Effective UV and blue light blocking filters with high visible transparency utilizing graphene quantum dots

Cesium lead halide perovskite nanocrystals for ultraviolet and blue light blocking

A number of commercially available art protection products have been compared and assessed for their suitability as UV blocking filters in the application of “visible light” photocatalytic research. Many groups claiming visible light photocatalytic success employ filters to block out stray UV radiation in order to justify that their photocatalysts are indeed visible light photocatalysts and not UV light photocatalysts. These filters come in varying degrees of ability and price and many authors fail to correctly characterise their filters in individual papers. The use of effective filters to prevent both false positive and false negative results is important to maintain scientific rigor and create accurate understanding of the subject. The optimum UV filter would have the highest UV blocking properties (<390 nm) and simultaneously the highest visible light transmission (390–750 nm). Single and double layers of each of the glass products were assessed as well as laminate products. The conclusions show an inexpensive and highly effective setup for the conduction of visible light photochemistry that should be incorporated as a standard part in any researcher’s work where the claim of visible light activity is made.

Using raw egg yolk and phosphoric acid, a simple hydrothermal treatment for synthesizing carbon quantum dots (CQDs) has been developed for the manufacture of UV and blue light-blocking filters. Several samples with different doping ratios of phosphoric acid were prepared. Namely: reference (REF.), 25%, 50%, 75% and 100%. The synthesized CQDs were embedded in polyvinyl alcohol (PVA) to produce blocking-light films with desired optical properties. Six films were prepared, one of which was PVA alone, and the other five samples were the prepared CQDs, with different phosphorus doping levels, mixed with PVA in a 1:1 ratio. We aimed to test the ability of these films to block ultraviolet rays and blue light. The experimental results revealed that the prepared films were able to block the blue light, emitted from a 450 nm blue LED, with blocking ratios of 7%, 17.5%, 27%, 30%, 37% and 70% for the films: PVA alone, REF., 25%, 50%, 75% and 100%, respectively. Moreover, it was found that these phosphorus-doped CQDs films can prevent destructive UV light with substantial value reaching 86%. These results suggest that carbon dots, derived from raw egg yolk, can be effectively applied to block harmful UV and blue lights.

Purpose: To assess and compare the effect of blue and yellow filters on visual acuity in amblyopes. Design of Study: Comparative cross-sectional study. Place and Duration of Study: Ophthalmology Department of Madinah Teaching Hospital, Faisalabad from November 2018 to May 2019. Methods: Participants (n꞊30) of age 7 to 28 years were studied. All types of amblyopia were included and subjects with systemic or ocular diseases were excluded. After history taking, ophthalmoscopy, visual acuity was measured with and without pinhole in the amblyopic eye. Visual acuity was also recorded by using blue and yellow filter with and without pinhole by placing in front of amblyopic eyes to assess the difference in visual acuity with filters and with pinhole. Comparative analysis of changes in visual acuity in amblyopic eye with and without blue filter, with and without yellow filters and with blue and yellow filters were performed by Paired sample T-test for qualitative variable (visual acuity) by using SPSS 20. Results: Visual acuity in amblyopic eye without filter (mean꞊0.52 ± .28) was lower than with blue (mean 0.31 ± .26) and yellow filters (mean 0.46 ± .30) and visual acuity with blue filter was higher than with yellow filter with the incorporation of Pinhole (P.H). The probability value of blue filters was (P = 0.00) and with yellow filters (P = 0.001) at the level of 5% of confidence interval. Participants feel more clarity, sharpness with blue filters but more comfort with yellow filters. Conclusion: Visual acuity of amblyopes was significantly improved with blue filters as compared to yellow filter.

