Apparatus and method for spatially resolved temperature measurement
Apparatus for spatially resolved temperature measurement, comprising at least one optical fiber ( 4 ) for spatially resolved temperature measurement, at least one laser light source ( 1 ), the light ( 11 ) from which can be coupled into the optical fiber ( 4 ), wherein those components ( 12, 12 a, 12 b ) of the light ( 11 ) produced by the laser light source ( 1 ) which are scattered back in the optical fiber ( 4 ) can be coupled out of the optical fiber ( 4 ) and detected, modulator means ( 2 ) permitting the modulation of the light ( 11 ) that is to be coupled into the optical fiber ( 4 ), and also demodulator means ( 5, 6 ) which permit a demodulation of those components ( 12, 12 a, 12 b ) of the light ( 11 ) which are coupled out of the optical fiber ( 4 ), wherein the demodulator means ( 5, 6 ) are designed as optical demodulator means ( 5, 6 ) and/or wherein the modulator means ( 2 ) are designed as optical modulator means ( 2 ).
1. An apparatus for spatially resolved temperature measurement, comprising:
at least one optical fiber ( 4 ) for the spatially resolved temperature measurement,
at least one laser light source ( 1 ), providing light which is coupled into the optical fiber ( 4 ), wherein the light ( 11 ) produced by the laser light source ( 1 ) includes components ( 12 , 12 a , 12 b ) which are backscattered in the optical fiber ( 4 ) and which are coupled out from the optical fiber ( 4 ) and detected,
an optical modulator ( 2 ) which performs modulation of the light ( 11 ) which is to be coupled into the optical fiber ( 4 ),
an optical demodulator which performs demodulation of the components ( 12 , 12 a , 12 b ) of the light ( 11 ) which are coupled out from the optical fiber ( 4 ),
wherein the optical demodulator comprise a beam splitter for producing an additional light signal ( 14 ), the beam splitter branching off a portion of the light ( 11 ) modulated by the optical modulator ( 2 ) before it is coupled into the optical fiber ( 4 ), wherein the additional light signal ( 14 ) is being detected together with the components ( 12 , 12 a , 12 b ) of the light ( 11 ) which are coupled out from the optical fiber ( 4 ),
wherein the optical fiber output is indicative of the spatially resolved temperature.
2. The apparatus as claimed in claim 1 , wherein the demodulator comprise at least one sensor ( 7 , 8 ) which detects the additional light signal ( 14 ) together with the components ( 12 , 12 a , 12 b ) of the light ( 11 ) which are coupled out from the optical fiber ( 4 ).
3. The apparatus as claimed in claim 2 , wherein the at least one sensor ( 7 , 8 ) comprise a photodiode.
4. The apparatus as claimed, in claim 1 , wherein the optical modulator ( 2 ) comprise a is a Mach-Zehnder modulator.
5. The apparatus as claimed in claim 4 , wherein the Mach-Zehnder modulator has two interferometer arms onto which the light ( 11 ) is split, wherein in one of the arms the light ( 11 ) is modulated by an electro-optical modulator.
6. The apparatus as claimed in one of claim 1 , wherein the apparatus is an OFDR-DTS appliance or an OTDR-DTS appliance.
7. A method for spatially resolved temperature measurement using an apparatus for spatially resolved temperature measurement including; at least one optical fiber ( 4 ) for the spatially resolved temperature measurement; at least one laser light source ( 1 ), providing light ( 11 ) which is coupled into the optical fiber ( 4 ), wherein the light ( 11 ) produced by the laser light source ( 1 ) includes components ( 12 , 12 a , 12 b ) which are backscattered in the optical fiber ( 4 ) and which are coupled out from the optical fiber ( 4 ) and detected, an optical modulator ( 2 ) which allows modulation of the light ( 11 ) which is to be coupled into the optical fiber ( 4 ); an optical demodulator which allow demodulation of the components ( 12 , 12 a , 12 b ) of the light ( 11 ) which are coupled out from the optical fiber ( 4 ); wherein the optical demodulator comprises a beam splitter for producing an additional light signal ( 14 ), the beam splitter branches off a portion of the light ( 11 ) modulated by the optical modulator ( 2 ) before it is coupled into the optical fiber ( 4 ): wherein the additional light signal ( 14 ) is being, detected together with the components ( 12 , 12 a , 12 b ) of the light ( 11 ) which are coupled out from the optical fiber ( 4 ), the method comprising, the following steps:
producing the light ( 11 ) using the laser light source ( 1 );
modulating the light ( 11 ) with the optical modulator;
coupling the modulated light ( 11 ) into the optical fiber ( 4 );
coupling out from the Optical fiber ( 4 ) the components ( 12 , 12 a , 12 b ) of the couple (light ( 11 ) which are backscattered in the optical fiber ( 4 );
the coupled out components ( 12 , 12 a , 12 b ) of the light are demodulated using the optical demodulator;
wherein a portion of the light ( 11 ) modulated by the optical modulator ( 2 ) is branched off as an additional light signal ( 14 ) before it is coupled into the optical fiber ( 4 ), the additional light signal ( 14 ) being detected together with the components ( 12 , 12 a , 12 b ) of the light ( 11 ) which are coupled out from the optical fiber ( 4 );
wherein the optical fiber output is indicative of the spatially resolved temperature.
8. The method as claimed in claim 7 , wherein the modulation is effected by a Mach-Zehnder modulator.
9. The method as claimed in claim 7 , wherein the method is an OFDR or OTDR method.
10. The method as claimed in claim 9 , wherein the OFDR method involves the intensity of the light ( 11 ) being modulated with fixed or discrete frequencies.
11. The method as claimed in claim 9 , wherein the OFDR method involves the intensity of the light ( 11 ) being modulated with a frequency which varies over time.