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Research Article | Open Access

Longwave infrared multispectral image sensor system using aluminum-germanium plasmonic filter arrays

Noor E Karishma Shaik1( )Bryce Widdicombe1Dechuan Sun1Sam E John2Dongryeol Ryu3Ampalavanapillai Nirmalathas1Ranjith R Unnithan1( )
Department of Electrical and Electronic Engineering, University of Melbourne, Parkville, VIC 3010, Australia
Department of Biomedical Engineering, University of Melbourne, Parkville, VIC 3010, Australia
Department of Infrastructure Engineering, University of Melbourne, Parkville, VIC 3010, Australia
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Graphical Abstract

In this work, we demonstrate a low-cost multispectral thermal sensor system composed of plasmonic imaging filters integrated with an uncooled monochrome thermal sensor and associated deep imaging methods.


A multispectral camera records image data in various wavelengths across the electromagnetic spectrum to acquire additional information that a conventional camera fails to capture. With the advent of high-resolution image sensors and color filter technologies, multispectral imagers in the visible wavelengths have become popular with increasing commercial viability in the last decade. However, multispectral imaging in longwave infrared (LWIR, 8–14 µm) is still an emerging area due to the limited availability of optical materials, filter technologies, and high-resolution sensors. Images from LWIR multispectral cameras can capture emission spectra of objects to extract additional information that a human eye fails to capture and thus have important applications in precision agriculture, forestry, medicine, and object identification. In this work, we experimentally demonstrate an LWIR multispectral image sensor with three wavelength bands using optical elements made of an aluminum (Al)-based plasmonic filter array sandwiched in germanium (Ge). To realize the multispectral sensor, the filter arrays are then integrated into a three-dimensional (3D) printed wheel stacked on a low-resolution monochrome thermal sensor. Our prototype device is calibrated using a blackbody and its thermal output has been enhanced with computer vision methods. By applying a state-of-the-art deep learning method, we have also reconstructed multispectral images to a better spatial resolution. Scientifically, our work demonstrates a versatile spectral thermography technique for detecting target signatures in the LWIR range and other advanced spectral analyses.

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Nano Research
Pages 10018-10025
Cite this article:
Karishma Shaik NE, Widdicombe B, Sun D, et al. Longwave infrared multispectral image sensor system using aluminum-germanium plasmonic filter arrays. Nano Research, 2023, 16(7): 10018-10025.








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Received: 26 September 2022
Revised: 13 March 2023
Accepted: 14 March 2023
Published: 25 May 2023
© The author(s) 2023

Copyright: © 2023 by the author(s). This article is an open access article distributed under Creative Commons Attribution License (CC BY 4.0), visit