Measuring device and method to optically measure an object

A measuring device for optical measuring of an object (13a), in particular for measuring a motion of the object (13a), comprising an interferometer (20) with a measuring beam exit (12), a reflection beam entry (14), an interference beam exit (15), and a light source (1) for creating a light beam (8), with the interferometer (20) being embodied such that the light beam (8) created by the light source (1) is split into at least first and second partial beams (9, 10), with the first partial beam (9) exiting the measuring beam exit (12) essentially at a predetermined angle and the second partial beam (10) being interfered with a reflection beam entering through the reflection beam entry (14), and the second partial beam (10) exiting with the interfered reflection beam at the interference beam exit (15), an optic detector (16), which is arranged at the interference beam exit (15) of the interferometer (20) such that a light beam exiting the interfering beam exit (15) impinges the detector (16), and a signal processing unit (17), which is connected to the detector (16) and embodied to collect and/or process measuring signals of the detector (16), the interferometer (20) is provided with a switched beam entry (18) and embodied such that depending on a switching signal connected to the switched beam entry (18), the light beam exits the measuring beam exit (12) essentially at a predetermined light intensity and at a predetermined angle and the signal processing unit (17) is provided with a beam switching exit, which is connected to the beam switching entry (18) of the interferometer, with the signal processing unit (17) being embodied to control the interferometer such that the light beam essentially with the predetermined light intensity only exits the measuring beam exit (12) during a measuring of measuring signals for taking measurements and at the predetermined angle.