Lens Structures Research Articles

Artificial intelligence in optical lens design

Traditional optical design entails arduous, iterative stages that significantly rely on the intuition and experience of lens designers. Starting-point design selection has always been the major hurdle for most optical design problem, and different designers might produce different final lens designs even if using the same initial specification. Lens designers typically choose designs from existing lens databases, analyse relevant lens structures, or explore patent literature and technical publications. With increased processing capability, producing automated lens designs using Artificial Intelligence (AI) approaches is becoming a viable alternative. Therefore, it is noteworthy that a comprehensive review addressing the latest advancements in using AI for starting-point design is still lacking. Herein, we highlight the gap at the confluence of applied AI and optical lens design, by presenting a comprehensive review of the current literature with an emphasis on using various AI approaches to generate starting-point designs for refractive optical systems, discuss the limitations, and suggest a potential alternate approach for further research.

Micro-optical elements from optical-quality ZIF-62 hybrid glasses by hot imprinting

Hybrid glasses derived from meltable metal-organic frameworks (MOFs) promise to combine the intriguing properties of MOFs with the universal processing ability of glasses. However, the shaping of hybrid glasses in their liquid state – in analogy to conventional glass processing – has been elusive thus far. Here, we present optical-quality glasses derived from the zeolitic imidazole framework ZIF-62 in the form of cm-scale objects. These allow for in-depth studies of optical transparency and refraction across the ultraviolet to near-infrared spectral range. Fundamental viscosity data are reported using a ball penetration technique, and subsequently employed to demonstrate the fabrication of micro-optical devices by thermal imprinting. Using 3D-printed fused silica templates, we show that concave as well as convex lens structures can be obtained at high precision by remelting the glass without trading-off on material quality. This enables multifunctional micro-optical devices combining the gas uptake and permeation ability of MOFs with the optical functionality of glass. As an example, we demonstrate the reversible change of optical refraction upon the incorporation of volatile guest molecules.

Comparison of Distance-Based Uncorrected Visual Acuity Based on the Optical Profile of Same Platform IOLs.

To compare and evaluate uncorrected visual acuity (UCVA) from far to near distance for four different optical designs of intraocular lenses (IOLs), developed on the same IOL platform. In a cohort of 121 patients, who underwent uncomplicated cataract surgery in Zengyo Suzuki Eye Clinic, Japan, between June 2018 and November 2023, and who received a single-piece TECNIS OptiBlue™ platform series IOL, the following four groups were established based on the IOL implant type: ZCB00V (TE), ZXR00V (SF), DFR00V (SG), and DIB00V (EH). UCVA at 5 m, 1 m, 70 cm, 50 cm, 40 cm, and 30 cm, as well as contrast sensitivity (with and without glare), was compared at one month post-operation. Regarding diffractive IOLs, patients in the SG group demonstrated significantly improved visual acuity at 5 m, 50 cm, 40 cm, and 30 cm, while those in SF group performed significantly better at 1 m. Among non-diffractive IOLs, patients in the EH group demonstrated significantly improved visual acuity scores at 1 m, 70 cm, 40 cm, and 30 cm, compared to individuals in the TE group, with comparable results between the two groups at 5 m and 50 cm. Patients in the SF and EH groups achieved similar results for visual acuity and contrast sensitivity, while those in the SG group exhibited a distinctive decrease in contrast sensitivity (with glare) relative to the other three groups. DFR00V seemingly provides excellent UCVA from near to far distances, aiming for spectacle independence, although at the potential cost of decreased contrast sensitivity compared to the other three IOL types. Furthermore, although ZXR00V and DIB00V differ lens structures, they may nonetheless provide similar visual quality and spectacle independence in daily life.

Miniaturized fluorescence pH sensor with assembly free ball lens on a tapered multimode optical fiber.

