Polymer Lens Research Articles

Modulating ultrasound field phase and amplitude using foam gratings as an alternative to acoustic lenses

There is an increasing number of applications for therapeutic ultrasound, including high intensity focused ultrasound surgery, neuromodulation and drug delivery. For many of these applications, accurate focusing of the ultrasound field at tissue depths of several cm is essential and thus patient-specific acoustic lenses have been widely investigated as an economical alternative to phased array transducers. Lenses can be cast or 3D printed from a range of polymers offering good acoustic impedance matching to human tissue. Disadvantages of polymer lenses, however, include their relatively large size and the difficulties involved in eliminating gas bubbles during production. In this study an alternative approach is investigated using a “grating” comprising a sheet of polymer foam, perforated with a series of pores that act as wave guides. The grating is placed in front of a transducer with the pores arranged to modulate the phase and amplitude of the sound field as required. The gratings can be cheaply and rapidly fabricated, are < 5 mm thick and can achieve phase changes of more than 180° were successfully achieved while maintaining a transmission amplitude of more than 50%.

Holographic multiplane augmented reality head-up display with switchable display modes based on polymer dispersed liquid crystal.

The multiplane augmented reality (AR) head-up display (HUD) is important in improving driving safety and comfort. In this paper, we propose an AR-HUD with switchable display modes based on polymer dispersed liquid crystal (PDLC) and lens holographic optical elements (HOEs), which can provide two display modes: the dual-virtual-image mode and the virtual-real-image mode. The dual-virtual-image mode can produce two virtual images at different depths, which can provide a better sense of reality integration for the driver to improve driving safety and comfort. The virtual-real-image mode can produce one far virtual image and one near real image at different depths, and it provides a larger eye box (EB) for both driver and passengers in the car and a higher image contrast. The two display modes can be switched by an electronically controlled scattering module consisting of a pair of PDLC films. The proposed AR-HUD system is compact and equipped with multiplane display and mode-switching functions, and is expected to be applied in the future.

Development of a bio-inspired optical system that mimics accommodation and lighting regulation like the human eye.

Bio-inspired optical systems have recently been developed using polarizers and liquid or rigid lenses. In this work, we propose a bio-inspired opto-mechatronic system that imitates the accommodation and regulation of light intensity as the human eye does. The system uses a polymeric lens as a cornea, an adjustable diaphragm as an iris, a tunable solid elastic lens as a crystalline lens, and a commercial sensor as a retina. We also present the development of the electronic control system to accommodate and regulate the amount of light that enters the system, for which two stepper motors, an Arduino control system, and light and movement sensors are used. The characterization of the system is presented together with the results obtained, where it can be seen that the system works in an acceptable range as the human eye does.

Surface Roughness in Ultra-High Precision Diamond Turning of Silicone Hydrogel Contact Lenses

The research work presented in this paper highlights the use of the process of ultra-high precision diamond turning when machining advanced contact lens polymers. The study is focused on investigating the effect of diamond cutting conditions on the surface quality of the polymers machined. A silicone hydrogel (Definitive 74) was used in this study. The surface roughness measurements were taken using a surface 3D profilometer. Response surface methodology techniques were employed to create predictive models for surface roughness with respect to the cutting speed, feed rate and depth of cut. The predictive surface roughness models were successfully generated for the polymer and the cutting speed and feed rate were identified as the most influential parameters on surface roughness.

Daily disposable contact lenses as a platform for ocular drug delivery of cyclosporine A

