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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • LED stage lighting
  • CRI
  • RGBW four-color mixing model
  • the blackbody locus fitting
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Communication University of China
416 条数据
?? 中文（中国） ▾

  • Performance Evaluation of Image Enhancement Techniques

    摘要： Color Image enhancement is a process in which the perceptual information of an image is improved to obtain more information and details contained in the image. It improves the subjective quality of an image by working with original data. This paper focuses on evaluating the performance of various image enhancement techniques. These techniques are either based on histogram modification or are based on fuzzy logic. The techniques are compared using two quantitative measures namely; Contrast Improvement index (CII) and Tenengrad measure. The results have shown that Lab and edge preservation based fuzzy image enhancement (LEFM) yields the best results.

    关键词： edge preserving smoothing,Lab color space,fuzzy logic,Color image,Histogram equalization

    更新于2025-09-23 15:21:01

  • Enhancement of THz Generation by Two-Color TW Laser Pulses in a Low-Pressure Gas

    摘要： We identify experimental conditions for efficient generation of THz pulses by high power near IR laser radiation: 2 TW, 30 fs, 800-nm laser pulses with their second harmonic were slightly focused in a low-pressure gas cell in such a way to avoid multiple filamentation and excessive ionization. This two-color scheme yields a microjoule level of THz pulses which is two orders of magnitude higher than the signal generated in the atmosphere of ambient air.

    关键词： THz,Two-color,Plasma absorption,Terawatt,Chirp,Filament,Low pressure,Saturation

    更新于2025-09-23 15:21:01

  • Design of color tunable thin film polymer solar cells for photovoltaics printing

    摘要： Color tunable thin film polymer solar cells have demonstrated the potentials of a wide applications in photovoltaics printing, which is significant for ink pollution reduction and energy saving. This work presents a new effective approach to realize color-tuning photovoltaic cells with optical microcavity structures. Aluminum-doped zinc oxide is utilized as electron transport layer material. With its high electrical conductivity, the thickness tuning range can be quite large, which means the cavity length has a wide variation range. It thus provides sufficient space for optical thin film design to obtain multi colors. By the transfer matrix method, device reflection and absorption spectra are numerically investigated. Based on that, the optical principles for color tunability are explored. In further step, the relationship between device photovoltaics performance and reflective colors are also discussed. Finally, the color coordinates and luminosities are calculated. As results, the colors of the devices designed are capable to cover a relatively large region in Commission Internationale de l′Eclairage (CIE) 1931 x, y chromaticity diagram, which is available to be integrated into the advertisement poster boards, building wall printing and other display applications.

    关键词： optical microcavity,thin film polymer solar cells,aluminum-doped zinc oxide,photovoltaics printing,color tunable

    更新于2025-09-23 15:21:01

  • Color tuning in Cu(In,Ga)Se <sub/>2</sub> thin-film solar cells by controlling optical interference in transparent front layers

    摘要： Aesthetic factors such as colorization in harmony with the surrounding environment are becoming important in the field of applied photovoltaics. Therefore, there exists a need to realize colors in solar cells, with minimum additional cost and efficiency loss. We tuned the color of Cu(In,Ga)Se2 thin-film solar cells by controlling the optical interference between the sputtered Zn(O,S) buffer layer and indium tin oxide (ITO) transparent electrode layer, which are intrinsic components of the solar cell device, without any additional process and/or material. The nontoxic Cd-free buffer layer was prepared in consideration of the environmental factor. In order to minimize the degradation of the photovoltaic performance of the solar cell, the experiment was conducted within the thickness (optical path length) of the Zn(O,S) and ITO transparent front layers, which affected the solar cell performance more optically and less electrically. As the antireflection coating thickness increased, the solar cell was calculated to have a wider color range, lower luminosity, and lower JSC loss. Relatively even efficiencies were obtained with a wide color range.

