| 摘要 |
A measurement apparatus comprises a mirror configured to reflect test light which passes through an optical system, an interferometer unit which includes an image sensor and is configured to form an interference fringe on an image sensing plane of the image sensor by reference light and the test light reflected by the mirror, and a controller configured to control the interferometer unit, and to compute a numerical aperture of the optical system based on the interference fringe captured by the image sensor, wherein the controller is configured to compute a numerical aperture NA of the optical system by multiplying a quotient &Dgr;NA/&Dgr;R, describing a change &Dgr;NA in numerical aperture NA of the optical system with respect to a change &Dgr;R in pupil radius R of the optical system in the image sensing plane, by the pupil radius R of the optical system in the image sensing plane.
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