US Patent 9146475 Projection exposure system and projection exposure method

A projection exposure system includes an illumination system configured to illuminate a mask with radiation. The projection exposure system also includes a projection objective configured to project an image of a pattern of the mask onto a radiation-sensitive substrate. The projection exposure system further includes an angle-selective filter arrangement arranged at or close to a field surface of the projection objective in a projection beam path optically downstream of the object surface. The angle-selective filter arrangement is effective to filter radiation incident on the filter arrangement according to an angle-selective filter function.