Ophthalmic drug delivery is an important area of research that aims to improve the efficacy and convenience of treatment for various eye conditions. There are multiple ways in which drugs can be delivered to the eye, including eye drops, ointments, gels, and inserts. The most prevalent way of administering medication to the eye is through eye drops. They are easy to use and can be self-administered by patients. Nonetheless, eye drops have the disadvantage of being prone to removal by tears, which may result in insufficient drug absorption and reduced effectiveness. Irregular use of active substances can exacerbate the disease, resulting in prolonged treatment with questionable efficacy. Soft contact lenses that serve as ophthalmic drug delivery systems (DDS) can become a viable substitute for traditional treatments. These polymeric lenses can be embedded with various active compounds, some of which are not readily soluble in water or physiological fluids. One such drug is Cyclosporine A (CyA), an immunosuppressant with a high molecular weight and hydrophobic properties, chronically used to treat dry eye syndrome (DES). The article discusses the development of a method for modifying Hilafilcon B contact lenses obtained from drugstores with Cyclosporine A (CyA). The drug was administered to the lenses using an immersion technique, and the process parameters were monitored to control drug release efficiency and profile. The drug release was measured in an Artificial Lacrimal Fluid (ALF) buffer, mimicking tear fluid with a pH of 7.9. The stability of CyA in this buffer was assessed. For the parameters used, the best drug application and release profile was achieved by immersing the contact lenses for 24 hours at 25 °C in a CyA solution containing 20 μg/ml of the active substance and adding 5 mg/ml of Vitamin E.

Environmental impact and end-of-life options of disposed polymeric spectacle and contact lenses

Background: Global population growth and ageing are factors that contribute towards an anticipated increase in the usage of spectacles and contact lenses for vision correction. The subsequent disposal of polymeric vision corrective devices currently, has uncertain environmental impacts.Aim: The purpose of this study was to explore potential environmental impacts and end-of-life (EOL) pathways of a sample of polymeric spectacle lenses and through the use of analytical chemistry processes.Setting: Laboratory analysis of ophthalmic lenses.Methods: Inductively coupled plasma–optical emission spectroscopy (ICP–OES), elemental analysis and calorific value investigations were conducted on a sample of spectacle lenses and contact lenses.Results: Metal ion analysis by ICP–OES confirmed the presence of manganese in all the lenses and chromium in two of the 13 contact lenses. All of the lenses had over 42% carbon while calorific values of up to 32.40 MJ/kg and 23.31 MJ/kg were found in the spectacle lenses and contact lenses, respectively.Conclusion: Further investigation is required regarding the presence of chromium in two of the contact lenses. In general, lenses are likely to remain as solid waste in landfills depending on the disposal conditions. Considering their calorific values, lenses would be useful in incineration with energy recovery processes however the suggested ideal EOL route would be the implementation of lens recycling, through non-toxic and green chemical processes, to retain material value and promote a circular economy.Contribution: This study provides new information on the environmental consequences of current modes of lens disposal and suggests EOL alternatives thereof.

Injection Molding of Encapsulated Diffractive Optical Elements.

Microstructuring techniques, such as laser direct writing, enable the integration of microstructures into conventional polymer lens systems and may be used to generate advanced functionality. Hybrid polymer lenses combining multiple functions such as diffraction and refraction in a single component become possible. In this paper, a process chain to enable encapsulated and aligned optical systems with advanced functionality in a cost-efficient way is presented. Within a surface diameter of 30 mm, diffractive optical microstructures are integrated in an optical system based on two conventional polymer lenses. To ensure precise alignment between the lens surfaces and the microstructure, resist-coated ultra-precision-turned brass substrates are structured via laser direct writing, and the resulting master structures with a height of less than 0.002 mm are replicated into metallic nickel plates via electroforming. The functionality of the lens system is demonstrated through the production of a zero refractive element. This approach provides a cost-efficient and highly accurate method for producing complicated optical systems with integrated alignment and advanced functionality.

Integrated TiO2 nanoparticle for electronic polymeric contact lenses

Integrated TiO2 nanoparticle for electronic polymeric contact lenses

P‐170: Late‐News Poster: Programmable and Pixelated Liquid Crystal Lens

We demonstrated a programmable and pixelated liquid crystal (LC) lens which can pixelated control optical power between negative lens and positive lens. The LC lens is composed of high aperture ratio thin film transistor (TFT) polarization rotator and wavelength insensitive geometric phase (GP) liquid crystal polymer (LCP) lens. It owns the properties of fast switching(<10ms), thin thickness(<1mm), large aperture size (40mm), and pixelated control. This approach opens new applications including VR/MR systems and ophthalmic lenses.

