Lens Surface Research Articles

A new method for testing wide range horizontal field angle

In order to solve the problems of small measurement range, large error and low efficiency of laboratory optical field angle testing, a high-precision, easy -operating, high-efficient, and widely used horizontal field angle test method is proposed. It comes to a conclusion that the test method can reduce the experimental error through the analysis of the principle of the field of view error and the calculation of laboratory simulation. The simulation results show that for cameras with a field of view of more than 150 degrees, the measurement error can be reduced by 37 degrees, and when the field of view of the camera under test is close to 170 degrees, the method can reduce the measurement error by nearly 54 degrees. Meanwhile, a wide-range horizontal field angle measurement method is proposed. The camera under test is moved on the supporting mobile platform to image the target test board, and then the imaging target is read by reading the scale value on the test board calculates the angle of the camera under test. This method can effectively avoid the measurement error of the angle caused by the distance between the center of the lens surface and the center of the entrance pupil, so as to quickly obtain the angle of view test results, and improve the testing accuracy, and it is also suitable for cameras that measure a wide range of field angles (wide-angle camera or fisheye camera, etc.) to solve the problem of laboratory testing a wide range of horizontal field angles.

Proposal of Lubrication Mechanism of Contact Lens Surface by Observation of Hydration Layer Using FM-AFM

Proposal of Lubrication Mechanism of Contact Lens Surface by Observation of Hydration Layer Using FM-AFM

Influence of the Distance between Focusing Lens and Target Surface on the Characteristics of Laser-excited Lead Plasma

The present work investigated the effect of distance from target surface on the parameters of lead plasma excited by 1064nm Q-switched Nd:YAG laser. The excitation was conducted in air, at atmospheric pressure, with pulse length of 5 ns, and at different pulse laser energies. Electron temperature was calculated by Boltzmann plot method based on the PbI emission spectral lines (369.03 nm, 416.98 nm, 523.48, and 561.94 nm). The PbI lines were recorded at different distances from the target surface at laser pulse energies of 260 and 280 mJ. The emission intensity of plasma increased with increasing the lens-to-target distance. The results also detected an increase in electron temperature with increasing the distance between the focal lens and the surface of the target in all laser energies under study. In addition, the electron number density was determined by using the Stark broadening method. The data illustrated that the electron number density was increased with increasing the distance from target surface, reaching the maximum at a distance of 11 cm for all pulse laser energy levels under study.

PERPINDAHAN PANAS HYBRID PHOTOVOLTAIC DAN THERMOELEKTRIC GENERATOR DENGAN HOT MIRROR

Heat transfer is the transfer of energy from one area to another due to the temperature difference between these areas. Wasted heat energy can be converted into electricity using (TEG) between the hot and cold sides. If the temperature difference is more significant, the efficiency may increase along with the operating temperature of the TEG-type material. So in this study, the author will calculate the heat transfer that occurs in Photovoltaic (PV), Thermoelectric Generator (TEG), and Hot Mirrors by utilizing thermal energy light produced from Muxindo LED bulbs with 10 Watt, 15 Watt, and 20 Watt power. The results of this study indicate that by using 10, 15, and 20 Watt LED bulbs for free convection heat transfer, the power generated from each point increases because it passes through several obstacles from objects that experience a decrease in temperature to PV and TEG, with the characteristics of the displacement. The movement of molecules from the medium importance follows convection heat at every point of transfer in the intermediate substance. The most significant power generated from radiant heat transfer is about 0.1873 Watt. It occurs on the surface of the fresnel lens using a 20 Watt LED bulb with the characteristic that the radiation propagates in a straight line and does not require an intermediate medium to transfer heat from one substance to another. The most significant conduction heat transfer power, 0.2453 Watt, occurs in Fresnel Lens using a 20 Watt LED bulb with heat transfer characteristics in solid objects.

