| 摘要 |
An interferometer, and corresponding method, for use in the measurement and correction of wavefront aberrations in a beam of radiation. The interferometer includes optical elements for generating a reference beam with a known wavefront phase characteristic. The reference beam is recombined with the sample beam, to produce an interference pattern indicative of the phase aberrations in the sample beam as compared with the reference beam. An array of detectors produces electrical signals corresponding to discrete elements of the detected pattern, and an electrical circuit for each elemental detector generates phase correction signals to be applied to a set of movable mirror elements arranged to effect phase changes in the sample beam path. The movable mirror elements adjust the elemental path lengths of the sample beam to yield zero detected phase differences. The mirror elements may be integrated into the interferometer, or may take the form of a deformable mirror used for phase compensation of a light beam. The reference beam in the preferred form of the invention is dithered at a high frequency to minimize the effect of noise, and each electrical circuit includes a synchronous detector to remove the dither-frequency component. In accordance with one disclosed form of the invention, the reference beam is not planar but is aberrated in a conjugate relationship with the radiation beam to be corrected, to provide improved control loop performance.
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