Birefringent optical temperature sensor and method

A method for optically sensing a temperature comprising:

• providing a LCI-based tandem interferometer setup having
• a polarization-based sensing interferometer comprising an optical temperature sensing component having a temperature-dependent birefringence for providing a path length difference sensitive to a temperature to be measured, said sensing interferometer having a birefringence dispersion;
• and
• a readout interferometer optically coupled to said sensing interferometer and comprising one of a Fizeau interferometer made of an optical wedge and a polarization interferometer made of a birefringent wedge, said readout interferometer for providing a spatially distributed interferogram, said readout interferometer having a readout dispersion;
• propagating a light in said sensing interferometer, said light having a coherence length smaller than said path length difference;
• measuring said interferogram;
• numerically compensating an unbalanced dispersion resulting from a difference between said sensing dispersion and said readout dispersion on the measured interferogram for calculating a temperature measurement using the measured interferogram;
• and
• producing the temperature measurement.

A tandem interferometer for temperature sensing comprising:

• a LCI-based polarization-based sensing interferometer comprising an optical temperature sensing component having a temperature-dependent birefringence for providing a path length difference sensitive to a temperature to be measured and a birefringence dispersion, hereinafter called a sensing dispersion;
• and
• a readout interferometer optically coupled to said sensing interferometer and comprising one of a Fizeau interferometer made of an optical wedge having a material dispersion a polarization interferometer made of a birefringent wedge having a birefringence dispersion, said material dispersion and said birefringence dispersion of said birefringence wedge hereinafter called a readout dispersion, said readout interferometer for providing a spatially distributed interferogram;
• an optical detection system for measuring said interferogram and for providing an interferogram signal;
• a signal processing unit for numerically compensating an unbalanced dispersion on said interferogram signal resulting from a difference between said sensing dispersion and said readout dispersion.

An optical temperature sensing system comprising:

• a LCI-based polarization-based sensing interferometer comprising an optical temperature sensing component having a temperature-dependent birefringence for providing a path length difference sensitive to a temperature to be measured and a sensing dispersion;
• and
• a readout interferometer optically coupled to said sensing interferometer and comprising one of a Fizeau interferometer made of an optical wedge and a polarization interferometer made of a birefringent wedge, said readout interferometer for providing a spatially distributed interferogram one of said optical wedge and said birefringent wedge having a readout dispersion;
• a light source optically coupled to said sensing interferometer and for generating a light having a coherence length smaller than said path length difference;
• an optical detection system for measuring said interferogram;
• a signal processing unit for numerically compensating an unbalanced dispersion on said interferogram signal resulting from a difference between said sensing dispersion and said readout dispersion for providing a temperature measurement using a measured interferogram.

A method for numerically compensating a dispersion effect in an interferogram produced by a LCI-based tandem interferometer setup in an optical temperature sensing system, said tandem interferometer comprising a sensing interferometer having an optical temperature sensing component having a birefringent dispersion, hereinafter called a sensing dispersion and a temperature-dependent birefringence for providing a path length difference sensitive to a temperature to be measured;

• a readout interferometer optically coupled to said sensing interferometer and having one of a Fizeau interferometer made of an optical wedge having a material dispersion and a polarization interferometer made of a birefringent wedge having a readout dispersion, said readout interferometer for providing a spatially distributed interferogram;
• and an unbalanced dispersion resulting from a difference between said birefringent dispersion and said readout dispersion, the method comprising:
• measuring said interferogram to provide an interferogram signal;
• producing a temperature measurement by calculating said temperature measurement using the measured interferogram, said calculating comprising numerically compensating said unbalanced dispersion.

An LCI-based optical temperature sensing system comprising:

• a polarization-based sensing interferometer comprising an optical temperature sensing component having a temperature-dependent birefringence for providing a path length difference sensitive to a temperature to be measured, said sensing interferometer having a sensing dispersion;
• a readout interferometer optically coupled to said sensing interferometer, said readout interferometer for providing a spatially distributed interferogram, said readout interferometer having a readout dispersion;
• an optical detection system for measuring said interferogram and for providing an interferogram signal;
• and
• a signal processing unit for numerically compensating an unbalanced dispersion on said interferogram signal resulting from a difference between said sensing dispersion and said readout dispersion.