Alignment Method and Apparatus

A method of determining a position of a feature on an object, the method comprising:

• determining an offset parameter, the offset parameter being a measure of a difference between:
• a first position that is indicative of the position of the feature;
• and
• a second position that is indicative of the position of the feature;
• determining the second position;
• and
• determining the first position from the second position and the offset parameter, the position of the mark being the first position.

An apparatus comprising:

• a substrate support for supporting an object having a feature with a position;
• and
• a measurement system operable to determine:
• a second position that is indicative of the position of the feature;
• and
• a first position that is indicative of the position of the feature from the second position and an offset parameter;
• wherein the offset parameter is a measure of a difference between a first position that is indicative of the position of the feature and a second position that is indicative of the position of the feature;
• and
• wherein the radiation system is configured to irradiate the object with measurement radiation having at least a first range of wavelengths or second range of wavelengths, and wherein the first position is a position of the feature that is determined using a first range of wavelengths and the second position is a position of the feature that is determined using a second range of wavelengths, the first range of wavelengths being greater than the second range of wavelengths.