A novel approach to achieve semi-sustained drug delivery to the eye through asymmetric loading of soft contact lenses

Soft contact lenses are increasingly being explored as a vehicle for controlled delivery of ophthalmic drugs. However, traditional methods of drug-loading by soaking have limitations such as burst delivery and the release of drugs at the front side of the lens, leading to poor drug efficacy and systemic side effects. This study introduces a new methodology, termed asymmetric drug loading, whereby the ophthalmic drug ‘Rebamipide’ is attached to and released from the post-lens (=cornea-contacting) surface exclusively. The methodology involves using polymeric microparticles that carry a lipophilic crystalline ophthalmic drug at their surface. These drug-loaded microparticles first transfer the drug to the concave surface of the contact lens, and when worn, the drug is transferred again, now from the lens to the cornea. This is achieved through the diffusion of the drug from one hydrophobic microenvironment (the silicone moieties of the contact lens polymer network) to another hydrophobic microenvironment (the corneal epithelium) over a short pathway. The second drug transfer was observed and studied in experiments using an ex vivo porcine eye model. The results show that the drug amount that was absorbed by the cornea after applying the rebamipide-loaded contact lenses is approximately 3× (10.7 ± 3.1 μg) as much as the amount of rebamipide that gets transferred after the instillation of one eye drop (1% solution (p < 0.001). The new drug-loading method offers a practical and reproducible means of delivering ophthalmic drugs to the cornea through soft contact lenses. The drug payloads achieved are comparable to dosages used during eye drop therapy.

The consequences of removing fluorinated compounds from rigid contact lenses

Abstract Fluorine free analogues of three commercially available rigid contact lens materials were prepared by replacing the fluorinated component, hexafluoroisopropyl methacrylate (HFPM), with the widely used, non-fluorinated monomers methyl methacrylate (MMA) and 3-methacryloxypropyltris-(trimethylsiloxy)silane (TRIS). The properties of the commercial materials and analogues were measured and compared. The oxygen permeabilities of the MMA analogues were found to be significantly lower than those of the commercial materials, decreasing by 87 % on average, while the TRIS analogues lacked sufficient hardness, dimensional stability and lipid deposit resistance to be viable for use in rigid contact lenses. Analogues prepared using a 1:1 mixture of MMA and TRIS had the best overall combination of properties, but were still on average 47 % less permeable to oxygen and also significantly less resistant to lipid deposition. The analogues prepared in this study did not adequately replicate the performance of marketed, fluorine containing rigid contact lens materials. These observations give an indication of the challenges that would face contact lens material manufacturers in preparing rigid lens polymers without the use of fluorinated species. A reduction in effectiveness would be almost inevitable, and would be expected to have a negative impact on the safety and eye health of rigid contact lens patients.

Prashant Kamat to give 2023 Crano Memorial Lecture

Prashant V. Kamat , the Rev. John A. Zahm, C.S.C., Professor of Science in the Department of Chemistry and Biochemistry and Radiation Laboratory at the University of Notre Dame, will present the 2023 Crano Memorial Lecture. Kamat was selected in recognition of his nearly 4 decades of work building bridges between physical chemistry and material science to develop advanced nanomaterials that promise cleaner and more efficient light energy conversion. He will give two lectures at the University of Akron on April 14. The afternoon talk is titled “Light Energy Conversion with Halide Perovskite-Molecular Hybrids. Energy versus Electron Transfer” and the evening talk is titled “Reducing Carbon Footprint with Next Generation Photovoltaics.” The Crano Memorial Lecture Series is organized by the ACS Akron Section in memory of John C. Crano, a past chair of the section and developer at PPG Industries of photochromic polymer lenses for eyeglasses.

Poly(2-hydroxyethyl methacrylate) surface chemistry and modulus differentially modulate neutrophils and lens epithelial cells-possible implications in cellular responses to intraocular lenses.

