最新刊期
卷 39 ， 期 6 ， 2024
- “最新研究突破：基于液晶的动态可调偏振转换器，解决了传输损耗和分子取向难题，实现了高效率、低功耗的片上集成系统。”摘要：The dynamic tunable polarization converter based on liquid crystals， which boastes large modulation amplitude and low power consumption， holds significant research interest in on-chip integrated systems. However， existing liquid crystal polarization converters encounter substantial transmission losses and difficulties in orienting the liquid crystal molecules. In response， this paper introduces a polarization converter based on a liquid crystal-clad slab waveguide. Initially， leveraging the anisotropy of liquid crystals and the four-layer waveguide theory， a polarization conversion analysis model that satisfied the physical characteristics of the liquid crystal-clad slab waveguide was developed. This model elucidated the internal mechanism of polarization conversion as mode coupling within the waveguide， induced by field-driven rotation of liquid crystal molecules. Subsequently， by precisely solving for the propagation constants and optical field distributions of the waveguide modes under coupled conditions， a polarization conversion analysis method suitable for liquid crystal-clad slab waveguides was proposed. This method summarized the theoretical formulas for polarization conversion efficiency and minimum conversion length， and elucidated the influence of mode coupling on polarization conversion efficiency. Finally， by comprehensively optimizing the parameters of each waveguide layer， a set of device parameters capable of achieving high polarization conversion efficiency was derived. The impact of deviations in the core layer thickness， orientation layer thickness， and electrode length on conversion efficiency was analyzed. The results indicate that the designed liquid crystal-clad slab waveguide polarization converter can achieve continuously adjustable conversion efficiency from 0% to 99.98% with a change in driving voltage of 0.2 V.关键词：liquid crystal;optical waveguide;polarization converter
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发布时间：2024-06-27 - “最新研究进展：直径16毫米大孔径液晶菲涅耳透镜设计成功，通过电控调焦技术，实现光焦度从-1D到+1D的调节，为光学成像领域提供创新解决方案。”摘要：In this paper， a large aperture liquid crystal Fresnel lens with a diameter of 16 mm is designed. The liquid crystal lens is divided into a central part and 13 Fresnel sidelobes， each of which has the same optical path difference. The structure design and simulation of liquid crystal Fresnel lens are studied. The power electrode is not a complete ring electrode， and the coupling electrode is a complete ring electrode. The non-complete ring electrode is aligned with the complete ring electrode， and the drive signal is transmitted by capacitive coupling to avoid the lead through the hole， which can reduce the difficulty of making liquid crystal lens. A high resistance film with low block resistance is designed in the liquid crystal lens， which can not only shield the crosstalk effect produced by the lead electrode， but also play the role of uniform voltage drop. By adjusting the voltage， the focal power varies from -1 D to +1 D. Liquid crystal Fresnel lens can form a circular symmetric refractive index distribution， and the deviation from the ideal optical path difference is less than λ/4， which satisfies the Rayleigh judgment.关键词：liquid crystal Fresnel lens;large aperture;capacitive coupling;lead crosstalk;simulation study
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发布时间：2024-06-27 - “在信息防伪和显示技术领域，研究人员通过分步掩膜曝光法制备图案化蓝相液晶薄膜，实现了高分辨率图案，为相关应用提供了新解决方案。”摘要：In order to improve the edge resolution of patterned Blue Phase Liquid Crystal Films （BPLCF） and make the patterns clearer while reducing the complexity of the preparation process， based on the thiola-crylate Michael addition reaction， this study utilizes stepwise mask exposure under constant temperature to design and prepare patterned BPLCF. Firstly， the changes in the optical properties of BPLCF during the Michael addition reaction were observed. Combining the spectral full width at half maximum （FWHM） and reflectance， the reaction time with relatively good BP I texture was determined. Then， based on the selected reaction time， the effects of different exposure intensities on the optical performance and pattern resolution of BPLCF under the same UV exposure time were explored. The optimal UV exposure intensity for producing patterned BPLCF with clear patterns and high edge resolution was determined. Finally， according to the experimentally obtained reaction time and UV exposure intensity， BPLCF with high-resolution orchid and plum blossom patterns were prepared. Experimental results showed that at a constant temperature of 33 ℃， Michael addition reaction time of 60 min， UV exposure intensity of 30 mW/cm²， and exposure time of 15 s， the BP I structure was well preserved， the BPLCF pattern was clear with no shadow at the edge， and the corresponding central wavelength and FWHM were 528 nm and 53 nm， respectively， with a resolution of up to 38 μm. This research is of great significance for the preparation of high-resolution blue phase liquid crystal patterns and their applications in information anti-counterfeiting and display fields.关键词：blue phase liquid crystal;patterned;michael addition reaction;high resolution;uv exposure intensity
