8 September 2014 Dynamic compensation for the lithographic object lens
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The nominal design residual aberrations are very small for the lithographic object lens. The RMS wavefront error is in a few milliwaves, and the distortion is in a few nanometers. However, The manufacturing-induced aberrations are inevitable and usually many times larger than the design residual level. One method to reduce the manufacturing-induced aberrations is making a few lens adjustable after the object lens is assembled. Dynamic compensation can correct element metrology and assembly errors effectively, especially for the low order Zernike aberrations. We introduce a dynamic compensation method in this paper. This technique is based on the simulated imaging performance using Zernike sensitivity, which is the simulated results of wavefront aberration change by lens element position change. We can select the potential moving lens by this technique. This method can find the optimum combination of moving lens position where the lithographic object lens imaging performance is improved remarkably.
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Hongwei Zhu, Hongwei Zhu, Tingwen Xing, Tingwen Xing, Zexiang Chen, Zexiang Chen, "Dynamic compensation for the lithographic object lens", Proc. SPIE 9195, Optical System Alignment, Tolerancing, and Verification VIII, 91950P (8 September 2014); doi: 10.1117/12.2060302; https://doi.org/10.1117/12.2060302

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