A system is provided for optically measuring internal dimensions of a sample object comprising internal interfaces at which the refraction index changes so that a portion of incident light is backreflected and/or backscattered and can be detected by means of optical coherence tomography. The system comprises at least one first OCT device adapted to measure internal dimensions in a first partial volume of the object and at least one second OCT device adapted to measure internal dimensions in a second partial volume of the same object, wherein the second partial volume is at least partially different from the first partial volume. The first and second OCT devices may share at least partially spatially superimposed first and second sample arms, which may have respective different focal lengths and pass through a common optical lens system toward the object
