Journal Description
Optics
Optics
is an international, peer-reviewed, open access journal on optics published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within ESCI (Web of Science), Scopus, EBSCO, and other databases.
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 17.7 days after submission; acceptance to publication is undertaken in 3.9 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: APC discount vouchers, optional signed peer review, and reviewer names published annually in the journal.
- Optics is a companion journal of Photonics.
Latest Articles
A Mach–Zehnder Fabry–Perot Hybrid Fibre-Optic Interferometer for a Large Measurement Range Based on the Kalman Filter
Optics 2024, 5(2), 277-292; https://doi.org/10.3390/opt5020020 - 16 May 2024
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To solve the short working distance and small measurement range of an all-fibre interferometer, we proposed a Mach–Zehnder Fabry–Perot hybrid fibre-optic interferometry system based on sinusoidal phase modulation. In this paper, a low-finesse fibre interferometer with a larger linear operating range for displacement
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To solve the short working distance and small measurement range of an all-fibre interferometer, we proposed a Mach–Zehnder Fabry–Perot hybrid fibre-optic interferometry system based on sinusoidal phase modulation. In this paper, a low-finesse fibre interferometer with a larger linear operating range for displacement measurement is realised using a self-collimating probe and incorporating a Kalman filter-based phase demodulation algorithm. Through experimental comparisons, it is demonstrated that the interferometer proposed in this paper can effectively reduce the phase delay, compensate for the depth of modulation drift, and correct the error due to parasitic interference introduced by the optical path structure through the algorithm. A linear large measurement working range of 20 cm is realised.
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Open AccessArticle
Creation of a Corneal Flap for Laser In Situ Keratomileusis Using a Three-Dimensional Femtosecond Laser Cut: Clinical and Optical Coherence Tomography Features
by
Antonio Leccisotti, Stefania V. Fields, Giuseppe De Bartolo, Christian Crudale and Matteo Posarelli
Optics 2024, 5(2), 267-276; https://doi.org/10.3390/opt5020019 - 10 May 2024
Abstract
Laser in situ keratomileusis (LASIK) is the most frequently used technique for the surgical correction of refractive errors on the cornea. It entails the creation of a superficial hinged corneal flap using a femtosecond laser, ablation of the underlying stromal bed using an
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Laser in situ keratomileusis (LASIK) is the most frequently used technique for the surgical correction of refractive errors on the cornea. It entails the creation of a superficial hinged corneal flap using a femtosecond laser, ablation of the underlying stromal bed using an excimer laser, and repositioning of the flap. A corneal flap with an angled side cut reduces the risk of flap dislocation and infiltration of epithelial cells and confers unique biomechanical properties to the cornea. A new laser software creating three-dimensional (3D) flaps using a custom angle side cut was retrospectively evaluated, comparing optical coherence tomography 3D (with intended 90° side cut) and 2D flaps (with tapered side cuts) as well as respective intra- and early postoperative complications. Four hundred consecutive eyes were included, two hundred for each group. In the 3D group, the mean edge angle was 92°, and the procedure was on average 5.2 s slower (p = 0). Non-visually significant flap folds were found in thirteen eyes of the 2D group and in seven eyes of the 3D group (p = 0.17). In conclusion, the creation of a LASIK flap using a 3D femtosecond laser cut, although slightly slower, was safe and effective. The side cut angle was predictable and accurate.
Full article
(This article belongs to the Section Biomedical Optics)
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Open AccessFeature PaperReview
Skin Imaging Using Optical Coherence Tomography and Photoacoustic Imaging: A Mini-Review
by
Mohsin Zafar, Amanda P. Siegel, Kamran Avanaki and Rayyan Manwar
Optics 2024, 5(2), 248-266; https://doi.org/10.3390/opt5020018 - 30 Apr 2024
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This article provides an overview of the progress made in skin imaging using two emerging imaging modalities, optical coherence tomography (OCT) and photoacoustic imaging (PAI). Over recent years, these technologies have significantly advanced our understanding of skin structure and function, offering non-invasive and
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This article provides an overview of the progress made in skin imaging using two emerging imaging modalities, optical coherence tomography (OCT) and photoacoustic imaging (PAI). Over recent years, these technologies have significantly advanced our understanding of skin structure and function, offering non-invasive and high-resolution insights previously unattainable. The review begins by briefly describing the fundamental principles of how OCT and PAI capture images. It then explores the evolving applications of OCT in dermatology, ranging from diagnosing skin disorders to monitoring treatment responses. This article continues by briefly describing the capabilities of PAI imaging, and how PAI has been used for melanoma and non-melanoma skin cancer detection and characterization, vascular imaging, and more. The third section describes the development of multimodal skin imaging systems that include OCT, PAI, or both modes. A comparative analysis between OCT and PAI is presented, elucidating their respective strengths, limitations, and synergies in the context of skin imaging.
