Patent ID: 6952107

Claim:
A self-monitoring electric field sensing system for measuring electric field comprising: a light source for generating a primary light wave; first and second photodetectors for providing first and second electrical detector output signals, respectively, in response to any light impinging thereon; an electric field optical sensing head having; at least a first optical sensing element that exhibits an electro-optic effect where transit time of light waves passing therethrough of different polarizations are affected differently in response to an electric field thereat; a first optical circuit responsive to said primary light wave for deriving first and second light wave components therefrom, and coupling said first and second light wave components to said optical sensing element, where said first and second light wave components have different polarizations and having a phase separation, φ o ; and a second optical circuit for deriving third and fourth light waves of different polarization from a light wave exiting from said first sensing element, and directing said third and fourth light waves to impinge upon said first and second photodetectors, respectively; and a signal processor for; (i) deriving sensing system specific characterization parameters K and φ o as a function of a pair of resultant signals a and b, where; signal a and b are derived from the first and second electrical detector output signals, respectively; φ o is the intrinsic phase shift between the first and second light wave components; and K is equal to the ratio K A /K B where K A and K B are characteristic loss factors of the specific electric field sensing system, X, associated with said signals a and b; and (ii) deriving an output signal, E, representative of the electric field intended to be measured by a specific electric field sensing system, X, as a sensing system specific characterized function, G x of; (a) said first and second electrical detector output signals; and (b) at least said sensing system specific characterization parameters K and φ o .