Optical system

The optical system (100) has a distance measuring unit (14) for measuring the distance between reference point and distance measuring point at target object. A photon detector (20) is connected with a control and computing unit (15). A radiation guide portion of measuring radiation and pointer radiation of a radiation device (10) is extended at the distance measuring point or at close proximity of light signal. The current azimuth angle of light signal and current distance of measuring point in specific operation modes are detected by control and computing unit.