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Open AccessCommunication
Multipolar Analysis in Symmetrical Meta-Atoms Sustaining Fano Resonances
by
Vittorio Bonino and Angelo Angelini
Optics 2024, 5(2), 238-247; https://doi.org/10.3390/opt5020017 - 15 Apr 2024
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We present an optical metasurface with symmetrical individual elements sustaining Fano resonances with high Q-factors. This study combines plane-wave illumination and modal analysis to investigate the resonant behavior that results in a suppression of the forward scattering, and we investigate the role of
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We present an optical metasurface with symmetrical individual elements sustaining Fano resonances with high Q-factors. This study combines plane-wave illumination and modal analysis to investigate the resonant behavior that results in a suppression of the forward scattering, and we investigate the role of the lattice constant on the excited multipoles and on the spectral position and Q-factor of the Fano resonances, revealing the nonlocal nature of the resonances. The results show that the intrinsic losses play a crucial role in modulating the resonance amplitude in specific conditions and that the optical behavior of the device is extremely sensitive to the pitch of the metasurface. The findings highlight the importance of near-neighbor interactions to achieve high Q resonances and offer an important tool for the design of spectrally tunable metasurfaces using simple geometries.
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Open AccessArticle
Enhancing Microwave Photonic Interrogation Accuracy for Fiber-Optic Temperature Sensors via Artificial Neural Network Integration
by
Roman Makarov, Mohammed R. T. M. Qaid, Alaa N. Al Hussein, Bulat Valeev, Timur Agliullin, Vladimir Anfinogentov and Airat Sakhabutdinov
Optics 2024, 5(2), 223-237; https://doi.org/10.3390/opt5020016 - 10 Apr 2024
Abstract
In this paper, an application of an artificial neural network algorithm is proposed to enhance the accuracy of temperature measurement using a fiber-optic sensor based on a Fabry–Perot interferometer (FPI). It is assumed that the interrogation of the FPI is carried out using
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In this paper, an application of an artificial neural network algorithm is proposed to enhance the accuracy of temperature measurement using a fiber-optic sensor based on a Fabry–Perot interferometer (FPI). It is assumed that the interrogation of the FPI is carried out using an optical comb generator realizing a microwave photonic approach. Firstly, modelling of the reflection spectrum of a Fabry–Perot interferometer is implemented. Secondly, probing of the obtained spectrum using a comb-generator model is performed. The resulting electrical signal of the photodetector is processed and is used to create a sample for artificial neural network training aimed at temperature detection. It is demonstrated that the artificial neural network implementation can predict temperature variations with an accuracy equal to 0.018 °C in the range from −10 to +10 °C and 0.147 in the range from −15 to +15 °C.
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(This article belongs to the Special Issue Optical Sensing and Optical Physics Research)
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Open AccessArticle
Wavelet-Based Machine Learning Algorithms for Photoacoustic Gas Sensing
by
Artem Kozmin, Evgenii Erushin, Ilya Miroshnichenko, Nadezhda Kostyukova, Andrey Boyko and Alexey Redyuk
Optics 2024, 5(2), 207-222; https://doi.org/10.3390/opt5020015 - 3 Apr 2024
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The significance of intelligent sensor systems has grown across diverse sectors, including healthcare, environmental surveillance, industrial automation, and security. Photoacoustic gas sensors are a promising type of optical gas sensor due to their high sensitivity, enhanced frequency selectivity, and fast response time. However,
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The significance of intelligent sensor systems has grown across diverse sectors, including healthcare, environmental surveillance, industrial automation, and security. Photoacoustic gas sensors are a promising type of optical gas sensor due to their high sensitivity, enhanced frequency selectivity, and fast response time. However, they have limitations such as dependence on a high-power light source, a requirement for a high-quality acoustic signal detector, and sensitivity to environmental factors, affecting their accuracy and reliability. Machine learning has great potential in the analysis and interpretation of sensor data as it can identify complex patterns and make accurate predictions based on the available data. We propose a novel approach that utilizes wavelet analysis and neural networks with enhanced architectures to improve the accuracy and sensitivity of photoacoustic gas sensors. Our proposed approach was experimentally tested for methane concentration measurements, showcasing its potential to significantly advance the field of gas detection and analysis, providing more accurate and reliable results.
