Patent attributes
A measurement apparatus for measuring a surface map comprises an image sensor, an optical system including a reference surface and arranged to form an interferogram of a reflected wavefront from a test surface and that from the reference surface on an image sensing surface of the image sensor and a calculation unit which calculates a surface map of the measurement target based on the interferogram. The calculation unit calculates the surface map of the measurement target by utilizing first data which expresses, by a first coordinate system, data in a state in which a central axis of the test surface is at a first angle to an optical axis of the optical system, and second data which expresses, by a second coordinate system obtained by shifting the first coordinate system, data in a state in which the central axis is at a second angle to the optical axis.
