In order to apply to the eyes of an autonomous running vehicle, a real time range finder has been developed that can measure the distance to every point on the plane without any pattern and its inclination. Though it seems contrary to the fact that the parallax is inversely proportional to the distance, this paper derives the mathematical grand that the plane in a real three dimensional space (X, Y, Z) is mapped also into the plane in a parallax space (x, y, Δx). On this grand, an electronic circuit has been manufactured which can compute in video rate the interpolation value between the parallaxes at two characteristic points by using several CPLDs. It is also shown that this device is applicable to the measurements of the slant angles of and the directions normal to the simple plane.