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Open AccessArticle
Angle-Resolved Optical Characterization of a Plasmonic Triangular Array of Elliptical Holes in a Gold Layer
by
Margherita Angelini, Konstantins Jefimovs, Paola Pellacani, Dimitrios Kazazis, Franco Marabelli and Francesco Floris
Optics 2024, 5(1), 195-206; https://doi.org/10.3390/opt5010014 - 21 Mar 2024
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Plasmonic arrays are grating-like structures able to couple an incoming electromagnetic field into either localized or propagating surface plasmonic modes. A triangular array of elliptical holes in a gold layer were realized resorting to displacement Talbot lithography. Scanning electron microscopy was used to
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Plasmonic arrays are grating-like structures able to couple an incoming electromagnetic field into either localized or propagating surface plasmonic modes. A triangular array of elliptical holes in a gold layer were realized resorting to displacement Talbot lithography. Scanning electron microscopy was used to evaluate the geometrical features and finite time domain simulations were performed to verify the consistency of the design. The optical response was characterized by angle-resolved reflectance and transmittance measurements. The results demonstrate the good quality and uniformity of the array. Furthermore, the study on the dependence of the optical response on both the hexagonal lattice and the elliptical hole-defined symmetry properties was conducted allowing the distinction of their effects on both the localized and propagating plasmonic modes. The results indicate that the localized component of the plasmonic modes is mainly affected by the elliptical shape, while the propagating part is influenced by the hexagonal lattice symmetry.
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Open AccessArticle
A Non-Destructive Study of Optical, Geometric and Luminescent Parameters of Active Optical Fibers Preforms
by
Yuri Aleksandrovich Konstantinov, Artem Timofeevich Turov, Konstantin Pavlovich Latkin, D Claude and Irina Sergeevna Azanova
Optics 2024, 5(1), 176-194; https://doi.org/10.3390/opt5010013 - 20 Mar 2024
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This work is devoted to the scientific and technical aspects of individual stages of active optical fibers preforms’ optical-geometric parameters metrological control. The concept of a system presented makes it possible to carry out a study of a rare earth element distribution in
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This work is devoted to the scientific and technical aspects of individual stages of active optical fibers preforms’ optical-geometric parameters metrological control. The concept of a system presented makes it possible to carry out a study of a rare earth element distribution in the preform of an active optical fiber and to monitor geometric parameters, and also to study the evolution of the refractive index profile along the length of the sample at a qualitative level. As far as it is known, it is the first description of the preform optical, geometric, and luminescent properties measurement within a single automated laboratory bench. Also, the novelty of the approach lies in the fact that the study of the refractive index profile variation along the length of the preform is, for the first time, conducted using the “dry” method, that is, without immersing the sample in synthetic oil, which makes the process less labor-intensive and safer.
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Open AccessArticle
Nanofabrication Process Scale-Up via Displacement Talbot Lithography of a Plasmonic Metasurface for Sensing Applications
by
Paola Pellacani, Konstantins Jefimovs, Margherita Angelini, Franco Marabelli, Valentina Tolardo, Dimitrios Kazazis and Francesco Floris
Optics 2024, 5(1), 165-175; https://doi.org/10.3390/opt5010012 - 8 Mar 2024
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The selection of an affordable method to fabricate plasmonic metasurfaces needs to guarantee complex control over both tunability and reproducibility of their spectral and morphological properties, making plasmonic metasurfaces suitable for integration into different sensing devices. Displacement Talbot lithography could be a valid
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The selection of an affordable method to fabricate plasmonic metasurfaces needs to guarantee complex control over both tunability and reproducibility of their spectral and morphological properties, making plasmonic metasurfaces suitable for integration into different sensing devices. Displacement Talbot lithography could be a valid solution thanks to the limited fabrication steps required, also providing the highly desired industrial scalability. Fabricated plasmonic metasurfaces are represented by a gold nanohole array on a glass substrate based on a triangular pattern. Scanning electron microscopy measurements have been recorded, showing the consistency of the surface features with the optimized design parameters. Reflectance and transmittance measurements have also been carried out to test the reliability and standardization of the metasurface’s optical response. Furthermore, these plasmonic metasurfaces have also been successfully tested for probing refractive index variations in a microfluidic system, paving the way for their use in sensitive, real-time, label-free, and multiplexing detection of bio-molecular events.
