| 摘要 |
A wavefront-aberration-measuring device measures wavefront aberration of a to-be-tested optical system (30) and includes a diffraction grating (40) that splits light transmitted through the optical system (30). A detecting unit (50) detects interference fringes produced by beams of the split light and an arithmetic unit (51) calculates the wavefront aberration from the detected interference fringes. An image-side mask (20) has an aperture (21) with a diameter smaller than 1.2 times a grating period of the diffraction grating (40) and is insertable into and retractable from an image plane of the optical system (30). An illuminating means (60) incoherently illuminates the image-side mask (20). The arithmetic unit (51) calculates the wavefront aberration of the optical system (30) from the interference fringes detected with the image-side mask (20) retracted from the image plane and with the interference fringes detected with the image-side mask (20) in the image plane. |
