摘要 |
The present invention relates to a method of increasing the operation lifetime of an optical collector unit (33)) arranged in an irradiation device. The irradiation device at least comprises a radiation source (1) emitting optical radiation, in particular extreme ultraviolet radiation or soft X-rays, said radiation source (1) generating substances and/or particles colliding with optical surfaces of the optical collector unit (33), which forms a radiation beam of a portion of said radiation emitted by said radiation source (1), and a debris mitigation unit (37) arranged between the radiation source (1) and said optical collector unit (33). In the proposed method the optical collector unit (33) is moved during operation and/or in operation pauses of the device such that deposits or degradation effects caused by collision of said substances and/or particles with said optical surfaces of the collector unit (33) are distributed more homogeneously on said optical surfaces than without such a movement. With the method and the corresponding device the optical surfaces of the collection unit are degraded more homogeneously resulting in an increased lifetime of the collector unit.
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