Large Lens Research Articles

Nautilus: The advent of large lens-based space telescopes

One of the most profound and philosophically captivating foci of modern astronomy is studies of Earth-like exoplanets in search of life in the Universe. The paradigm-shifting investigation described here calls for a new type of space telescope that redefines the available light-collecting area in space, far beyond what is currently possible with the 6.5 m diameter James Webb Space Telescope. The Nautilus Space Observatory, which is enabled by multiple-order diffractive optics, is ushering in the advent of large space telescope lenses designed to search for biosignatures on a thousand exo-earths.

Image segmentation for analyzing galaxy-galaxy strong lensing systems

Aims. The goal of this Letter is to develop a machine learning model to analyze the main gravitational lens and detect dark substructure (subhalos) within simulated images of strongly lensed galaxies. Methods. Using the technique of image segmentation, we turn the task of identifying subhalos into a classification problem, where we label each pixel in an image as coming from the main lens, a subhalo within a binned mass range, or neither. Our network is only trained on images with a single smooth lens and either zero or one subhalo near the Einstein ring. Results. On an independent test set with lenses with large ellipticities, quadrupole and octopole moments, and for source apparent magnitudes between 17−25, the area of the main lens is recovered accurately. On average, only 1.3% of the true area is missed and 1.2% of the true area is added to another part of the lens. In addition, subhalos as light as 108.5 M⊙ can be detected if they lie in bright pixels along the Einstein ring. Furthermore, the model is able to generalize to new contexts it has not been trained on, such as locating multiple subhalos with varying masses or more than one large smooth lens.

Compact internal sensing phase locking system for coherent combining of fiber laser array

A compact internal sensing phase locking system for coherent combining of large aperture fiber laser beams is demonstrated in this paper. Herein, the phase noises in the laser channels are detected and compensated before the lasers form a large cross-section laser array. Therefore, the large aperture beam splitters and lens are no longer needed for phase locking, and the phase-locking system can be more compact, especially for the coherent laser array with large cross-section. We built a 7-channel fiber laser array to experimentally verify the feasibility of this technique. The phase deviation was less than λ/31 RMS, and the visibility of far-field interference pattern of the combined beam was ∼96.3%. This technique can be used in high-power coherent beam combining system with the large aperture laser beams.

The rare earth element geochemistry of mafic granulites from the Neoarchaean northern marginal zone of the Limpopo Belt, Zimbabwe: Insights into mantle processes during an episode of crustal growth

The granulites of the Northern Marginal Zone of the Limpopo belt, Zimbabwe represent the lower crust of the Zimbabwe Craton. They are predominantly felsic in composition and represent magmas of the tonalite-trondhjemite-granodiorite suite which formed during a period of major crustal growth in the Neoarchaean. However, enclosed within the felsic gneisses of the NMZ are mafic granulites (metabasalts) which make up between 5 and 10% of the rock volume and which both predate and post-date the main TTG magmatism. These rocks show a diverse range of trace element compositions and are used here to characterize those mantle processes which were taking place during this period of crustal growth.The mafic granulites can be subdivided into two main groups. 1. Large metabasite lenses, associated with banded iron formation, represent a supracrustal suite of basalts which predate the emplacement of the TTGs and may be time equivalents of the lower greenstones of the Zimbabwe Craton. Samples can be grouped into three different types of REE pattern – depleted, chondritic and enriched – which is interpreted to show that they were partial melts of a depleted mantle source, which in places interacted with and was contaminated with older felsic crust. 2. Narrow dykes post-date the emplacement of the NMZ TTG suite. There are two geochemical types. Dykes with light-enriched REE patterns are derived from a depleted mantle source but were contaminated with felsic crust during their emplacement. Dykes highly enriched in light REE were derived from an enriched mantle source formed through the refertilisation of a previously depleted mantle source. The deep melting of this refertilised source gave rise to highly enriched mafic melts.The large metabasite lenses could be indicative of the metabasaltic source which subsequently partially melted to form the NMZ TTG magmatic suite. Later deep mantle melting to form the post TTG dykes may be related to the creation of thick Neoarchaean continental crust and associated mantle lithosphere.

