| 摘要 |
An aberration correction device useable in lithography comprises two elements, at least one of which is relatively rotatable to the other about, for example, an optical axis. One surface of each element has an aspheric form describable by higher Zernike polynomials. When the two surfaces are rotationally aligned, the device has the optical effect of a plane plate. If there is a small relative rotation of the two elements the effect of the device is a phase shift describable by the derivative of the aspheric form. The correction device may be used to correct aberrations caused by lens heating, especially with illumination modes and pattern types resulting in strong off-axis localized pupil filling in the projection system.
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