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Kim WY, Seo BW, Lee SH, Lee TG, Kwon S, Chang WS, Nam SH, Fang NX, Kim S, Cho YT. Quasi-seamless stitching for large-area micropatterned surfaces enabled by Fourier spectral analysis of moiré patterns. Nat Commun 2023; 14:2202. [PMID: 37072425 PMCID: PMC10113184 DOI: 10.1038/s41467-023-37828-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 04/03/2023] [Indexed: 04/20/2023] Open
Abstract
The main challenge in preparing a flexible mold stamp using roll-to-roll nanoimprint lithography is to simultaneously increase the imprintable area with a minimized perceptible seam. However, the current methods for stitching multiple small molds to fabricate large-area molds and functional surfaces typically rely on the alignment mark, which inevitably produces a clear alignment mark and stitched seam. In this study, we propose a mark-less alignment by the pattern itself method inspired by moiré technique, which uses the Fourier spectral analysis of moiré patterns formed by superposed identical patterns for alignment. This method is capable of fabricating scalable functional surfaces and imprint molds with quasi-seamless and alignment mark-free patterning. By harnessing the rotational invariance property in the Fourier transform, our approach is confirmed to be a simple and efficient method for extracting the rotational and translational offsets in overlapped periodic or nonperiodic patterns with a minimized stitched region, thereby allowing for the large-area and quasi-seamless fabrication of imprinting molds and functional surfaces, such as liquid-repellent film and micro-optical sheets, that surpass the conventional alignment and stitching limits and potentially expand their application in producing large-area metasurfaces.
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Affiliation(s)
- Woo Young Kim
- Department of Smart Manufacturing Engineering, Changwon National University, Changwon, South Korea
| | - Bo Wook Seo
- Department of Smart Manufacturing Engineering, Changwon National University, Changwon, South Korea
| | - Sang Hoon Lee
- Department of Smart Manufacturing Engineering, Changwon National University, Changwon, South Korea
| | - Tae Gyung Lee
- Department of Smart Manufacturing Engineering, Changwon National University, Changwon, South Korea
| | - Sin Kwon
- Department of Flexible & Printed Electronics, Korea Institute of Machinery and Materials, Daejeon, South Korea
| | - Won Seok Chang
- Department of Nano Manufacturing Technology, Korea Institute of Machinery and Materials, Daejeon, South Korea
- Department of Nanomechatronics, University of Science and Technology, Daejeon, South Korea
| | - Sang-Hoon Nam
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Nicholas X Fang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, Hong Kong, Special Administrative Region of China
| | - Seok Kim
- Department of Smart Manufacturing Engineering, Changwon National University, Changwon, South Korea.
- Department of Mechanical Engineering, Changwon National University, Changwon, South Korea.
| | - Young Tae Cho
- Department of Smart Manufacturing Engineering, Changwon National University, Changwon, South Korea.
- Department of Mechanical Engineering, Changwon National University, Changwon, South Korea.
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Millán MS, Escofet J. Fabric inspection by near-infrared machine vision. OPTICS LETTERS 2004; 29:1440-1442. [PMID: 15259706 DOI: 10.1364/ol.29.001440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Fabrics that have superstructures of colored squares, bands, etc., superimposed upon the basic web structure can be advantageously analyzed by use of near-infrared (NIR) illumination and a conventional monochrome camera. The reduction in contrast of the superstructure signal in the NIR image facilitates inspection of the fabric's structure and defect segmentation. Underdetection and misdetection errors are noticeably reduced. This inspection takes advantage of the residual sensitivity of a monochrome camera, which can reach 1000 nm. The light source is an array of NIR LEDs emitting in a band to which the camera is still sensitive. NIR visual inspection can be performed by machines or by humans. In the latter case the observer looks at the NIR image of the fabric displayed on a TV monitor.
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Affiliation(s)
- Maria S Millán
- Departament d'Optica i Optometria, Universitat Politècnica de Catalunya, Violinista Vellsolà, 37, 08222 Terrassa, Barcelona, Spain.
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Ralló M, Escofet J, Millán MS. Weave-repeat identification by structural analysis of fabric images. APPLIED OPTICS 2003; 42:3361-3372. [PMID: 12816323 DOI: 10.1364/ao.42.003361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Two descriptions of the image of a web structure, a convolution model and an additive model, in both the spatial and frequency domains, are combined in the design of a method to extract information about the fabric structure by image analysis. The method allows the extraction of the conventional and also the minimal weave repeats, their size in terms of number of threads, their interlacing patterns, and their patterns of repetition. It is applicable to fabrics with square and nonsquare conventional weave repeat. Experimental results with image of real samples are presented and discussed.
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Affiliation(s)
- Miquel Ralló
- Departament de Matemàtica Aplicada III, Universitat Politècnica de Catalunya, Edifici T8S, Campus de Terrassa, 08222, Terrassa, Barcelona, Spain.
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Escofet J, Millán MS, Ralló M. Modeling of woven fabric structures based on fourier image analysis. APPLIED OPTICS 2001; 40:6170-6176. [PMID: 18364917 DOI: 10.1364/ao.40.006170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The periodic woven structures of fabrics can be defined on the basis of the convolution theorem. Here an elementary unit with the minimum number of thread crossings and a nonrectangular two-dimensional comb function for the pattern of repetition is used to define woven structures. The expression derived is more compact than the conventional diagram for weaving, and the parameters that one needs to determine a given fabric can easily be extracted from its Fourier transform. Several results with real samples of the most common structures-plain, twill, and satin-are presented.
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