Patent ID: 7609389

Claim:
A measurement apparatus for measuring a surface map, the apparatus comprising: an image sensor; an optical system including a reference surface and arranged to form an interferogram of a reflected wavefront from a test surface of a measurement target and that from said reference surface on an image sensing surface of said image sensor; and a calculation unit which calculates a surface map of the measurement target based on the interferogram, wherein said calculation unit calculates the surface map of the measurement target by utilizing first data which expresses, by a first coordinate system, data on an image taken by said image sensor in a state in which a central axis of the test surface is at a first angle to an optical axis of said optical system, and second data which expresses, by a second coordinate system obtained by shifting the first coordinate system, data on an image taken by said image sensor in a state in which the central axis of the test surface is at a second angle to the optical axis of said optical system, wherein each of the first coordinate system and the second coordinate system comprises a coordinate system in which an angle is uniformly divided, that is, a unit scale is equal to an angle obtained by uniformly dividing an angle formed by the optical axis of said optical system and a marginal ray.