Compound parabolic collectors for projection lens metrology

摘要

A new and useful optical element for an optical imaging system is provided, characterized in that the optical element comprises a reflecting surface that is rotationally symmetric and oriented at a grazing angle to a relatively small slit that is illuminated over a relatively large range of angles, such that the optical element collects radiation from the relatively small slit that is illuminated over a large range of angles, and the reflecting surface reflects the collected radiation. The optical element is configured to convert a large range of angles leaving a very small slit, to a much smaller range of angles over a larger area.

主权项

1. An aerial image sensor (AIS) system for use in a photolithographic imaging system, the AIS system comprising:
a first component of the AIS system having
a slit in a surface of said first component, andan axis that is perpendicular to said surface,said first component transmitting radiation incident thereon through the slit to form first radiation; and a light collector of the AIS system disposed behind said first component at a working distance defining a gap between said light collector and said first component, said light collector having
an entrance region bound by an entrance edge,an exit region bound by an exit edge, anda reflecting surface connecting the entrance and exit edges, said reflecting surface being rotationally symmetric about said axis and disposed at a grazing angle with respect to said slit such that the entrance region receives the first radiation within a first range of angles, said reflecting surface reflecting radiation received by the entrance region towards the exit region, and said exit region emits said radiation within a second range of angles.