The invention relates to a method and to a device for optically scanning a sample (1). The device comprises an adjusting unit (2, 3) and a scanning device (4, 5) which comprises an optical unit (4) and a scanning unit (5). The inventive device also comprises a control arrangement (6) which controls the optical unit (4), the scanning unit (5) and the adjusting unit (2, 3). The sample (1) is displaced in relation to the scanning device (4, 5), or vice-versa, by means of the adjusting unit (2, 3) which is impinged upon by the control arrangement (6). As a result, individual images (7), which are obtained by means of the scanning device (4, 5) are assembled to make at least one global image in the control arrangement (6). According to the invention, the respectively detected individual image (7) is evaluated either partially or totally in relation to the contrast thereof, and the obtained contrast values (K) influence the functionality of the entire arrangement.