Formation of sub-half-wavelength focal spot with ultra long depth of focus |
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| Authors: | Cuifang Kuang Xiang Hao Xu Liu Tingting Wang Yulong Ku |
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| Institution: | State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China |
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| Abstract: | We theoretically demonstrate the creation of sub-wavelength focal spot with ultra long depth of focus (DOF) non-diffracting. To achieve a sub-half-wavelength focal spot (0.4λ) with modulation, extended DOF (over 9.5λ) in vacuum, an integration of amplitude phase encoding, cylindrical polarization and the combination of dual-beams is utilized. Further analysis also predicts that a flattop intensity distribution along z axis can be observed around the ideal focus point. |
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| Keywords: | Depth of focus Sub-half-wavelength focal spot Radial polarization Diffraction theory |
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