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Open AccessArticle
Lidar-Based Spatial Large Deflection Measurement System for Wind Turbine Blades
by
Yue Hu, Yutian Zhu, Aiguo Zhou and Penghui Liu
Optics 2024, 5(1), 151-164; https://doi.org/10.3390/opt5010011 - 4 Mar 2024
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With the advancement of China’s wind power industry, research into full-scale structural testing of wind turbine blades, including static testing and fatigue testing, has shown increasing significance. Static testing measures the deflection at fixed points, using pull-wire sensors in industrial practice. However, the
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With the advancement of China’s wind power industry, research into full-scale structural testing of wind turbine blades, including static testing and fatigue testing, has shown increasing significance. Static testing measures the deflection at fixed points, using pull-wire sensors in industrial practice. However, the demerits of this method involve single dimension, excessive deviation, costly experiment, and complex installment. Given the advantages that lidar provides, correspondingly, high data density, precision, and convenience, we proposed a simple and efficient spatial large deflection measurement system for wind turbine blades with multi lidars. For point clouds collected from lidar scanners, registration based on point primitives and geometric primitives, dynamic radius DBSCAN clustering, spatial line clustering, and line integrals are applied to calculate the 3D coordinates of measured points on the blade. Experimentally validated, the proposed method demonstrates its effectiveness in serving as a viable alternative to the traditional pull-wire sensor measurement approach. In the minimum oscillation direction test, the measurement error is controlled within 3% compared to the theoretical value. Simultaneously, in the maximum swing direction test, the 3D coordinates of the measured point remain consistent with the changing trend observed under small deformation. These results confirm the feasibility of the system and its potentials to be generalized.
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Open AccessReview
Photoacoustic Imaging of Human Skin for Accurate Diagnosis and Treatment Guidance
by
Yue Ying, Hong Zhang and Li Lin
Optics 2024, 5(1), 133-150; https://doi.org/10.3390/opt5010010 - 1 Mar 2024
Abstract
Photoacoustic imaging (PAI) is a cutting-edge biomedical imaging modality, providing detailed anatomical and functional information about the area beneath the skin surface. Its light energy deposition is such that PAI typically provides clear images of the skin with high signal-to-noise ratios. Specifically, the
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Photoacoustic imaging (PAI) is a cutting-edge biomedical imaging modality, providing detailed anatomical and functional information about the area beneath the skin surface. Its light energy deposition is such that PAI typically provides clear images of the skin with high signal-to-noise ratios. Specifically, the rich optical contrast of PAI allows biological information related to lesion growth, malignancy, treatment response, and prognosis to be seen. Given its significant advantages and emerging role in imaging skin lesions, we summarize and comment on representative studies of skin PAI, such as the guidance of skin cancer biopsies and surgical excisions, and the accurate diagnosis of psoriasis. We conclude with our insights about the clinical significance of skin PAI, showing how its use to identify biological characteristics in lesion microenvironments allows early diagnosis and prognosis of disease.
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(This article belongs to the Special Issue Advanced Optical Imaging for Biomedicine)
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Open AccessArticle
Design of Planar Multilayer Devices for Optical Filtering Using Surrogate Model Based on Artificial Neural Network
by
Davi F. Rêgo, Fabrício G. S. Silva, Rodrigo C. Gusmão and Vitaly F. Rodriguez-Esquerre
Optics 2024, 5(1), 121-132; https://doi.org/10.3390/opt5010009 - 1 Mar 2024
Abstract
Artificial intelligence paradigms hold significant potential to advance nanophotonics. This study presents a novel approach to designing a plasmonic absorber using an artificial neural network as a surrogate model in conjunction with a genetic algorithm. The methodology involved numerical simulations of multilayered metal–dielectric
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Artificial intelligence paradigms hold significant potential to advance nanophotonics. This study presents a novel approach to designing a plasmonic absorber using an artificial neural network as a surrogate model in conjunction with a genetic algorithm. The methodology involved numerical simulations of multilayered metal–dielectric plasmonic structures to establish a dataset for training an artificial neural network (ANN). The results demonstrate the proficiency of the trained ANN in predicting reflectance spectra and its ability to generalize intricate relationships between desired performance and geometric configurations, with values of correlation higher than 98% in comparison with ground-truth electromagnetic simulations. Furthermore, the ANN was employed as a surrogate model in a genetic algorithm (GA) loop to achieve target optical behaviors. The proposed methodology provides a powerful means of inverse designing multilayered metal–dielectric devices tailored for visible band wavelength filtering. This research demonstrates that the integration of AI-driven approaches in nanophotonics leads to efficient and effective design strategies.