During cataract surgery, diseased lenses in the eye are surgically removed and replaced with polymeric artificial intraocular lenses (IOLs). Patients can experience a complication called posterior capsular opacification (PCO) that is corrected through the removal of part of the posterior capsule using a neodymium: yttrium-aluminum-garnet (Nd-YAG) laser to restore the optical path. These interventions have increased costs and can damage the retina and the IOL. PCO develops when lens epithelial cells (LECs) proliferate, migrate, and undergo epithelial-to-mesenchymal transition. Neutrophils involved in the immune response triggered during implantation impact LEC behavior and produce damaging neutrophil extracellular traps (NETs). In this research, poly(2-hydroxyethyl methacrylate) (PHEMA) -based disks were synthesized with varying amounts of comonomer (HEMA with 0, 2, and 12 mol% MMA) and functionalized with carboxyl and amine groups, yielding nine different hydrogels. Material and chemical properties of the disks were characterized, and neutrophil-like HL60 cells and B3 LECs were incubated with the disks. HL60 cell behavior was more strongly influenced by chemical functionalization than by mechanical properties with increases in adherence and NET accumulation. Conversely, the behavior and viability of B3 LECs were more strongly influenced by mechanical properties with increases in cell adhesion and α-SMA expression with increasing compressive moduli. Interestingly, B3 LECs had decreased viability and increased α-SMA expression when cultured on PHEMA2 disks pretreated with isolated NETs. Critical to the understanding of PCO and its prevention are both surface chemistry and mechanics as well as the inflammatory response.

Low-Divergence hBN Single-Photon Source with a 3D-Printed Low-Fluorescence Elliptical Polymer Microlens.

Efficiently collecting light from single-photon emitters is crucial for photonic quantum technologies. Here, we develop and use an ultralow fluorescence photopolymer to three-dimensionally print micrometer-sized elliptical lenses on individual precharacterized single-photon emitters in hexagonal boron nitride (hBN) nanocrystals, operating in the visible regime. The elliptical lens design beams the light highly efficiently into the far field, rendering bulky objective lenses obsolete. Using back focal plane imaging, we confirm that the emission is collimated to a narrow low-divergence beam with a half width at half-maximum of 2.2°. Using photon correlation measurements, we demonstrate that the single-photon character remains undisturbed by the polymer lens. The strongly directed emission and increased collection efficiency is highly beneficial for quantum optical experiments. Furthermore, our approach paves the way for a highly parallel fiber-based detection of single photons from hBN nanocrystals.

Large-scale achromatic flat lens by light frequency-domain coherence optimization

Flat lenses, including metalens and diffractive lens, have attracted increasing attention due to their ability to miniaturize the imaging devices. However, realizing a large scale achromatic flat lens with high performance still remains a big challenge. Here, we developed a new framework in designing achromatic multi-level diffractive lenses by light coherence optimization, which enables the implementation of large-scale flat lenses under non-ideal conditions. As results, a series achromatic polymer lenses with diameter from 1 to 10 mm are successfully designed and fabricated. The subsequent optical characterizations substantially validate our theoretical framework and show relatively good performance of the centimeter-scale achromatic multi-level diffractive lenses with a super broad bandwidth in optical wavelengths (400–1100 nm). After comparing with conventional refractive lens, this achromatic lens shows significant advantages in white-light imaging performance, implying a new strategy in developing practical planar optical devices.

Software integration for 3D lens prototyping and complex lens analysis workflows

PhotonicsViewsVolume 19, Issue 5 p. 40-43 Optics DesignFree Access Software integration for 3D lens prototyping and complex lens analysis workflows Ansys Zemax solutions enable rapid prototyping and yield optimization for UpNano's in-house and external projects First published: 27 August 2022 https://doi.org/10.1002/phvs.202200038Citations: 1AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract UpNano combined their additive manufacturing system NanoOne with Ansys Zemax' virtual prototyping technologies to help companies optimize polymer lens development and achieve high-resolution precision at an unprecedentedly tiny scale. The high-powered lasers and data-driven system design enhancements yielded rapid fabrication techniques at the nano, micro, meso, and macro range. Citing Literature Volume19, Issue5October/November 2022Pages 40-43 RelatedInformation

Printing Polymeric Convex Lenses to Boost the Sensitivity of a Graphene-Based UV Sensor.

