Chromatic Aberration Research Articles

The potential role of fixation eye movements in the development of myopia

Myopia, a globally public health problem, referring to an abnormal refractive state in which the focus falls in front of retina due to extended axial length, is always regarded as an excessive emmetropia process and extreme ocular growth. Fixation eye movements (FEMs), small eye movements occurring incessantly during our gazes to maintain continuous attention and keep clear vision, have been considered to participate in the emmetropization process, yet their role in relation to myopia development has not been clearly demonstrated. It is possible that abnormal fixation eye movements could contribute to the onset and progression of myopia. Although the role of fixation eye movements (FEMs) in the setting of myopia has not yet been investigated, previous researches have demonstrated that patients with myopic refractive error performed significantly abnormal FEMs characteristics, suggesting the potential association between FEMs and myopia development. In this article we hypothesized that abnormal fixation movements would result in disturbed spatiotemporal and defocus visual signal, abnormal longitudinal chromatic aberration, amplified eye-growth signal and extraocular muscle pressure, thereby inducing myopia development. In order to dissect any association between FEMs and myopia, further work is required to prospectively investigate the characteristics of FEMs during development and/or in populations affected by myopia or hyperopia. Future studies will be needed to update new understanding of myopia mechanism and propose suggestive prevention measures.

Quantitative phase imaging endoscopy with a metalens

Quantitative phase imaging (QPI) recovers the exact wavefront of light from intensity measurements. Topographical and optical density maps of translucent microscopic bodies can be extracted from these quantified phase shifts. We demonstrate quantitative phase imaging at the tip of a coherent fiber bundle using chromatic aberrations inherent in a silicon nitride hyperboloid metalens. Our method leverages spectral multiplexing to recover phase from multiple defocus planes in a single capture using a color camera. Our 0.5 mm aperture metalens shows robust quantitative phase imaging capability with a 28∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${28}^{\\circ}$$\\end{document} field of view and 0.2π\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${2}{\\pi}$$\\end{document} phase resolution ( ~ 0.1λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${1}{\\lambda}$$\\end{document} in air) for experiments with an endoscopic fiber bundle. Since the spectral functionality is encoded directly in the imaging lens, the metalens acts both as a focusing element and a spectral filter. The use of a simple computational backend will enable real-time operation. Key limitations in the adoption of phase imaging methods for endoscopy such as multiple acquisition, interferometric alignment or mechanical scanning are completely mitigated in the reported metalens based QPI.

Do diffractive intraocular lenses break the beneficial interaction between chromatic and monochromatic aberrations in the eye?

Do diffractive intraocular lenses break the beneficial interaction between chromatic and monochromatic aberrations in the eye?

Color‐Accurate Camera Capture with Multispectral Illumination and Multiple Exposures

AbstractCameras cannot capture the same colors as those seen by the human eye because the eye and the cameras' sensors differ in their spectral sensitivity. To obtain a plausible approximation of perceived colors, the camera's Image Signal Processor (ISP) employs a color correction step. However, even advanced color correction methods cannot solve this underdetermined problem, and visible color inaccuracies are always present. Here, we explore an approach in which we can capture accurate colors with a regular camera by optimizing the spectral composition of the illuminant and capturing one or more exposures. We jointly optimize for the signal‐to‐noise ratio and for the color accuracy irrespective of the spectral composition of the scene. One or more images captured under controlled multispectral illuminants are then converted into a color‐accurate image as seen under the standard illuminant of D65. Our optimization allows us to reduce the color error by 20–60% (in terms of CIEDE 2000), depending on the number of exposures and camera type. The method can be used in applications in which illumination can be controlled, and high colour accuracy is required, such as product photography or with a multispectral camera flash. The code is available at https://github.com/gfxdisp/multispectral_color_correction.

Chromatic aberration in homogeneous diameter expansion growth of AlN crystals by the PVT method

AbstractHomogeneous diameter expansion growth is the preferred method for preparing large-sized AlN single crystals using the PVT method. However, chromatic aberration between the expansion and seed regions, as well as localized chromatic aberrations within the expansion region, are commonly observed, but not deeply investigated yet. This paper investigates the homoepitaxial lateral growth of AlN crystals using Al-polar face seeds and analyzes the crystal structure, composition, and optical properties of both the expansion and seed regions. XRD and Raman spectroscopy indicate no significant differences in crystallization quality between the expansion and seed regions. XPS and photoluminescence characterizations reveal that the light yellow color of the seed region is mainly due to $$V_{Al}$$ V Al defects. In contrast, the deeper yellow color in the expansion region is caused by $$V_{Al}$$ V Al –$$O_N$$ O N complex defects. Additionally, etching results exhibit a polarity reversal from the Al-polar to N-polar growth face in localized chromatic aberration region. The bonding angle of approximately $${90}^\circ$$ 90 ∘ at the $$B_{1}$$ B 1 bond (formation by the half-filled orbitals of the Al and N atoms) site, which occurs during the bonding of Al and N atoms, results in the polarity reversal during m-plane lateral growth. This work provides implications for the preparation of large-sized AlN single crystals.

