25 January 1990 Compact Optical Fiber Faraday Ring Ammeter
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The magneto-optic (Faraday) effect in dia-magnetic materials is a promising method of measuring magnetic fields or electric currents in space plasmas due to its non-invasive character. Fiber-optic sensors with coherent detection schemes are attractive for these measurements. The Faraday Ring Ammeter (FRA) is the first in a series of space plasma ammeters under development whose ultimate goal is detecting currents with a pA/m2 resolution. This instrument has 450 meters of twisted single mode optical fiber as its sensing element. The optics for injection (including GRIN lenses) and for coherent detection (po-larimetry) are integrated with the electronics in a (6" x 5" x 3") box. Operating at a laser wavelength of 830mn currents as small as a few hundred milliamperes through the FRA have been measured.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Indu Saxena, Roy B. Torbert, "Compact Optical Fiber Faraday Ring Ammeter", Proc. SPIE 1166, Polarization Considerations for Optical Systems II, (25 January 1990); doi: 10.1117/12.962916; https://doi.org/10.1117/12.962916

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