A method including: scanning a sample over a period of time using an electro-magnetic radiation source, the period of time including a first time period and a second time period, a sample portion of the electro-magnetic radiation source being directed to the sample in a sample arm of an optical interferometric system, and a reference portion of the electro-magnetic radiation source being directed to a reference arm of the optical interferometric system； applying, using a phase modulator, a phase shift comprising a first phase shift and a second phase shift to at least one of the reference portion or the sample portion of the electro-magnetic radiation source, the first phase shift being applied during the first time period and the second phase shift being applied during the second time period, the second phase shift having a difference of 90 degrees from the first phase shift； acquiring in-phase data based on a first interference between first backscattered electro-magnetic radiation during the first time period and the at least one of the reference portion or the sample portion subjected to the first phase shift； acquiring quadrature data based on a second interference between second backscattered electro-magnetic radiation during the second time period and the at least one of the reference portion or the sample portion subjected to the second phase shift； and determining a complex interference signal based on the in-phase data and the quadrature data.Procédé comprenant : le balayage d'un échantillon pendant un laps de temps à l'aide d'une source de rayonnement électromagnétique, le laps de temps comprenant un premier laps de temps et un second laps de temps, une partie échantillon de la source de rayonnement électromagnétique étant dirigée vers l'échantillon dans un bras d'échantillon d'un système interférométrique optique, et une partie de référence de la source de rayonnement électromagnétique étant dirigée vers un bras de référence du système interférométrique
