A calibration cassette pod for robot teaching and a method of using the calibration cassette pod are described. In the calibration cassette pod, a cassette pod body and a cassette pod door are first provided wherein the cassette pod body is constructed of a top panel, a bottom panel, two side panels and a front panel to enclose a cavity therein. A first plurality of ribs is formed on an inside surface of the cassette pod body, each having a predetermined depth sufficient to support an edge portion of a wafer. An optical detector housing is mounted on an opening in the front panel and is adapted for receiving an optical detector therein. An optical detector that includes a light emission source and a photo diode receiver for determining the position of the edge portion of the wafer is mounted in the optical detector housing.