Enhancing Visual Perception in Immersive VR and AR Environments: AI-Driven Color and Clarity Adjustments Under Dynamic Lighting Conditions

The visual fidelity of virtual reality (VR) and augmented reality (AR) environments is essential for user immersion and comfort. Dynamic lighting often leads to chromatic distortions and reduced clarity, causing discomfort and disrupting user experience. This paper introduces an AI-driven chromatic adjustment system based on a modified U-Net architecture, optimized for real-time applications in VR/AR. This system adapts to dynamic lighting conditions, addressing the shortcomings of traditional methods like histogram equalization and gamma correction, which struggle with rapid lighting changes and real-time user interactions. We compared our approach with state-of-the-art color constancy algorithms, including Barron’s Convolutional Color Constancy and STAR, demonstrating superior performance. Experimental results from 60 participants show significant improvements, with up to 41% better color accuracy and 39% enhanced clarity under dynamic lighting conditions. The study also included eye-tracking data, which confirmed increased user engagement with AI-enhanced images. Our system provides a practical solution for developers aiming to improve image quality, reduce visual discomfort, and enhance overall user satisfaction in immersive environments. Future work will focus on extending the model’s capability to handle more complex lighting scenarios.

Relative Radiometric Correction Method Based on Temperature Normalization for Jilin1-KF02

The optical remote sensors carried by the Jilin-1 KF02 series satellites have an imaging resolution better than 0.5 m and a width of 150 km. There are radiometric problems, such as stripe noise, vignetting, and inter-slice chromatic aberration, in their raw images. In this paper, a relative radiometric correction method based on temperature normalization is proposed for the response characteristics of sensors and the structural characteristics of optical splicing of Jilin-1 KF02 series satellites cameras. Firstly, a model of temperature effect on sensor output is established to correct the variation of sensor response output digital number (DN) caused by temperature variation during imaging process, and the image is normalized to a uniform temperature reference. Then, the horizontal stripe noise of the image is eliminated by using the sensor scan line and dark pixel information, and the vertical stripe noise of the image is eliminated by using the method of on-orbit histogram statistics. Finally, the method of superposition compensation is used to correct the vignetting area at the edge of the image due to the lack of energy information received by the sensor so as to ensure the consistency of the image in color and image quality. The proposed method is verified by Jilin-1 KF02A on-orbit images. Experimental results show that the image response is uniform, the color is consistent, the average Streak Metrics (SM) is better than 0.1%, Root-Mean-Square Deviation of the Mean Line (RA) and Generalized Noise (GN) are better than 2%, Relative Average Spectral Error (RASE) and Relative Average Spectral Error (ERGAS) are greatly improved, which are better than 5% and 13, respectively, and the relative radiation quality is obviously improved after relative radiation correction.

Ultra-broadband achromaticity of metalens with low-relative phase enabled by wide-band fusion

Metalenses have a high design degree of freedom in controlling the light field and excellent performance in chromatic aberration elimination. However, in designing ultra-broadband achromatic metalenses, integrating multiple types of unit structures is necessary to compensate for phase differences caused by different incident wavelengths. Here, we propose an ultra-broadband achromatic metalens composed only of a single type of square nano-pillar. which controls the entire operating band by utilizing three wide-band fusions, and have characteristics depending on the phase coverage and relative phase. In the operational range of 2–5 μm, the achromatic metalens demonstrates a maximum focal shift of 2.1 μm. The average focal shift is 0.98 %, the average NA value is 0.35, with an average relative phase of 0.77π. The average transmittance and focus efficiency are 94.17 % and 58.7 %, respectively. This broad-spectrum fusion design strategy simplifies manufacturing complexity while maintaining high focusing efficiency and transmittance levels throughout the entire operational bandwidth. This design approach can improve image resolution and quality by minimizing chromatic aberration.

Integratable high-efficiency achromatic metalens across the entire low-loss bands of optical fiber from 1260 to 1625 nm

A challenge in optic fiber is to control dispersion over the entire low-loss bands covering the O + E + S + C + L bands with integratable ultracompact devices, which inevitably limits the range of fiber-based applications. Metalens supplies a dynamic platform for correcting chromatic aberration of optical devices in a flexible, integratable, and ultracompact way. Hence, we propose a broadband achromatic metalens integrated on the end face of a single-mode fiber covering the entire low-loss wavelength region. Utilizing the particle swarm optimization algorithm, we have substantially mitigated the phase-compensated matching error in the achromatic scheme. It demonstrates that the metalens is achievable with achromatic aberration and focuses over the entire low-loss wavelength band with a high mean focusing efficiency of 84.55%. Furthermore, this device exhibits a remarkable capability to break through the diffraction limit of the output field. This work provides a theoretical basis for fiber-integrated achromatic metalens over the entire low-loss bands, which has promising applications in imaging, sensing, and optical communication.

