Astigmatism Aberration Research Articles

Optical aberration effects on beam quality in microlens array scanning systems

Microlens array scanning (MLAS) has emerged as a promising semi-solid micromechanical beam scanning technology, which has significant potential in fields such as LIDAR and free-space optical communication. Beam quality is a crucial performance index in MLAS, which directly affects the overall performance of the system. To better evaluate and optimize the performance of the MLAS system, we investigate the effect of aberrations on this critical parameter of MLAS beam quality. This paper commences by constructing a model of the Kepler-structured MLAS system affected by aberrations based on the wave aberration theory. A detailed examination is conducted on the influence of both uniform and non-uniform wave aberrations within the MLAS on the beam quality. This paper investigates the effects of defocus, astigmatism, coma, and spherical aberration on the far-field intensity distribution of the MLAS system by using the Zernike aberration decomposition technique. Employing the Strehl ratio (SR) and power-in-the-bucket (PIB) as quantitative evaluation indices of beam quality, this study calculates the aberration-induced alterations in far-field focusing ability and energy concentration. The findings of this study provide valuable insights for the design optimization, manufacturing, and assembly testing of MLAS technologies.

Effects of clear corneal incision location and morphology on corneal surgically induced astigmatism and higher-order aberrations after ICL V4c implantation.

To evaluate the effects of clear corneal incision (CCI) location and morphology on corneal surgically induced astigmatism (SIA) and higher-order aberrations (HOAs) in patients receiving implantable collamer lens (ICL V4c) implantation. This retrospective study classified right eyes that underwent ICL implantation into two groups based on temporal or superior CCI. The Pentacam HR analyzer was used to measure the corneal astigmatism and HOAs. Analysis of the clear corneal incision (CCI) morphology, including incision width (Angle-W), incision length (IL), incision angles (Angle-En/Ex), and distance from the incision to corneal apex (Dis-En/Ex), was conducted using anterior segment optical coherence tomography (AS-OCT). There were 75 eyes in the temporal CCI group and 47 eyes in the superior CCI group. Both groups showed satisfactory safety and efficacy postoperatively. In the temporal CCI group, Dis-En and Dis-Ex were considerably longer, whereas the superior CCI group displayed a significantly wider Angle-W. The anterior and posterior corneal SIA were comparable in both groups. Anterior corneal SIA was significantly correlated to Dis-En and Dis-Ex in the superior CCI group. Superior CCI caused a notable rise in corneal Z (3, 3), while temporal CCI led to increased Z (3, 1). CCI morphology was correlated to corneal Z (4, -4) and Z (4, 4) in the superior CCI group. CCI locations caused slight variations in postoperative corneal SIA and HOAs following ICL implantation. Optimal postoperative visual outcomes may be better achieved with a CCI design featuring an increased distance from the corneal centroid and a decreased Angle-W.

Effects of introducing astigmatism aberration to spiral elements of diverse geometrical shapes

Effects of introducing astigmatism aberration to spiral elements of diverse geometrical shapes

Influence of astigmatic aberration on partially coherent Gaussian-Schell vortex beam focused by lensacon

Based on the mathematical framework of the partially coherent Gaussian Schell model vortex (PCGSMV) beam and the Huygens-Fresnel integral, we conducted a study to analyze the intensity distribution and depth of focus (DOF) of the PCGSMV beam as it propagates through a classical axicon. Our numerical results indicate the influence of factors such as the beam width, spatial degree of coherence, topological charge, and axicon base angle on the intensity distribution and DOF. In addition, we investigated the relationship between the beam spot size and propagation distance, as well as the effects of the spatial degree of coherence and propagation distance on the intensity profile. Our findings highlight the importance of the intensity values along the DOF for various applications, including the optical trapping and manipulation of micro particles.

