In this study an active vision system using a laser range finder is proposed for the mavigation of a mobile robot in unknown environment. The laser range finder consists of a slitted laser beam generator, a scanning mechanism, CCD camera, and a signal processing unit. A laser beam from laser source is slitted by a set of cylindrical lenses and the slitted laser beam is emitted up and down and rotates on the surface of an object is engraved on the CCD array. A high speed image processing algorithm is proposed for the real-time navigation of the mobile robot. Through experiments it is proved that the accurate and real-time reconition of environment is able to be realized using the proposed laser range finder.