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US 6,297,625 B1Granted
Method and device for measuring a magnetic field
AssigneeSiemens Aktiengesellschaft
InventorsThomas Bosselmann, Stefan Hain, Michael Willsch
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Abstract
According to the present invention, in a method, two polarized light signals are sent in opposite directions through a sensor exhibiting the Faraday effect. To minimize the influence of light portions that are reflected on light paths, one light signal is transmitted on one wavelength, and the other is transmitted on another wavelength. The present invention is applicable in particularly vibration-compensated magneto-optical current converters for purposes of avoiding the influence of back-reflections on the measuring signal.
Claims12
A method for measuring a magnetic field, said method comprising the steps of:
- transmitting a first light signal having a first polarization and a first wavelength through an optical sensor in a first direction, said optical sensor exhibiting a Faraday effect and being arranged in a region of said magnetic field;
- passing said transmitted first light signal through a first analyzer set to a second polarization;
- sending said passed first light signal to a first optical detector for detecting said first light signal, said first optical detector responding only to said first wavelength and at least not significantly to a second wavelength;
- generating a first intensity signal corresponding to a light intensity of said detected first light signal;
- transmitting a second light signal having a third polarization and said second wavelength different from said first wavelength through said optical sensor in a second direction opposite said first direction;
- passing said transmitted second light signal through a second analyzer set to a fourth polarization;
- sending said passed second light signal to a second optical detector for detecting said second light signal, said second optical detector responding only to said second wavelength and at least not significantly to said first wavelength;
- generating a second intensity signal corresponding to a light intensity of said detected second light signal;
- and
- deriving a measuring signal containing information about said magnetic field from said first intensity signal and said second intensity signal.
7 more elements
A device for measuring a magnetic field, said device comprising:
- an optical sensor exhibiting the Faraday effect and being arranged in a region of a magnetic field, said optical sensor having a first gate and a second gate for coupling light into said optical sensor and for coupling out light that has been coupled into said optical sensor through an other of said first gate and second gate and that has passed through said optical sensor;
- a first light source for generating a first light signal at a first wavelength;
- a second light source for generating a second light signal at a second wavelength;
- a first optical path leading from said first light source to one of said first gate and second gate for transmitting said first light signal to said first gate and said second gate;
- a second optical path leading from said second light source to an other of said first gate and said second gate than said first optical path for transmitting said second light signal to said other of said first gate and said second gate;
- a first polarizer for generating a polarization of said first light signal, said first polarizer being arranged in said first optical path;
- a second polarizer for generating a polarization of said second light signal, said second polarizer being arranged in said second optical path;
- a first optical detector that responds only to said first wavelength and at least not significantly to said second wavelength, said first optical detector for generating a first intensity signal corresponding to a light intensity of said detected first light signal;
- a second optical detector that responds only to said second wavelength and at least not significantly to said first wavelength, said second optical detector for generating a second intensity signal corresponding to a light intensity of said detected second light signal;
- a third optical path connected between said second gate of said optical sensor and said first optical detector for transmitting said first light signal that is coupled out of said second gate to said first optical detector means;
- a fourth optical path connected between said first gate of said optical sensor and said second optical detector for transmitting said second light signal that is coupled out of said first gate to said second optical detector;
- a first analyzer arranged in said third optical path and being set to a third polarization that is allocated to said first light signal;
- a second analyzer arranged in said fourth optical path and being set to a fourth polarization that is allocated to said second light signal;
- and
- an evaluator for deriving a measuring signal containing information about said magnetic field from said first intensity signal and said second intensity signal.
12 more elements
Dependencies are inferred from the claim text.