Efficacy of Large Optic Intraocular Lenses in Myopic Eyes with Posterior Segment Pathology.

We report a case series of patients with high myopia (axial length 25.04–27.59 mm) diagnosed with cataract and maculopathy who underwent a combined procedure of phacoemulsification with implantation of a large optic intraocular lens (IOL) and intravitreal injection. Six patients with a mean (± standard deviation) age of 73.20 ± 7.19 years received the 7.0-mm optic ASPIRA-aXA IOL (HumanOptics AG, Erlangen, Germany) and intravitreal injection of aflibercept at the end of the surgery. The corrected distance visual acuity (CDVA) improved significantly (p = 0.001) from a preoperative logMAR of 0.87 ± 0.28 logMAR to 0.49 ± 0.18 logMAR at 10 weeks postoperatively. Even though all patients had a persisting central scotoma due to their maculopathy, there was a significant improvement in their subjective quality of life and self-autonomy. Patients reported no postoperative dysphotopsia. During surgery and postoperative examinations, the wide IOL optic permitted an enhanced view of the fundus. The IOLs remained stable after implantation, especially during the intravitreal injection at the end of the surgery. No IOL displacement or shift of the lens was observed. Retinal diseases are sight-threatening and diminish the patient’s quality of life due to reduced visual acuity and visual field defects. When cataract surgery is performed in this patient group, a reduced prognosis can be assumed. Our results show that implantation of the large optic IOL enables a wide view of the fundus during and after surgery without any additional risks or negative effects. It may also reduce the risk of dysphotopsia in cases of IOL decentration in large capsular bags, but comparative studies with a higher number of cases are needed to confirm this. A large rhexis and large IOL optic seem to be advantageous for the retinal surgeon in follow-up surgeries on the posterior segment of the eye.

Shaping an optical dome: The size and shape of the insect compound eye

The insect compound eye is the most abundant eye architecture on earth. It comes in a wide variety of shapes and sizes, which are exquisitely adapted to specific ecosystems. Here, we explore the organisational principles and pathways, from molecular to tissular, that underpin the building of this organ and highlight why it is an excellent model system to investigate the relationship between genes and tissue form. The compound eye offers wide fields of view, high sensitivity in motion detection and infinite depth of field. It is made of an array of visual units called ommatidia, which are precisely tiled in 3D to shape the retinal tissue as a dome-like structure. The eye starts off as a 2D epithelium, and it acquires its 3D organisation as ommatidia get into shape. Each ommatidium is made of a complement of retinal cells, including light-detecting photoreceptors and lens-secreting cells. The lens cells generate the typical hexagonal facet lens that lies atop the photoreceptors so that the eye surface consists of a quasi-crystalline array of these hexagonal facet-lenses. This array is curved to various degree, depending on the size and shape of the eye, and on the region of the retina. This curvature sets the resolution and visual field of the eye and is determined by i) the number and size of the facet lens – large ommatidial lenses can be used to generate flat, higher resolution areas, while smaller facets allow for stronger curvature of the eye, and ii) precise control of the inter facet-lens angle, which determines the optical axis of the each ommatidium. In this review we discuss how combinatorial variation in eye primordium shape, ommatidial number, facet lens size and inter facet-lens angle underpins the wide variety of insect eye shapes, and we explore what is known about the mechanisms that might control these parameters.

Indications for surgical management of retained lens fragments.

