Femtosecond Laser Fabrication of Cavity Microball Lens (CMBL) inside a PMMA Substrate for Super‐Wide Angle Imaging |
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| Authors: | Chong Zheng Anming Hu Kenneth D. Kihm Qian Ma Ruozhou Li Tao Chen W. W. Duley |
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| Affiliation: | 1. Institute of Laser Engineering, Beijing University of Technology, Chaoyang District, Beijing, P.R. China;2. Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN, USA;3. School of Electronic Science and Engineering, Southeast University, Key Laboratory of Micro‐Inertial Instrument and Advanced Navigation Technology, Ministry of Education, Nanjing, China;4. Department of Physics and Astronomy, University of Waterloo, Waterloo, Canada |
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| Abstract: | Since microlenses have to date been fabricated primarily by surface manufacturing, they are highly susceptible to surface damage, and their microscale size makes it cumbersome to handle. Thus, cavity lenses are preferred, as they alleviate these difficulties associated with the surface‐manufactured microlenses. Here, it is shown that a high repetition femtosecond laser can effectively fabricate cavity microball lenses (CMBLs) inside a polymethyl methacrylate slice. Optimal CMBL fabrication conditions are determined by examining the pertinent parameters, including the laser processing time, the average irradiation power, and the pulse repetition rates. In addition, a heat diffusion modeling is developed to better understand the formation of the spherical cavity and the slightly compressed affected zone surrounding the cavity. A micro‐telescope consisting of a microscope objective and a CMBL demonstrates a super‐wide field‐of‐view imaging capability. Finally, detailed optical characterizations of CMBLs are elaborated to account for the refractive index variations of the affected zone. The results presented in the current study demonstrate that a femtosecond laser‐fabricated CMBL can be used for robust and super‐wide viewing micro imaging applications. |
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| Keywords: | cavity microball lens femtosecond lasers micromachining micro‐telescope wide angle imaging |
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