Haze Measurements Research Articles

Corneal Scheimpflug Densitometry Following Photorefractive Keratectomy in Myopic Eyes.

To evaluate the modification of corneal optical densitometry following photorefractive keratectomy (PRK) using Scheimpflug topography. Corneal densitometry (0 to 100 grayscale units [GSU]), pachymetry, and keratometry were evaluated using a rotating Scheimpflug camera (Pentacam HR; Oculus Optikgeräte, GmbH, Wetzlar, Germany) at baseline and 1 and 3 months following PRK in myopic patients. Subjective refraction, uncorrected distance visual acuity, corrected distance visual acuity, and corneal haze (0 to 4 on common subjective scale) were evaluated preoperatively at baseline, 1 month, and 3 months. The study included 75 eyes (38 right eyes, 37 left). The preoperative mean spherical equivalent and cylinder were -2.28 ± 1.24 and 0.92 ± 0.65 diopters (D), respectively. Maximal corneal densitometry (central 4 mm) was 27.44 ± 1.93 GSU at baseline. At 1 month postoperatively, corneal haze with a mean clinical grade of 0.54 ± 0.45 (P < .0001) was observed, associated with corneal densitometry increased to 29.69 ± 5.16 GSU (P > .05). At 3 months postoperatively, mean clinical haze decreased to 0.11 ± 0.24 (P < .0001) and was associated with a significant decrease (P < .0001) in maximal densitometry (25.13 ± 3.42 GSU). Corneal densitometry could represent a useful objective measurement of postoperative mild corneal haze and aid in the rating and follow-up of refractive surgery. [J Refract Surg. 2016;32(11):788-791.].

Use of new imaging in detecting and monitoring ocular manifestations of the mucopolysaccharidoses.

The aim of this review is to summate the eye involvement in patients with mucopolysaccharidoses (MPS) using current ocular imaging techniques, their advantages and disadvantages and how they may aid diagnosis, management and monitoring. We critically reviewed the current literature surrounding MPS and recent imaging technology as well as histology. Primary searches of PubMed and Web of Science were performed. We reviewed all papers on the topic published and summarized the findings of each medical device as well as the advantages and disadvantages of using these for the MPS patient. We discussed the potential of each of these devices to monitor potential ocular pathology in the MPS cohorts in the order of MPS subtype. We reviewed imaging techniques involving use of the Iris Camera, Pentacam, Optical Coherence Tomography (OCT) as well as ultrasound and Heidelberg OCT. The need for reliable objective quantification of eye findings in MPS has led to utilization of new imaging technologies described here, and future use will enhance our understanding of the unique eye features in MPS. In particular, we note that the Pentacam and iris camera are able to provide objective measurements of corneal haze and monitor ocular response to treatment.

Corneal Densitometry: Repeatability in Eyes With Keratoconus and Postcollagen Cross-Linking.

To assess the repeatability of densitometry, a measure of corneal haze, in the control (group I), keratoconic (group II), and postcollagen cross-linking (CXL, group III) eyes as measured on Scheimpflug imaging. Densitometry values for 160 eyes of 160 patients (50 eyes of 50 patients in group I, 50 eyes of 50 patients in group II, and 60 eyes of 60 patients in group III) were obtained for the 0- to 2-mm, 2- to 6-mm, and 6- to 10-mm zones of the anterior (up to 120 μm), posterior (posterior 60 μm), and central (between the anterior and posterior) cornea. The repeatability of these values was assessed by within-subject standard deviation, coefficient of repeatability, and coefficient of variation. Range of within-subject standard deviation and coefficient of variation in the control group (0.2%-0.5% and 2%-4%, respectively) was significantly better (less variable) than those in the keratoconus group (0.4%-0.6% and 3%-5%). The same parameters in the post-CXL group (0.8%-3.8% and 7%-15%) were significantly worse (more variable) than that in the other 2 groups. The repeatability measures of densitometry were significantly worse in the central 0- to 2-mm zone compared with the other 2 zones and for the anterior region compared with the central and posterior regions of cornea in all the 3 groups. Consequent to the low repeatability in post-CXL eyes, densitometry should be used with caution to gauge response to treatment and visual outcomes in treated keratoconus eyes.

