Patent ID: 8400612

Claim:
A measurement apparatus for measuring a wavefront aberration of an optical system to be measured, the apparatus comprising: a calculation unit configured to calculate the wavefront aberration based on an interference fringe generated by light from the optical system to be measured, and generate wavefront aberration data in which a wavefront aberration amount is mapped at each of a plurality of two dimensionally arrayed evaluation points based on the calculated wavefront aberration; and a determination unit configured to calculate an evaluation value indicating a wavefront state based on the wavefront aberration data generated by said calculation unit, and determine the calculated wavefront aberration as the wavefront aberration of the optical system if the evaluation value falls within an allowable range, wherein the evaluation value indicates the total number of evaluation points whose wavefront aberration amounts have a difference that exceeds a threshold from adjacent evaluation points among evaluation points in the wavefront aberration data generated by said calculation unit.