Lens Surface Research Articles

Minimum solar tracking system for a Fresnel lens-based LCPV

The aim of the work is to study a low concentration photovoltaic (LCPV) system based on a Fresnel lens with a plano-concave lens and reflective surfaces. The proposed system is aimed at working with single-junction polycrystalline silicon solar cells with a wider reception angle which reduces the energy consumption of the solar tracking system. A software for multiphysics simulations COMSOL was used to simulate the proposed LCPV system with a maximum concentration ratio (6.5), and calculations were carried out to determine the relative position of the lenses from the solar cell. The proposed LCPV system achieves higher acceptance angle (±9.1°) and concentration acceptance angle product (0.447) compared to the conventional LCPV system (±3.1°, 0.153). Calculations of the power consumption of a dual-axis solar tracker using the proposed optical system show a reduction in power consumption of 21% in azimuth, 37% in altitude, and 27% overall when using the proposed optical system.

Research on Support Structure of Rectangular Cryogenic Infrared Lens with Large Aperture

This paper presents the design and optimization of a composite flexible support structure aimed at addressing the challenges associated with maintaining the positional accuracy and surface integrity of large-aperture cryogenic infrared lenses with long focal lengths. The primary objective of the structure is to maintain precise lens alignment while preserving the surface shape under operational conditions. The design complexities and underlying principles of the flexible support structure are systematically explored. A mechanical model of the flexible support structure was derived based on its structural characteristics, and the equilibrium equation was established to ensure the lens meets thermal deformation requirements in various directions. Optimization of key design parameters was conducted for a lens operating at 200 K, measuring 304 mm × 230 mm. The gravitational deformation of the optimized lens exhibited a root mean square (RMS) surface accuracy of 7.72 nm in the X direction, 7.08 nm in the Y direction, and 9.60 nm in the Z direction for lens surface 1. For lens surface 2, RMS values were 8.62 nm in the X direction, 8.41 nm in the Y direction, and 9.64 nm in the Z direction. At 200 K and lower temperatures, the RMS values of lens surfaces 1 and 2 were 2.41 nm and 2.74 nm, respectively, with a first-order mode frequency of 143.37 Hz.

Exact Equations for the Back and Effective Focal Lengths of a Plano-Concave Thick Lens

In this work, we present the exact equations for the back and effective focal lengths of a plano-concave thick lens. These equations are derived through a detailed ray-tracing approach, calculating the meridional ray’s path parallel to the optical axis while taking into account lens thickness, refractive index, and surface curvature. Our analysis bridges the gap between paraxial approximations and exact ray behavior, highlighting how traditional models (e.g., thin-lens equations) can be extended to thick lenses. Additionally, we review recent advancements in negative refraction and surface phase manipulation techniques to demonstrate how our equations compare to modern numerical methods and metacoating-enhanced designs. This work provides a comprehensive and exact framework for understanding the optical properties of plano-concave thick lenses, offering new insights into their application in precision optics.

Enhancing Performance of Silicone Hydrogel Contact Lenses with Hydrophilic Polyphenolic Coatings

This study explores the application of a dopamine-assisted co-deposition strategy to modify the surface of daily disposable silicone hydrogel contact lenses. Aiming to enhance the hydrophilicity of these typically hydrophobic lenses, we developed an industry-friendly process using simple dip coating in aqueous solutions. By co-depositing tannic acid, dopamine and chitosan derivative and employing periodate oxidation, we achieved a rapid and efficient coating process. High-molecular-weight branched polyethylene imine was introduced to promote surface reactions. The resulting lenses exhibited extreme hydrophilicity and lipid repellency without compromising their intrinsic properties or causing cytotoxicity. While the coating demonstrated partial antimicrobial activity against Gram-positive Staphylococcus aureus, it offers a foundation for the further development of broad-spectrum antimicrobial coatings. This versatile and efficient process, capable of transforming hydrophobic contact lenses into hydrophilic ones in just 15 min, shows significant potential for improving comfort and performance in daily disposable contact lenses.

Accommodating version of a schematic eye for emmetropia and myopia.