Mechanical Properties and Isothermal Crystallization Behaviour of Poly(lactide)/Poly(methyl methacrylate)/α-Cellulose Composites

Polylactide (PLA)/polymethylmethacrylate (PMMA)/α-cellulose composites were fabricated using a twin-screw extruder. During fabrication, α-cellulose short fibres were incorporated for improving the toughness of the brittle PLA and a chain extender was used for reducing PLA hydrolysis. Highly transparent PLA and PMMA were blended to obtain miscible and transparent blends. For evaluating the performance of the PLA/PMMA/α-cellulose composites, a series of measurements, including tensile and Izod impact tests, light transmission and haze measurements, thermomechanical analysis, and determination of isothermal crystallisation behaviour, was conducted. Adding the chain extender considerably reduced the occurrence of hydrolytic degradation. Both the chain extender and α-cellulose short fibres increased the elongation at break and Izod impact strength of the composites. Compared with the neat PLA, including 1.0 wt% α-cellulose short fibres increased the elongation at break and Izod impact strength of the composite PLA by approximately 211 and 219 %, respectively. According to the observed mechanical performance, the optimal blending ratios for PLA and PMMA were between 90:10 and 80:20. The total light transmittance of the composites was as high as 91 %, indicating that the PLA/PMMA blend was highly miscible. The haze value of the PLA/PMMA/α-cellulose composites was lower than 32 %. Incorporating cellulose short fibres increased the number of crystallisation sites and crystallinity of the PLA/PMMA/α-cellulose composites while reducing the spherulite dimensions.

Additive roll printing activated cold welding of 2D crystals and 1D nanowires layers for flexible transparent conductor and planer energy storage

Large scale integration of 2D crystals and metal nanowires (NWs) with low junction resistance has been a long time challenge for functional structures. Herein, roll to roll printing technique was utilized to directly produce graphene oxide (GO) nanoplatelets stack laminated with metal NWs. This 2D/1D laminated structure activates high pressure between AgNWs, enables localized fusion, and opens a new way to tackle with local nanojunction resistance. Molecular dynamic simulations reveal that this cold nanojoining originates from high localized pressure activated isolated metal atoms, which possess high mobility, flow over nanojunction and recrystallize to form nanojoints. Compared with bare AgNWs network, the GO laminated counterparts achieve excellent performance (17Ω/sq, 93%@λ=550nm), which enlightens optoelectronics applications. The cross nanowire junction resistance decrease is verified by classical percolation theory and experimental characterizations. Haze measurements show that the scattering is significantly reduced. Laminated structure has been engineered layer by layer to accomplish quasi-3D hybrid film, which demonstrated application in flexible supercapacitors with high specific capacitance of 109 F g−1. This hybrid 2D/1D nanomaterial thin film also demonstrated excellent stability during cyclic foldability, stretchability, high temperature and oxidation tests. These investigations provide insight for layered manufacturing of 2D crystals/1D NWs structure and quasi-3D hybrid film for energy storage applications.