In biochemistry, the absence of a compact, assembly-free pH sensor with high sensitivity and signal-to-noise ratio has been a persistent hurdle in achieving accurate pH measurements in real time, particularly in complex liquid environments. This manuscript introduces what we believe to be a novel solution in the form of a miniaturized pH sensor utilizing an assembly-free ball lens on a tapered multimode optical fiber (TMMF), offering the potential to revolutionize pH sensing in biochemical applications. A multimode optical fiber (MMF) was subjected to tapering processes, leading to the creation of an ultra-thin needle-like structure with a cross-sectional diameter of about 12.5 µm and a taper length of 3 mm. Subsequently, a ball lens possessing a diameter of 20 µm was fabricated at the apex of the taper. The resultant structure was coated utilizing the dip-coating technique, involving a composite mixture of epoxy and pH-sensitive dye, 2',7'-bis(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF), thereby ensconcing the tapered ball lens with dye molecules for pH sensing. This study encompassed the fabrication and evaluation of six distinct fiber structures, incorporating the cleaved endface, the convex lens, and the ball lens structures to compare light focal lengths and propagation intensities. Computational simulations and numerical analyses were conducted to elucidate the encompassing light focal distances across the full array of lens configurations. The efficacy of the proposed pH sensor was subsequently assessed through its deployment within a complex liquid medium spanning a pH spectrum ranging from 6 to 8. Real-time data acquisition was performed with a fast response time of 0.5 seconds. A comparative analysis with a pH sensor predicated upon a single TMMF embedded with the fluorescent dye underscored the substantial signal enhancement achieved by the proposed system twice the fluorescence signal magnitude. The proposed assembly-free miniaturized pH sensor not only substantiates enhanced signal collection efficiency but also decisively addresses the persistent challenges of poor signal-to-noise ratio encountered within contemporary miniaturized pH probes.

Optimization of a plasmonic lens structure for maximum optical vortices induced on Weyl semimetal surface states.

Optical vortices have a topologically charged phase singularity and zero intensity distribution in the centre. Optical vortex creation is regarded as a significant means for information transmission for applications in quantum computing, encryption, optical communication, etc. In this study, using finite-difference time-domain (FDTD) simulation, we calculated the electric field intensity and phase distribution of 2D lattices of optical vortices generated from various polygonal plasmonic lens structures using surface states of a Weyl semimetal (MoTe2). It was shown that a hexagonal lens is the best performing plasmonic lens. Further, we posited here a unified mathematical formulation for optical electrical field and phase distribution in the near field for any polygonal plasmonic lens. Our theoretical calculation corroborated well with FDTD results, validating the proposed generalized formula. Such plasmonic lens structures demonstrating scaling behavior offer great potential for designing next-generation optical memories.

Nanoparticle-Epoxy Composite Molding for Undeformed Acoustic Holograms with Tailored Acoustic Properties.

Acoustic hologram lenses were typically produced by high-resolution 3D printing methods, such as stereolithography (SLA) printing. However, SLA printing of thin, plate-shaped lens structures has major limitations including vulnerability to deformation during photo-curing and limited control of acoustic impedance. To overcome these limitations, we demonstrated a nanoparticle epoxy composite (NPEC) molding technique, and we tested its feasibility for acoustic hologram lens fabrication. The characterized acoustic impedance of the 22.5% NPEC was 4.64 MRayl which is 55% higher than the clear photopolymer (2.99 MRayl) used by SLA. Simulations demonstrated that the improved pressure transmission by the higher acoustic impedance of the NPEC resulted in 21% higher pressure amplitude in the region of interest (ROI, -6 dB pressure amplitude pixels) than the photopolymer. This improvement was experimentally demonstrated after prototyping NPEC lenses through a molding process. The NPEC lens showed no significant deformation and 72% lower thickness profile errors than the photopolymer which otherwise experienced deformed edges due to thermal bending. Beam mapping results using the NPEC lens validated the predicted improvement, demonstrating 24% increased pressure amplitude on average and 10% improved structural similarity with the simulated pressure pattern compared to the photopolymer lens. This method can be used for acoustic hologram lens applications with improved pressure output and accurate pressure field formation.

