Diffractive optical element (DOE) is used for off-axis illumination extensively in DUV lithographic system. A method for testing the optical performance of DOE using a visible laser is proposed to simplify the test process. In principle, the optical performance of DOE with a visible laser is analyzed with scalar diffraction theory and numerically simulated using MATLAB program. Compared with the DUV condition, the diffractive pattern distribution is enlarged proportionally with a zero-order spike under the visible laser condition. In experiments, the DOE is tested under He-Ne laser. Its far field diffractive pattern is compared and analyzed with the result tested under the working wavelength of 193.368nm. The shape, the opening angle, the azimuth angle and the pole balance coincide with the values tested in DUV condition. The usefulness of method is verified.
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Zhonghua Hu ; Jing Zhu ; Baoxi Yang ; Yanfen Xiao ; Aijun Zeng, et al.
Test of diffractive optical element for DUV lithography system using visible laser
", Proc. SPIE 8557, Optical Design and Testing V, 855709 (November 26, 2012); doi:10.1117/12.999681; http://dx.doi.org/10.1117/12.999681