To develop an accommodating, wide-angle, schematic eye for emmetropia and myopia in which spectacle refraction and accommodation level are input parameters. The schematic eye is based on an earlier unaccommodated refraction-dependent eye for myopia developed by Atchison in 2006. This has a parabolic gradient index lens and parameters derived from biometric and optical measurements on young adults. Several parameters are linearly dependent upon spectacle refraction (anterior radius of curvature of the cornea, axial length and vertex radii of curvature and conic asphericities of a biconic retina). The new accommodated schematic eye incorporates accommodation-dependent changes in several lens-related parameters. These changes are based on literature values for anterior chamber depth, lens thickness, vitreous chamber depth, lens surface radii of curvature and lens front surface asphericity. A parabolic variation of refractive index with relative distance from the lens centre is retained, with the same edge and centre refractive indices as the earlier model, but the distribution has been manipulated to maintain focus near the retina for the emmetropic case at 0 and 4 D accommodation. The asphericity of the lens back surface is changed so that spherical aberration and peripheral refraction approximately match typical literature trends. The model is used to compare spherical aberration and peripheral refraction in eyes with up to 4 D of myopia and 4 D of accommodation. The levels of spherical aberration in the unaccommodated schematic eyes are similar to literature values for young adults, but the changes in spherical aberration with accommodation are approximately two-thirds of that found in an experimental study. As intended, peripheral refractions in the accommodated schematic eyes are similar to those of their unaccommodated counterparts. The wide-angle model extends the range of schematic eyes to include both refraction and accommodation as variable input parameters. It may be useful in predicting aspects of retinal image quality.

Agreement between a new fully automatic ocular biometer based on optical low-coherence reflectometry and an optical biometer based on Scheimpflug imaging combined with partial coherence interferometry

BackgroundTo analyze the difference and agreement between measurements obtained by a new fully automatic optical biometer, the SW-9000 μm Plus, based on optical low-coherence reflectometry (OLCR) and a commonly used optical biometer (Pentacam AXL) based on Scheimpflug imaging with partial coherence interferometry (PCI).MethodsThe central corneal thickness (CCT), anterior chamber depth (ACD, from epithelium to anterior lens surface), lens thickness (LT), mean keratometry (Km), corneal astigmatism, corneal diameter (CD), pupil diameter (PD), and axial length (AL) of 74 eyes (from 74 healthy subjects) were measured using the SW-9000 μm Plus and the Pentacam AXL to determine the agreement. Double angle plots were used for astigmatism vector analysis. Bland–Altman and 95% limits of agreement (LoA) were calculated.ResultsStatistically significant differences were detected for all parameters but J0 vector. The Bland–Altman analysis of AL, CCT, ACD, Km, CD, J0 and J45 indicated a high level of agreement between the two devices. Among AL, CCT, ACD, Km, J0, J45, CD, and PD, the 95% LoA ranged from -0.07 to 0.05 mm, -9.67 to 7.34 mm, -0.11 to 0.04 mm, -0.25 to 0.50 D, -0.22 to 0.20 D, -0.15 to 0.20 D, -0.23 to 0.35 mm and 1.55 to 3.77 mm, respectively.ConclusionsThe measurements of AL, CCT, ACD, Km, corneal astigmatism, and CD showed a narrow LoA and may be used interchangeably in healthy subjects between the new OLCR optical biometer and the Scheimpflug/PCI biometer; however, a poor agreement was noted for PD values.

Hydroxypropyl methylcellulose remove dense water droplets during fluid-air exchange on the posterior surface of intraocular lenses with posterior capsule loss

Purpose: The research investigates the efficacy of hydroxypropyl methylcellulose (HPMC) treatment in facilitating the development of compact water droplets on the rear surface of synthetic lenses with capsule imperfections during the process of fluid-air exchange. Method: This study examined four patients with intraocular lens (IOL) implants and posterior capsule defects who experienced the formation of dense water droplets on the posterior surface following fluid-air exchange. When this occurrence obstructs fundus visualization during surgery, it is recommended to suspend the surgical procedure. Upon removal of the non-contact fundoscope and inspection of the IOL, the presence of dense water droplets becomes evident. Subsequently, the removal of bubbles can be achieved by employing a blunt needle filled with HPMC, which is subsequently administered to the area posterior to the intraocular lens. Subsequently, the HPMC should be uniformly distributed on IOL back surface using the blunt needle. Results: During the surgical procedure, it was noted that all patients attained a clear fundus field of vision after the administration of HPMC and insertion of the IOL, facilitating the successful execution of subsequent surgical procedures. Conclusion: HPMC serves as a suitable viscoelastic agent for the elimination of dense water droplets adhered to the surface of intraocular lenses following application, consequently maintaining a clear visual field of the fundus. This surgical intervention is characterized by its efficacy and safety.