Effects and safety of combined corneal collagen crosslinking and intrastromal corneal ring segment treatment in patients with keratoconus: a retrospective study

PurposeTo evaluate the safety and efficacy of different time-point combinations of intrastromal corneal ring segment (ICRS) implantation using femtosecond technology) and corneal collagen crosslinking (CXL) for the treatment of moderate-to-severe keratoconus (KCC).MethodsThis study included 69 eyes of 69 patients with keratoconus who underwent ICRS and CXL treatment at an Eye Hospital between March 2020 and March 2023. The patients were divided into two groups: Group 1 (n = 33 eyes of 33 patients), which received ICRS and CXL treatment in one session, and Group 2 (n = 36 eyes of 36 patients), which included treatment with ICRS for at least 6 months following CXL application. Preoperative and postoperative evaluations included visual acuity, autorefractometer refraction, corneal tomographic measurements using the Sirius (CSO) Scheimpflug camera and the TONOREF™ III device, and documentation of observed complications. Uncorrected visual acuity (UCVA) and best-corrected spectacle visual acuity (BCVA) were measured in each eye individually, and visual acuity was assessed using the logarithm of the minimum angle of resolution (logMAR).ResultsIn Group 1, mean UCVA improved from 0.81 ± 0.34 to 0.45 ± 0.25 (p < 0.01), and mean BCVA improved from 0.76 ± 0.35 to 0.38 ± 0.20 (p < 0.01). In Group 2, mean UCVA improved from 0.71 ± 0.32 to 0.43 ± 0.30 (p < 0.01), and mean BCVA improved from 0.65 ± 0.25 to 0.31 ± 0.23 (p < 0.01). Both groups showed significant reductions in manifest spherical and cylindrical refraction (p < 0.01). Group 1 exhibited greater reductions in maximum keratometry (Kmax), flat keratometry (K1), steep keratometry (K2) (p < 0.05), and astigmatic aberration compared with group 2 (p < 0.01). The use of simultaneous or separate CXL and ICRS does not significantly increase the incidence of complications.ConclusionsBoth combined and separate CXL and ICRS treatments resulted in significant improvement in UCVA and BCVA and reduced manifest refraction. Although improvements were observed in groups 1 and 2 in terms of K1, K2, and Kmax at 6 months, the improvements were more pronounced in Group 1. These results highlight the potential benefits of simultaneous ICRS + CXL treatment and underscore the importance of optimising the timing of CXL treatment to achieve the best visual outcomes.

Comparative visual performance of ultraviolet light-filtering and violet light-filtering monofocal intraocular lenses of the same material and basic design

We compared the visual performance of ZCB00 ultraviolet light-filtering and ZCB00V violet light-filtering monofocal intraocular lenses (IOLs) (both Johnson & Johnson Surgical Vision) with the same materials and basic design in cataract patients treated from 2011 to 2020. The evaluations were performed 10 weeks after the last surgery for implantation of bilateral lenses ≤ 3 months apart. The ZCB00 and ZCB00V groups included 904 eyes from 452 patients (age 72.3 ± 6.8 y; women/men, 268/184) and 1374 eyes from 687 patients (age 73.0 ± 7.4 y; women/men, 415/272), respectively. Statistical validity was confirmed using a linear mixed-effects model with binocular data and adjustments for age, sex, subjective refraction cylinder, subjective refraction spherical equivalent, corneal astigmatism, axial length, pupil diameter, and corneal higher-order aberrations. ZCB00 showed slightly but significantly better results (p < 0.05, Wald) for uncorrected intermediate/near visual acuity, corrected near visual acuity, and components of the 25-item Visual Function Questionnaire (VFQ-25) (Role_Limitation, Mental_Health, Social_Function, Distance_Vision, Color_Vision). Additionally, ZCB00V showed significantly better contrast sensitivity with glare (visual angle of target: 6.3°/4.0°/0.7°; p < 0.00068, Wald); slightly but significantly better contrast sensitivity without glare (4.0°/2.5°/1.6°) and with glare (2.5°/1.6°/1.0°), VFQ-25 General_Health scores, and near spectacle independence; and slightly but significantly smaller higher-order aberrations (internal, scaled to a 6-mm pupil; Wavefront_6_post_I_Trefoil) (p < 0.05, Wald).

Impact of Scleral Lenses on Visual Acuity and Ocular Aberrations in Corneal Ectasia: A Comprehensive Review.

