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- 2018
- LED stage lighting
- CRI
- RGBW four-color mixing model
- the blackbody locus fitting
- Optoelectronic Information Science and Engineering
- Communication University of China
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Transparent colored display enabled by flat glass waveguide and nanoimprinted multi-layer gratings
摘要： In this paper, a type of transparent colored static display consisting of a flat glass waveguide and embedded multi-layer gratings is presented, by which multiple patterns and colors with a wide field of view (FOV) can be displayed. The embedded grating is achieved by nanoimprinting followed by deposition of a high refractive index dielectric layer. The process can be repeated to produce multi-layer gratings, which are shaped into specific patterns to be displayed, and they are designed to have proper periods and orientations to independently extract light incident from different edges of the glass plate. Such transparent display offers the advantages of low cost, easy fabrication and wide FOV, and it is suitable for colored signage and decorative applications.
关键词： multi-layer gratings,transparent display,waveguide display,nanoimprint lithography,multi-color display
更新于2025-09-23 15:21:01
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Color Routing via Cross-Polarized Detuned Plasmonic Nanoantennas in Large Area Metasurfaces
摘要： Bidirectional nanoantennas are of key relevance for advanced functionalities to be implemented at the nanoscale, and in particular for color routing in an ultracompact flat-optics configuration. Here we demonstrate a novel approach avoiding complex collective geometries and/or restrictive morphological parameters, based on cross-polarized detuned plasmonic nanoantennas in a uniaxial (quasi-1D) bimetallic configuration. The nanofabrication of such a flat-optics system is controlled over a large-area (cm2) by a novel self-organized technique exploiting ion-induced nanoscale wrinkling instability on glass templates to engineer tilted bimetallic nanostrip dimers. These nanoantennas feature broadband color routing with superior light scattering directivity figures, which are well described by numerical simulations and turn out to be competitive with the response of lithographic nanoantennas. These results demonstrate that our large-area self-organized metasurfaces can be implemented in real world applications of flat optics color routing from telecom photonics to optical nanosensing.
关键词： Tilted Nanostrips,Flat-Optics,Plasmonic Dimers,Plasmonic metasurfaces,Color Routing,Self-organized Nanoantennas
更新于2025-09-23 15:21:01
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Stretchable and Higha??Adhesive Plasmonic Metasheet Using Al Subwavelength Grating Embedded in an Elastomer Nanosheet
摘要： Plasmonic metasurfaces have attracted much attention for use in device applications over the past decade. Dynamic color tuning (DCT), where the displacement of periodic nanostructures is controlled to generate different colors in real time, is one of the great possibilities of plasmonic metasurfaces for optical strain sensors or display devices. In this study, an Al metasurface embedded in an elastomer nanosheet with film thickness 400 nm is fabricated by means of sacrificial release using a polyvinyl alcohol sacrificial layer. This plasmonic metasheet shows not only the seven colors produced by surface plasmons, but also DCT by stretching the elastomer nanosheet. Each pixel, designed with a grating period of 300–600 nm, emits the bright colors expected in electromagnetic simulation. Moreover, stretching the plasmonic metasheet demonstrates DCT from 495 to 660 nm in the visible light range. The freestanding metasheet with maximum thickness 400 nm may be easily integrated into any active device by post-processing transfer. Stretching the metasheet requires an estimated × 10?3 lower force than previously reported for plasmonic metasurfaces, owing to a film thickness of only several hundreds of nanometers. These results facilitate the realization of microdevices with novel capabilities based on plasmonic metamaterials.
