| 摘要 |
The invention relates to a method and to an apparatus for interferometrically determining a deviation of an actual shape of an effective reflection surface (12) of a test object (14) from a desired shape of the effective reflection surface (12). In the method according to the invention electromagnetic illumination radiation (24) is produced by means of an illumination device (16) and provided as an input wave (30). The input wave (30) passes through a diffractive optical element (18) and leaves the latter as an incoming measuring wave (42), the wave front of the input wave (30) being transformed upon passing through the optical element (18) such that the wave front of the incoming measuring wave (42) is adapted to the desired shape of the effective reflection surface (12). Furthermore, the test object (14) is disposed in a test position in which the incoming measuring wave (42) is reflected back to the diffractive optical element (18) by the effective reflection surface (12) of the test object (14) as a reflected measuring wave, the reflected measuring wave (44) passes through the diffractive optical element (18) and leaves the latter as an outgoing measuring wave (46), the propagation direction (48) of the outgoing measuring wave (46) being deviated upon passing out of the diffractive optical element (18) in relation to the opposite propagation direction (50) of the input wave (30) upon passing into the diffractive optical element (18). A reference wave (32) is branched off from the illumination radiation (24) such that the reference wave (32) interferes with the outgoing measuring wave (46), and records the intensity distribution of an interference pattern produced by the interference of the reference wave (32) with the outgoing measuring wave (46) by means of a recording device (20).
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