雾霾治理中加速更新老旧机动车政策法律问题研究

近年来雾霾天气问题愈发猛烈，经济发展和人民身体健康都造成了严重的损害。机动车排放污染作为造成雾霾天气的主要因素之一，一直是雾霾治理工作的重点。同等行使里程条件下，一辆国I标准汽油小客车的排放相当于六辆以上国V标准小客车。因此，雾霾治理的一项重要举措就是加速更新老旧机动车。通过分析机动车污染排放数据，本文以北京市为例剖析了与更新老旧机动车政策有关的法律问题。发现现在实施的补贴和限行措施都存在着一定的问题。通过进一步对美国加州雾霾治理的成熟经验进行研究；笔者为构建我国更新老旧机动车政策长效实施机制，提出推动机动车污染防治专门立法和引入排污权交易两个层面的建议。 In recent years, the haze weather problems have caused serious damage to economic development and people’s health. As one of the main factors causing haze weather, the motor vehicle emission pollution has always been the focus of the haze governance. Under the same exercise mileage, the emission of one national I standard petrolic car is equivalent to six national V standard petrolic cars. Therefore, an important measure of governance haze is to accelerate the update of the old motor vehicle. This paper takes Beijing as an example to analyze the legal issues related to the renewal of the old motor vehicle policy by the analysis of motor vehicle pollution emission data. It is found that there are some problems in the subsidy and the limit line. Through further research on the mature experience of the United States California haze governance, the author puts forward two proposals for constructing the long term implementation mechanism of China’s renewal of old motor vehicles policy. One is to promote the legislation of Motor vehicle pollution prevention and control; the other is to introduce the emission trading.

Highly transparent conductive electrode with ultra-low HAZE by grain boundary modification of aqueous solution fabricated alumina-doped zinc oxide nanocrystals

Commercial production of transparent conducting oxide (TCO) polycrystalline films requires high electrical conductivity with minimal degradation in optical transparency. Aqueous solution deposited TCO films would reduce production costs of TCO films but suffer from low electrical mobility, which severely degrades both electrical conductivity and optical transparency in the visible spectrum. Here, we demonstrated that grain boundary modification by ultra-violet laser crystallization (UVLC) of solution deposited aluminium-doped zinc oxide (AZO) nanocrystals results in high Hall mobility, with a corresponding dramatic improvement in AZO electrical conductance. The AZO films after laser irradiation exhibit electrical mobility up to 18.1 cm2 V−1 s−1 with corresponding electrical resistivity and sheet resistances as low as 1 × 10−3 Ω cm and 75 Ω/sq, respectively. The high mobility also enabled a high transmittance (T) of 88%-96% at 550 nm for the UVLC films. In addition, HAZE measurement shows AZO film scattering transmittance as low as 1.8%, which is superior over most other solution deposited transparent electrode alternatives such as silver nanowires. Thus, AZO films produced by the UVLC technique have a combined figure of merit for electrical conductivity, optical transparency, and optical HAZE higher than other solution based deposition techniques and comparable to vacuumed based deposition methods.

Physical properties and crystallization behavior of poly(lactide)/poly(methyl methacrylate)/silica composites

ABSTRACTPoly(lactide)/poly(methyl methacrylate)/silica (PLA/PMMA/SiO2) composites were fabricated using a twin‐screw extruder. Nanosilica particles were incorporated to improve the toughness of the brittle PLA, and a chain extender reagent (Joncryl ADR 4368S) was used to reduce the hydrolysis of the PLA during fabrication. Highly transparent PLA and PMMA were designated to blend to obtain the miscible and transparent blends. To estimate the performance of the PLA/PMMA/SiO2 composites, a series of measurements was conducted, including tensile and Izod impact tests, light transmission and haze measurements, thermomechanical analysis, and isothermal crystallization behavior determination. A chain extender increases the ultimate tensile strength of the PLA/PMMA/SiO2 composites by ∼43%, and both a chain extender and nanosilica particles increase Young's modulus and Izod impact strength of the composites. Including 0.5 wt % nanosilica particles increase the elongation at break and Izod impact strength by ∼287 and 163%, respectively, compared with those of the neat PLA. On account of the mechanical performances, the optimal blending ratio may be between PLA/PMMA/SiO2 (90/10) and PLA/PMMA/SiO2 (80/20). The total light transmittance of the PLA/PMMA/SiO2 composites reaches as high as 91%, indicating a high miscible PLA/PMMA blend. The haze value of the PLA/PMMA/SiO2 composites is less than 35%. Incorporating nanosilica particles can increase the crystallization sites and crystallinities of the PLA/PMMA/SiO2 composites with a simultaneous decrease of the spherulite dimension. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42378.