Corneal ectasias, including keratoconus (KC), pellucid marginal degeneration (PMD), and post-LASIK ectasia, poses significant visual rehabilitation challenges due to the resultant irregular astigmatism, myopia, and higher-order aberrations (HOAs). These conditions often resist traditional corrective methods, necessitating advanced optical solutions. Scleral lenses (SLs) have emerged as a primary non-surgical option for managing these complex corneal irregularities. SLs form a smooth optical interface by forming a tear-filled chamber between the lens and the cornea, effectively mitigating HOAs and improving both high-contrast and low-contrast visual acuity (VA). This review evaluates the efficacy of SLs in enhancing VA and reducing aberrations in patients with corneal ectasia. It also explores the technological advancements in SLs, such as profilometry and wavefront-guided systems, which enable more precise and customized lens fittings by accurately mapping the eye's surface and addressing specific visual aberrations. The current body of evidence demonstrates that custom SLs significantly improve visual outcomes across various ectatic conditions, offering superior performance compared to conventional correction methods. However, challenges such as the complexity of fitting and the need for precise alignment remain. Ongoing innovations in SL technology and customization are likely to further enhance their clinical utility, solidifying their role as an indispensable tool in the management of corneal ectasias.

Importance of different topographic, biometric, and retinal parameters for calculating IOL power

The objective is to evaluate the parameters significantly related to calculating the power of the implanted lens and to determine the importance of different biometric, retina, and corneal aberrations variables. A retrospective cross-sectional observational study used a database of 422 patients who underwent cataract surgery at the Oftalvist Center in Almeria between January 2021 and December 2022. A random forest based on machine learning techniques was proposed to classify the importance of preoperative variables for calculating IOL power. Correlations were explored between implanted IOL power and the most important variables in random forests. The importance of each variable was analyzed using the random forest technique, which established a ranking of feature selections based on different criteria. A positive correlation was found with the random forest variables. Selection: axial length (AL), keratometry preoperative, anterior chamber depth (ACD), measured from corneal epithelium to lens, corneal diameter, lens constant, and astigmatism aberration. The variables coma aberration (p-value = 0,12) and macular thickness (p-value = 0,10) were almost slightly significant. In cataract surgery, the implanted IOL power is mainly correlated with axial length, anterior chamber depth, corneal diameter, lens constant, and preoperative keratometry. New variables such as astigmatism and anterior coma aberration and retina variables such as the preoperative central macular thickness could be included in the new generation of biometric formulas based on artificial intelligence techniques.

Assembly-induced nonuniform deformation prediction and control method for circular flange connectors with spacers in an optical lens support structure

Widely utilized in engineering, circular flange connections are typically secured by multiple bolts, but always result in nonuniform deformations that significantly impact the system shape and position accuracies. Numerous scholars have studied the deformation characteristics under various structures, external loads, bolt preloads, and tightening sequences in classical rough mechanical systems, but there is a lack of research regarding a high-precision optical system. In optical systems, nonuniform deformation of the support structure can be transmitted to the lens, causing astigmatic aberrations and affecting imaging accuracy. In the optical lens support structure as a circular flange connector, spacers need to be introduced to adjust the gap between two parts for controlling the optical path. These spacers tend to be more flexible than the support structures, thereby significantly affecting assembly-induced nonuniform deformations. However, the influence of spacers has been overlooked in previous works and thus needs to be investigated. In this paper, the effects of spacer parameters and bolt tightening sequences on the assembly-induced nonuniform deformation are investigated by the finite element method, which is verified experimentally, and an empirical formula is proposed to predict the nonuniform assembly-induced deformation based on the FEM results. According to the prediction results, a method for controlling the assembly-induced nonuniform deformation by optimizing the bolt preload distribution is proposed. The influence rules can guide the optimization of spacers and the bolt tightening process. The prediction and control method can effectively predict and reduce the assembly-induced nonuniform deformation of the circular flange with a spacer, reducing the aberration caused by the assembly and improving the accuracy of high-precision optical systems.

