A device for the optic measuring of an object (1), including a signal processing unit (2) as well as an interferometer with a light source (3) and with at least one detector (4a, 4d). The interferometer is embodied such that a light beam (12) created by the light source (3) is split at least into a working beam (12a) and a reference beam (12b), with the working beam (12a) impinging the object (1) and the working beam (12a) is at least partially reflected by the object and interfered with the reference beam (12b) on the detector (4a, 4b). The signal processing unit (2) is connected to the detector (4a, 4b) and includes a vibrometer processing unit (2f), which detects the motion of the object (1) from the measuring signals of the detector (4a, 4d). It is essential that the light source (3) creates light with a coherence length shorter than 1 cm and that the interferometer comprises a device for changing the optic path length (11), and the signal processing unit comprises a focus control (2d) controlling a device for changing the optic path length which controls the device for changing the optic path length such that the optic path length of the working beam and the reference beam are approximately adjusted to each other.