Modeling of formation regularities of conical surfaces

The scheme of processing conical surfaces by grinding them to a flat tool is considered and a technical solution for the implementation of such processing is proposed. Using the created device allows implementing the group method of forming conical parts with a deviation of the generatrix of the cone from straightness of not more than ± 0.00012 mm. A mathematical model of the patterns of removal of stock from a conical part with a flat tool is developed. A formula is obtained for calculating the modulus of the sliding velocity at any point on the processed conical surface, which implements engineering methods for controlling the shaping of conical parts without conducting preliminary labor-intensive experimental studies. An optimization technique for the adjustment parameters of technological equipment was proposed. The most effective axicon processing modes were revealed at the stages of preliminary, medium and fine grinding, as well as at the polishing stage, depending on the technological heredity of the workpiece from the point of view of distribution of the stock to be removed over its surface. It has been established that changes in the eccentricity between the axes of rotation of the tool and the faceplate as well as the amplitudes of the reciprocating rotational movements of the latter practically do not affect both accuracy and processing productivity, therefore, in practice, these parameters can not be optimized, but their average values can be assigned. The operating modes of the basic lever grinding and polishing machine are established, at which the required accuracy of the working surface of the tool is provided, which directly affects the straightness of the generatrix of the cone. Studies of the regularities of the shaping of the side surface of a conical lens in the conditions of free grinding are carried out and the adjustment parameters of technological equipment that affect the quality and productivity of the processing process are determined.

Optimum | Tangible Hydra-PEG™ – Gaining Momentum in the Industry

The issue of hydrophilicity of the surface of gas permeable contact lenses remains one of the persistent problems. Tangible Hydra-PEG™ surface coating is applied to gas permeable contact lenses to significantly improve wettability and wearing comfort. Although it is mainly used to alleviate dry eye symptoms in scleral and corneal lens users, particularly for those patients with corneal ectasia and/or Ocular Surface Disease (OSD), it can be used in other modalities. This article describes the development of the product and describes the benefits of its use in a clinical case.

Lens Biometry in Congenital Lens Deformities: A Swept-Source Anterior Segment OCT Analysis.

Aims: To investigate the lens biometric parameters in congenital lens deformities, using a novel technique of swept-source anterior segment optical coherence tomography (SS-ASOCT).Methods: This prospective study included patients with microspherophakia (MSP), coloboma lentis (CL), and posterior lenticonus (PL). For this cohort, 360-degree high-resolution lens images were obtained using the latest SS-ASOCT (CASIA2, Tomey Corp, Nagoya, Japan). The lens biometric parameters were calculated by the CASIA2 built-in software for anterior lens radius (ALR), posterior lens radius (PLR), anteroposterior distance (APD), anterior chamber depth (ACD), equatorial diameter (Eq Dia), rear projection length (RPL), and maximum diameter of the lesion (MDL).Results: This study included two eyes each with MSP and CL and one eye with PL. The lens of MSP was spherical and posteriorly dislocated, with decreased ALR and PLR, Eq Dia, but increased APD. In patients with CL, the coloboma was isolated, bilateral, inferior, and located toward the maldeveloped ciliary body. High astigmatism was mainly lenticular, and this was calculated by the ALR and PLR. Regarding the site of coloboma, a significant decrease in ALR was observed, while the PLR and APD were not affected. The PL eyes had a cone-shaped protrusion of the posterior lens surface with a subtle cataractous region around the apex. An extremely high posterior surface curvature was observed with a mean PLR of 1.67 mm. The RPL and MDL were about 1.80 and 0.4 mm, respectively, which were homogenous at different sections.Conclusions: The CASIA2 is a valuable option for in vivo crystalline lens measurement for congenital lens deformities, enabling the accurate diagnosis and providing illuminating insights into the pathogenesis of MSP, CL, and PL

Uveitis-mediated immune cell invasion through the extracellular matrix of the lens capsule.

