Patent ID: 11934104
Assignee: NIKON CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An illumination optical system which illuminates an illumination area on a first plane with a light from a light source, and which is to be used in combination with a projection optical system configured to form an image of an object on the first plane with a light from the illumination optical system, the illumination optical system comprising:
a fly's eye optical system which includes a plurality of curved reflection surfaces arranged two-dimensionally on a second plane different from the first plane, and which is configured to reflect the light from the light source, wherein
each of the plurality of curved reflection surfaces is formed to have a first dimension in a first direction and a second dimension in a second direction crossing the first direction, each of the first and second directions being a direction along the second plane, the first dimension being smaller than the second dimension,
the plurality of curved reflection surfaces is arranged along the first direction, and rows each formed by the plurality of curved reflection surfaces arranged along the first direction are arranged along the second direction,
the light from the light source irradiates the fly's eye optical system with an irradiation area having, on the second plane, a third dimension along the first direction and a fourth dimension along the second direction, the third dimension being smaller than the fourth dimension,
a light reflected by the fly's eye optical system illuminates the illumination area on the first plane without crossing an optical axis of the projection optical system, and
the fly's eye optical system is configured to fold the light from the light source in the first direction.