Evaluation of endolight-assisted phacoemulsification in cataract with absent red reflex

Purpose The aim of this study was to evaluate the outcome of cataract extraction in eyes with absent red reflex using anterior chamber endolight. Patients and methods This is a prospective interventional case series study that was performed on 32 eyes of 32 patients with cataract associated with absent red reflex. Phacovitrectomy was performed in all patients. An anterior chamber endolight, introduced through a paracentesis, was used to enhance the phacoemulsification technique. The effectiveness of the technique in facilitating the visualization of the lens structures during the procedure and in enhancing the easiness of the operation as well as the complications related to this technique were evaluated. In addition, the improvement in visual acuity in these patients after surgery was evaluated. Results No complications were reported during any of the operations. The endolight promptly enhanced the visualization of the lens structures especially the posterior capsule. The mean best corrected visual acuity significantly improved from 2±0.31 LogMAR preoperatively to 0.38±0.17 postoperatively after combined phacovitrectomy (P<0.001). Conclusion The endolight aided in improving the safety profile of phacoemulsification in cataract with absent red reflex by increasing the visibility of anterior chamber structures during the procedure.

Beam Steering 3D Printed Dielectric Lens Antennas for Millimeter-Wave and 5G Applications.

Two types of cost-efficient antennas based on dielectric gradient index dielectric lens have been designed for 5G applications at 28 GHz. The first is a linearly polarized flat lens antenna (LP-FLA) for terrestrial 5G communications. The second is a novel circularly polarized stepped lens antenna (CP-SLA) for 5G satellite services. An efficient design method is presented to optimize and conform the lens topology to the radiation pattern coming from the antenna feeder. The LP-FLA is fed by a traditional linearly polarized pyramidal horn antenna (PHA). The CP-SLA is fed by an open-ended bow-tie waveguide cavity (BCA) antenna. This cavity feeder (BCA), using cross-sections with bow-tie shapes, allows having circular polarization at the desired frequency bandwidth. The two types of presented antennas have been manufactured in order to verify their performance by an easy, low-cost, three-dimensional (3D) printing technique based on stereolithography. The peak realized gain value for the flat (LP-FLA) and stepped (CP-SLA) lens antennas have been increased at 28 GHz to 25.2 and 24.8 dBi, respectively, by disposing the lens structures at the appropriated distance from the feeders. Likewise, using an array of horns (PHA) or open-ended bow-tie waveguide cavity (BCA) antenna feeders, it is possible to obtain a maximum steering angle range of 20° and 35°, for a directivity over 15 dBi and 10 dBi, in the planar and stepped lens antennas, respectively.

G9a inactivation in progenitor cells with Isl1-Cre with reduced recombinase activity models aspects of Dandy-Walker complex.

G9a, also known as EHMT2, is essential for embryogenesis and has specific functions in multiple developmental processes. G9a inactivation affects development of the nervous system, which is formed with contribution of descendants of progenitor cells expressing the transcription factor Isl1. However, the function of G9a in Isl1-expressing progenitors is unknown. Here, we show that G9a is required for proper development of multiple structures formed with contribution of Isl1-expressing progenitors. A Cre-dependent GFP reporter revealed that the recombinase activity of the Isl1-Cre used in this study to inactivate G9a was reduced to a subset of Isl1-expressing progenitor cells. G9a mutants reached endpoint by 7 weeks of age with cardiac hypertrophy, hydrocephalus, underdeveloped cerebellum and hind limb paralysis, modeling aspects of Dandy-Walker complex. Moreover, neuroepithelium of the lateral ventricle derived from Isl1-expressing progenitors was thinner and disorganized, potentially compromising cerebrospinal fluid dynamics in G9a mutants. Micro-computed tomography after iodine staining revealed increased volume of the heart, eye lens and brain structures in G9a mutant fetuses. Thus, altered development of descendants of the second heart field and the neural crest could contribute to multicomponent malformation like Dandy-Walker.