Desensitization design of freeform off-axis TMA optical systems with configuration selection

The off-axis three-mirror anastigmatic (TMA) optical system has the advantages of eliminating all primary aberrations, having no aperture obscuration, no chromatic aberration, and good environmental adaptability, making it essential in high-performance optical instruments. Freeform surfaces, with their rich degrees of freedom (DOFs) in mathematical representation, positively affect the image quality and sensitivity of optical systems. When applied correctly to off-axis TMA optical systems, they can achieve fast F-numbers, large fields of view (FOVs), and long focal lengths. There are dozens of configurations for off-axis TMA optical systems, and freeform surfaces can be combined in numerous ways within these systems. This paper first analyzes the sensitivity of off-axis TMA optical systems with different configurations, selects the configuration with the lowest sensitivity, and combines it with a low sensitivity freeform surface combination to achieve high-performance freeform off-axis TMA optical systems with low sensitivity.

Long-Distance Measurements Using a Chromatic Confocal Sensor

In this work, we demonstrate the use of a chromatic confocal sensor for long-distance measurements. The sensor increases the working distance of state-of-the-art confocal sensors by a factor of 10, reaching a working distance of 620 mm. The chromatic aberration exhibited by a lens was utilized to establish the working range. The chromatic dispersion of the optics led to images of the different wavelength components at different longitudinal points along the optical axis. The sensor employs a robust algorithm to measure relative displacements of the sample’s motion. The calibration process simplifies data analysis and improves the accuracy of displacement measurements in experimental setups. To facilitate the design process, a simulator was developed specifically for this purpose. The calibration data obtained in both the experimental and the simulated data show that the simulator was able to predict the sensitivity with an error of 5%. We also describe the effect on the sensitivity of oversampling the spectrum. In addition, the superiority of low-pass filtering over Gaussian fitting over the detected spectrum is shown.

Accurate measurement of wavelength-Dependent beam parameters of a supercontinuum light source focused by a lensed fiber probe

In this work, an supercontinuum (SC) light is focused by an optical lensed fiber (OLF). We demonstrate a new method to meticulously analyze multi-wavelength beam parameters of the OLF probe and the focused SC beam by applying a spectrometer to measure the variation of back-coupling efficiency for different wavelengths. By contrast, inevitable and relatively small errors in the OLF parameters that are obtained by using the conventional method lead to significant errors in the spatial information of the focused SC beam. Therefore, this method is expected to be a necessary calibration procedure for a system with an OLF probe. The SC beam focused by our OLF has little chromatic aberration in the beam size and the focal length in a range of approximately 120 μm.

How do intraocular lens materials influence the outcome of cataract surgery?

This review summarizes the evidence on the effect of intraocular lens (IOL) material on the outcomes of cataract surgery, as well as on the surgical procedure itself. Differences in capsular biocompatibility between IOL materials lead to variations in capsular stability and posterior capsule opacification (PCO), while differences in uveal biocompatibility affect postoperative inflammatory response. Refractive outcomes are affected by both incision size and the rotational stability of toric IOLs. Small incision sizes favour hydrophilic IOLs. Rotational stability of hydrophobic and hydrophilic IOLs were comparable in recent studies. Visual outcomes are affected by chromatic aberrations, dysphotopsia, lens opacifications and PCO. Hydrophilic IOLs are associated with reduced chromatic dispersion. Hydrophobic IOL opacifications are caused by sub-surface glistenings, while hydrophilic IOL opacifications are due to surface calcifications. Some surgeries, including pars plana vitrectomy and lamellar corneal transplants, were shown to increase the risk of IOL calcifications, although the mechanism is still unknown. Hydrophilic IOLs have greater ease of manipulation, greater resistance to IOL damage, and higher uveal biocompatibility. Hydrophobic IOLs show better PCO prevention than hydrophilic IOLs, and should be preferred in highly myopic eyes where Nd:YAG capsulotomy might increase the risk of retinal detachment.

