| 摘要 |
PROBLEM TO BE SOLVED: To easily obtain each aberration by overlapping the diffraction light of light through an optical element for forming a sharing interference image, and by obtaining the phase difference of light intensity of a plurality of specific spots in the interference image. SOLUTION: An optical system 1 that evaluates the aberration of a lens 12 that an optical device 10 such as the optical head of a DVD reproduction device has is provided with, for example, a reflection-type diffraction grating 40 and an image reception part 28 such as a CCD. Then, while the diffraction grating 40 is carried in a direction 50, light 16 is applied from a laser source 14, and an image is formed in a groove 44 of the diffraction grating 40 passing through the focus of the lens 12. Diffracted reflected light returns to the lens 12, is reflected by a beam splitter 24, and is sent to the image reception part 28, and the image with a sharing interference image being influenced by diffraction light with 0- and 1-degree orders appears on a display part 34. Each aberration of the lens 12 is evaluated by the phase difference of light intensity change with the movement of the diffraction grating 40 among a plurality of selected spots in the sharing region of the interference image.
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