| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical unit in which the ratio of non-exposure light arriving at an irradiated surface, e.g. a mask, can be reduced, and to provide an illumination optical device, an exposure device and a manufacturing method of device.SOLUTION: The optical unit includes an incidence side fly-eye mirror 21 having a plurality of mirror elements which divide a flux of incident illumination light IL, and an exit side fly-eye mirror 22 having a plurality of mirror elements which reflect the illumination light IL the flux of which is divided by the incidence side fly-eye mirror 21. At least one of each mirror element has a diffraction grating which reflects the EUV light out of the illumination light IL in the first direction, and reflects the light of non-exposure wavelength excluding the EUV wavelength region to a second direction different from the first direction. |
