Electronic method for extracting the amplitude and phase of a signal in a synchronous detector and application thereof in interferometric circuits

Abstract

The invention concerns an electronic method for extracting the amplitude Eand the phase φof an electrical signal in a synchronous detector, the signal containing a modulated part Iof the form I∝ Ef(t)*cos(φ−φ(t)), where φ(t) and f(t) are two known temporal modulation functions. The method comprises the following steps: multiplying the signal by two reference signals C(t) and S(t) constructed from φ(t) and f(t); integrating the resulting signals over a time t; determining the amplitude and phase of said signal from the quantities X and Y resulting from the previous integrations. The method is characterised in that: said electrical signal is multiplied by C(t) and S(t) that can be decomposed on the same set of frequencies as those present in I. The invention also concerns the application of the above method in interferometric circuits and the use and execution of the above method.