In many situations in everyday life, sunlight levels need to be reduced. Optical filters with asymmetric transmittance dependent on the incident angle would be useful for sunglasses and vehicle or architectural windows, among others. Herein, we realized the production of optical filters, called "louver filters", comprising HAN-type LC film produced using liquid crystalline ink with dichroic dyes. For the formation of the HAN-type LC film, the liquid crystalline ink was aligned on a rubbed polyimide layer and polymerized by UV irradiation. Two kinds of filters are proposed: one is a filter composed of HAN-type LC film and a polarizer, and the other is composed of two HAN-LC films with a half-wave plate between them. The dependence of the asymmetric transmittance on the incident angle was confirmed for these filters. The dependence changed depending on the pretilt angle of the alignment layers. Photographs taken with the optical filters displayed their effectiveness.
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http://dx.doi.org/10.3390/ma16165584 | DOI Listing |
Front Optoelectron
January 2025
Institution of Physics, Saratov State University, Saratov, 410012, Russia.
Current study presents an advanced method for improving the visualization of subsurface blood vessels using laser speckle contrast imaging (LSCI), enhanced through principal component analysis (PCA) filtering. By combining LSCI and laser speckle entropy imaging with PCA filtering, the method effectively separates static and dynamic components of the speckle signal, significantly improving the accuracy of blood flow assessments, even in the presence of static scattering layers located above and below the vessel. Experiments conducted on optical phantoms, with the vessel depths ranging from 0.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
University of Miami Miller School of Medicine, Boca Raton, FL, USA.
Background: When performing a picture description task, healthy individuals tend to look only briefly at a target before beginning its description, after which they move promptly onto the next target. This sequence may be disrupted in those with cognitive impairment. Just as cognitively impaired individuals produce greater numbers of disfluencies and pauses, those with mild cognitive impairment (MCI) may delay speech production by extending their gaze behavior towards a target before beginning its description.
View Article and Find Full Text PDFSci Rep
January 2025
Center for Radiological Research, Columbia University Irving Medical Center, 630 West 168th Street, New York, 10032, USA.
Scientific bodies overseeing UV radiation protection recommend safety limits for exposure to ultraviolet radiation in the workplace based on published peer-reviewed data. To support this goal, a 3D model of the human cornea was used to assess the wavelength dependence of corneal damage induced by UV-C radiation. In the first set of experiments the models were exposed with or without simulated tears; at each wavelength (215-255 nm) cells with DNA dimers and their distribution within the epithelium were measured.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Electronic Engineering, Tsinghua University, Beijing, China.
Optical neural networks are considered next-generation physical implementations of artificial neural networks, but their capabilities are limited by on-chip integration scale and requirement for coherent light sources. This study proposes a spectral convolutional neural network (SCNN) with matter meta-imaging. The optical convolutional layer is implemented by integrating very large-scale and pixel-aligned spectral filters on CMOS image sensor.
View Article and Find Full Text PDFSci Rep
January 2025
School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China.
In recent years, research on chiral bound states in the continuum (BIC) has surged, leading to the development of various chiral metasurfaces with narrow bandwidths by breaking of in-plane and out-of-plane symmetries. However, the ability to dynamically tune the working band remains relatively unexplored, which is valuable for chiral sensing applications. Optical phase-change materials, with tunable dielectric constants and switchable properties during phase transition, offer the potential for dynamic control of optical metasurfaces.
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