Ultraviolet (UV) is widely used in daily life as well as in industrial manufacturing. In this study, a single-step postprocess to improve the sensitivity of a graphene-based UV sensor is studied. We leverage the advantage of electric-field-assisted on-demand printing, which is simply applicable for mounting functional polymers onto various structures. Here, the facile printing process creates optical plano-convex geometry by accelerating and colliding a highly viscous droplet on a micropatterned graphene channel. The printed transparent lens refracts UV rays. The concentrated UV photon energy from a wide field of view enhances the photodesorption of electron-hole pairs between the lens and the graphene sensor channel, which is coupled with a large change in resistance. As a result, the one-step post-treatment has about a 4× higher sensitivity compared to bare sensors without the lenses. We verify the applicability of printing and the boosting mechanism by variation of lens dimensions, a series of UV exposure tests, and optical simulation. Moreover, the method contributes to UV sensing in acute angle or low irradiation. In addition, the catalytic lens provides about a 9× higher recovery rate, where water molecules inside the PEI lens deliver fast reassembly of the electron-hole pairs. The presented method with an ultimately simple fabrication step is expected to be applied to academic research and prototyping, including optoelectronic sensors, energy devices, and advanced manufacturing processes.

Nano-Titanium Oxide in Polymeric Contact Lenses: Short Communication

Many individuals suffer from myopia or hyperopia and astigmatism owing to the refractive defects of the eye optics or because of the use of inappropriate contact lenses. This study dealt with three polymers Poly(methyl methacrylate) (PMMA), Poly(Hydroxyl methacrylate) (PHEMA), and Poly(glycidyl methacrylate) (PGMA) and doping them with TiO2 nanoparticles to evaluate the difference between the effect of each lens on the human eye. The TiO2 NPs were prepared in this work by the sol–gel method to obtain 70–90 nm sized particles. Modulation transfer (MTF) and spot diagram were assessed to measure ocular performance. The PGMA-TiO2 contact lens provided the highest image quality at the lowest probability (P) of about p &lt; 0.0001 when inserted on an aberrated eye system because of its ability to eliminate the chromatic aberrations created inside the eyes having a smaller spot size.

A Monochromatic Optical Analytical Study of a Stepped Refractive Index Shell Spherical Polymeric Lens

The GRIN (gradient refractive index) Luneburg lens cannot be used in visible region applications including imaging systems and in the integrated photonic lens as static concentric symmetry lenses. Furthermore, in order to obtain free monochromatic aberration, the ray must be focused on the lens's rear surface. As a result, the detector must be movable on the rear surface. Technically, this procedure is difficult. This work presented a straightforward and practical method based on the usage of a double shell gradient stepped index of symmetry concentric polymeric lens (SCPL). The obtained results revealed that the proposed lens can be used in the visible region, as well as the shifting of the focus point from the lens's rear surface. The (SCPL) lens was optically evaluated using the trigonometric ray tracing method. The evaluation was performed using a mathematical iterative method applied in MATLAB program. The iterative method was used to determine the best shell thicknesses of shelled ball lens (double shell) for constructing the (SCPL) parameters. The constructive parameters were examined using the ZEMAX optical design program for infinite conjugate conditions and monochromatic wavelength. According to the analysis results, the Sterhl ratio is greater than (0.97), and the total transverse aberration coefficients are approaching zero.

Scanning high-sensitive x-ray polarization microscopy

We report on the realization of an extremely sensitive x-ray polarization microscope, allowing to detect tiniest polarization changes of 1 in 100 billion (10−11) with a μm-size focused beam. The extreme degree of polarization purity places the most stringent requirements on the orientation of the polarizer and analyzer crystals as well as the composition and the form fidelity of the lenses, which must not exhibit any birefringence. The results show that these requirements are currently only met by polymer lenses. Highly sensitive scanning x-ray polarization microscopy thus is established as a new method. It can provide new insights in a wide range of applications ranging from quantum electrodynamics and quantum optics to x-ray spectroscopy, materials research, and laser physics.