Retained lens fragments are a relatively rare occurrence after cataract surgery. While no definite guidelines for the surgical management or timing of surgery of this complication exist, surgery is indicated for patients with large lens fragments, persistent inflammation, secondary glaucoma, corneal edema, retinal tears or detachments, and associated endophthalmitis. The aim of this review is to summarize the current surgical management of retained lens material. The Intelligent Research in Sight registry database of 2.26 million patients who underwent cataract surgery in the US indicated that 0.18% (1 in 563) had secondary removal of retained lens fragments in the anterior chamber in the operating room within 1 year of the original cataract surgery. The risk of returning to the operating room for retained lens material removal was greater among men, smokers, patients with Medicaid or military insurance, and those who had complex cataract surgery. Medical management with topical corticosteroids or observation may be considered for small lens fragments, but surgical removal remains the mainstay of the treatment for large lens fragments. Retained lens fragments following cataract surgery may result in various vision-threatening complications. Understanding the risk factors, diagnosis, and surgical management of retained lens fragments are critical to preserving good visual outcomes. Vitrectomy is effective in patients with posterior nuclear fragments, retinal detachment, endophthalmitis, or uncontrolled glaucoma not responding to medical management. The best timing for surgery for retained lens fragments should be further investigated in a prospective study.

Image-type displacement measurement resolution improvement without magnification imaging

The imaging-type displacement measurement (IDM) technique is better-suited to high-resolution measurement than the traditional moiré fringe technique. In Angular displacement measurement, IDM generally requires lens-magnified imaging processes to reach the proper resolution, which depends on overly large imaging lenses and highly complex, generally unreliable equipment, making the technique not conducive to industrial application. The resolution of an IDM device was improved in this study without the use of an imaging lens. The lensless imaging principle was established, then a new algorithm based on multi-line fusion and denoising was developed to improve the displacement subdivision resolution. The proposed algorithm was verified by both simulation and experimentation. The simulation shows that the proposed algorithm effectively reduces positioning operation noise. In the experiment, an angular measurement resolution of 0.039″ (25-bit) was achieved on a 70 mm diameter circular grating. The proposed method lays a foundation for further high-resolution displacement measurement techniques.

Ommatophore (Eyestalk) Magic: Lobatus costatus

The conch (Lobatus costatus) (Fig A; Image by Martin S. Gilman, MEd), a slow-moving, herbivorous bottom-dweller has a relatively large (up to 1.5 mm in diameter) and sophisticated eye compared with other gastropods. The stalks are modified tentacles and support olfactory and visual organs (Fig B). These stalks protrude from beneath the shell and move independently. The stalks will regenerate topographically correct eyes after injury or loss of the eyes. The stalked eye (Fig C) shows the olfactory organ (black arrow) and large spherical crystalline lens (green arrow).

Preoperative Factors Affecting Visual Acuity Following the Implantation of Diffractive Multifocal Intraocular Lenses.

To investigate the preoperative factors affecting visual acuity after the implantation of a diffractive multifocal intraocular lens. This study evaluated 774 eyes of 774 patients who underwent cataract surgery with TECNIS Multifocal ZLB00 lens (Johnson & Johnson Surgical Vision) implantation. Anterior segment optical coherence tomography (CASIA2; Tomey Corporation) was performed as a part of the preoperative eye examination. Sex, age, axial length, and CASIA2 parameters, such as crystalline lens diameter and lens tilt relative to the corneal topographic axis, were investigated. The eyes considered were classified into good (20/20 or better) or poor (worse than 20/20) far vision groups based on corrected distance visual acuity, and good (20/25 or better) or poor (worse than 20/25) near vision groups based on distance-corrected near visual acuity, respectively. Preoperative characteristics of both groups were compared to determine factors affecting postoperative visual acuity. Multivariate logistic regression analysis revealed that older age (P < .001), a short axial length (P = .010), and a large lens tilt (P < .001) were associated with poor near vision. There was no significant difference between the two far vision groups. There was a significant negative correlation between lens tilt and axial length (r = -0.513, P < .001). The results of this study suggest that age, axial length, and lens tilt to the corneal topographic axis may predict poor visual acuity after the implantation of a diffractive multifocal intraocular lens. Eyes with a short axial length tended to have a large degree of lens tilt and should be considered particularly carefully. [J Refract Surg. 2021;37(10):674-679.].