Elimination of chromatic aberration in high-order harmonic generation using a plasma-induced flat-top beam in a gas medium

Elimination of chromatic aberration in high-order harmonic generation using a plasma-induced flat-top beam in a gas medium

Chromatic aberration compensation in a digital camera lens for fringe projection profilometry

This work presents a simplified method for compensating the chromatic aberration of a digital camera lens using orthogonal fringe patterns displayed on an LCD monitor. The proposed compensation method drastically reduces the complex mathematical calculations to an arithmetic procedure of the simple rule of three. First, the implemented method is simulated, and then the experimental results confirm the simulated model. The mean squared error and standard deviation of the chromatic aberration compensation are calculated. Additionally, an arrangement is presented to avoid systematic errors when calculating the chromatic aberration of the lens to be compensated without additional digital processing.

Design of an Objective Magnetic Lens and Study of its Magnetic and Optical Properties in the Scanning Electron Microscope

The study's objective is to investigate the optical properties of the objective magnetic lens, which is considered as the most crucial part of the electron microscope. Three models of objective lenses (Snorkel, Pinhole, Gemini), equal in geometric dimensions were taken, and their optical properties, as well as their magnetic properties. It was found that the lens (P) achieved the best results, which were studied at a continuous excitation (NI=2000 A-t) and different acceleration voltages ranging from (8-16 kV), in addition to different values for the aperture angle (α). Then, we conducted an improvement on the selected lens by changing the width of the air gap between the poles (S) and studying the properties of the lens. We obtained better results for spherical (Cs=1.62 mm) and chromatic (Cc=1.84 mm) aberrations, focal length (fₒ=2.92 mm), as well as the highest value of the magnetic field (Bz=0.38 T) at an acceleration voltage (Vr=10000 V), excitation (NI=2000 A-t), and air gap width (S=5 mm), and the diameter of the electron probe (dp=11.25 nm) at an aperture angle (α=2 mrad).

The Influence of Chromatic Aberration on Visual Quality in Patients With Trifocal Intraocular Lenses

The Influence of Chromatic Aberration on Visual Quality in Patients With Trifocal Intraocular Lenses

The influence of "advancing" and "receding" colors on figure-ground perception under monocular and binocular viewing.

Research on figure-ground perception has consistently found that red images are more likely to be perceived as figure/nearer, yet the mechanisms behind this are not completely clear. The primary theories have pointed to optical chromatic aberrations or cortical mechanisms, such as the antagonistic interactions of the magno-/parvocellular (M/P) systems. Our study explored this color-biased figure-ground perception by examining the duration for which a region was perceived as figure under both binocular and monocular conditions, using all combinations of red, blue, green, and gray. In Experiment 1, we used figure-ground ambiguous Maltese crosses, composed of left- and right-tilting sectors of equal area. In Experiment 2, the crosses were figure-ground biased with size and orientation cues. Here, small sectors of cardinal orientations, likely perceived as figure, were contrasted with larger, obliquely oriented sectors, likely perceived as ground. Under monocular conditions, the results aligned with chromatic aberration predictions: red advanced and blue receded, regardless of size and orientation. However, under binocular conditions, the advancing effect of red continued, but the receding effect of blue was generally not observed. Notably, blue, along with red and green, was more frequently perceived as figure compared to gray. The results under binocular viewing are in line with the expectations of the antagonistic M/P system interactions theory, likely due to the collective input from both eyes, facilitating the anticipated effects. Our findings suggest that color-biased figure-ground perception may arise from the synergistic effect of antagonistic M/P system interactions and other optical and cortical mechanisms, together compensating for chromatic aberrations.

Biodegradable packaging paper derived from chitosan-based composite barrier coating for agricultural products preservation

Development of green packaging materials is essential to replace traditional plastics in fresh agricultural products preservation. Herein, a coated paper was designed by applying chitosan-based composite coating on paper substrate through a facile automatic coating method. The hydroxypropyl trimethyl ammonium chloride chitosan (HACC) was obtained by direct quaternization via the introduction of hydroxypropyl trimethyl ammonium chloride into the amino group of chitosan, then mixed with polyvinyl alcohol (PVA) to prepare the HACC/PVA coating. Accordingly, the key performance of coated paper were improved ascribed to the synergy effect of HACC/PVA coating and paper substrate. In particular, the minimum oxygen permeability of the coated paper could reach to 0.87 × 10−13 cm3·cm/cm2·s·Pa, and the optimum water vapor permeability and tensile strength of HACC/PVA coated paper was 0.75 × 10−12 g·cm/cm2·s·Pa and 6.88 kN/m, respectively. The coated paper used as packaging material not only reduced weight loss ratio of strawberry and greengrocery, but also exhibited lower chromatic aberration and better sensory evaluation, indicating a favorable effect on fruit and vegetable storage. Taken together, the designed eco-friendly coated paper has shown tremendous potential for green and biodegradable packaging material in agricultural products preservation.

Simple, innovative and attractive approach for geometrical optics, chromatic aberration and colour combination experiments

Simple, innovative and attractive approach for geometrical optics, chromatic aberration and colour combination experiments