Comparison of ocular biometric measurements and intraocular lens power calculation using different methods in eyes with implantable collamer lenses

This prospective cohort study included 80 healthy candidates for Implantable Collamer Lens (ICL) implantation who underwent biometric assessments with Scheimpflug imaging (the Pentacam-AXL) and swept-source optical coherence tomography (SS-OCT; the IOLMaster-700), both before and 3 months after surgery. The main outcome measures were mean keratometry, anterior chamber depth, axial length, and various intraocular lens (IOL) calculation formulas (Haigis, SRK/T, Hoffer Q, Holladay 1, Barrett Universal 2, and Olsen). The interchangeability of the devices was assessed by generating 95% limits of agreement (95% LoA) and associated Bland-Altman plots. The average age of the participants was 31.5 ± 5.4 years (22–43), with 58 (72.5%) being female. Among the cases analyzed, 11 (13.4%) had incorrect anterior lens surface segmentation using the IOLMaster-700, and 1 case (1.2%) had inappropriate segmentation using the Pentacam-AXL. Postoperative IOL power calculation resulted in readings that were, on average, 0.15 to 0.30 D higher compared to preoperative measurements. The 95% LoAs could differ by up to 0.85 D higher after surgery, indicating weak agreement between pre- and postoperative measurements. There was poor agreement between the IOLMaster-700 and Pentacam-AXL in IOL power calculation for eyes with post-ICL implantation, with a difference of more than 1 D in the 95% LoAs. In conclusion, Scheimpflug imaging was found to be less susceptible than the SS-OCT technique to segmentation errors of the anterior lens surface after ICL implantation. Neither device showed interchangeable results for pre- versus postoperative IOL power calculation. The determination of IOL power by the IOLMaster-700 versus Pentacam-AXL was not interchangeable in eyes with ICL implantation.

Design and optimization of acoustic reflector for uniform diffusion

Sound diffusion performance is considered as an important issue in building acoustics. A well-diffused sound field can effectively enhance the human listening experience. To this end, we have investigated several optimization strategies to design a sub-wavelength acoustic metasurface that can achieve broadband uniform diffuse reflections. These designs are based on Fresnel lens surface, groove-like structure, level-set method, topology optimization approach, respectively. Meanwhile, a strategy combining Monte-Carlo searches and other derivative-free algorithms has been analyzed and used to ensure, as far as possible, a global optimum for the objective function when dealing with the multi-peak problem encountered in complex sound fields. Numerical simulations show that the resulting metasurfaces with the best diffusion performance have similar configurations between different design methods. The simulated sound pressure field was also verified by experimental measurements. From a general perspective, the proposed optimization strategy and simulation framework can provide a greater degree of freedom for geometric configuration and benefit the design of interior components in building acoustics.

Large depth-of-focus achievement based on an aspheric lens with a ring

Terahertz (THz) imaging technology has been widely studied because of its easy penetration of non-polar materials and low photon energy. To acquire a beam featuring both excellent transverse spatial resolution and a considerable depth-of-focus (DOF) to fulfill the demands of two-dimensional and three-dimensional THz imaging, this paper presents an aspheric lens with ring (ALR). The ALR has a controlled diameter of 50 mm, can be machined by 3D-printed technology, and does not need to use complex imaging optical paths to achieve the large DOF function. In a transmitted point-scan imaging system with a 140 GHz light source, the lens can achieve both a resolution of 6 mm and an effective DOF of 66.4 mm for objects greater than 27 mm from the lens surface.

