristic of the member 3 varies with the electrical signal to turn an optical signal passing through the member 3 to an optical signal with varying degree of polarization, which is optically transmitted to a unit 6 via a fiber 5. An analyzer 63 lets an optical signal of a specified polarized component alone pass from an optical output signal accompanied by changes in the degree of polarization to irradiate a photo detector 64 so that it is converted into an electrical signal to be supplied to an amplifier 65. Thus, an output signal of the amplifier 65 is such a signal that faithfully corresponds to an electrical signal detected with the probe 1.
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