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US 6,208,129 B1Granted
Optical method and arrangement for measuring a periodic value having at least one frequency component
AssigneeSiemens Aktiengesellschaft
InventorsMichael Willsch, Thomas Bosselmann, Peter Menke, Stefan Hain
Life of this patent
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Abstract
Polarized measuring light propagates through a sensor device and is then split into two differently linearly polarized partial light signals. An intensity-normalized measuring signal is derived from the two partial light signals and their direct components.
Claims8
A method for measuring a periodic variable having at least one frequency component, the method comprising the steps of:
- propagating a polarized measuring light having a polarization at least once through a sensor device, the sensor device being under an influence of the periodic variable;
- varying by the sensor device the polarization of the polarized measuring light as a function of the periodic variable;
- splitting the polarized measuring light into a first linearly polarized partial light signal and a second linearly polarized partial light signal, the first linearly polarized partial light signal having a first polarization plane and a first light intensity, the first light intensity having a first direct component, the second linearly polarized partial light signal having a second polarization and a second light intensity, the second light intensity having a second direct component;
- generating a first proportional electric intensity signal as a function of the first light intensity of the first linearly polarized partial light signal;
- generating a second proportional electric intensity signal as a function of the first direct component of the first light intensity;
- generating a third proportional electric intensity signal as a function of the second light intensity of the second linearly polarized partial light signal;
- generating a fourth proportional electric intensity signal as a function of the second direct component of the second light intensity;
- and
- generating a measuring signal as a function of the first proportional electric intensity signal, the second proportional electric intensity signal, the third proportional electric intensity signal, and the fourth proportional electric intensity signal, the measuring signal being proportional to the following quotient:
- (I2DC·I1−I1DC·I2)/(I2DC·I1+I1DC·I2),
- wherein I1 is the first light intensity of the first linearly polarized partial light signal,
- wherein I1DC is the first direct component of the first light intensity,
- wherein I2 is the second light intensity of the second linearly polarized partial light signal,
- wherein I2DC is the second direct component of the second light intensity,
- wherein the first polarization plane of the first linearly polarized partial light signal is different from the second polarization plane of the second linearly polarized partial light signal, and
- wherein the first direct component and the second direct component do not contain any one of the at least one frequency components of the periodic variable.
13 more elements
An arrangement for measuring a periodic variable having at least one frequency component, comprising:
- a sensor device receiving through a coupling member a polarized measuring light having a polarization, the polarized measuring light propagating at least once through the sensor device, the sensor device varying the polarization of the polarized measuring light as a function of the periodic variable
- a splitter device for splitting the polarized measuring light into a first linearly polarized partial light signal and a second linearly polarized partial light signal, the first linearly polarized partial light having a first polarization and a first light intensity, the first light intensity having a first direct component, the second linearly polarized partial light having a second polarization and a second light intensity, the second light intensity having a second direct component;
- a first circuit arrangement generating:
- a first proportional electric intensity signal as a function of the first light intensity of the first linearly polarized partial light signal,
- a second proportional electric intensity signal as a function of the first direct component of the first light intensity,
- a third proportional electric intensity signal as a function of the second light intensity of the second linearly polarized partial light signal, and
- a fourth proportional electric intensity signal as a function of the second direct component of the second light intensity;
- and
- a second circuit arrangement generating a measuring signal as a function of the first proportional electric intensity signal, the second proportional electric intensity signal, the third proportional electric intensity signal, and the fourth proportional electric intensity signal, the measuring signal being proportional to the following quotient:
- (I2DC·I1−I1DC·I2)/(I2DC·I1+I1DCI2),
- wherein I1 is the first light intensity of the first linearly polarized partial light signal,
- wherein I1DC is the first direct component of the first light intensity,
- wherein I2 is the second light intensity of the second linearly polarized partial light signal, and
- wherein I2DC is the second direct component of the second light intensity,
- wherein the first polarization of the first linearly polarized partial light is different from the second polarization of the second linearly polarized partial light, and
- wherein the first direct component and the second direct component do not contain any one of the at least one frequency components of the periodic variable.
13 more elements
Dependencies are inferred from the claim text.