Unveiling the Mysteries of the Chinese lens zonule balance tension: A statistical analysis

BackgroundThis study aims to provide an estimated dataset of lens zonule balance tension (LZBT) measurements in cataractous lenses among Chinese patients and to conduct a statistical analysis of anterior segment parameters. MethodsThis is a cross-sectional study. We included a total of 833 eyes from 833 Chinese participants aged 23–91 years who underwent cataract surgery. Anterior segment parameters were measured using swept-source anterior segment optical coherence tomography (SS-AS OCT) to calculate lens gravity (LG) and crystalline lens volume (VOL). Axial length (AL) was measured using IOL-Master 700. LZBT was calculated using force decomposition and synthesis methods. ResultsThe mean LZBT in the horizontal direction was 8.48E-05 ± 3.23E-05 N across all eyes. The LZBT in the subtemporal-supraspinal and supraspinal-temporal directions was 2 times greater than in the vertical direction. The balanced force on the suspensory ligament in the horizontal direction was twice as strong as in the vertical direction. Additionally, anterior segment parameters such as lens equivalent diameter (LE-dia), radius of the anterior lens surface curvature (RAL), radius of the posterior lens surface curvature (RPL), anterior chamber depth (ACD), iris area, iris volume, and iris thickness showed positive correlations with AL. ConclusionsAccounting for gravitational effects, we concluded that zonule force is asymmetrically distributed. Importantly, this study establishes the normal range of LZBT across different meridians using force synthesis and decomposition, offering new insights and feasibility for studying suspensory ligament biomechanics.

3D Optical Wedge and Movable Optical Axis LC Lens

Current liquid crystal (LC) lenses cannot achieve lossless arbitrary movement of the optical axis without mechanical movement. This article designs a novel bottom electrode through simulation and optimization, which forms a special LC lens with an Archimedean spiral electrode, realizing a 3D LC wedge and an arbitrarily movable LC lens. When only the bottom electrode is controlled, it achieves a maximum beam steering angle of 0.164°, which is nearly an order of magnitude larger than the current design. When the top and bottom electrodes are controlled jointly, a 0.164° movement of the lens optical axis is achieved. With focal length varies, the movement of the optical axis ranges from zero to infinity, and the lens surface remains unchanged during movement. The focus can move in a 3D conical area. When the thickness of the LC layer is 30 μm, the fastest response time reaches only 0.635 s, much faster than now.

Overlapping clinical features of persistent fetal vasculature and combined hamartoma of the retina and retinal pigment epithelium

PurposeTo investigate cases exhibiting overlapping features of persistent fetal vasculature (PFV) and combined hamartoma of the retina and retinal pigment epithelium (CHRRPE) and to explore potential associations between these developmental ocular anomalies. MethodsThis retrospective, descriptive case series included 9 eyes of 8 patients aged 0-7 years with shared clinical features of PFV and CHRRPE. Diagnoses were established through clinical examination and intraoperative findings. ResultsAll eyes exhibited elevated pigmented retinal thickening, increased vascular tortuosity, and preretinal fibrotic/gliotic changes or epiretinal membranes. Macular involvement was observed in 56% of cases; peripapillary involvement, in 44%. Four eyes showed hyaloid stalklike fibrotic remnants extending from the lesion to the posterior lens surface, suggestive of PFV component; the other 5 harbored isolated CHRRPE. One patient presented with PFV in one eye and CHRPPE in the other. ConclusionsThis study reveals significant clinical overlap between PFV and CHRRPE, with some cases displaying features typically associated with the other condition. The presence of both diagnoses in the same patient further suggests a potential association between these entities. Further research, including molecular studies, is needed to explore this potential connection and deepen our understanding of ocular development.

Analysis of the optical performance of intraocular lenses using profilometric measurements.

