| 摘要 |
1,180,869. Photo-electric current measurement. MERLIN GERIN. Aug. 30, 1968 [Sept. 1, 1967], No.41586/68. Headings G1A and G1U. An electric parameter e. g. current of a high voltage line is measured by directing light, polarized by a polarizer 18, from a source 1 at earth up through a Faraday modulator 22 energized by the line current and reflecting the light back through the same modulator to a photo-cell or photomultiplier 30 at earth. The output of detector 30 is fed back in a null balance arrangement to a Faraday compensator 20, and the compensation current indicated at 34 is a measure of the line current. A 22¢ degrees rotation of the plane of polarization of the up and down going beams may be produced by a Faraday cell or polarization rotator made of quartz, sugar or colloidal iron suspended in resin. The position of the source and detector may be interchanged or they may be located close together, beam splitter 16 being replaced by suitable focussing devices. A plurality of sources may be used, the light being directed upwards by a multiple faced plate at 16. The Faraday cells may be replaced by Kerr, Pockets or Cotton-Mouton cells. |
