Patent ID: 8243281

Claim:
A method of measuring a surface of an object, the method comprising: illuminating a first portion of the surface of the object with a first portion of measuring light; detecting light emanating from the first portion of the surface, the light being superimposed with a second portion of the measuring light by interference; modifying at least one optical property of a variable light shaping member; displacing the surface of the object, to illuminate a second portion of the surface of the object with the first portion of the measuring light; and detecting light emanating from the second portion of the surface, the light being superimposed with the second portion of the measuring light by interference, wherein one of the following holds: the first portion of the measuring light has traversed the variable light shaping member before illuminating the surface of the object; and the second portion of the measuring light has traversed the variable light shaping member before being detected and superimposed with the first portion of the measuring light emanating from the surface of the object, and wherein the variable light shaping member comprises two diffraction gratings arranged in a beam path of the measuring light and wherein said modifying of the at least one optical property of the variable light shaping member comprises displacing the two diffraction gratings relative to each other.