Abstract: An improved laser rangefinder and thermal imager with enhanced scanning mirror control is disclosed. Optical axes (11,12) are aligned parallel to each other. The system includes only one common thermal image/laser reception channel (8,9,10,11). The angular movement of scanning mirror 8 is compensated during the range finding operation. Synchronizing means (1,2,3,4) located in the beam path controls the movement of the scanning mirror. An improved method for controlling the movement of the scanning mirror which enhances the measuring range of the device is also disclosed. In order to receive CO.sub.2 radiation of narrow bandwidth which is reflected from a target, the cyclical movement of the scanning mirror (8) is precisely controlled in order to position it favorably during the range measuring operation. The frequency of the scanning function is retarded so that the scanning mirror (8) is moved only through a fraction of the width of the image field.