Light Scattering and Current Enhancement for Microcrystalline Silicon Thin-Film Solar Cells on Aluminium-Induced Texture Glass Superstrates with Double Texture

Microcrystalline silicon (μc-Si:H) thin-film solar cells are processed on glass superstrates having both micro- and nanoscale surface textures. The microscale texture is realised at the glass surface, using the aluminium-induced texturing (AIT) method, which is an industrially feasible process enabling a wide range of surface feature sizes (i.e., 700 nm–3 μm) of the textured glass. The nanoscale texture is made by conventional acid etching of the sputter-deposited transparent conductive oxide (TCO). The influence of the resulting “double texture” on the optical scattering is investigated by means of atomic force microscopy (AFM) (studying the surface topology), haze measurements (studying scattering into air), and short-circuit current enhancement measurements (studying scattering into silicon). A predicted enhanced optical scattering efficiency is experimentally proven by a short-circuit current enhancementΔIscof up to 1.6 mA/cm2(7.7% relative increase) compared to solar cells fabricated on a standard superstrate, that is, planar glass covered with nanotextured TCO. Enhancing the autocorrelation length (or feature size) of the AIT superstrates might have the large potential to improve theμc-Si:H thin-film solar cell efficiency, by reducing the shunting probability of the device while maintaining a high optical scattering performance.

Sol-Gel Derived Single Layer Zeolite-MgF2 Composite Antireflective Coatings with Improved Mechanical Properties on Polycarbonate

Single layer antireflective coatings with good optical and mechanical properties are difficult to be obtained on temperature sensitive substrates like plastics. This challenge has been taken up in the present study. Single layer MgF2 and for the first time, zeolite 4Å and zeolite 4Å - MgF2 composite antireflective coatings were generated by a wet chemical route on flat polycarbonate sheets and characterized for their reflectance, surface roughness, thickness, porosity, surface morphology and scratch hardness by haze measurement. Autoclaving and boiling water treatment under microwave irradiation were used in case of MgF2 sols and zeolite/zeolite-MgF2 coatings respectively. Pure MgF2 coatings deposited after autoclaving of the MgF2 sol yielded a low refractive index of 1.28 and an average reflectance of 1.9% vis-à-vis 9.7% reflectance for an uncoated polycarbonate substrate over the wavelength range of 400-1100 nm. Single layer zeolite coatings after a brief treatment in boiling water under microwave irradiation yielded a reflectance of 5.1%. A composite zeolite-MgF2 coating exhibited a reflectance of 2.8% and the percentage change in haze after crockmeter testing in case of the composite coating was lower than that of a pure MgF2 coating. This implied that the composite layer had improved mechanical properties combined with good optical properties and could be suitable for practical applications.

Sol–gel derived scattering layers as substrates for thin-film photovoltaic cells

Agglomerated silica particles were coated on glass by dip-coating; the resulting films exhibited optical scattering. With constant optical transmittances >80% their haze could be modified by the withdrawal rate applied for the respective deposition procedure. Film thickness, surface topography and coverage of the substrate were characterized by Scanning Electron Microscopy and Atomic Force Microscopy.For the use in radiation management in thin-film silicon solar cells in a first step the scattering layers were coated with aluminum-doped zinc oxide by sputtering; the optical performance of the resulting bilayer was characterized by haze measurements and angle resolved scattering spectroscopy. Quantum efficiencies of complete solar cells could be determined after the deposition of a hydrogenated amorphous Si/hydrogenated microcrystalline Si tandem absorber and application of metallic back contacts. It turned out that the external quantum efficiency of the resulting cells is not directly related to the light scattering performance of the scattering layer used.

