| 摘要 |
<p>PURPOSE:To compensate a temperature characteristic of a Pockels element and to enable execution of accurate measurement by making a prescribed direct-current electric field act, together with an alternating-current electric field act, together with an alternating-current electric field, on the element and by determining the electric field and a voltage from the relative ratio between angular frequency signals being the same and twice as large as the alternating-current electric field. CONSTITUTION:A light emitted from a light-emitting unit 15 enters a sensor head unit 2 and passes through a Pockels element 4 provided between a polarizer 6 and an analyzer 8. In the element 4, the light is subjected to modulation by an alternating- current voltage V to be measured and a direct-current voltage VDC and then enters a light-receiving unit 24, and an electric signal is supplied therefrom to an identical angular frequency component detector 26 and a double angular frequency component detector 28. A division circuit 30 subjects signal components from the detectors 26 and 28 to division and outputs a division signal ET (=E2w/Ew), wherefrom the voltage V is measured. By selecting the voltage VDC satisfying ET = V/4VDC, the signal ET is made free from an effect due to the temperature of the element 4 and others and thus accurate measurement can be attained in a stable manner.</p> |
