Entropy-Inspired Aperture Optimization in Fourier Optics

The trade-off between resolution and contrast is a transcendental problem in optical imaging, spanning from artistic photography to technoscientific applications. To the latter, Fourier-optics-based filters, such as the 4<i>f</i> system, are well-known for their image-enhancement propert...

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Main Authors: Marcos Miotti, Daniel Varela Magalhães
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Entropy
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Online Access:https://www.mdpi.com/1099-4300/27/7/730
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author Marcos Miotti
Daniel Varela Magalhães
author_facet Marcos Miotti
Daniel Varela Magalhães
author_sort Marcos Miotti
collection DOAJ
description The trade-off between resolution and contrast is a transcendental problem in optical imaging, spanning from artistic photography to technoscientific applications. To the latter, Fourier-optics-based filters, such as the 4<i>f</i> system, are well-known for their image-enhancement properties, removing high spatial frequencies from an optically Fourier-transformed light signal through simple aperture adjustment. Nonetheless, assessing the contrast–resolution balance in optical imaging remains a challenging task, often requiring complex mathematical treatment and controlled laboratory conditions to match theoretical predictions. With that in mind, we propose a simple yet robust analytical technique to determine the optimal aperture in a 4<i>f</i> imaging system for static and quasi-static objects. Our technique employs the mathematical formalism of the <i>H</i>-theorem, enabling us to directly access the information of an imaged object. By varying the aperture at the Fourier plane of the 4<i>f</i> system, we have empirically found an optimal aperture region where the imaging entropy is maximum, given that the object is fitted to the imaged area. At that region, the image is lit and well-resolved, and no further aperture decrease improves that, as information of the whole assembly (object plus imaging system) is maximum. With that analysis, we have also been able to investigate how the imperfections in an object affect the entropy during its imaging. Despite its simplicity, our technique is generally applicable and passable for automation, making it interesting for many imaging-based optical devices.
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spelling doaj-art-b1193dedaf3942ebaf1748e726f8a4672025-08-20T03:58:31ZengMDPI AGEntropy1099-43002025-07-0127773010.3390/e27070730Entropy-Inspired Aperture Optimization in Fourier OpticsMarcos Miotti0Daniel Varela Magalhães1Sao Carlos Institute of Physics, University of Sao Paulo, IFSC–USP, Sao Carlos 13566-590, BrazilSao Carlos Institute of Physics, University of Sao Paulo, IFSC–USP, Sao Carlos 13566-590, BrazilThe trade-off between resolution and contrast is a transcendental problem in optical imaging, spanning from artistic photography to technoscientific applications. To the latter, Fourier-optics-based filters, such as the 4<i>f</i> system, are well-known for their image-enhancement properties, removing high spatial frequencies from an optically Fourier-transformed light signal through simple aperture adjustment. Nonetheless, assessing the contrast–resolution balance in optical imaging remains a challenging task, often requiring complex mathematical treatment and controlled laboratory conditions to match theoretical predictions. With that in mind, we propose a simple yet robust analytical technique to determine the optimal aperture in a 4<i>f</i> imaging system for static and quasi-static objects. Our technique employs the mathematical formalism of the <i>H</i>-theorem, enabling us to directly access the information of an imaged object. By varying the aperture at the Fourier plane of the 4<i>f</i> system, we have empirically found an optimal aperture region where the imaging entropy is maximum, given that the object is fitted to the imaged area. At that region, the image is lit and well-resolved, and no further aperture decrease improves that, as information of the whole assembly (object plus imaging system) is maximum. With that analysis, we have also been able to investigate how the imperfections in an object affect the entropy during its imaging. Despite its simplicity, our technique is generally applicable and passable for automation, making it interesting for many imaging-based optical devices.https://www.mdpi.com/1099-4300/27/7/730Fourier opticsoptical imagingapplied information theory
spellingShingle Marcos Miotti
Daniel Varela Magalhães
Entropy-Inspired Aperture Optimization in Fourier Optics
Entropy
Fourier optics
optical imaging
applied information theory
title Entropy-Inspired Aperture Optimization in Fourier Optics
title_full Entropy-Inspired Aperture Optimization in Fourier Optics
title_fullStr Entropy-Inspired Aperture Optimization in Fourier Optics
title_full_unstemmed Entropy-Inspired Aperture Optimization in Fourier Optics
title_short Entropy-Inspired Aperture Optimization in Fourier Optics
title_sort entropy inspired aperture optimization in fourier optics
topic Fourier optics
optical imaging
applied information theory
url https://www.mdpi.com/1099-4300/27/7/730
work_keys_str_mv AT marcosmiotti entropyinspiredapertureoptimizationinfourieroptics
AT danielvarelamagalhaes entropyinspiredapertureoptimizationinfourieroptics