While the eye is considered an immune privileged site, its privilege is abrogated when immune cells are recruited from the surrounding vasculature in response to trauma, infection, aging, and autoimmune diseases like uveitis. Here, we investigate whether in uveitis immune cells become associated with the lens capsule and compromise its privilege in studies of C57BL/6J mice with experimental autoimmune uveitis. These studies show that at D14, the peak of uveitis in these mice, T cells, macrophages, and Ly6G/Ly6C+ immune cells associate with the lens basement membrane capsule, burrow into the capsule matrix, and remain integrated with the capsule as immune resolution is occurring at D26. 3D surface rendering image analytics of confocal z‐stacks and scanning electron microscopy imaging of the lens surface show the degradation of the lens capsule as these lens‐associated immune cells integrate with and invade the lens capsule, with a subset infiltrating both epithelial and fiber cell regions of lens tissue, abrogating its immune privilege. Those immune cells that remain on the surface often become entwined with a fibrillar net‐like structure. Immune cell invasion of the lens capsule in uveitis has not been described previously and may play a role in induction of lens and other eye pathologies associated with autoimmunity.

4D Printing of Plasmon‐Encoded Tunable Polydimethylsiloxane Lenses for On‐Field Microscopy of Microbes

AbstractHere the 4D printing of a magnifying polydimethylsiloxane (PDMS) lens encoded with a tunable plasmonic rejection filter is reported. The lens is formed by moldless printing of PDMS pre‐polymer on a nanostructured porous silicon (PSi) templating layer. A nanometer‐thick plasmonic filter is integrated on the lens surface by in situ synthesis of Ag and Au nanoparticles (NPs) with programmed density. The filter can be designed to reject light at the plasmonic resonance wavelength of the NPs with an optical density tunable from 0 to 3 and retreive light at longer wavelengths with a pass‐to‐stop band ratio tunable from 0 to 60 dB. Swelling of PDMS in hexane and ether is used to change the NP density on the lens surface and modulate, in turn, the transmittance properties of the NP‐decorated lens over 3 orders of magnitude. The plasmon‐encoded lens is coupled to a commercial smartphone demonstrating: shaping of the emission spectrum of a white light‐emitting diode to tune the color from yellow to purple; real‐time bright‐field and fluorescence microscopy of living microbes in water, namely, the auto‐fluorescent green alga Chlorogonium sp. and the ciliated protozoan Euplotes daidaleos.

Ray tracing in thermally loaded optical systems

AbstractHigh‐power laser beams are usually imaged with the help of suitable optics. The propagation of such beams, through optical systems, often result in a focus shift. This is mainly due to the deposited power in the beam acting as a heat source in the optical elements. Finally, the resulting change in temperature leads to both, a deformation of the lens surface, and a change of the refractive index in the lens. Ray tracing and the finite element method are needed in order to analyze the above effects. The accuracy and the computational time of focus shift calculations, in both simulation techniques, are strongly influenced by the interpolation of the data. This paper will present, a newly proposed interpolation method, allowing a fast and accurate interpolation of data using an unstructured finite element grid. This method will specifically focus on the accurate calculation of laser beam thermal load inside an optical lens.

Morphological Characteristics of Drug-Eluting Biodegradable Polymeric Thin Films Developed on the Surface of Intraocular Lenses by Three Techniques: A Comparative Study.

BackgroundCataract surgery is a very popular operation that requires a postoperative period of frequent instillation of antibiotic and anti-inflammatory eye drops. Modified drug-eluting intraocular lenses (IOLs) may eliminate the need for eye drops after surgery.AimThe purpose of this study is to compare the morphological characteristics of dexamethasone eluting biodegradable polymeric thin films developed on the surface of commercially available IOLs by three different methods.MethodThis experimental study was conducted between May and August of 2021 in the Lab for Thin Films - Nanobiomaterials - Nanosystems & Nanometrology (LTFN) of the Aristotle University of Thessaloniki. A mixture of two organic polymers [Poly (D, L-lactide-co-glycolide)(PLGA), lactide: glycolide (75:25) and Polycaprolactone (PCL)] and dexamethasone was prepared and then deposited on the surface of three-piece IOLs by spin coating, by spray coating, and by gravure printing. The modified IOLs were sterilized with the use of ultraviolet (UV) radiation and plasma treatment. Their structural properties were studied with the use of atomic force microscopy (AFM).ResultsSpin coating and gravure printing produced uniform thin films on the surface of the IOLs which were not damaged during the sterilization process. Spray coating led to the partial coating of the surface of the IOLs; the thin films underwent alterations following plasma treatment.ConclusionsThin films developed by spin coating and gravure printing on IOLs demonstrate the desired morphological characteristics that make them suitable candidates for further research.