    关键词： color,transparent front layer,optical interference,CIGS thin-film solar cell,nontoxic Cd-free buffer

    更新于2025-09-23 15:21:01

  • Full-visible-spectrum lighting enabled by an excellent cyan-emitting garnet phosphor

    摘要： The development of phosphor materials with outstanding photoluminescence properties is critical for next-generation high-quality solid-state white lighting. As there is a blue-green cavity existed in the emission spectra of the traditional phosphor-converted white-light-emitting diodes (w-LEDs), cyan-emitting phosphor serves an important function in compensating the spectral gap to realize the “full-visible-spectrum lighting”. Herein, we reported the discovery of an efficient cyan-emitting Ce3+-doped Ca2YHf2Al3O12 (CYHAO) garnet phosphor with good thermal stability. The as-prepared CYHAO:Ce3+ phosphor exhibited a broad excitation band in the range of 360 to 460 nm with a maximum at 408 nm, making this phosphor compatible with an efficient 400 nm NUV-emitting LED chip. Under the 408 nm excitation, the optimal sample of CYHAO:0.03Ce3+ exhibited bright broadband cyan emission (λem = 493 nm; bandwidth = 100 nm) together with extra-high internal quantum efficiency (IQE) of 89.5% and external quantum efficiency (EQE) of 69.1%. Notably, the as-prepared CYHAO:0.03Ce3+ phosphor showed good thermal stability (64.2% of emission intensity retained at 423K) and excellent color stability when working in the temperature range of 303-463 K. Importantly, the constructed w-LED device exhibited bright well-distributed warm white light with high color rendering index (CRI; Ra = 93.5 and R12 = 90.4) and low correlated color temperature (3700 K) under 60 mA driven current, indicating that the title cyan phosphor can be utilized as the compensation of the blue-green cavity to apply in full-visible-spectrum lighting. Furthermore, these findings provide new insights into exploring high-performance cyan phosphors for NUV-pumped high-CRI warm w-LEDs.

    关键词： White LEDs,Color rendering index,Cyan emissions,Phosphors,Full-visible-spectrum lighting

    更新于2025-09-23 15:21:01

  • Effect of Uncontrollable Impurities on the Absorption Spectrum of a NaGd(WO4)2 Laser Crystal

    摘要： Three NaGd(WO4)2 single crystals were grown by the Czochralski method using charges of different chemical purity. The impurity compositions of the grown crystals were analyzed by inductively coupled plasma mass spectrometry. The optical absorption spectra of the crystals were measured, and the effect of uncontrollable impurities on their optical properties and color was analyzed. The green color encountered in NaGd(WO4)2 crystals in some cases was shown to be due to the uncontrollable impurities of d elements, among which the chromium impurity had the most significant effect.

    关键词： optical absorption,impurity purity,color centers,single crystals,zinc tungstate,ytterbium

    更新于2025-09-23 15:21:01

  • [IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Structure Colors Realized by TiN-Si <sub/>3</sub> N <sub/>4</sub> -Si Nanostructure Array

    摘要： In this paper, a nanostructure array is proposed to achieve a full-wavelength structural color in the visible range. The nanostructure is designed form of triangular prism which is composed of three layers of TiN, Si3N4 and Si materials. The cross section of the triangular prism is an isosceles triangle. By calculating the reflectance of such nanostructure array, it is found that the periodic variation has little effect on the scattering peak of the nanostructure array when we vary the cross-sectional area of the triangular prism and the period respectively. As the cross-sectional area of the triangular prism increases, the scattering peak shifts to red. According to our simulation, a variety of colors such as purple, green, cyan, orange, and red can be obtained. The proposed nanostructure array, which utilizes TiN as capping layer, can provide some new ways for realizing a sustainable structural color for various applications.

