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Title: Deeply sub-wavelength non-contact optical metrology of sub-wavelength objects
Authors: Rendón-Barraza, Carolina
Chan, Eng Aik
Yuan, Guanghui
Adamo, Giorgio
Pu, Tanchao
Zheludev, Nikolay, I.
Keywords: Science::Physics
Issue Date: 2021
Source: Rendón-Barraza, C., Chan, E. A., Yuan, G., Adamo, G., Pu, T. & Zheludev, N. I. (2021). Deeply sub-wavelength non-contact optical metrology of sub-wavelength objects. APL Photonics, 6(6), 066107-.
Project: MOE2016-T3-1-006
SERC A1685b0005
Journal: APL Photonics
Abstract: Microscopes and various forms of interferometers have been used for decades in optical metrology of objects that are typically larger than the wavelength of light λ. Metrology of sub-wavelength objects, however, was deemed impossible due to the diffraction limit. We report the measurement of the physical size of sub-wavelength objects with deeply sub-wavelength accuracy by analyzing the diffraction pattern of coherent light scattered by the objects with deep learning enabled analysis. With a 633 nm laser, we show that the width of sub-wavelength slits in an opaque screen can be measured with an accuracy of ∼λ/130 for a single-shot measurement or ∼λ/260 (i.e., 2.4 nm) when combining measurements of diffraction patterns at different distances from the object, thus challenging the accuracy of scanning electron microscopy and ion beam lithography. In numerical experiments, we show that the technique could reach an accuracy beyond λ/1000. It is suitable for high-rate non-contact measurements of nanometric sizes of randomly positioned objects in smart manufacturing applications with integrated metrology and processing tools.
ISSN: 2378-0967
DOI: 10.1063/5.0048139
Rights: © 2021 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:SPMS Journal Articles

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