Patent ID: 7706072

Claim:
An optical integrator of a wavefront splitting type comprising: a first optical member including a plurality of first entrance surfaces having a predetermined refractive power in a first direction in a plane perpendicular to the optical axis and substantially no refractive power in a second direction perpendicular to the first direction in the plane perpendicular to the optical axis, and a plurality of first exit surfaces formed so as to correspond to the plurality of first entrance surfaces and having a predetermined refractive power in the first direction and substantially no refractive power in the second direction; and a second optical member arranged on an exit side of the first optical member, the second optical member including a plurality of second entrance surfaces formed so as to correspond to the plurality of first entrance surfaces and having a predetermined refractive power in the second direction and substantially no refractive power in the first direction, and a plurality of second exit surfaces formed so as to correspond to the plurality of first entrance surfaces and having a predetermined refractive power in the second direction and substantially no refractive power in the first direction, wherein the predetermined refractive power of the second entrance surfaces is greater than the predetermined refractive power of the second exit surfaces.