Patent ID: 6043648
Filing Date: 2000-03-28
Classification: G01R

Abstract:
A method for temperature calibration of an optical measurement array for measuring a magnetic field, which comprises:a) providing an optical series circuit having a first optical transmission path, a first polarizer with a polarization axis forming a first polarizer angle .theta. with a predetermined reference axis, a sensor device indicating the Faraday effect, a second polarizer with a polarization axis forming a second polarizer angle .eta. with the reference axis, and a second optical transmission path;b) placing the sensor device in a calibrating magnetic field;c) passing at least one light signal through the optical series circuit;d) ascertaining a measurement signal for the calibrating magnetic field from a light intensity of the at least one light signal after passing through the series circuit;e) in a first calibration step, setting the first polarizer angle .theta. to a value .theta..sub.1 and setting the second polarizer angle .eta. to a value .eta..sub.1, thus essentially meeting a condition:sin(2.theta..sub.1 -2.eta..sub.1)=1 or sin(2.theta..sub.1 -2.eta..sub.1)=-1 ,and ascertaining a resultant measurement signal as a first calibration signal M.sub.1 over a predetermined temperature range including at least two temperature values;f) in a second calibration step, setting the first polarizer angle .theta. to a value .theta..sub.2 and setting the second polarizer angle .eta. to a value .eta..sub.2, thus essentially meeting conditions:sin(2.theta..sub.2 -2.eta..sub.2)=1 or sin(2.theta..sub.2 -2.eta..sub.2)=-1 andcos(2.theta..sub.2 +2.eta..sub.2)=-cos(2.theta..sub.1 +2.eta..sub.1), andascertaining a resultant measurement signal as a second calibration signal M.sub.2 over the predetermined temperature range;g) in a third calibration step, ascertaining a correction factor K so that a calibration function:M.sub.K =(2.multidot.M.sub.1 .multidot.M.sub.2)/(M.sub.1 +M.sub.2 +K.multidot.(M.sub.1 -M.sub.2))dependent on the first calibration signal, the second calibration signal and the correction factor, is substantially constant over the predetermined temperature range; andh) in a fourth calibration step, adjusting the polarizer angles .theta. and .eta. of the two polarizers to essentially meet equations:sin(2.theta.-2.eta.)=1 or sin(2.theta.-2.eta.)=-1, andcos(2.theta.+2.eta.)=K.multidot.cos(2.theta..sub.1 +2.eta..sub.1).