The fine tuning of a sensor designed to locate interfaces using a two-dimensional gassolid fluidized bed (FB) as reference is described. The sensor works through computer vision and consists of a charge coupled device camera that is placed alongside the bed and, as the human eye would do, first establishes a straight segment of the bed's top surface to define the phase boundary and then through pattern recognition continuously scans the interface in search of a similar pattern. The field of view is 582 x 752 pixels2. The experimentally measured Pixel size is 216 x 208 mu m2. The device allows for experimentally obtaining the position of the probe with a resolution of +/- 0.01 pixels at 25 Hz. We also describe its use to measure the height of the FB and observe a linear relationship with fluidization velocity. (C) 2012 American Institute of Chemical Engineers AIChE J, 2012