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(This article belongs to the Section Photonics and Optical Communications)
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Open AccessFeature PaperArticle
Surface Topological Plexcitons: Strong Coupling in a Bi2Se3 Topological Insulator Nanoparticle-Quantum Dot Molecule
by
George Kountouris and Vassilios Yannopapas
Optics 2024, 5(1), 101-120; https://doi.org/10.3390/opt5010008 - 27 Feb 2024
Abstract
Strong coupling of quantum states with electromagnetic modes of topological matter offer an interesting platform for the exploration of new physics and applications. In this work, we report a novel hybrid mode, a surface topological plexciton, arising from strong coupling between the surface
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Strong coupling of quantum states with electromagnetic modes of topological matter offer an interesting platform for the exploration of new physics and applications. In this work, we report a novel hybrid mode, a surface topological plexciton, arising from strong coupling between the surface topological plasmon mode of a topological insulator nanoparticle and the exciton of a two-level quantum emitter. We study the power absorption spectrum of the system by working within the dipole and rotating-wave approximations, using a density matrix approach for the emitter, and a classical dielectric-function approach for the topological-insulator nanoparticle. We show that a Rabi-type splitting can appear in the spectrum suggesting the presence of strong coupling. Furthermore, we study the dependence of the splitting on the separation of the two nanoparticles as well as the dipole moment of the quantum emitter. These results can be useful for exploring exotic phases of matter, furthering research in topological insulator plasmonics, as well as for applications in the far-infrared and quantum computing.
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(This article belongs to the Section Photonics and Optical Communications)
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Open AccessFeature PaperArticle
Electronic Population Reconstruction from Strong-Field-Modified Absorption Spectra with a Convolutional Neural Network
by
Daniel Richter, Alexander Magunia, Marc Rebholz, Christian Ott and Thomas Pfeifer
Optics 2024, 5(1), 88-100; https://doi.org/10.3390/opt5010007 - 26 Feb 2024
Abstract
We simulate ultrafast electronic transitions in an atom and corresponding absorption line changes with a numerical, few-level model, similar to previous work. In addition, a convolutional neural network (CNN) is employed for the first time to predict electronic state populations based on the
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We simulate ultrafast electronic transitions in an atom and corresponding absorption line changes with a numerical, few-level model, similar to previous work. In addition, a convolutional neural network (CNN) is employed for the first time to predict electronic state populations based on the simulated modifications of the absorption lines. We utilize a two-level and four-level system, as well as a variety of laser-pulse peak intensities and detunings, to account for different common scenarios of light–matter interaction. As a first step towards the use of CNNs for experimental absorption data in the future, we apply two different noise levels to the simulated input absorption data.
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(This article belongs to the Special Issue Ultrafast Light-Matter Interaction)
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Open AccessArticle
Dual-Band Image Fusion Approach Using Regional Weight Analysis Combined with a Multi-Level Smoothing Filter
by
Jia Yi, Huilin Jiang, Xiaoyong Wang and Yong Tan
Optics 2024, 5(1), 76-87; https://doi.org/10.3390/opt5010006 - 21 Feb 2024
Abstract
Image fusion is an effective and efficient way to express the feature information of an infrared image and abundant detailed information of a visible image in a single fused image. However, obtaining a fused result with good visual effect, while preserving and inheriting
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Image fusion is an effective and efficient way to express the feature information of an infrared image and abundant detailed information of a visible image in a single fused image. However, obtaining a fused result with good visual effect, while preserving and inheriting those characteristic details, seems a challenging problem. In this paper, by combining a multi-level smoothing filter and regional weight analysis, a dual-band image fusion approach is proposed. Firstly, a series of dual-band image layers with different details are obtained using smoothing results. With different parameters in a bilateral filter, different smoothed results are achieved at different levels. Secondly, regional weight maps are generated for each image layer, and then we fuse the dual-band image layers with their corresponding regional weight map. Finally, by imposing proper weights, those fused image layers are synthetized. Through comparison with seven excellent fusion methods, both subjective and objective evaluations for the experimental results indicate that the proposed approach can produce the best fused image, which has the best visual effect with good contrast, and those small details are preserved and highlighted, too. In particular, for the image pairs with a size of 640 × 480, the algorithm could provide a good visual effect result within 2.86 s, and the result has almost the best objective metrics.