Al, with a passband in the wavelength range of 17-60 nm, and Zr, with a passband in the wavelength range of 6.5-17 nm, thin films on a support grid or support membrane are frequently used as UV, visible, and near-IR blocking filters in solar observatories. Although they possess acceptable optical performance, these filters also have some shortcomings such as low mechanical strength and low resistance to oxidation. These shortcomings hinder meeting the requirements for filters of future telescopes. We propose multilayer thin film filters on the basis of Al, Zr, and other materials with improved characteristics. It was demonstrated that stretched multilayer films on a support grid with a mesh size up to 5 mm can withstand vibration loads occurring during spacecraft launch. A large mesh size is preferable for filters of high-resolution solar telescopes, since it allows image distortion caused by light diffraction on the support grid to be avoided. We have investigated the thermal stability of Al/Si and Zr/Si multilayers assuming their possible application as filters in the Intergelioprobe project, in which the observation of coronal plasma will take place close to the Sun. Zr/Si films show high thermal stability and may be used as blocking filters in the wavelength range of 12.5-17 nm. Al/Si films show lower thermal stability: a significant decrease in the film's transmission in the EUV spectral range and an increase in the visible spectrum have been observed. We suppose that the low thermal stability of Al/Si films restricts their application in the Intergelioprobe project. Thus, there is a lack of filters for the wavelength range of λ>17 nm. Be/Si and Cr/Si filters have been proposed for the wavelength range near 30.4 nm. Although these filters have lower transparency than Al/Si, they are superior in thermal stability. Multilayer Sc/Al filters with relatively high transmission at a wavelength of 58.4 nm (HeI line) and simultaneously sufficient rejection in the wavelength range near 30.4 nm (HeII line) have been fabricated. They are planned to be used in the project KORTES, whose telescopes will have an EUV channel at 58.4 nm.

Cyanopyridone doped PMMA films as UV and blue light filters: Preparation and characterization

Nanoparticles have made a substantial contribution to the field of skincare products with UV filters in preserving human skin from sun damage. The current study aims to create new polymer nanocomposite filters for the efficient block of UV light that results from the stratospheric ozone layer loss. The casting approach was used to add various mass fractions of copper oxide nanoparticles (CuO-NPs) to a solution of carboxymethyl cellulose (CMC). The amorphous nature of CMC was revealed by XRD analysis, with the intensity of the typical peak of virgin polymer in the nanocomposite spectrum decreasing dramatically as the doping amount was increased. The FTIR spectra revealed the functional groups of CMC and the good interaction between the CMC chain and CuO-NPs. Optical experiments revealed that the optical transmittance of pure CMC was over 80%, whereas it dropped to 1% when CuO-NPs content was increased to 8 wt.%. Surprisingly, the inclusion of CuO-NPs considerably improved the UV blocking property of the films extended from the UV region (both UV-A: 320–400 nm and UV-B: 280–320 nm) to the visible region. Optical band gap of CMC decreased sharply with increasing CuO concentration. The tunable optical characteristics can be utilized in UV- blocking filters and various optoelectronics applications.

Evaluation of the impact of a new selective blue light filter and class 1 UV blocking SiHy lens (75% WC) examining contrast sensitivity and colour perception

IntroductionThe purpose of this study was to measure luminance contrast sensitivity and color vision thresholdfs in normal subjects using a blue light filter lens and transparent intraocular lens material.MethodsMonocular luminance grating contrast sensitivity was measured with Psycho for Windows (version 2.36; Cambridge Research Systems) at 3.0, 6.0, 12.0, 20.0, and 30.0 cycles per degree of visual angle (cpd) in 15 normal subjects (eight female), with a mean age of 21.6 years (SD = 3.8 years). Chromatic discrimination was assessed with the Cambridge colour test (CCT) along the protan, deutan, and tritan color confusion axes. Both tests were performed in a darkened room under two situations: with a transparent lens and with blue light filter lens. Subjective impressions were taken by subjects regarding their visual experience under both conditions.ResultsNo difference was found between the luminance contrast sensitivity measured with transparent and blue light filter. However, 13/15 (87%) of the subjects reported more comfortable vision with the blue filter. In the color vision test, tritan thresholds were significantly higher for the blue filter compared with the transparent filter (p = 0.003). For protan and deutan thresholds no differences were found.ConclusionBlue-yellow color vision is impaired with the blue light filter, and no impairment occurs with the transparent filter. No significant differences in thresholds were found in the luminance contrast sensitivity comparing the blue light and transparent filters. The impact of short wavelength light filtering on intrinsically photosensitive retinal ganglion cells is also discussed.