Nanoscaled Morphology and Mechanical Properties of a Biomimetic Polymer Surface on a Silicone Hydrogel Contact Lens.

Materials taking advantage of the characteristics of biological tissues are strongly sought after in medical science and bioscience. On the natural corneal tissue surface, the highly soft and lubricated surface is maintained by composite structures composed of hydrophilic biomolecules and substrates. To mimic this structure, the surface of a silicone hydrogel contact lens was modified with a biomimetic phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), and the nanoscaled morphology and mechanical properties of the surface were confirmed with advanced surface characterization and imaging techniques under an aqueous medium. Concavities and convexities on the nanometer order were recognized on the surface. The surface was completely covered with a PMPC layer and remained intact even after 30 days of clinical use in a human ocular environment. The mechanical properties of the natural corneal tissue and the PMPC-modified surface were similar in the living environment, that is, low modulus and frictional properties comparable to natural tissues. These results show the validity of material preparation by biomimetic methods. The methodologies developed in this study may contribute to future development of human-friendly medical devices.

Centrifugally concentric ring-patterned drug-loaded polymeric coating as an intraocular lens surface modification for efficient prevention of posterior capsular opacification

Posterior capsular opacification (PCO) is the main postoperative complication after intraocular lens (IOL) implantation in cataract surgery, because of the proliferation of the residual lens epithelial cells (LECs) in the lens capsule. Drug-eluting IOLs, aimed to develop an in situ drug delivery device, are the promising concept in recent years. As IOLs are optical devices other than implants, the feasibility and applicability remain a challenge for drug-eluting coatings. In this investigation, a centrifugally concentric ring-patterned drug-loaded poly(lactide-co-glycolic acid) (PLGA) coating was designed and fabricated by the spin coating technique. The concentric ring-patterned morphologies and the drug loading and release properties were carefully investigated, and the spin coating parameters were optimized. A concentric annular coating with a thin center and thick periphery was obtained, which was particularly suitable for the surface modification of IOLs, as the visual pathway of the intraocular light transmission greatly requires good light transmittance of the IOLs. IOLs with the immunosuppressant cyclosporin A (CsA)-loaded coating (CsA @ PLGA) modification were then fabricated for PCO prevention. The in vitro LECs culture results showed that the CsA @ PLGA coating-modified IOLs significantly inhibited cell proliferation and induced cell death. Western blot analysis showed that the efficient cell inhibition behavior of CsA was due to the autophagy-mediated cell death pathway. The in vivo intraocular implantation results confirmed the desired PCO inhibition effect. Thus, the centrifugally concentric ring-patterned drug-loaded PLGA coating obtained by the spin coating technique provides a simple yet effective alternative of IOL modification for PCO prevention. Statement of Significance• Concentric ring-patterned polymer coating, specifically for drug-eluting IOL fabrication, was developed by the spin coating technique.• The immunosuppressant CsA inhibited LEC proliferation through the autophagy-mediated cell death pathway.• Concentric ring-patterned CsA-eluting IOLs exhibited reliable in vivo PCO prevention.• The drug-eluting IOLs fabricated by the simple and economical spin coating technique have a great potential in clinical translation.

Silicone Oil Adhesion to Hydrophobic Acrylic Intraocular Lenses: A Comparative Laboratory Study of a New versus an Established Hydrophobic Acrylic Intraocular Lens Material.