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(This article belongs to the Section Engineering Optics)
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Open AccessFeature PaperArticle
Introducing Optical Nonlinearity in PDMS Using Organic Solvent Swelling
by
Sudhakara Reddy Bongu, Maximilian Buchmüller, Daniel Neumaier and Patrick Görrn
Optics 2024, 5(1), 66-75; https://doi.org/10.3390/opt5010005 - 15 Feb 2024
Abstract
The feasibility of introducing optical nonlinearity in poly-dimethyl siloxane (PDMS) using organic solvent swelling was investigated. The third-order nonlinear refraction and absorption properties of the individual materials, as well as the PDMS/solvent compounds after swelling were characterized. The well-established Z-scan technique served as
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The feasibility of introducing optical nonlinearity in poly-dimethyl siloxane (PDMS) using organic solvent swelling was investigated. The third-order nonlinear refraction and absorption properties of the individual materials, as well as the PDMS/solvent compounds after swelling were characterized. The well-established Z-scan technique served as characterization method for the nonlinear properties under picosecond pulsed laser excitation at a 532 nm wavelength. These experiments included investigations on the organic solvents nitrobenzene, 2,6-lutidine, and toluene, which showed inherent optical nonlinearity. We showed that nitrobenzene, one of the most well-known nonlinear optical materials, has proven suboptimal in this context due to its limited swelling effect in PDMS and comparatively high (non)linear absorption, resulting in undesirable thermal effects and potential photo-induced damage in the composite material. Toluene and 2,6-lutidine not only exhibited lower absorption compared to nitrobenzene but also show a more pronounced swelling effect in PDMS. The incorporation of toluene caused a weight change of up to 116% of PDMS, resulting in substantial nonlinear optical effects, reflected in the nonlinear refractive index of the PDMS/toluene composite .
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(This article belongs to the Section Nonlinear Optics)
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Open AccessArticle
Simple Estimate of the Impact of M2 and Strehl Ratio on the Effective Focusable Spot Size
by
Samuel Arba-Mosquera, Pascal Naubereit and Simas Sobutas
Optics 2024, 5(1), 56-65; https://doi.org/10.3390/opt5010004 - 29 Jan 2024
Abstract
A simple method (first-order approximation) to determine the impact of M2 and the Strehl Ratio on the effective focusable spot size avoiding complex propagations of the beam wavefront is proposed. The model is based upon previous models and the definition of M
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A simple method (first-order approximation) to determine the impact of M2 and the Strehl Ratio on the effective focusable spot size avoiding complex propagations of the beam wavefront is proposed. The model is based upon previous models and the definition of M2 and the Strehl Ratio in a simple manner. This work provides qualitative and quantitative estimates for the interplay of M2 and the Strehl Ratio on the effectively focusable spot size.
Full article
(This article belongs to the Special Issue Advanced Optical Imaging for Biomedicine)
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Open AccessArticle
An Anti-Noise-Designed Residual Phase Unwrapping Neural Network for Digital Speckle Pattern Interferometry
by
Biao Wang, Xiaoling Cao, Meiling Lan, Chang Wu and Yonghong Wang
Optics 2024, 5(1), 44-55; https://doi.org/10.3390/opt5010003 - 19 Jan 2024
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DSPI (Digital Speckle Pattern Interferometry) is a non-destructive optical measurement technique that obtains phase information of an object through phase unwrapping. Traditional phase unwrapping algorithms depend on the quality of the images, which demands preprocessing such as filtering and denoising. Moreover, the unwrapping
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DSPI (Digital Speckle Pattern Interferometry) is a non-destructive optical measurement technique that obtains phase information of an object through phase unwrapping. Traditional phase unwrapping algorithms depend on the quality of the images, which demands preprocessing such as filtering and denoising. Moreover, the unwrapping time is highly influenced by the size of the images. In this study, we proposed a new deep learning-based phase unwrapping algorithm combining the residual network and U-Net network. Additionally, we incorporated an improved SSIM function as the loss function based on camera characteristics. The experimental results demonstrated that the proposed method achieved higher quality in highly noisy phase unwrapping maps compared to traditional algorithms, with SSIM values consistently above 0.98. In addition, we applied image stitching to the network to process maps of various sizes and the unwrapping time remained around 1 s even for larger images. In conclusion, our proposed network is able to achieve efficient and accurate phase unwrapping.