Development of a fabrication process for production of diffractive optics.

In this study, a novel fabrication process, to the best of our knowledge, was developed to fabricate a glass harmonic diffractive lens. In this process, a polymethylmethacrylate master of the diffractive lens was machined using single-point diamond turning. Then an electrolytic plating process was conducted to grow a reverse nickel (Ni) mold. Precision compression molding was performed using the Ni mold to replicate the diffractive lens structures onto a glass surface. Surface measurements and optical testing show that the replicated diffractive lenses by the proposed method have high tolerances and require optical performance, demonstrating a high-volume, high-precision, and cost-effective process. The proposed method will be critical for consumer products where glass optics are increasingly used in lens assemblies.

System design of segmented planar imaging system

Based on photonic integrated circuit (PIC) technology and synthetic aperture technology, the advanced technology of segmented planar imaging, which can be used to realize ultrathin and high-resolution imaging, is proposed. We develop a sampling lens array structure that combines coherent detection and traditional imaging; it can improve the sampling of low- and medium-frequency information. Based on the proposed lens array structure, a full-chain simulation model of the segmented planar imaging system is established. Under the premise of similar imaging quality, compared with the existing sampling lens structures, the proposed lens array has a simpler structure, lower processing difficulty, and lower cost. The simulation analyses of the duty ratio of the lens array, the light splitting number of PIC arrayed waveguide gratings, and the radius of the single lens are carried out. The simulation results provide a certain reference value for the optimal design of the segmented planar optical imaging system and further prove the advantages of the proposed structure.

Retinoblastoma Radiotherapy Treatment Optimizations Through GATE Simulations

One of the most frequent children tumors in the area around the eyes is defined as retinoblastoma. Proton radiotherapy treatment is a particularly effective type of radiation therapy due to the prolonged survival rates of children with childhood cancers such as retinablastoma, continued growth of nearby organs and tissues, low radiation dose restriction of vision-related tissues and systems of these tissues. In this study, a geometry phantom including eyeball, lens, lacrimal gland, optic nerve, optic chiasm, retina, cancer, cornea and bone structures was modeled with Monte Carlo simulation tool GATE (vGATE 9.0). With this simulation, the doses absorbed by the tissues were calculated using the DoseActor and TLEDoseActor algorithms. Secondary doses were determined by the TLEDoseActor algorithm. Determination of secondary radiations is important because of the low radiation dose limit of tissues and systems that affect vision. The best treatment results were tried to be obtained by giving the beam thickness of the radiation used in our study, 4 different angles towards the target and different energies. These results show that it can be helpful in calculating a treatment plan for proton therapy in clinical practice.

Using wavelets to capture deviations from smoothness in galaxy-scale strong lenses

Modeling the mass distribution of galaxy-scale strong gravitational lenses is a task of increasing difficulty. The high-resolution and depth of imaging data now available render simple analytical forms ineffective at capturing lens structures spanning a large range in spatial scale, mass scale, and morphology. In this work, we address the problem with a novel multiscale method based on wavelets. We tested our method on simulated Hubble Space Telescope (HST) imaging data of strong lenses containing the following different types of mass substructures making them deviate from smooth models: (1) a localized small dark matter subhalo, (2) a Gaussian random field (GRF) that mimics a nonlocalized population of subhalos along the line of sight, and (3) galaxy-scale multipoles that break elliptical symmetry. We show that wavelets are able to recover all of these structures accurately. This is made technically possible by using gradient-informed optimization based on automatic differentiation over thousands of parameters, which also allow us to sample the posterior distributions of all model parameters simultaneously. By construction, our method merges the two main modeling paradigms – analytical and pixelated – with machine-learning optimization techniques into a single modular framework. It is also well-suited for the fast modeling of large samples of lenses.

