| 摘要 |
An apparatus for determining the orientation and/or position of a structure comprises a light source ( 28 ) for generating a light beam. A structure ( 31 ) is mounted in the optical path of the light beam such that the position and/or orientation of the structure, relative to the light beam, may be altered. The apparatus further comprises first capture means ( 32 ) for capturing a diffraction pattern produced by the first structure. Information about the alignment of the structure may be obtained from the diffraction pattern, and the position and/or orientation of the structure ( 31 ) relative to the light beam may be adjusted if necessary.
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