We have built an active omni-directional range range sensor that can obtain an omni-directional depth data through the use of a laser conic plane and a conic mirror. In the navigation of the mobile robot, the proposed sensor system makes a laser conic plane by rotating the laser point source at high speed which creates a two-dimensional depth map, in real time, once an image is captured. Also, since the proposed sensor system measures the actual distance of the target objects, it is able to apply the proposed sensor system to other measurement tasks.