A device for three-dimensional imaging by full-field interferential microscopy of a volumic and scattering sample includes an imaging interferometer of variable magnification, allowing for the acquisition of at least one first and one second interferometric images resulting from the interference of a reference wave obtained by reflection of the incident wave on a reference mirror and an object wave obtained by backscattering of the incident wave by a slice of the sample at a given depth of the sample. The invention also relates to a processing unit that processes the interferometric images, a unit for axially displacing the interferometer relative to the sample for the acquisition of tomographic images for slices at different depths of the sample, and a unit for varying the magnification of the imaging interferometer for the acquisition of interferometric images of a slice for different magnification values.