Patent ID: 8692975

Claim:
A measurement apparatus which measures an imaging performance of an optical system to be measured, the apparatus comprising: a first reference substrate which is placed on an object plane of the optical system to be measured, and has periodic patterns arranged in accordance with a plurality of object heights; a second reference substrate which is placed on an image plane of the optical system to be measured, and has apertures which pass light from the periodic patterns; a detection unit configured to detect an intensity of the light which comes from the periodic patterns and has passed through the apertures; a driving unit configured to drive at least one of said first reference substrate or said second reference substrate; and a processing unit configured to perform a process for obtaining the imaging performance of the optical system to be measured, wherein said processing unit obtains, for each of a plurality of image heights corresponding to the plurality of object heights, a phase difference between two light beams, which are diffracted by the periodic pattern and pass through two positions on a pupil plane of the optical system to be measured, from a change in the intensity of the light from the periodic patterns, which is detected by said detection unit upon driving at least one of said first reference substrate or said second reference substrate in a direction perpendicular to an optical axis of the optical system to be measured by said driving unit, under a first diffraction condition in which the two diffracted light beams are generated, obtains, for each of the plurality of image heights corresponding to the plurality of object heights, a phase difference between two light beams, which are diffracted by the periodic pattern and pass through two positions on the pupil plane, from a change in the intensity of the light from the periodic patterns, which is detected by said detection unit upon driving at least one of said first reference substrate or said second reference substrate in the direction perpendicular to the optical axis by said driving unit, under a second diffraction condition in which the two diffracted light beams are generated and a position where at least one of the two diffracted light beams is incident on the pupil plane is different from positions where the two light beams diffracted by the periodic pattern are incident on the pupil plane under the first diffraction condition, and obtains an imaging performance, including a curvature of field, of the optical system to be measured, based on the phase difference between the two diffracted light beams and the positions where the two diffracted light beams are incident on the pupil plane at each of the plurality of image heights under the first diffraction condition, and the phase difference between the two diffracted light beams and the positions where the two diffracted light beams are incident on the pupil plane at each of the plurality of image heights under the second diffraction condition.