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Continuous Vat Photopolymerization for Optical Lens Fabrication (Small 40/2023) |
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| Authors: | Han Xu Shuai Chen Renzhi Hu Muqun Hu Yang Xu Yeowon Yoon Yong Chen |
| Affiliation: | 1. Center for Advanced Manufacturing, University of Southern California, Los Angeles, CA, 90007 USA Daniel J. Epstein Department of Industrial and Systems Engineering, University of Southern California, Los Angeles, CA, 90089 USA;2. Center for Advanced Manufacturing, University of Southern California, Los Angeles, CA, 90007 USA Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA, 90089 USA;3. Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA, 90089 USA;4. Center for Advanced Manufacturing, University of Southern California, Los Angeles, CA, 90007 USA Daniel J. Epstein Department of Industrial and Systems Engineering, University of Southern California, Los Angeles, CA, 90089 USA Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA, 90089 USA |
| Abstract: | Optical lenses require feature resolution and surface roughness that are beyond most (3D) printing methods. A new continuous projection-based vat photopolymerization process is reported that can directly shape polymer materials into optical lenses with microscale dimensional accuracy (< 14.7 µm) and nanoscale surface roughness (< 20 nm) without post-processing. The main idea is to utilize frustum layer stacking, instead of the conventional 2.5D layer stacking, to eliminate staircase aliasing. A continuous change of mask images is achieved using a zooming-focused projection system to generate the desired frustum layer stacking with controlled slant angles. The dynamic control of image size, objective and imaging distances, and light intensity involved in the zooming-focused continuous vat photopolymerization are systematically investigated. The experimental results reveal the effectiveness of the proposed process. The 3D-printed optical lenses with various designs, including parabolic lenses, fisheye lenses, and a laser beam expander, are fabricated with a surface roughness of 3.4 nm without post-processing. The dimensional accuracy and optical performance of the 3D-printed compound parabolic concentrators and fisheye lenses within a few millimeters are investiagted. These results highlight the rapid and precise nature of this novel manufacturing process, demonstrating a promising avenue for future optical component and device fabrication. |
| Keywords: | additive manufacturing continuous printing optical lens slant angle vat polymerization |