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发布时间：2024-06-27
Liquid Crystal Optics
- “最新研究进展显示，科学家们成功研制出一种新型全息聚合物分散液晶（H-PDLC）体全息光栅，具有化学稳定性高、制作简便、成本低廉等优点。该研究为全息光波导耦合器件提供了新思路，有望在波导显示系统领域实现广泛应用。”摘要：Holographic-polymer dispersed liquid crystal （H-PDLC） volume holographic gratings provide a better approach for holographic waveguide couplers due to stable chemical state， simple fabrication and low cost advantages. This article proposes the development of H-PDLC transmissive volume gratings using composite acrylic high/low refractive index matching modulation. Firstly， the formation mechanism of H-PDLC grating was introduced based on the combination of coupled wave theory and molecular diffusion theory. Then， grating materials with different functional monomers were screened through experiments， and holographic diffraction properties were studied. On this basis， the performance of high-frequency volume holographic H-PDLC gratings was further optimized by increasing the content of initiators. The experimental results show that the H-PDLC formulation of this dual monomer can achieve a visible light transmittance of over 90%， with a diffraction efficiency of 90% and a response bandwidth of 99 nm at 973 lp/mm； At 2 941 lp/mm， the diffraction efficiency is 75.4% and the response bandwidth is 29 nm. The H-PDLC grating has considerable application prospects as a coupler in waveguide display systems.关键词：Holographic-polymer dispersed liquid crystal;Transmittance volume holographic gratings;diffraction efficiency;Wavelength response bandwidth
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发布时间：2024-06-27 - “最新研究进展显示，科学家们通过共混策略和器件多层结构设计，成功制备了一种新型光子人工突触器件，能够在可见光范围内识别并记忆圆偏振光。这一突破为构建高级神经形态视觉系统提供了重要基础。”摘要：Photonic artificial synapse （PAS） devices with the functions of circularly polarized light （CPL） recognition and memory learning are of great value to advanced neuromorphological vision systems. In this study， CPL synaptic transistor devices in the visible range are fabricated by simple blending strategy and multilayer structure design. Experiments show that films prepared by blending chiral small molecules benzoic acid，4-［［4-（hexyloxy）benzoyl］oxy］-，1，1'-［1，1'-binaphthalene］-2，2'-diyl ester（S6N） or benzoic acid，4-（hexyloxy）-，［1，1'-binaphthalene］-2，2'-diylbis（oxycarbonyl-4，1-phenylene） ester，（R）-（9CI） （R6N） with poly（9，9-dioctylfluorene-2，7-diyl） （PFO） had strong chiral optical activity after annealing induction.Using the blend film as the chiral layer and the dithiophene-azaindigo-nitrogen-containing benzodifurandione donor-acceptor conjugated polymer （C13P3.75） as the charge transport layer， the prepared double-layer phototransistor can simulate various biological synaptic behaviors under 405 nm CPL irradiation. Excitatory postsynaptic current （EPSC）， paired-pulse facilitation （PPF） and the transition from short-term memory （STM） to long-term memory （LTM） were successfully simulated. The experimental results show that the device has excellent CPL discrimination ability， and the photocurrent asymmetry factor of 405 nm CPL reaches -0.492.关键词：chiral induction;blending;organic field effect transistor;circularly polarized light;photonic artificial synapse
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发布时间：2024-06-27 - “最新研究揭示，通过在聚（乙烯二氧噻吩）∶聚苯乙烯磺酸盐薄膜中掺杂金属卤化物，可显著提升量子点发光二极管性能。实验显示，2%的LiCl掺杂浓度最优化，使蓝光QLED亮度、效率等指标显著提高。这一发现为提升QLED性能提供了有效策略。”摘要：Full solution-processed quantum dot light-emitting diodes （QLEDs） typically suffer from the problem of electron-hole injection imbalance， which severely limits the performance improvement of blue QLEDs devices. The effects of metal halide （LiCl） doping on the morphology， conductivity and light transmittance of poly（ethylenedioxythiophene）∶polystyrene sulfonate （PEDOT∶PSS） films and the device performance of the prepared QLEDs were investigated. The experimental results show that the best effect on the enhancement of blue QLED device performance is achieved when the doping concentration of LiCl is 2% （mass fraction）， which is mainly attributed to the enhancement of conductivity and transmittance of LiCl-doped PEDOT∶PSS films as well as the improvement of hole injection efficiency in the devices. Compared with the undoped PEDOT∶PSS-based QLED devices，the maximum brightness， current efficiency，power efficiency and external quantum efficiency of the LiCl-doped blue QLED devices are increased to 7 451 cd·m-2， 1.38 cd·A-1， 0.89 lm·W-1 and 3.51% from 5 083 cd·m-2， 0.91 cd·A-1， 0.59 lm·W-1 and 2.31%， respectively.The results show that the use of LiCl-doped PEDOT∶PSS hole injection layer is an effective strategy to improve the performance of blue QLEDs.关键词：blue quantum-dot light-emitting diodes;PEDOT∶PSS;LiCl-doping;hole injection layer;hole injection
