Patent ID: 8384882

Claim:
A calibration method for calibrating an optimum take over height of a substrate in a lithographic apparatus between a substrate table and at least one ejector element which is moveable to load and unload the substrate on and from the substrate table, the method comprising: clamping the substrate on the substrate table; moving the ejector element between an unloaded state wherein the substrate is supported by the substrate table and a loaded state wherein the substrate is at least partly supported by the ejector element; determining a reference height of the ejector element when the weight of the substrate is at least partly taken over by the ejector element; and determining an optimum take over height for the ejector element from the determined reference height, wherein the reference height is determined based on a quantifiable difference in velocity of the ejector element when moved between the unloaded and loaded state, during which movement the ejector element partly moves with a first velocity in the unloaded state, and partly moves with a second velocity in the loaded state, and wherein a discontinuity between the first and the second velocity is used to determine the reference height.