Measurement of Atmospheric Haze and its Effect on Image Detail

The Photogrammetric RecordVolume 29, Issue 146 p. 266-266 Letters to the Editor Measurement of Atmospheric Haze and its Effect on Image Detail Grant H. Thomson, Grant H. Thomson Great Missenden, UKSearch for more papers by this author Grant H. Thomson, Grant H. Thomson Great Missenden, UKSearch for more papers by this author First published: 15 June 2014 https://doi.org/10.1111/phor.12066_2Read the full textAboutPDF ToolsRequest permissionExport 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 onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume29, Issue146June 2014Pages 266-266 RelatedInformation

Forward light scatter and visual acuity through scratched protective eyewear

BackgroundScratches and other surface abrasions on protective eyewear can shorten their life cycle by scattering light from the image, which will compromise visual performance. Although scratch and abrasion resistance testing is well developed, there is little information available regarding visual acuity through lenses scratched in an actual work environment.MethodsWe collected protective eyewear from mine and smelting operations that had been returned because vision through the lenses was unacceptable due to scratches and abrasions. Forward scattered light was measured on both cleaned and partially cleaned lenses using both haze and light diffusion measurements. Visual acuity through a selection of lenses was determined for both high and low contrast letters under photopic light levels.ResultsLenses with scratches in the central region had haze values ranging from one to 30 per cent. The highest haze values were measured on lenses that were both scratched and covered with dirt, whereas haze values less than 10 per cent were measured on lenses that had the dirt removed and just had scratches in the central region. Light diffusion values were highly correlated with haze. Visual acuity for high and low contrast letters became worse as the percentage haze increased but the linear correlation was only moderate.ConclusionThe appearance of the scratches on the lens surfaces strongly suggests that they were a result of improper lens cleaning. The findings also suggest that haze values less than two per cent or a luminance reduction factor less than 3.0-cd/(m2 lx) are unlikely to affect high and low contrast acuity.

Properties of reactive sputtered alumina–silica mixtures

Standard antireflective coatings applied to hard substrates like sapphire suffer from poor abrasion resistance. Silica is used as low refractive index layer in many multilayer systems although it has a lower hardness than the substrate. In this work an attempt was made to enhance the hardness by the addition of alumina. Magnetron sputtering was used in two different ways because it delivers dense coatings with high durability. Nanoindention hardness measurements of mixed alumina-silica films are presented in comparison to haze measurements after a sand trickling test. The hardness of silica is unexpectedly lowered by the addition of small amounts of alumina. Two different stacks were coated in which the low refractive index layers were sputtered as pure material and material mixtures. The thickness loss results after an oscillation abrasion test are presented.

Analytical solution for haze values of aluminium-induced texture (AIT) glass superstrates for a-Si:H solar cells.

Light scattering at randomly textured interfaces is essential to improve the absorption of thin-film silicon solar cells. Aluminium-induced texture (AIT) glass provides suitable scattering for amorphous silicon (a-Si:H) solar cells. The scattering properties of textured surfaces are usually characterised by two properties: the angularly resolved intensity distribution and the haze. However, we find that the commonly used haze equations cannot accurately describe the experimentally observed spectral dependence of the haze of AIT glass. This is particularly the case for surface morphologies with a large rms roughness and small lateral feature sizes. In this paper we present an improved method for haze calculation, based on the power spectral density (PSD) function of the randomly textured surface. To better reproduce the measured haze characteristics, we suggest two improvements: i) inclusion of the average lateral feature size of the textured surface into the haze calculation, and ii) considering the opening angle of the haze measurement. We show that with these two improvements an accurate prediction of the haze of AIT glass is possible. Furthermore, we use the new equation to define optimum morphology parameters for AIT glass to be used for a-Si:H solar cell applications. The autocorrelation length is identified as the critical parameter. For the investigated a-Si:H solar cells, the optimum autocorrelation length is shown to be 320 nm.

Three-layered coextruded cast films based on conventional and metallocene poly(ethylene/α-olefin) copolymers

Multilayer films of a conventional linear low-density poly(ethylene/α-octene) (LLDPE) and a metallocene linear low-density poly(ethylene/α-hexene) (mLLDPE) copolymers were produced by cast co-extrusion process. Coextruded films were obtained by varying the position and the relative thicknesses of the two polymers. Mechanical (tensile and impact) tests, permeability, haze and hot tack measurements were carried out on the produced films in order to verify the effect of layer composition and position on the performances of the coextruded samples. Thermal and atomic force microscopy characterizations of the three-layer structures were also performed to correlate the resulting morphology with the film properties. The experiments demonstrated that, at fixed composition, the structures having the mLLDPE copolymer as external layers exhibit generally better mechanical performances and a widening in the sealability temperature window due to a lowering of 5℃ in the seal-initiation temperature, with only a small increase (max 3.5%) in the film haze percentages. The oxygen permeability values do not seem to be significantly affected by the structure composition and layout.