Single-shot dual-wavelength telecentric in-line-and-off-axis hybrid digital holography with non-prior reconstruction

Dual-wavelength in-line-and-off-axis hybrid digital holography (iohDH) can achieve high-resolution holographic dynamic imaging. However, it requires the prediction of the diffraction distance and the complex amplitude of the reference beam, which is time consuming and results in complications and accuracy limitations. While telecentric imaging technique can obtain nondiffractive images without predicting the diffraction distance, it also can even eliminate spherical aberration and astigmatic aberration. Therefore, a dual-wavelength telecentric iohDH is proposed to realize non-prior high-resolution reconstruction in a single shot. Employing the dual-wavelength telecentric iohDH, our approach acquires the focused in-line-and-off-axis hologram using a color camera in a single shot. In this case, we perform wavelength conversion on the phase and low-frequency information about the off-axis hologram as constraints for in-line iteration. Then, the in-line amplitude constraints are performed in the spatial and frequency domains until the algorithm converges. Compared to the state-of-the-art dual-wavelength iohDH, our approach can streamline the reconstructed processes without demanding a priori information of the diffraction distance and the complex amplitude of the reference beam. More importantly, our approach enables higher quality and efficient reconstruction under the telecentric system. We verified our approach using simulations and experiments, and the results indicate that our approach can allow the amplitude and phase reconstruction with high resolution in a single shot.

Spot diagram borders are always caustic curves and/or marginal rays III: segmented mirror in hexagons and trapezoids

For annular (circular and elliptical) and hexagonal exit pupils with any optical path differences (described by Zernike Polynomials), it was proven [Appl. Opt. 61, 1876 (2022)APOPAI0003-693510.1364/AO.449270; Appl. Opt. 61, C20 (2022)APOPAI0003-693510.1364/AO.435850] that the border of any spot diagram is composed of the caustic surface and/or marginal rays. In this paper, the previous results are extended to segmented (by hexagons or trapezoids) exit pupils. Examples with exact spherical, coma, and astigmatism aberrations are included, while a mathematical demonstration is also included.

Time characteristics of aero-optical imaging degeneration of the ellipsoidal dome under variable operating conditions

As a missile flies at high speed, the index and surface shape of the conformal dome will vary under the influence of the aero-optical effect, which will degenerate the performance of the seeker’s imaging detection system. However, many previous studies on aero-optical imaging deterioration of optical domes were usually carried out under fixed operating conditions, which are not in line with the real flight scene of the missile. In addition, the aero-optical imaging degeneration of the dome is diverse as the flight time increases. Therefore, it is of great significance to study the time characteristics of aero-optical imaging degradation of optical domes under variable work conditions. In this study, taking an air-to-air missile as an example, the Zernike polynomials, wavefront aberration, Strehl ratio, and image simulation are applied to evaluate the aero-optical imaging deterioration of an ellipsoidal dome in the flight time range of 0–10 s under variable working conditions. The simulation results show that, as the flight time increases, (1) the dynamic range of tilt, defocus, astigmatism, coma, and wavefront aberration increase; and (2) the Strehl ratio and the peak signal-to-noise ratio (PSNR) of the simulated images decrease. Therefore, the influence of flight time on the aero-optical image degradation of the ellipsoidal dome gradually becomes more serious.

Assessing the Relationship between Graft–Host Junction Profile and Corneal Astigmatism and Higher-Order Aberrations in Postpenetrating Keratoplasty Eyes

Assessing the Relationship between Graft–Host Junction Profile and Corneal Astigmatism and Higher-Order Aberrations in Postpenetrating Keratoplasty Eyes

Higher order aberrations according to spherical, and astigmatic refractive errors in children

