Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Using radiant energy
Patent
1990-02-16
1992-05-12
Nguyen, Vinh
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Using radiant energy
324158R, 324 77K, 359246, G01R 1900, G01R 3100, G02F 109
Patent
active
051131315
ABSTRACT:
An apparatus and method for measuring an unknown voltage using electro-optic materials includes a beam transmitter, voltage sensor, and a receiver. The beam transmitter generates an electro-magnetic beam directed at an electro-optic material in the sensor. The electro-optic material has a voltage gradient across it due to the unknown voltage. The beam is such that it has components both parallel and perpendicular to the direction of the voltage gradient so that passing through the electro-optic material creates a phase difference between the parallel and perpendicular components. This beam with the phase difference passes to the receiver where the beam passes through a compensator formed by another electro-optic material subjected to a voltage gradient from a measurable voltage. The measurable voltage is controlled to produce another relative phase retardation which compensates for the phase retardation produced at the sensor. The net retardation caused by the two electro-optic materials is detected using first and second detectors for converting the intensities of the parallel and perpendicular components into respective first and second voltages. The first and second voltages are compared and the resulting difference signal is used for driving the voltage gradient across the electro-optic material in the compensator. This feedback arrangement creates a comparator output of zero when the net retardation caused by the sensor and compensator is equal to .pi./4 or .pi./4+n .pi./2 where n is any integer number. Several variations of this embodiment are disclosed.
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Cooper David E.
Houy Thomas J.
Nguyen Vinh
Southern California Edison Company
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