High-Identical Numerical Aperture, Multifocal Microlens Array through Single-Step Multi-Sized Hole Patterning Photolithography

Lee, Joong Hoon; Chang, Sehui; Kim, Min Seok; Kim, Yeong Jae; Kim, Hyun Myung; Song, Young Min

doi:10.3390/mi11121068

Open AccessArticle

High-Identical Numerical Aperture, Multifocal Microlens Array through Single-Step Multi-Sized Hole Patterning Photolithography

by

Joong Hoon Lee

,

Sehui Chang

,

Min Seok Kim

,

Yeong Jae Kim

,

Hyun Myung Kim

and

Young Min Song

^*

School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Korea

^*

Author to whom correspondence should be addressed.

Micromachines 2020, 11(12), 1068; https://doi.org/10.3390/mi11121068

Submission received: 16 November 2020 / Revised: 28 November 2020 / Accepted: 29 November 2020 / Published: 30 November 2020

(This article belongs to the Special Issue Micro-Manufacturing and Applications)

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Abstract

Imaging applications based on microlens arrays (MLAs) have a great potential for the depth sensor, wide field-of-view camera and the reconstructed hologram. However, the narrow depth-of-field remains the challenge for accurate, reliable depth estimation. Multifocal microlens array (Mf-MLAs) is perceived as a major breakthrough, but existing fabrication methods are still hindered by the expensive, low-throughput, and dissimilar numerical aperture (NA) of individual lenses due to the multiple steps in the photolithography process. This paper reports the fabrication method of high NA, Mf-MLAs for the extended depth-of-field using single-step photolithography assisted by chemical wet etching. The various lens parameters of Mf-MLAs are manipulated by the multi-sized hole photomask and the wet etch time. Theoretical and experimental results show that the Mf-MLAs have three types of lens with different focal lengths, while maintaining the uniform and high NA irrespective of the lens type. Additionally, we demonstrate the multi-focal plane image acquisition via Mf-MLAs integrated into a microscope.

Keywords: optical MEMS; microlens array; multiple focal lengths; three-dimensional imaging

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MDPI and ACS Style

Lee, J.H.; Chang, S.; Kim, M.S.; Kim, Y.J.; Kim, H.M.; Song, Y.M. High-Identical Numerical Aperture, Multifocal Microlens Array through Single-Step Multi-Sized Hole Patterning Photolithography. Micromachines 2020, 11, 1068. https://doi.org/10.3390/mi11121068

AMA Style

Lee JH, Chang S, Kim MS, Kim YJ, Kim HM, Song YM. High-Identical Numerical Aperture, Multifocal Microlens Array through Single-Step Multi-Sized Hole Patterning Photolithography. Micromachines. 2020; 11(12):1068. https://doi.org/10.3390/mi11121068

Chicago/Turabian Style

Lee, Joong Hoon, Sehui Chang, Min Seok Kim, Yeong Jae Kim, Hyun Myung Kim, and Young Min Song. 2020. "High-Identical Numerical Aperture, Multifocal Microlens Array through Single-Step Multi-Sized Hole Patterning Photolithography" Micromachines 11, no. 12: 1068. https://doi.org/10.3390/mi11121068

APA Style

Lee, J. H., Chang, S., Kim, M. S., Kim, Y. J., Kim, H. M., & Song, Y. M. (2020). High-Identical Numerical Aperture, Multifocal Microlens Array through Single-Step Multi-Sized Hole Patterning Photolithography. Micromachines, 11(12), 1068. https://doi.org/10.3390/mi11121068

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High-Identical Numerical Aperture, Multifocal Microlens Array through Single-Step Multi-Sized Hole Patterning Photolithography

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