Background In vitro assessment of silicone oil adhesion to a new hydrophobic acrylic intraocular lens (IOL) material, the Clareon model CNA0T0, compared with the established AcrySof model SN60WF was carried out. Methods Silicone oil adhesion was assessed for two types of IOLs, Clareon CNA0T0 (n = 10) and AcrySof SN60WF (n = 10). Lenses were immersed in an aqueous sodium chloride solution for 12 hours and then incubated at room temperature in silicone oil for 12 hours. The lenses were washed with distilled water and photographed at 25x magnification using a microscope. The percent coverage was calculated by dividing the area of oil coverage by the total surface area of the lens. Results Silicone oil adhesion to the surface of the CNA0T0 lens ranged from 4% to 22%, with a mean ± SD coverage of 8% ± 4%. Silicone oil adhesion to the surface of the SN60WF lens ranged from 1% to 17%, with a mean coverage of 9% ± 4%. The silicone oil adhesion of CNA0T0 was equivalent to that of SN60WF (P > 0.05). Conclusions The new Clareon model CNA0T0 IOL has silicone oil adhesion and interaction that are equivalent to the established AcrySof IOL.

Effect of the target positions on the rapid identification of aluminum alloys by using filament-induced breakdown spectroscopy combined with machine learning

Filament-induced breakdown spectroscopy (FIBS) combined with machine learning algorithms was used to identify five aluminum alloys. To study the effect of the distance between focusing lens and target surface on the identification accuracy of aluminum alloys, principal component analysis (PCA) combined with support vector machine (SVM) and K-nearest neighbor (KNN) was used. The intensity and intensity ratio of fifteen lines of six elements (Fe, Si, Mg, Cu, Zn, and Mn) in the FIBS spectrum were selected. The distances between the focusing lens and the target surface in the pre-filament, filament, and post-filament were 958 mm, 976 mm, and 1000 mm, respectively. The source data set was fifteen spectral line intensity ratios, and the cumulative interpretation rates of PC1, PC2, and PC3 were 97.22%, 98.17%, and 95.31%, respectively. The first three PCs obtained by PCA were the input variables of SVM and KNN. The identification accuracy of the different positions of focusing lens and target surface was obtained, and the identification accuracy of SVM and KNN in the filament was 100% and 90%, respectively. The source data set of the filament was obtained by PCA for the first three PCs, which were randomly selected as the training set and test set of SVM and KNN in 3:2. The identification accuracy of SVM and KNN was 97.5% and 92.5%, respectively. The research results can provide a reference for the identification of aluminum alloys by FIBS.

End-to-end learned single lens design using fast differentiable ray tracing.

In traditional imaging system design, the optical lens is often optimized toward the artificial optimization target like modulation transfer function and field-of-view (FoV). This usually leads to complex stacks of lenses. In order to reduce the complexity, we propose an end-to-end single lens imaging system design method. First, the imaging and processing model is established, whose input end is the ground truth image, and the output end is the restored image by Res-Unet. Then, with the optimization target of minimizing the difference between the restored image and the ground truth image, the parameters of the lens surface and the parameters of the restoration algorithm are optimized simultaneously by deep learning. In order to realize the end-to-end design, the imaging model is required to be differentiable to the lens parameters, so a fast differentiable ray tracing model is proposed. A single lens imaging system with high-quality large FoV (47°) has been designed by the end-to-end method. This method will have a wide application prospects in the design of light and small optoelectronic imaging systems.