关键词： plasmonic metamaterials,elastomer nanosheets,dynamic color tuning,subwavelength gratings,surface plasmons
更新于2025-09-23 15:21:01
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Improved Two-wavelength Lidar algorithm for Retrieving Atmospheric Boundary Layer Height
摘要： The atmospheric boundary layer height (BLH) is a critical parameter for the spread and dispersion of atmospheric pollutants. We propose an improved two-wavelength Lidar algorithm for retrieving the BLH based on particle clustering. The algorithm was improved from two aspects: sample sequence selection and classifier optimisation. The backscatter coefficient and color ratio were chosen for the sample sequence construction, and Gaussian mixture models were used for the sample sequence classification. The improved method was tested on different real cases and compared with radiosonde measurements. The experimental results demonstrated the viability of the algorithm under weak mixing conditions, which can be problematic for prior methods. In addition, Lidar data from June 2015 to June 2016 were collected to investigate the stability of the improved method. The correlation between the BLH retrieved using the improved algorithm and that from the radiosonde measurements was R2 = 0.92, with an RMSE of 170 m. The correlation between the two-wavelength Lidar algorithm and radiosonde measurements was R2 = 0.82, with an RMSE of 180 m. The results show that the improved algorithm can obtain the BLH effectively and stability.
关键词： Color ratio,Lidar,Atmospheric boundary layer,Aerosol detection,Radiosonde
更新于2025-09-23 15:21:01
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The naked-eye NH3 sensor based on fluorinated graphene
摘要： Graphene has aroused continual and tremendous interest in gas sensing applications because of its unique properties. However, the graphene-based sensors still meet limitations such as inconvenient device fabrication, sustained power supply, specific measuring equipment, etc. Here, we find that fluorinated graphene (FG) shows an obvious color change (from white to dark yellow) in the presence of NH3 which can be observed directly by the naked eye. PL measurement shows that the sensitivity of color change can reach a high value of ca. 4.05 % ppm-1. The density functional theory calculations reveal that the F atoms on FG increase the adsorption ability and charge transfer of NH3 molecules, resulting in the efficient color change. This work develops a naked-eye sensor which needs no device fabrication, power supply or measuring equipment, thus, can be potentially used to manufacture a cheap, sensitive and miniaturized NH3 sensor.
关键词： fluorinated graphene,charge transfer,NH3 sensor,naked-eye color change,adsorption ability
更新于2025-09-23 15:21:01
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Estimation of Data Hiding Capacities in Spatio-Chromatic Fourier Transform (SCFT) Representations of Color Images
摘要： Despite the abundance of color images, a vast majority of digital image watermarking algorithms are specifically designed for gray-scale images in terms of perceptual modeling, watermark embedding and data hiding capacity. This paper tries to bridge this gap and provides information theoretic estimates of data hiding capacities for standard color images using an improved version of the CIEL*a*b* color space. These capacity estimates are derived based on appropriate color models of the spatio-chromatic Fourier transform (SCFT) of the host image, distortion constraints imposed on the watermarking game players (watermark embedder and attacker), and side information available to both players. This paper considers full-frame and block-based SCFT statistical representations for color images and derive data hiding bounds for these image sources assuming invariance to affine and geometric attacks. Finally, the estimated data hiding capacities are used to assess the performance of a color-based SCFT image watermarking algorithm. The performance results highlight the importance of combining the estimated hiding capacities and perceptual model in designing a high capacity, robust and perceptual color image watermarking system.
关键词： Spatio-chromatic Fourier transform (SCFT),Watermarking games,Color image watermarking,Data hiding capacity
更新于2025-09-23 15:21:01
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A dual colorimetric and near-infrared fluorescent turn-on probe for Hg2+ detection and its applications
摘要： The increasing Hg2+ contamination in environment and ecosystem has gained wide attention and thus demands for its facile and effective detection. In this study, we constructed a new fluorescent probe (E)-2-(2-(3-(1,3-dithian-2-yl)-4-hydroxystyryl)-4H-chromen-4-ylidene)malononitrile (DCM-Hg) for Hg2+ detection by incorporating the 1, 3-dithiane group to the dicyanomethylene-4H-pyran fluorophore for the first time. This probe can selectively detect Hg2+ via the Hg2+-triggered deprotection reaction of thioacetals, which leads to a distinct color change from purple to pink and obvious fluorescence enhancement in the near-infrared (NIR) region. The NIR fluorescence intensity increased linearly with Hg2+ level within the range from 0 to 100 μM and the detection limit of DCM-Hg for Hg2+ was found to be 6.8 × 10-8 mol/L. Moreover, the probe could sense Hg2+ on paper strips and image Hg2+ in living cells with low cytotoxicity, which demonstrates its potential application in environment and biological science.