    关键词： Periodic array,Structural color,Nanostructure

    更新于2025-09-23 15:21:01

  • Dimensioning a full color LED microdisplay for augmented reality headset in a very bright environment

    摘要： This paper focuses on the dimensioning of a very bright full color 10 μm-pitch light-emitting device (LED) microdisplay for avionics application. Starting from the specifications of head-mounted display to be used in an augmented reality optical system, a theoretical approach is proposed that enables predicting the specifications of the main technology building blocks entering into the microdisplay manufacturing process flow. By taking into account various material and technological parameters, kept as realistic as possible, it is possible to assess the feasibility of a very bright LED microdisplay (1 Mcd/m2 full white) and to point out the main limitations. The theoretical specifications are then compared with the technical results obtained so far in the framework of the H2020 Clean Sky “HILICO” project. It shows that 350 000 cd/m2 of white emission may be accessible with the present gallium nitride (GaN)-micro-LED technology provided a color conversion solution with stable external quantum efficiency of 30% is available. Beyond such level of luminance, the inherent limitations of driving circuit (4 V, 15 μA per pixel) commands working with materials enabling higher external quantum efficiency (EQE). In particular, 10-μm-pitch micro-LEDs with electroluminescence EQE of 15% and color conversion EQE approaching 60% are needed, opening the way to future challenging material and technology research developments.

    关键词： active matrix,high luminance,microdisplay,GaN,color conversion

    更新于2025-09-23 15:21:01

  • [IEEE 2019 15th International Conference on Signal-Image Technology & Internet-Based Systems (SITIS) - Sorrento, Italy (2019.11.26-2019.11.29)] 2019 15th International Conference on Signal-Image Technology & Internet-Based Systems (SITIS) - Assessment of OLED Head Mounted Display for Vision Research with Virtual Reality

    摘要： Vision researchers often rely on visual display technology to present observers with controlled stimuli, usually by means of a calibrated computer screen. Virtual Reality (VR) may allow a similar level of control, together with higher realism of the stimulation and a visual field larger than what is achievable on a standard computer monitor. To produce the desired the stimuli, accurate characterization of the spectral properties of the display is necessary. However, this process might not be trivial on VR displays, because 1) the Head Mounted Displays (HMD) used in VR are typically designed to be light-weight and low energy consuming, thus they might not meet some of the standard assumptions in display calibration, 2) the VR software might affect the color and luminance signal in a complex way, further complicating the calibration process. Here we show that 1) a common, off-the-shelf display used in our experiments behaves similarly to a standard OLED monitor, 2) the VR gaming engine we tested (Unreal Engine 4) introduces a complex behavior, 3) which can be disabled. This allows to accurately control colors and luminance emitted by the display, thus enabling its use for perceptual experiments.

    关键词： Head Mounted Display,Color Calibration,Vision Research,Virtual Reality,OLED

    更新于2025-09-23 15:21:01

  • Improved Color Purity of Monolithic Full Color Micro-LEDs Using Distributed Bragg Reflector and Blue Light Absorption Material

    摘要： In this study, CdSe/ZnS core-shell quantum dots (QDs) with various dimensions were used as the color conversion materials. QDs with dimensions of 3 nm and 5 nm were excited by gallium nitride (GaN)-based blue micro-light-emitting diodes (micro-LEDs) with a size of 30 μm × 30 μm to respectively form the green and red lights. The hybrid Bragg re?ector (HBR) with high re?ectivity at the regions of the blue, green, and red lights was fabricated on the bottom side of the micro-LEDs to re?ect the downward light. This could enhance the intensity of the green and red lights for the green and red QDs/micro-LEDs to 11% and 10%. The distributed Bragg re?ector (DBR) was fabricated on the QDs color conversion layers to re?ect the non-absorbed blue light that was not absorbed by the QDs, which could increase the probability of the QDs excited by the re?ected blue light. The blue light absorption material was deposited on the DBR to absorb the blue light that escaped from the DBR, which could enhance the color purity of the resulting green and red QDs/micro-LEDs to 90.9% and 90.3%, respectively.

    关键词： micro-light-emitting diodes,color conversion layer,distributed Bragg re?ector,quantum dots,hybrid Bragg re?ector,blue light absorption material

    更新于2025-09-23 15:21:01