Fitting Pearls for Scleral Lenses

Scleral lenses are the large diameter rigid gas permeable lenses which have a large number of potential benefits, the dispensing of this lenses are increased exponentially over the last decade. Scleral lenses now-a-days are designed with the use of software and advanced manufacturing machines. This not only allow the eye care practitioner to design the lens on micro level but also increase the optical quality and comfort of the lens on eye. In the past, one major disadvantage of fitting scleral is chair time, skills and expense required to fit them. Scleral lenses are available in different diameters and sag values which helps ECP to fit lens accordingly. Scleral lens fitting philosophy differs from that of corneal GP lenses. Different scleral lenses may use different fitting methods.

An attempt to optimize the outcome of penetrating keratoplasty in congenital aniridia-associated keratopathy (AAK)

PurposeTo propose an optimized microsurgical and medical approach to reduce the risk of complications after penetrating keratoplasty (PKP) in patients with aniridia-associated keratopathy (AAK).MethodsRetrospective observational case series of 25 PKP performed in 16 patients with AAK. Preoperative indications were endothelial decompensation and vascularized scars (68%) or graft failure (32%) due to limbal stem cell deficiency. The optimized approach included a combination of a small corneal graft size (around 7.0 mm), interrupted 10–0nylon sutures, simultaneous AMT as a patch, large bandage contact lens, temporary lateral tarsorrhaphy, postoperative autologous serum eye drops, and systemic immunosuppression. Main outcome measures included: visual acuity, transplant survival, and complications encountered during follow-up of 107 weeks on average.ResultsA complete modified keratoplasty scheme was used in 10 of 25 PKP (group 1), while at least one of the modifications was missing in the other 15 PKP (group 2). After 8 weeks of follow-up, the epithelium was closed in 23 eyes. Visual acuity improved in 19 eyes at 6 months of follow-up, and remained stable in six eyes. None of the eyes showed a decrease in visual acuity. At the last post-operative follow-up, this visual improvement persisted in 14 eyes and graft survival rate after 156 weeks (3 years) was 69% in group 1 versus 44% in group 2 (p = 0.39, log-rank test). Secondary corneal neovascularization (8%), scarring (4%), ulcer (4%), or graft rejection (8%) happened mostly in the second group which was missing at least one of the suggested modifications.ConclusionsPKP in congenital aniridia must be considered as a high-risk keratoplasty. An optimized therapeutic approach seems to be promising in order to reduce the postoperative complication rate in these most difficult eyes.

Experimental study of combined transparent solar panel and large Fresnel lens concentrator based hybrid PV/thermal sunlight harvesting system

Solar energy is immensely available during daytime on the earth. It is a sustainable, renewable and green energy. Improvement in efficiency of harnessing solar energy is the utmost concern of the present research due to its renewable nature. This article presents a complete utilization of solar irradiation over the broad spectrum of solar energy efficiently. The design, development and implementation of the hybrid solar photo voltaic & thermal (SPVT) system are reported, in which a tandem structure of transparent solar panel and large Fresnel lens concentrator are mounted for sunlight harvesting. In this hybrid system a semi-transparent solar panel mounted on the top for PV application and large Fresnel lens is for concentrating the transmitted light onto a solar thermal absorber unit for heating water efficiently. The partial visible portion of solar energy is converted into voltage generation using semi transparent solar panel (TSP) while remaining transmitted radiations is further concentrated by a large Fresnel lens which was fixed below semi-transparent solar panel. Concentrated sunlight was focused on solar thermal unit which was utilized for water heating. Two different color filter semi-transparent solar panel modules were integrated with the system for testing and reported that the red color filter solar panel generates more power and overall efficiency as compared to other one. Experimental results using the prototype developed system are reported. Due to simultaneous electricity generation and domestic hot water application the hybrid system becomes more efficient, robust and cost effective for sustainable development of the country.

Integral imaging display with enhanced depth of field based on bifocal lens array

AbstractIn this paper, we propose a depth‐enhanced integral imaging display based on bifocal lens array. The bifocal lens array consists of a small lens array with plano‐convex circular lens units and a large lens array with square lens units. The proposed display device generates two central depth planes and stitches two reconstructed 3‐D images in depth, which largely improves the depth of field. The experimental results indicate that the proposed structure reconstructed 3‐D image with the depth of field as large as 150.8 mm, which is double of conventional integral imaging display.