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Open AccessArticle
Degree of Polarization of Cathodoluminescence from a (100) GaAs Substrate with SiN Stripes
by
Daniel T. Cassidy, Philippe Pagnod-Rossiaux and Merwan Mokhtari
Optics 2024, 5(1), 11-43; https://doi.org/10.3390/opt5010002 - 17 Jan 2024
Abstract
Notes on fits of analytic estimations, 2D finite element method (FEM), and 3D FEM simulations to measurements of the cathodoluminescence (CL) and to the degree of polarization (DOP) of the CL from the top surface of a GaAs substrate with
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Notes on fits of analytic estimations, 2D finite element method (FEM), and 3D FEM simulations to measurements of the cathodoluminescence (CL) and to the degree of polarization (DOP) of the CL from the top surface of a GaAs substrate with a 6.22 m wide SiN stripe are presented. Three interesting features are found in the DOP of CL data. Presumably these features are noticeable owing to the spatial resolution of the CL measurement system. Comparisons of both strain and spatial resolutions obtained by CL and photoluminescence (PL) systems are presented. The width of the central feature in the measured DOP is less than the width of the SiN, as measured from the CL. This suggests horizontal cracks or de-laminations into each side of the SiN of about 0.7 m. In addition, it appears that deformed regions of widths of ≈1.5 m and adjacent to the SiN must exist to explain some of the features.
Full article
(This article belongs to the Special Issue Strain in III–V Materials and Devices: Methods for Estimation and Effects)
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Open AccessArticle
Hybrid Approach for Multiscale and Multimodal Time-Resolved Diagnosis of Ultrafast Processes in Materials via Tailored Synchronization of Laser and X-ray Sources at MHz Repetition Rates
by
Nikita Marchenkov, Evgenii Mareev, Anton Kulikov, Fedor Pilyak, Eduard Ibragimov, Yuri Pisarevskii and Fedor Potemkin
Optics 2024, 5(1), 1-10; https://doi.org/10.3390/opt5010001 - 16 Jan 2024
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The synchronization of laser and X-ray sources is essential for time-resolved measurements in the study of ultrafast processes, including photo-induced piezo-effects, shock wave generation, and phase transitions. On the one hand, optical diagnostics (by synchronization of two laser sources) provides information about changes
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The synchronization of laser and X-ray sources is essential for time-resolved measurements in the study of ultrafast processes, including photo-induced piezo-effects, shock wave generation, and phase transitions. On the one hand, optical diagnostics (by synchronization of two laser sources) provides information about changes in vibration frequencies, shock wave dynamics, and linear and nonlinear refractive index behavior. On the other hand, optical pump–X-ray probe diagnostics provide an opportunity to directly reveal lattice dynamics. To integrate two approaches into a unified whole, one needs to create a robust method for the synchronization of two systems with different repetition rates up to the MHz range. In this paper, we propose a universal approach utilizing a field-programmable gate array (FPGA) to achieve precise synchronization between different MHz sources such as various lasers and synchrotron X-ray sources. This synchronization method offers numerous advantages, such as high flexibility, fast response, and low jitter. Experimental results demonstrate the successful synchronization of two different MHz systems with a temporal resolution of 250 ps. This enables ultrafast measurements with a sub-nanosecond resolution, facilitating the uncovering of complex dynamics in ultrafast processes.
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Optics
Advanced Optical Imaging for Biomedicine
Guest Editors: Li Lin, Zhiyi LiuDeadline: 10 August 2024
Special Issue in
Optics
Advances in Biophotonics Using Optical Microscopy Techniques
Guest Editor: Ellas SpyratouDeadline: 20 October 2024
Special Issue in
Optics
Optoelectronic Thin Films
Guest Editors: Jigang Wang, Junming Li, Zhenjun Li, Tao Jiang, Meng LiDeadline: 30 October 2024
Special Issue in
Optics
Ultrafast Light-Matter Interaction
Guest Editor: Daria Popova-GorelovaDeadline: 15 December 2024
Topical Collections
Topical Collection in
Optics
Feature Paper Collection of Emerging Trends on Optics
Collection Editors: Costantino De Angelis, Thomas Seeger