ABSTRACT Clinical relevance The results of this study present novel insights into the impact of spherical and astigmatic refractive errors on overall, corneal and internal aberrations and may provide a clear understanding of the emmetropisation process and the development of visual function. Background This study aimed to assess the association between overall, corneal and internal higher-order aberrations and the spherical and astigmatic components (magnitude and angle) of refractive error in a large sample of children. Methods A total of 311 children aged 7 – 8 years old were classified based on spherical equivalent refraction (myopic, emmetropic and hyperopic); magnitude of astigmatism (none, low and moderate); and angle of astigmatism (with-the-rule, against-the-rule and oblique). Refractive error and overall, corneal and internal higher-order aberrations were measured using the OPD-Scan III workstation. Results Regarding spherical equivalent refraction, myopic eyes had greater root mean square (RMS) overall higher-order values, total spherical, tetrafoil and secondary astigmatism aberrations, and internal higher-order, total spherical and tetrafoil aberrations in comparison to emmetropic eyes. The magnitude of astigmatism was positively associated with all overall RMS aberrations and with internal higher order, coma, total coma, total spherical and tetrafoil aberrations. Eyes with with-the-rule astigmatism showed higher RMS values of coma and total coma compared to eyes with against-the-rule and oblique astigmatism. Conclusions Higher-order aberrations are dependent on the spherical as well as astigmatic components of refractive error. These findings enhance the current understanding of the emmetropisation process and visual function development.

Dynamic control of defocus, astigmatism, and tilt aberrations with a large area foveal liquid crystal lens

We have recently reported the dynamic adjustment of the focal length in an electrically tunable liquid crystal “foveal” lens, the center of which can be shifted over a large working area. In the present work, we show that this design allows also the independent generation of astigmatism with arbitrary axis and tilt of the light wavefront by simply changing the phase and the voltage differences between 4 control electrodes. Furthermore, we also demonstrate the capability of generating highly localized negative (defocusing) lenses with the same device by using a dual frequency liquid crystal.

Accuracy comparison of tomography devices for ray tracing-based intraocular lens calculation.

To evaluate the interchangeability of different tomography devices used for ray tracing-based intraocular lens (IOL) calculation. Eye clinic, Castrop-Rauxel, Germany. Retrospective analysis. Measurements from 3 Placido-Scheimpflug devices and 3 optical coherence tomography (OCT) devices were compared in 83 and 161 other eyes after cataract surgery, respectively. 2-dimensional matrices of anterior local corneal curvature and local corneal thickness are transferred to the ray-tracing software OKULIX. Calculations are performed with the same IOL in the same position of an eye with the same axial length. Differences in spherical equivalent (SE), astigmatism, and spherical aberration are evaluated. Furthermore, the influence of the size of the matrices (optical zone) on the accuracy is quantified. For the Placido-Scheimpflug devices, the deviations from the average of three measurements taken for each eye in SE (mean ± SD) were 0.17 ± 0.24 diopters (D), -0.26 ± 0.29 D, and 0.08 ± 0.39 D ( P < .001, analysis of variance [ANOVA]), for the centroids of the astigmatic differences 0.04 D/173 degrees, 0.14 D/93 degrees, and 0.10 D/7 degrees, and for the median of the absolute values of the vector differences 0.31 D, 0.33 D, and 0.29 D. For OCT devices, the corresponding results were 0.01 ± 0.21 D, -0.03 ± 0.21 D, and 0.02 ± 0.20 D ( P = .005, ANOVA); 0.18 D/120 degrees, 0.07 D/70 degrees, and 0.22 D/4 degrees; and 0.26 D, 0.30 D, and 0.33 D. The accuracy of the calculated spherical aberrations allows for an individual selection of the best fitting IOL model in most cases. The differences are small enough to make the devices interchangeable regarding astigmatism and spherical aberration. Although there are significant differences in SE between Scheimpflug and OCT devices, the differences between OCT devices are also small enough to make them interchangeable, but the differences between Placido-Scheimpflug devices are too large to make these devices interchangeable.

