| 摘要 |
A pulse stretcher with a first prism and a second prism positioned opposite each other. A first coupling prism is optically coupled to the first prism with a partially reflective interface that directs a beam towards the second prism in a helical path. The first prism and the first coupling prism form a beamsplitter. A recirculating prism (or a reflective element) reflects the beam from the first prism into the second prism. Mirrors are positioned around the first and second prisms to permit recirculation of the beam through the first and second prisms. The partially reflective interface is about 80-95% reflective. The beam recirculates through the first and second prisms using two or four (or more) helical paths. The mirrors include convex and concave mirrors. The first and second prisms and the recirculating prism can be a unitary component. The pulse stretcher can be incorporated into a lithographic system that is arranged, in order of light propagation, with an illumination source, the pulse stretcher, illumination optics, a reticle, and projection optics.
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