The aim of this study was to develop a methodology, based on profilometer measurements to assess the optical behaviour of Intraocular Lenses (IOls). The "Modulation Transfer Function through-object" (MTF through-object) based on vergence object displacement was calculated for different pupil sizes and pseudophakic eyes. Tilt and decentration were also analysed in a realistic cornea eye model. For comparison between the different IOLs, an optical quality criterion based on a minimum value the MTF through-object and the recognition of simulated vision optotypes was introduced. Five IOLs were used in this study: Tecnis Eyhance, Mini Well, Tecnis Symfony, Tecnis Synergy and RayOne EMV. The technique was validated with previous methodologies. A general narrowing of the through-object MTF curve compared to the through-focus MTF curve was shown, resulting in greater distances between near and intermediate points and less depth of field around the far peak. The comparison between the IOLs showed that variations in corneal aberrations, pupil size and decentration caused relevant changes in IOL performance. A decrease of the SA produced a hypermetropic shift of the far focus between + 0.3 D and + 0.4 D. Most of IOLs worsen the optical quality as pupil size increased, even the MTF through-object shape changed. Decentration was an important factor in IOL implantation, causing a significant change in MTF through-object shape in most of IOLs. This study highlights the need to evaluate pre-operative patients for corneal aberrations and pupillary size to have the best optical success after cataract surgery in multifocal or extended depth of focus IOLs. What is known MTF(Modulation Transfer Function)through-focus curves (calculated in image space by moving the detector plane) can be obtained from optical bench assembly or from commercial devices. Recently, some studies proposed to characterize the lens surface design based on the profilometric measurements What is new A novel methodology based on profilometer measurements to assess the optical behaviour of Intraocular Lenses (IOls) was shown. The "Modulation Transfer Function through-object" based on vergence object displacement was introduced in order to analyse five premium IOLs. MTF through-object curve is more appropriate for studying clinical behaviour, as it provides further near and intermediate points distances and lower depth of focus around far peak compare to MTF through-focus curves. The optical behaviour of the five IOLs can vary considerably depending on the eye model and pupil size. The effect of tilt and decentration on the MTF through-object the IOLs was analysed.

Street photography and the flâneur: reflections on Australian city narratives

This original photographic work investigates the intersection of street photography and the concept of the flâneur within an Australian urban context. By transforming cityscapes into visual texts, the study captures urban narratives through the absence and reflection of inhabitants, rather than their direct representation. The photographic work employs window reflections as a key technique, introducing multiple visual dimensions to enrich street scenes and overall narratives. Drawing on Baudelaire's notion of the flâneur and Tomanić-Trivundža's three-stage journey of the flâneur (perambulating observation, critical reflection, and production of communicable texts), this work synthesises street photography with flâneur-like observation. It employs a multi-layered visual approach to city streets, representing a less-explored facet of lens-based practice in Australia. While the use of window reflections and the flâneur in street photography are well-established in European and North American contexts, their application in Australian settings remains less explored. This work aims to contribute to the street photography canon by translating these established techniques to Australian cities, offering insights into unique local urban characteristics. By exploring the interplay between global photographic traditions and local realities, this work seeks to provide a fresh perspective on Australian city life through the flâneur lens and reflective urban surfaces, thus expanding the geographical and cultural scope of this photographic tradition.

The Effect of Face Mask Wear on the Ocular Surface and Contact Lens Microbiome.

As face mask wear can result in the redirection of nasal and oral exhalation toward the ocular region, this study investigated the impact of face mask wear on the conjunctiva, eyelid margin, and contact lens (CL) surface microbiome. In this prospective, cross-over study, experienced CL wearers (N=20) were randomized to wear a face mask for 6 hr/day (minimum) for a week or no mask for a week. The conjunctiva, eyelid, and CLs were then sampled. After a 1-week washout period, participants were crossed over into the alternate treatment for 1 week and sampling was repeated. Sampling was bilateral and randomly assigned to be processed for culturing or 16S ribosomal(r) RNA gene sequencing. Culturing showed no effect of mask wear on the average number of bacterial colonies isolated on the conjunctiva, eyelid, or CL, but there was increased isolation of Staphylococcus capitis on CL samples with mask wear ( P =0.040). Culture-independent sequencing found differences in the taxonomic complexity and bacterial composition between the three sites ( P <0.001), but there was no effect of bacterial diversity within and between sites. Mask wear did not impact dry eye or CL discomfort, but increased ocular surface staining was reported ( P =0.035). Mask wear did not substantially alter the microbiome of the conjunctiva, eyelid margin, or CL surfaces in uncompromised healthy eyes.

Estimating the astigmatic power of the crystalline lens and eye from ocular biometry.

