Harmonic-Based Gain Compensation Method in Optic Sensors with Separate Light Paths

We describe a method for the compensation of gain unbalance in optical sensors with separate light paths that involve two separate detection and conditioning electronic devices. The method is based on the digital measurement of harmonics of the output intensities from each path by means of the fast Fourier transform algorithm. The quotient of the amplitude of harmonics allows us to calculate the unbalance between paths and to compensate for it. In particular, this method can be applied in electric power and current sensors that use Faraday and Pockels cells to measure current and voltage, respectively.