Measuring corneal clouding in patients suffering from mucopolysaccharidosis with the Pentacam densitometry programme

AimTo identify a means to objectively measure corneal clouding in patients with mucopolysaccharidosis in a prospective controlled clinical trial.MethodsCorneal haze was assessed by slit lamp examination and measured using the...

Comparison of abrasive tests for transparent optical coatings

Sometimes, optical interference coatings have to provide wear durability. This study reports on two standardised methods that can be applied for abrasion resistance testing of transparent metal oxides: the oscillating sand method as a hard scratching test and the sand trickling as an impact test. Both tests were carried out with silica and corundum sand to reveal the geometric influence of the test medium. Appropriate cleaning procedures, based on the norms, are discussed and developed. It is shown that water purging has to be complemented by wiping or ultrasonic cleaning. The abrasion is qualified by haze and ellipsometry measurements as well as optical microscopy. The results of Al2O3, Nb2O5, SiO2 and Ta2O5 are discussed with respect to the hardness order of the thin films and compared to two glass types.

An Overview of the Scratch Resistance of Automotive Coatings: Exterior Clearcoats and Polycarbonate Hardcoats

The scratch resistance of coatings used on two highly visible automotive applications (automotive bodies and window glazings) were examined and reviewed. Types of damage (scratch vs. mar), the impact on customers, and the causes of scratch events were investigated. Different exterior clearcoat technologies, including UV curable and self-healing formulations were reviewed, including results from nano- and macro-scratch tests. Polycarbonate hardcoat glazings were tested vs. annealed glass samples using a Taber abraser, with the resulting damage analyzed using transmitted haze measurements and optical profilometry. A correlation between the damage seen in glass samples (many smooth, shallow mars) and the best hardcoat samples (fewer, deeper scratches) and the haze measurements was discussed. Nano-scratch results showed similar fracture forces, but measurably improved mar resistance for the hardcoats/glass system compared to exterior clearcoats.

WMAP7 and future CMB constraints on annihilating dark matter: implications for GeV-scale WIMPs

(Context) We calculate constraints from current and future cosmic microwave background (CMB) measurements on annihilating dark matter (DM) with masses below the electroweak scale: m_{DM}=5-100 GeV. In particular, we focus our attention on the lower end of this mass range, as DM particles with masses m_{DM} ~ 10 GeV have been recently claimed to be consistent with the CoGeNT and DAMA/LIBRA results, while also providing viable DM candidates to explain the measurements of Fermi and WMAP haze. (Aims) We study the model (in)dependence of CMB spectrum on particle physics DM models, large scale structure formation and cosmological uncertainties. We attempt to find a simple and practical recipe for estimating current and future CMB bounds on a broad class of DM annihilation models. (Results) We show that in the studied DM mass range the CMB signal of DM annihilations is independent of the details of large scale structure formation, distribution and profile of DM halos and other cosmological uncertainties. All particle physics models of DM annihilation can be described with only one parameter, the fraction of energy carried away by neutrinos in DM annihilation. As the main result we provide a simple and rather generic fitting formula for calculating CMB constraints on the annihilation cross section of light WIMPs. We show that thermal relic DM in the CoGeNT, DAMA favoured mass range is in a serious conflict with present CMB data for the annihilation channels with few neutrinos, and will definitely be tested by the Planck mission for all possible DM annihilation channels. Also, our findings strongly disfavor the claim that thermal relic DM annihilations with m_{DM} ~ 10 GeV and $<sigma_av> ~ 9x10^{-25} cm^{3}s^{-1} could be a cause for Fermi and WMAP haze.