关键词： Selectivity,Near-infrared,Imaging,Color change,Hg2+
更新于2025-09-23 15:21:01
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Pulsed interleaved excitation-based line-scanning spatial correlation spectroscopy (PIE-lsSCS)
摘要： We report pulsed interleaved excitation (PIE) based line-scanning spatial correlation spectroscopy (PIE-lsSCS), a quantitative fluorescence microscopy method for the study of dynamics in free-standing lipid bilayer membranes. Using a confocal microscope, we scan multiple lines perpendicularly through the membrane, each one laterally displaced from the previous one by several ten nanometers. Scanning through the membrane enables us to eliminate intensity fluctuations due to membrane displacements with respect to the observation volume. The diffusion of fluorescent molecules within the membrane is quantified by spatial correlation analysis, based on the fixed lag times between successive line scans. PIE affords dual-color excitation within a single line scan and avoids channel crosstalk. PIE-lsSCS data are acquired from a larger membrane region so that sampling is more efficient. Moreover, the local photon flux is reduced compared with single-point experiments, resulting in a smaller fraction of photobleached molecules for identical exposure times. This is helpful for precise measurements on live cells and tissues. We have evaluated the method with experiments on fluorescently labeled giant unilamellar vesicles (GUVs) and membrane-stained live cells.
关键词： lipid bilayer membranes,dual-color excitation,live cells,line-scanning spatial correlation spectroscopy,fluorescence microscopy,tissues,GUVs,confocal microscope,photobleaching,Pulsed interleaved excitation
更新于2025-09-23 15:21:01
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Ocean Dynamics Observed by VIIRS Day/Night Band Satellite Observations
摘要： Three cases of Day/Night Band (DNB) observations of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP) are explored for applications to assess the ocean environment and monitor ocean dynamics. An approach to use the ratio between the target radiance and the reference radiance was developed in order to better assess the ocean diurnal and short-term environmental changes with VIIRS DNB observations. In the La Plata River Estuary, the sediment fronts showed 20–25 km diurnal inshore-offshore movements on 13 March 2017. In the waters off the coast of Argentina in the South Atlantic, VIIRS DNB measurements provided both daytime and nighttime observations and monitoring of the algal bloom development and migration between 24 and 26 March 2016. This algal bloom generally kept the same spatial patterns, but moved nearly 20 km eastward in the three-day period. In the Yangtze River Estuary and Hangzhou Bay region along China’s east coast, VIIRS DNB observations also revealed complicated coastal dynamic changes between 12 and 14 April 2017. Even though there are still some challenges and limitations for monitoring the ocean environment with VIIRS DNB observations, this study shows that satellite DNB observations can provide additional data sources for ocean observations, especially observations during the nighttime.
关键词： satellite remote sensing,VIIRS,DNB observation,ocean color,nocturnal study,ocean dynamics
更新于2025-09-23 15:21:01
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A Low-Light Sensor Image Enhancement Algorithm Based on HSI Color Model
摘要： Images captured by sensors in unpleasant environment like low illumination condition are usually degraded, which means low visibility, low brightness, and low contrast. In order to improve this kind of images, in this paper, a low-light sensor image enhancement algorithm based on HSI color model is proposed. At ?rst, we propose a dataset generation method based on the Retinex model to overcome the shortage of sample data. Then, the original low-light image is transformed from RGB to HSI color space. The segmentation exponential method is used to process the saturation (S) and the specially designed Deep Convolutional Neural Network is applied to enhance the intensity component (I). At the end, we back into the original RGB space to get the ?nal improved image. Experimental results show that the proposed algorithm not only enhances the image brightness and contrast signi?cantly, but also avoids color distortion and over-enhancement in comparison with some other state-of-the-art research papers. So, it effectively improves the quality of sensor images.
关键词： convolutional neural network,Retinex model,image enhancement,color model,batch normalization,feature learning
更新于2025-09-23 15:21:01