Lightning current measuring device and lightning current measuring method

摘要

This lightning current measuring device (10) is provided with: a polarized light separation element (18) which separates light outputted from a sensor fiber (14) into a horizontal component and a vertical component which have orthogonal planes of polarization, a Faraday rotation angle calculation unit (46A) which calculates the Faraday rotation angle by arc-sine processing of the digitized signal of the difference between the horizontal component and the vertical component converted to a signal by photo-electric conversion after separation by means of the polarized light separation element (18), amplifiers (42x, 42y) which amplify the horizontal component and the vertical component converted to a signal by photoelectric conversion after separation by means of the polarized light separation element (18), a Faraday rotation angle calculating unit (46B) which calculates the Faraday rotation angle on the basis of the digitized signal of the difference between the amplified horizontal component and vertical component, and current value conversion units (48A, 48B) which convert the current value on the basis of the calculated Faraday rotation angle. By this means, this lightning current measuring device (10) is able to calculate lightning currents in which the DC-component has a high dynamic range, including large lightning currents and small lightning currents.