Fabrication and transfer printing based integration of free-standing GaN membrane micro-lenses onto semiconductor chips

We demonstrate the back-end integration of optically broadband, high-NA GaN micro-lenses by micro-assembly onto non-native semiconductor substrates. We developed a highly parallel process flow to fabricate and suspend micron scale plano-convex lens platelets from 6" Si growth wafers and show their subsequent transfer-printing integration. A growth process targeted at producing unbowed epitaxial wafers was combined with optimisation of the etching volume in order to produce flat devices for printing. Lens structures were fabricated with 6 − 11 µm diameter, 2 µm height and root-mean-squared surface roughness below 2 nm. The lenses were printed in a vertically coupled geometry on a single crystalline diamond substrate and with µm-precise placement on a horizontally coupled photonic integrated circuit waveguide facet. Optical performance analysis shows that these lenses could be used to couple to diamond nitrogen vacancy centres at micron scale depths and demonstrates their potential for visible to infrared light-coupling applications.

Lens Design Method Prediction of Local Optimization Algorithm by Using Deep Learning

A design rule prediction is proposed to assist a lens design in this paper. Deep learning was applied in order to predict a lens design rule that is based on a local optimization algorithm. Three separate lens design rules related to the aperture stop and FOV variation were made for the optimization in the two-lens element optical systems whose structural parameters were created randomly. These random lens structures were optimized by using three separate lens design rules that were developed by Zemax OpticStudio API to create a big optimization dataset. All of the optimization results were collected by means of a further deep learning process to determine which optimization rule would be the better choice for lens optimization when given the lens parameters. The model developed via deep learning shows that the prediction has a 78.89% accuracy in determining an appropriate optimization rule for an assistant lens design.

Endoilluminator-aided cataract surgery in eyes with corneal opacity - A modified surgical approach.

Background:Cataract and corneal blindness continue to be leading causes of reversible blindness in India. These can co-exist in a multitude of pathologies such as trauma, healed keratitis (old herpetic scar), chronic degenerative changes such as labrador keratopathy, bullous keratopathy, corneal dystrophies etc. Phacoemulsification in such eyes is rewarding to the patient in terms of minimal intervention, less risk of complications owing to reduced open sky time (as in case of combined keratoplasty), and better predictable visual outcomes. Approach to such eyes with poor visualisation is highly challenging.Purpose:We illustrate a modified surgical technique of chandelier illumination through pars plana for cataract surgery in eyes with corneal opacity of varying grades.Synopsis:Five patients with dense cataract and small pupils, associated with corneal opacity (leucomatous and macular grade) are described. Closed chamber phacoemulsification with intraocular lens with or without pupil expanders was performed assisted by 23 or 25 gauge pars plana chandelier illumination introduced in the vitreous cavity through a sclerotomy wound made prior to phacoemulsification in the inferotemporal quadrant.Highlights:Chandelier illumination aids in reducing the light scatter that occurs due to corneal opacity. Ease of visualisation of lens structures and of performing cataract surgery was noticed. One case was combined with penetrating keratoplasty with reduced open sky time. This assisted technique has advantages such as enhancing visualisation intraoperatively and allowing working in closed chamber. Its self-retaining nature aids bimanual manipulation. No complications were encountered. The video highlights the utility, advantages and practicality of chandelier retroillumination in patients with corneal opacities of varying degree undergoing phacoemulsification.Video Link: https://youtu.be/I3z6QG-_wD8