Research on Off-axis Aberration Optimization Model for Bifocal Glass Lens

Presbyopia entails the gradual deterioration of the eye’s ability to focus, and bifocal lenses have become a common remedy to alleviate blurred near vision and counteract eye strain induced by prolonged usage. The refractive index and Abbe number of these lenses play a crucial role in precisely correcting focal points within the near vision range. Nevertheless, when light rays approach the lens at off-axis angles or with tilts, aberrations occur, often with uneven distribution across real glass materials. The amalgamation of bifocal lenses further compounds the complexity of these aberrations. To enhance the correction of aberrations in bifocal glass lenses, distortion and astigmatism aberration serve as input parameters to calculate the optical quality assessment of the lenses. This study introduces a novel approach to optimize the pairing of bifocal glass lenses through the Taguchi method and fuzzy inference. The experimental design involves the application of the LS9 orthogonal array, streamlining the number of experiments while upholding the reliability of experimental data. The objective is to refine the selection of glass lenses and successfully devise an optimized design model that can be effectively applied to the configuration of bifocal glass lenses.

The effect of pterygium on front and back corneal astigmatism and aberrations in natural-light and low-light conditions

BackgroundTo investigate the effect of different sizes of pterygium on the front and back corneal topography, refractive changes and aberrations in natural-light and low-light conditions.MethodsSixty subjects with unilateral primary nasal pterygium were enrolled in this study. All the patients’ uncorrected, best spectacle-corrected visual acuity, corneal topographic aberration data in 3 mm and 7 mm areas were collected. The pterygium size was evaluated by the slit-lamp photography and Sirius Scheimpflug Analyzer.ResultsThe front topographic astigmatism values, corneal total aberrations, and higher-order aberrations in 3 mm and 7 mm areas were higher in the pterygium group than those in the control group. The pterygium horizontal length and thickness were moderately to strongly correlated with astigmatism and RMS of aberrations, while pterygium vertical length showed no or just mild correlation with the corneal astigmatism and aberrations. Compared to the readings in 3 mm area, the front and back corneal astigmatism and aberrations were larger in 7 mm area.ConclusionsPterygium led to visual impairment by inducing astigmatism and aberrations. In low-light condition, the visual function worsened due to increased corneal astigmatism values and aberrations.

Head-mounted adaptive optics visual simulator.

Adaptive optics visual simulation is a powerful tool for vision testing and evaluation. However, the existing instruments either have fixed tabletop configurations or, being wearable, only offer the correction of defocus. This paper proposes a novel head-mounted adaptive optics visual simulator that can measure and modify complex ocular aberrations in real-time. The prototype is composed of two optical modules, one for the objective assessment of aberrations and the second for wavefront modulation, all of which are integrated into a wearable headset. The device incorporates a microdisplay for stimulus generation, a liquid crystal on silicon (LCoS) spatial light modulator for wavefront manipulation, and a Hartmann-Shack wavefront sensor. Miniature optical components and optical path folding structures, together with in-house 3D printed mounts and housing, were adapted to realize the compact size. The system was calibrated by characterizing and compensating the internal aberrations of the visual relay. The performance of the prototype was analyzed by evaluating the measurement and compensation of low-order and higher-order aberrations induced through trial lenses and phase masks in an artificial eye. The defocus curves for a simulated bifocal diffractive lens were evaluated in real eyes. The results show high accuracy while measuring and compensating for the induced defocus, astigmatism, and higher-order aberrations, whereas the MTF analysis shows post-correction resolution of up to 37.5 cycles/degree (VA 1.25). Moreover, the subjective test results show the defocus curves closely matched to a commercial desktop visual simulator.

Numerical study of satellite image quality in the presence of Seidel aberrations

AbstractWe present estimated images of a hypothetical satellite system in the presence of Seidel aberrations. We exemplified the effects of defocus, spherical, coma, astigmatism, field curvature, and distortion aberrations. Our analysis methods allow the investigation of aberration effects individually and in any combined form. Thereby, we introduce a potentially rich analysis dimension for the imaging chain, image processing, and image quality analyses. For a number of degrees of aberrations, we provide image estimates, show and quantify how individual (field‐dependent) aberrations would introduce degradations on the satellite images. We got correlation coefficient values for defocus, spherical, coma, astigmatism, field curvature, and distortion aberrations as 0.69, 0.71, 0.66, 0.79, 0.76, and 0.60, respectively. Thereby, we identfied the significance order of Seidel aberrations for this system by using image simulations and image similarity measures.