SAW-driven self-cleaning drop free glass for automotive sensors

This paper presents surface acoustic wave (SAW)-driven self-cleaning glass aimed at removing contaminants that occur on the surfaces of automotive sensors for autonomous driving. The proposed self-cleaning glass comprises an interdigitated transducer (IDT) patterned on top of the transparent piezoelectric substrate (LiNbO3) and a hydrophobic layer (Cytop) covering the IDT. First, the sliding angle and contact angle of a droplet on a hydrophobic layer are measured in different volumes without the application of any external forces. The experiment shows that the droplets smaller than 4 μl do not slide on the inclined surface. To investigate the effect of SAW on droplet removal, the traveled distances and speeds of droplets are measured in different volumes, viscosities, and applied voltages when the droplets are removed on the surface by the SAW operation of the fabricated self-cleaning glass. Then, it is also investigated that the motion of the droplets by SAW on the inclined substrate in the direction of gravity and the opposite direction. Quantitative tests on the droplet removal performance of the SAW-driven self-cleaning glass are carried out by analyzing captured images recorded during the droplet removal by the SAW operation. As proof of concept, the proposed self-cleaning technology is demonstrated on droplets formed on a lens surface of a camera on which the SAW device is mounted. The demonstration shows that the camera image distorted by droplets that occur on the initial glass cover of the camera module is quickly restored by the SAW operation. The proposed SAW-driven drop free glass can promptly remove various contaminants on the surface of the sensors. Hence, it can be applied not only for automotive sensors but also for outdoor security cameras for daily life safety and future industries such as smart factories and smart cities.

3D Printing of Customized Aspheric Lenses for Imaging.

A simple and efficient process for fabricating customized aspheric lenses is reported, in which a stereolithographic 3D printer combined with the meniscus equilibrium post-curing technique is employed. Two kinds of UV-curable resins, DentaClear and HEMA, were used for printing aspheric lenses in our experiments. The printed DentaClear lens featured low surface profile deviation of ~74 and showed satisfactory optical imaging resolution of 50.80 lp/mm, i.e., 4.92 . The surface roughness of the printed lens with DentaClear was measured to be around 2 nm with AFM. The surface roughness was improved as a result of post-curing, which reduced the ripples on printed lens surfaces. In contrast, the printed HEMA lens exhibited a significant stair-stepping effect with a large surface profile deviation of ~150 . The ripples were somewhat apparent even if the printed HEMA lens surface was smoothed by means of post-curing. No sharp image can be obtained with the HEMA lens in the resolution testing. The composition of HEMA resin may be the reason for the relatively poor surface quality and optical properties.

Correlation between surface friction and the hydrophobicity of structure-related side-chain exposure of albumin on contact lens

The management of contact lens discomfort remains a challenge leading to the increased contact lens dropout rates. Tear protein accumulates on the lens surfaces with different configurations observed are correlated to the lens friction, with the improved comfort experienced by reduced surface friction in the eye. However, protein adsorption is a complex process with the combined protein-protein interactions (PPI) and protein-surface interactions (PSI) involved, which is difficult to explain the complicated tribological behavior in terms of protein structural shifts alone on lens surfaces. On the other hand, the type of solvent-exposed side chains from specific protein conformations on lens surfaces should be more important to the lens friction involved. We aim to investigate the correlation between the structure-related side-chain exposure and corresponding lens friction of adsorbed tear proteins on lens surfaces under varied PPI and PSI. Albumin was the model protein adsorbed onto the conventional lens material. Such as polymethylmethacrylate (PMMA) or the poly-2-hydroxyethyl methacrylate (PHEMA) surfaces applied here. Adsorption was conducted under varying protein solution concentrations to saturate the model surface to change the PPI effects over a wide range. Our results indicate that PPI effects help stabilize protein structures on both surfaces. When PPI is minimized, a distinct correlation was observed between the surface friction and the hydrophobicity of structure-related side-chain exposure of albumin on lens surfaces depending on the different PSI involved. At a fundamental understanding, our results would provide insights for developing new lens materials or the lens care solution designs to reduce the lens discomfort.

Cosmetics and Contact Lenses: Influence on Safety

The article describes the effect of decorative cosmetics on the material of soft contact lenses and studies specific features that can be observed in SCL wearers who use cosmetics extensively. Examples of complications associated with the use of various cosmetic products that may occur in contact lens wearers are given. Conclusion: in cases when patients have complaints about discomfort and dry eyes, doctors should pay attention to the amount of decorative cosmetics used as well as study the effect it can have on the surface of the contact lenses.