A Large Subsurface Anticyclonic Eddy in the Eastern Equatorial Indian Ocean

AbstractSubsurface eddies are pervasive in the ocean, but those in the eastern equatorial Indian Ocean are not well understood due to the lack of in‐situ observations. Using multiple‐platform observations and reanalysis product, we investigate the characteristics, evolutionary process, origin, and underlying generation mechanism of a subsurface anticyclonic eddy (SAE) in the eastern equatorial Indian Ocean during January‒February 2020. Results show that the horizontal radius of the SAE was slightly greater than 250 km, and the SAE core was located at ∼100‐m depth near the 24.7σ0 isopycnal. This warm, saline and oxygen‐rich SAE was weakly stratified and characterized by tilted lens structures. Further water‐mass tracing analysis indicates that the SAE shifted westward along 4°N with a mean propagation speed of 0.18 m/s from the northwest coast of Sumatra Island. The hydrographic characteristics of the SAE are similar to those of the strong Equatorial Undercurrent, it is speculated that the SAE was probably generated by the north branch flow as the eastward undercurrent reached Sumatra Island. Both lateral shear of undercurrent and conservation of potential vorticity were attributed to the formation of the observed SAE.

Asymmetrical dipole antenna based on a phase-correcting dielectric lens

Problem. Modern mobile robotic systems are increasingly used in various fields of human activity. More and more stringent requirements are imposed on them to ensure high throughput, broadband and reliability of data transmission and control channels at the maximum distance from the control center. And what I would like to note separately is the requirement to reduce the cost of such complexes as much as possible. Therefore, the development of technologically advanced, economically feasible antenna systems that provide an increase in the energy potential of the radio channel in the interval of the robotic complex - control point is one of the ways to solve this problem. Formulation of the problem. It is required to develop a mechanically strong, technological antenna, built on the basis of lens structures of various configurations, made of modern dielectric materials, characterized by reduced weight and size characteristics and cost price, which will increase the level of radiated electromagnetic energy in a wide frequency band. Purpose of the article. Present the developed model of an asymmetric dipole antenna and the results of a numerical experiment. Result. The antenna design is made on a metallized round substrate and is a polystyrene cylinder with a funnel-shaped hole, inside which there is an asymmetrical conical vibrator arm. The results of calculations showed that in the frequency band, which is used to organize direct broadband radio communication channels with robotic complexes, the gain varies within 5.5-9 dB, which is superior in this parameter to the commonly used whip antennas. The calculated standing wave ratio confirms the performance of the developed antenna model in a wide frequency band. The impedance response and the Smith-Smith diagram showed a preliminary calculated spread of the input impedance of the antenna from 30 to 95 ohms. Practical significance. The proposed antenna model ensures manufacturability, mechanical strength, and low cost. The full-azimuth radiation mode and increased gain make it possible to predict the possibility of using this antenna as part of the equipment for the data transmission channel and control of robotic complexes such as unmanned aerial vehicles.

Alignment tolerant analysis of a compact 4 × 25 Gbps TOSA with a thin-film filter multiplexer

A 100 Gbps transmitter optical sub-assembly (TOSA) based on a thin-film filter (TFF) multiplexer (MUX) demonstrated high alignment tolerance in a small volume. The model was based on the transfer-matrix method to investigate the effect of collimation and focus lens structures on coupling efficiency. The tolerances of the focus lens, MUX, and collimation lens were analyzed by simulation and experiment, obtaining the main values in 1 dB coupling loss of ±25, ±450, and ±3.3 um, respectively. Test results indicate that the transmission in a single mode fiber over 10 km is achieved with the 100 Gbps TOSA extinction ratio over 40 dB.

Protein and Imaging Biomarkers in the Eye for Early Detection of Alzheimer's Disease.

Alzheimer’s disease (AD) is one of the most common causes of dementia worldwide. Although no formal curative therapy exists for the treatment of AD, considerable research has been performed to identify biomarkers for early detection of this disease, and thus improved subsequent management. Given that the eye can be examined and imaged non-invasively with relative ease, it has emerged as an exciting area of research for evidence of biomarkers and to aid in the early diagnosis of AD. This review explores the current understanding of both protein and retinal imaging biomarkers in the eye. Herein, primary findings in the literature regarding AD biomarkers associated with the lens, retina, and other ocular structures are reviewed.