Application of big-data for epidemiological studies of refractive error.

To examine whether data sourced from electronic medical records (EMR) and a large industrial spectacle lens manufacturing database can estimate refractive error distribution within large populations as an alternative to typical population surveys of refractive error. A total of 555,528 patient visits from 28 Irish primary care optometry practices between the years 1980 and 2019 and 141,547,436 spectacle lens sales records from an international European lens manufacturer between the years 1998 and 2016. Anonymized EMR data included demographic, refractive and visual acuity values. Anonymized spectacle lens data included refractive data. Spectacle lens data was separated into lenses containing an addition (ADD) and those without an addition (SV). The proportions of refractive errors from the EMR data and ADD lenses were compared to published results from the European Eye Epidemiology (E3) Consortium and the Gutenberg Health Study (GHS). Age and gender matched proportions of refractive error were comparable in the E3 data and the EMR data, with no significant difference in the overall refractive error distribution (χ2 = 527, p = 0.29, DoF = 510). EMR data provided a closer match to the E3 refractive error distribution by age than the ADD lens data. The ADD lens data, however, provided a closer approximation to the E3 data for total myopia prevalence than the GHS data, up to age 64. The prevalence of refractive error within a population can be estimated using EMR data in the absence of population surveys. Industry derived sales data can also provide insights on the epidemiology of refractive errors in a population over certain age ranges. EMR and industrial data may therefore provide a fast and cost-effective surrogate measure of refractive error distribution that can be used for future health service planning purposes.

Autostereoscopic display for multiviewers positioned at different distances using time-multiplexed layered directional backlight.

In this paper, an autostereoscopic display system based on a time-multiplexed directional backlight using a large aperture Fresnel lens is proposed. High-resolution stereoscopy for multiple viewers positioned at different distances from the screen is achieved in the proposed system by layering polymer dispersed liquid crystal screens behind the Fresnel lens. The screens with segmented electrodes are electrically controlled to change the position of light diffusion, while the time-multiplexed backlight is projected by a digital mirror device projector at a high refresh rate. The light is diffused at the conjugate focal points of the observers' eyes to deliver directional light to each eye. The right-eye image and the left-eye image are alternated on the LCD panel in front of the lens to synchronize with the backlight.

The impact of line-of-sight structures on measuring H0 with strong lensing time delays

ABSTRACT Measurements of the Hubble–Lemaitre constant from early- and local-Universe observations show a significant discrepancy. In an attempt to understand the origin of this mismatch, independent techniques to measure H0 are required. One such technique, strong lensing time delays, is set to become a leading contender amongst the myriad methods due to forthcoming large strong lens samples. It is therefore critical to understand the systematic effects inherent in this method. In this paper, we quantify the influence of additional structures along the line of sight by adopting realistic light-cones derived from the cosmoDC2 semi-analytical extragalactic catalogue. Using multiple-lens plane ray tracing to create a set of simulated strong lensing systems, we have investigated the impact of line-of-sight structures on time-delay measurements and in turn, on the inferred value of H0. We have also tested the reliability of existing procedures for correcting for line-of-sight effects. We find that if the integrated contribution of the line-of-sight structures is close to a uniform mass sheet, the bias in H0 can be adequately corrected by including a constant external convergence κext in the lens model. However, for realistic line-of-sight structures comprising many galaxies at different redshifts, this simple correction overestimates the bias by an amount that depends linearly on the median external convergence. We therefore conclude that lens modelling must incorporate multiple-lens planes to account for line-of-sight structures for accurate and precise inference of H0.

