| 摘要 |
The invention relates to a multi-axis differential interferometer (1) for measuring a displacement and/or rotation between a first reflective surface (21, 321) and a second reflective surface (81, 381), wherein said measuring is carried out using at least two pairs of beams, wherein each pair is formed by a measurement beam (Mb) to be emitted onto a first one (21, 321) of said reflective surfaces, and a reference beam (Rb) to be emitted onto another one (81, 381) of said reflective surfaces, said interferometer (1) comprising: a first optical module (20) and a second optical module (40), wherein each optical module (20, 40) is configured for receiving a respective coherent beam and for creating one of said pairs therefrom. The invention further relates to a lithography system comprising such an interferometer and to a method for assembling such a multi-axis differential interferometer. |
| 主权项 |
1. A multi-axis differential interferometer (1) for measuring a displacement and/or rotation between a first reflective surface (21, 321) and a second reflective surface (81, 381), wherein said measuring is carried out using at least three pairs of beams, wherein each pair is formed by a measurement beam (Mb) to be emitted onto said first reflective surface (21, 321), and a reference beam (Rb) to be emitted onto said second reflective surface (81, 381), said interferometer (1) comprising:
a first optical module (20), a second optical module (40) and a third optical module (60), wherein each optical module (20, 40, 60) is configured for receiving a respective coherent beam and for creating one of said pairs therefrom, wherein each of said optical modules (20, 40, 60) comprises: i) a beam splitter (301, 401) for splitting the respective coherent beam into said measurement beam (Mb) and said corresponding reference beam (Rb), ii) a beam combiner (301, 401) for combining said measurement beam (Mb) reflected by said first reflective surface (21, 321) with its associated reference beam (Rb) reflected by said second reflective surface (81,381) to a corresponding combined beam (Cb), and iii) a beam receiver (305, 306, 307, 308, 309, 310, 311, 408) for receiving said combined beam (Cb), wherein said optical modules (20, 40, 60) are arranged in a stack to form a side-by-side stack, the multi-axis differential interferometer thus forming a differential interferometer stack module, and wherein said three optical modules (20, 40, 60) are arranged to emit said measurement beams (Mb) non-coplanarly and substantially in parallel. |
