Fourier analysis as a means of contemporary measurements of several quantities influencing the refractive index of intensity-based fiber sensors

Contemporary measurement of several quantities takes out the information signal to have so independent parameters as the number of measured quantities. These quantities (e.g. temperature, pressure, concentration, ...) influence refractive index of the optical fiber or optical channel and the magnitude of light energy in this way. Resolution of single contribution is possible if the measured quantities are linearly independent. Then their resultant operating can be expressed as linearly combination of the all quantities. The signal independent parameters are possible to get with Fourier analysis of the output sensor signal. If the intensity-based sensor is excited with composed periodic signal (with known amplitude and frequency structure) then the change of the optical channel properties is appeared as the change of the amplitude frequency structure. It follows from Fourier analysis that every harmonic component behaves as independent signal and can be used for measurement. Sensor matrix or sensor network matrix is the result as well as calibration matrix.