| 摘要 |
PURPOSE:To detect the focusing position of an optical image by an image-forming by making a sharpness comparison between optical images formed by two split pieces of luminous flux. CONSTITUTION:Two groups 6 and 7 of photodetector arrays each consist of one or plural photodetector arrays, and lenses 11 and 12 as luminous flux splitting means splits luminous flux passed through the iris of the image-forming lens 1 divided into two along a boundary line nearly parallel to said photodetector arrays corresponding to the areas of the two-divided iris, and allows the pieces of the luminous flux to strike the photodetector groups 6 and 7. Further, a phase plate 14 as a phase delaying means gives those two split pieces of the luminous flux some optical path difference. Then, a sharpness comparison or spatial phase comparison between the optical images formed by the two-split pieces of the luminous flux is made to detect the focusing positions of the optical images passed through the image-forming lenses 11 and 12. |
