An apparatus for position-detection of an object within a region is disclosed. The apparatus includes first and second target elements mounted on an object and having a known separation distance between the two. A scanning light source is configured to issue a beam of light along a substantially one-dimensional scanning path, which illuminates a point that moves over the first and second target elements. A detector is provided for detecting light reflected from, or received by, the first and second target elements. A processing system is configured to determine the position of the object within the region based on first and second points in the scanning path at which the detector detects light returned from, or received by, the first and second target elements and the known separation distance between the two reflective elements.