Fabrication of ellipticity-controlled microlens arrays by controlling the parameters of the multipleexposure two-beam interference technique Do D.B., Lai N.D., Wu C.Y., Lin H.J., Hsu C.C. Department of Physics, National Chung Cheng University, Ming Hsiung, Chiayi 621, Taiwan; Department of Physics, Hanoi National University of Education, 136 Xuan Thuy, Hanoi, Viet Nam; Laboratoire de Photonique Quantique et Moléculaire, Unité Mixte de Recherche, Ecole Normale Supérieure de Cachan, 94235 Cachan Cedex, France; Display Technology Center, Industrial Technology Research Institute, Hsinchu 310, Taiwan; Graduate Institute of Opto-Mechatronics, National Chung Cheng University, Ming Hsiung, Chiayi 621, Taiwan; Department of Photonics, National Sun Yat-sen University, Kaohsiung 804, Taiwan Abstract: We demonstrate a promising method for fabrication of plastic microlens arrays (MLAs) with a controllable ellipticity and structure, by using the combination of multiple-exposure two-beam interference and plastic replication techniques. Multiple exposures of a two-beam interference pattern with a wavelength of 442nm into a thick positive photoresist (AZ-4620) were used to form different two-dimensional periodic structures. Thanks to the developing effect of the positive photoresist, fabricated structures consisting of hemielliptical- or hemispherical-shaped concave holes were obtained. By controlling the rotation angle between different exposures, both the shape and structure of the holes varied. By adjusting the dosage ratio between different exposures, the shape of the holes was modified while the structure of the holes was unchanged. The photoresist concave microstructures were then transferred to plastic MLAs by employing replication and embossing techniques. The fabricated MLAs were characterized by a scanning electron microscope and atomic force microscope measurements. We show that the ellipticity of the microlenses can be well controlled from 0 (hemispherical) to 0.96 (hemielliptical) by changing the rotation angle or dosage ratio between the two exposures. © 2011 Optical Society of America. Index Keywords: Atomic force microscopes; Embossing techniques; Fabricated structures; Micro-lens arrays; Multiple exposure; Plastic replication; Rotation angles; Scanning Electron Microscope; Two-beam interference; Two-dimensional periodic structures; Microlenses; Microoptics; Optical instrument lenses; Photoresists; Rotation; Scanning electron microscopy; Fabrication Year: 2011 Source title: Applied Optics Volume: 50 Issue: 4 Page : 579-585 Link: Scorpus Link Correspondence Address: Hsu, C. C.; Department of Physics, National Chung Cheng University, Ming Hsiung, Chiayi 621, Taiwan; email:
[email protected] ISSN: 36935
CODEN: APOPA DOI: 10.1364/AO.50.000579 Language of Original Document: English Abbreviated Source Title: Applied Optics Document Type: Article Source: Scopus Authors with affiliations: 1. Do, D.B., Department of Physics, National Chung Cheng University, Ming Hsiung, Chiayi 621, Taiwan, Department of Physics, Hanoi National University of Education, 136 Xuan Thuy, Hanoi, Viet Nam 2. Lai, N.D., Laboratoire de Photonique Quantique et Moléculaire, Unité Mixte de Recherche, Ecole Normale Supérieure de Cachan, 94235 Cachan Cedex, France 3. Wu, C.Y., Department of Physics, National Chung Cheng University, Ming Hsiung, Chiayi 621, Taiwan, Display Technology Center, Industrial Technology Research Institute, Hsinchu 310, Taiwan 4. Lin, H.J., Department of Physics, National Chung Cheng University, Ming Hsiung, Chiayi 621, Taiwan 5. Hsu, C.C., Department of Physics, National Chung Cheng University, Ming Hsiung, Chiayi 621, Taiwan, Graduate Institute of Opto-Mechatronics, National Chung Cheng University, Ming Hsiung, Chiayi 621, Taiwan, Department of Photonics, National Sun Yat-sen University, Kaohsiung 804, Taiwan
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