To investigate the effect of contact lenses with blue light filters on contrast sensitivity and any alteration in tear quantity and quality. This prospective longitudinal pilot study required three visits by each participant. Monocular visual acuity, contrast sensitivity, phenol red thread test, and tear breakup time were measured at each visit. There were significant differences in logarithmic contrast sensitivity between the groups. The breakup time (BUT) was significantly lower after using video display terminals than before (P<0.05). No differences in BUT were found between groups video display terminals and contact lenses having the blue filter (P>0.05). However, higher mean values were observed in the group after video display terminal use with contact lenses having the blue filter than that with standard contact lenses (P>0.05 in both groups). Furthermore, the mean value of phenol red thread test on the group after video display terminal use with contact lenses having the blue filter was lower than the group before its use (P>0.05). The results establish a possible relationship between tear stability, improved contrast sensitivity, and the use of a blue filter in contact lenses.

Ultraviolet (UV) vision is widespread among teleost fishes, of which many exhibit UV skin colors for communication. However, aside from its role in mate selection, few studies have examined the information UV signaling conveys in other socio-behavioral contexts. Anemonefishes (subfamily, Amphiprioninae) live in a fascinating dominance hierarchy, in which a large female and male dominate over non-breeding subordinates, and body size is the primary cue for dominance. The iconic orange and white bars of anemonefishes are highly UV-reflective, and their color vision is well tuned to perceive the chromatic contrast of skin, which we show here decreases in the amount of UV reflectance with increasing social rank. To test the function of their UV-skin signals, we compared the outcomes of staged contests over dominance between size-matched Barrier Reef anemonefish (Amphiprion akindynos) in aquarium chambers viewed under different UV-absorbing filters. Fish under UV-blocking filters were more likely to win contests, where fish under no-filter or neutral-density filter were more likely to submit. For contests between fish in no-filter and neutral density filter treatments, light treatment had no effect on contest outcome (win/lose). We also show that sub-adults were more aggressive toward smaller juveniles placed under a UV filter than a neutral density filter. Taken together, our results show that UV reflectance or UV contrast in anemonefish can modulate aggression and encode dominant and submissive cues, when changes in overall intensity are controlled for.

Eye damage control by reduced blue illumination

This work reports the use of the slot‐die (SD) coating solution processing method to fabricate large‐area organic thin films composed of photochromic dyes as UV indicators and UV light absorbers as UV filters on polyethylene terephthalate flexible substrates. This is the first demonstration of large‐area SD coated organic photochromic films and UV filters. Impressively, highly uniform photochromic films comprised of small molecules are formed in air, from green solvents (i.e., alcohols) and show rapid color changes upon external stimuli (i.e., light and heat). The UV filters processed under the same conditions and comprised of only small molecules show highly transparent films in the visible and near‐IR range with T% &gt; 97%@550 nm and excellent UV blocking ability. The work highlights the utility of roll‐to‐roll compatible SD‐coating methods to make prototype organic devices in an academic laboratory setting and opens the door for additive manufacturing of simple and low‐cost UV active films for healthcare and electronic applications.

Purpose To evaluate pupil size variations induced by optical filter by using filters with different materials and spectral characteristics, focussing on UV and blue light transmission properties of the filters Methods 220 pupil measurements (20 eyes, 20‐55 years old) were made using the pupillometer Procyon P2000SA at high Mesopic level (4.0lux). 10 filters of varying transmittance (visible, 4%‐65%, 5 filters UV‐transmitting and 5 filters UV‐absorbing) were used in a randomised way. 5 filters (UV‐transmitting) were dye‐coated polyester films with a substrate of PET (polyethylene terephthalate) and the another 5 filters (UV‐absorbing) were Ophthalmic CR39 lenses with a tinted coating in order to get the same absorbing characteristics than the PET filters. Measurements in the absence of a filter served as control Results Significant results on pupil size variation were obtained with lower UV and blue light transmittance filters (F14, F15 and F16; p=0.00) for both materials, PET and CR39 (Mydriasis obtained: F14R=13.99%; F15R=17.57%; F16R=22.90%; F14E=23.95%; F15E=22.69%; F16E=29.87%). Also significant differences in mydriasis‐induced by the filter were obtained when materials and blue‐light transmission properties were compared for filters 14 and 16 (PET vs. CR39: F14 (p=0.006), F16 (p=0.0167) Conclusion Filters with similar visible but different UV and/or blue‐light transmission properties significantly produce variations in pupil size at high Mesopic condition (4.0lux). Differences obtained in mydriasis‐induced by the filter depend not only on the material of the filter, but also the UV and/or blue‐light transmitted by the filter

An Optically Reconfigurable Förster Resonance Energy Transfer Process for Broadband Switchable Organic Single-Mode Microlasers