Fabrication and characterization of large aperture adaptive modal liquid crystal lens with a PEDOT:PSS/PVA/DMSO blend used as the modal and rubbing layer

An adaptive modal liquid crystal lens (AMLCL) with a 5 mm aperture and thickness of 20 µm was fabricated and studied. PEDOT:PSS/PVA/DMSO polymer blend film was used as both the modal and rubbing layers simultaneously. Using the modal layer as the rubbing layer facilitates and simplifies cell preparation. An optimal concentration of polymer blend, the 0.1-µm-thick modal layer had a 5 MΩ/□ sheet resistance. AMLCL electrodes were broken down into four parts and the cell placed in the optical setup to study the wavefront shape. It was shown that by applying the trigger voltage to different parts of the electrode and removing parts of the circuit, the cell could function as a spherical, cylindrical, or prismatic lens. Further, the electric power consumption was studied at different voltages and frequencies, showing that the spherical lens requires 0.5 mW to reach its maximum optical power at 1 kHz. Shack-Hartmann wavefront sensor was used to study the AMLCL’s aberrations. Tip aberration in this cell is attributed to the pretilt of the Liquid Crystal (LC) molecules at the surfaces that deflect the transmitting light from its straight path. It was shown that higher-order aberrations are negligible compared to the spherical aberration, which is reduced by raising the frequency to 1 kHz.

Stark trade-offs and elegant solutions in arthropod visual systems.

Vision is one of the most important senses for humans and animals alike. Diverse elegant specializations have evolved among insects and other arthropods in response to specific visual challenges and ecological needs. These specializations are the subject of this Review, and they are best understood in light of the physical limitations of vision. For example, to achieve high spatial resolution, fine sampling in different directions is necessary, as demonstrated by the well-studied large eyes of dragonflies. However, it has recently been shown that a comparatively tiny robber fly (Holcocephala) has similarly high visual resolution in the frontal visual field, despite their eyes being a fraction of the size of those of dragonflies. Other visual specializations in arthropods include the ability to discern colors, which relies on parallel inputs that are tuned to spectral content. Color vision is important for detection of objects such as mates, flowers and oviposition sites, and is particularly well developed in butterflies, stomatopods and jumping spiders. Analogous to color vision, the visual systems of many arthropods are specialized for the detection of polarized light, which in addition to communication with conspecifics, can be used for orientation and navigation. For vision in low light, optical superposition compound eyes perform particularly well. Other modifications to maximize photon capture involve large lenses, stout photoreceptors and, as has been suggested for nocturnal bees, the neural pooling of information. Extreme adaptations even allow insects to see colors at very low light levels or to navigate using the Milky Way.

Large diameter scleral lens benefits for Asians with intractable ocular surface diseases: a prospective, single-arm clinical trial

To report the efficacy and safety of large diameter scleral lenses and determine their suitability in Asian subjects with intractable ocular surface diseases. This prospective study enrolled intractable ocular surface diseases subjects with uncorrected visual acuity > counting finger but ≥ 0.3 logMAR and best-corrected visual acuity (BCVA) ≥ 0.3 logMAR, to fit large diameter scleral lenses for 12 weeks. 21 eyes (13 subjects) consisting ten eyes (47.6%) with persistent epithelial defects, 6 (28.6%) with graft-versus-host disease, 4 (19.0%) with Stevens–Johnson syndrome and one (4.8%) with severe dry eye were ultimately enrolled. Primary outcome measures were the visual acuity, corneal and conjunctival fluorescein staining, Ocular Surface Disease Index (OSDI), and National Eye Institute 25-Item Visual Function Questionnaire (NEI-VFQ-25). At week 12 with large diameter scleral lenses, BCVA improved from 0.77 logMAR to 0.27 logMAR (P < 0.001). High-grade corneal and conjunctival fluorescein staining proportion decreased from 61.90 to 14.29% and 52.38 to 9.52%, respectively (P = 0.0036 and 0.0063, respectively). OSDI and NEI-VFQ-25 improved from 67.89 to 34.69 and 51.40 to 64.48, respectively (P < 0.001). No adverse effects were observed. In Asians with intractable ocular surface diseases, large diameter scleral lens improves visual acuity and alleviates signs and symptoms of ocular surface diseases without any significant complications.Trial registration Korean Health Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (Project No. HI12C0015 (A120018)). Clinical Trials.gov, NCT04535388. Registered 18 August 2020—Retrospectively registered, http://clinicaltrials.gov/ct2/show/NCT04535388.