To estimate the astigmatic power of the crystalline lens and the whole eye without phakometry using a set of linear equations and to provide estimates for the astigmatic powers of the crystalline lens surfaces. Linear optics expresses astigmatic powers in the form of matrices and uses paraxial optics and a 4 × 4 ray transfer matrix to generalise Bennett's method comprehensively to include astigmatic elements. Once this is established, the method is expanded to estimate the contributions of the front and back lens surfaces. The method is illustrated using two examples. The first example is of an astigmatic model eye and compares the calculated results to the original powers. In the second example, the method is applied to the biometry of a real eye with large lenticular astigmatism. When the calculated powers for the astigmatic model eye were compared to the actual powers, the difference in the power of the eye was (where T represents the matrix transpose) and for the crystalline lens, the difference was (power vector format). A second example applies the method to a real eye, obtaining lenticular astigmatism of -5.84 × 175. The method provides an easy-to-code way of estimating the astigmatic powers of the crystalline lens and the eye.

Biometry study of foveal isoplanatic patch variation for adaptive optics retinal imaging.

The change in ocular wavefront aberrations with visual angle determines the isoplanatic patch, defined as the largest field of view over which diffraction-limited retinal imaging can be achieved. Here, we study how the isoplanatic patch at the foveal center varies across 32 schematic eyes, each individualized with optical biometry estimates of corneal and crystalline lens surface topography, assuming a homogeneous refractive index for the crystalline lens. The foveal isoplanatic patches were calculated using real ray tracing through 2, 4, 6 and 8 mm pupil diameters for wavelengths of 400-1200 nm, simulating five adaptive optics (AO) strategies. Three of these strategies, used in flood illumination, point-scanning, and line-scanning ophthalmoscopes, apply the same wavefront correction across the entire field of view, resulting in almost identical isoplanatic patches. Two time-division multiplexing (TDM) strategies are proposed to increase the isoplanatic patch of AO scanning ophthalmoscopes through field-varying wavefront correction. Results revealed substantial variation in isoplanatic patch size across eyes (40-500%), indicating that the field of view in AO ophthalmoscopes should be adjusted for each eye. The median isoplanatic patch size decreases with increasing pupil diameter, coarsely following a power law. No statistically significant correlations were found between isoplanatic patch size and axial length. The foveal isoplanatic patch increases linearly with wavelength, primarily due to its wavelength-dependent definition (wavefront root-mean-squared, RMS <λ/14), rather than aberration chromatism. Additionally, ray tracing reveals that in strongly ametropic eyes, induced aberrations can result in wavefront RMS errors as large as λ/3 for an 8-mm pupil, with implications for wavefront sensing, open-loop ophthalmic AO, spectacle prescription and refractive surgery.

Scleral lens surface crazing in an eye with giant papillary conjunctivitis and keratoconus: Outcome of lens surface polishing

We present a case of scleral lens surface crazing in a patient with keratoconus (KC) and chronic giant papillary conjunctivitis (GPC). A 45-year-old Asian male with known keratoconus (KC) and allergic eye disease in both eyes, who is an experienced scleral lens user, presented with a 3-month history of lens intolerance in the right eye. On examination, the right eye scleral lens showed extensive lens surface crazing with poor surface wettability. The upper tarsal conjunctiva showed conjunctival hypertrophy – active GPC. After allergy treatment and symptomatic improvement, the scleral lens was refitted after intensive cleaning and polishing with aluminum oxide. The lens surface showed significant improvement and good fitting characteristics, and the patient resumed lens wear. At 6 months of follow-up, the patient was asymptomatic, and the ocular condition was stable.

Layer-by-layer self-assembled smart antibacterial coatings for surface management of orthokeratology lens

ABSTRACT Orthokeratology (OK) lenses are designed to reshape the cornea overnight, allowing users to see clearly during the day without glasses. However, prolonged wear increases the risk of microbial contamination and eye infections. Even with cleaning techniques, the surface of OK lenses can become contaminated due to residual bacterial debris. Therefore, developing self-cleaning antibacterial technology for OK lens surfaces is an urgent clinical challenge. Herein, we integrated the temperature responsiveness of PNIPAM molecular chains with the surface contact-killing mechanism of AMP into the surface of OK lenses for the first time, constructing an intelligent OK lens with synergistic antibacterial and self-cleaning properties. The modified OK lenses can achieve over 95% bacterial efficiency against Staphylococcus aureus and Pseudomonas aeruginosa. More importantly, in both worn and removed states, the modified OK lenses can achieve a surface bacterial debris self-cleaning efficiency of 50–75%. These research findings provide important references and insights for the future development of more efficient self-cleaning lens materials.