| 摘要 |
<p>A lithographic apparatus comprises a radiation system for providing a projection beam of radiation; an aperture, through which a radiation beam is directed; a detector for measuring an intensity of the radiation beam through said aperture; a focussing element; and means for directing the radiation beam through said aperture. The lithographic apparatus according to the invention comprises a processing unit coupled to said means for directing the radiation beam in order to vary the intensity of said radiation beam through said aperture by a relative movement or a change in pointing direction of the radiation beam, the processing unit further coupled to said detector for measuring said intensity, the processor arranged to calculate the beam size or beam divergence from the measured intensity and relative movement. The apparatus of the invention offers a simple and reliable possibility for determining beam quality characteristics such as beam size and/or beam divergence.
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