Abstract: A laser measuring device is to be provided which should be substantially maintenance-free. In front of a window for the passage of laser beams (2) that contains a protective pane or lens, a compressed-air chamber (3) is provided. The latter has a compressed-air connection (4) that is connected by a compressed-air line (5) containing a control element (10) to a source of compressed air, and to which compressed air is supplied in operation. On the side of the compressed-air chamber (3) remote from the window, there is provided an air lock (6) which is only open during a measurement. In the open condition (6) of the air lock, a light channel (7) is open to permit the passage of the laser beams (2) and of light beams reflected from an object (8). In the closed condition (6′) of the air lock, the light channel (7) is closed. In this way, dirt deposits on the lens or protective pane in the window are avoided as far as possible, and cleaning, particularly prior to each measurement, is unnecessary.