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发布时间：2024-06-27 - “最新研究揭示了有机发光二极管（OLED）显示器在汽车智能座舱应用中的潜力，通过改进薄膜封装技术，提升了OLED的环境可靠性，为智能座舱显示技术的发展提供了新思路。”摘要：Organic light emitting diode （OLED） as a new generation of display technology， compared to the liquid crystal display （LCD） has many advantages， including wide color gamut， high contrast， low power consumption and lightweight， etc.There is a replacing trend of LCD in the field of consumer electronics such as smart phones， tablets， monitors， televisions. With the increasing intelligent demand of new energy vehicles， and the display， as the final output unit of the human-machine interface of the electronic system in the intelligent cabin， has the trend of large screen and multi-screen. Considering the limitation of space in the cabin， the light and thin self-emitting OLED has obvious advantages， especially its characteristics of fabricating on flexible substrates， which makes OLED displays more suitable for multi-form flexible display schemes. At present， OLED displays are rarely used in vehicle applications， which is mainly limited by the poor environmental reliability of OLED devices. This paper analyzes the methods of improving the environmental reliability of OLED display by improving the thin film encapsulation in three aspects： improving the barrier ability， improving the stability and improving the heat dissipation ability， which provides reference for the subsequent application of OLED display in automotive intelligent cabin.关键词：OLED displays;thin film encapsulation;environmental reliability;intelligent cabin
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发布时间：2024-06-27
Device Physics and Device Preparation
- “在液晶屏显示缺陷检测领域，研究者提出了YOLO-Mura改进模型，通过引入Involution算子、CARAFE上采样算子、BiFormer注意力模块和BiFPN加权双向金字塔结构，显著提升了微弱特征缺陷的检测精度和计算效率。”摘要：To address the problem of low detection accuracy of weak feature defects in LCD display defects caused by multiple convolution and background texture assimilation， an improved model YOLO-Mura for LCD weak feature defect detection based on YOLOv5 is proposed. Firstly， Involution operator is introduced in the backbone network to expand perceptual field， enhance the information of weak feature defects in spatial range， and reduce model FLOPs. Secondly， the CARAFE upsampling operator is used to optimize the upsampling method and enhance the ability to focus on weak feature defects. Then， in the neck network， the feature extraction ability of the network under strong background interference is enhanced by embedding the BiFormer attention module. Finally， the BiFPN weighted bidirectional pyramid structure is adopted to improve the feature fusion utilization at different levels. Experimental results on the homemade LCD Mura defect dataset show that the accuracy， recall， and mAP@0.5 of YOLO-Mura model are improved by 2.2%， 6.6%， and 2.7%， respectively， and the model computation is reduced by 66.5%. In comparison with the mainstream target detection algorithms， the results show that the final improved model in this paper has better detection performance for Mura defects with weak features of LCDs.关键词：LCD screen;Mura defects;YOLOv5 algorithm;weak feature detection
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发布时间：2024-06-27 - “在公路隧道等弱光照环境下车辆检测领域，研究者提出了一种改进YOLOx算法，通过图像增强和网络结构优化，显著提升了检测精度和实时性，为车辆检测提供了高效解决方案。”摘要：For the low light environment such as road tunnels， the acquired vehicle images are affected by external factors， which leads to low vehicle detection accuracy. For this problem， a real-time vehicle detection method for low light environment with improved YOLOx algorithm is proposed. Firstly， the collected vehicle images are enhanced based on the guiding filter and regional energy characteristic fusion criterion to solve the problems of uneven illumination and blurred target contour information in the images. Secondly， based on the Swin-Transformer network structure， the backbone network of the vehicle detection algorithm with improved YOLOx is constructed， and the global modeling capability of Transformer is used to encode the key semantic information in the images and strengthen the extraction capability of the network detail features. Meanwhile， recursive gated convolution is introduced to replace the null convolution in the neck network to improve the network's high-level semantic modeling capability. Finally， a convolutional attention mechanism is introduced to enhance the network's extraction and fusion of key features for low-illumination images. Experimental validation on the constructed tunnel vehicle detection dataset UA-DETTUN shows that the proposed method achieves an average detection accuracy of 96.1%， which is 6.5% better than the YOLOx algorithm before improvement， while the detection speed of the network meets the requirement of real-time detection. The proposed method has high application value in vehicle detection.关键词：Low-light environment;Swin-Transformer;vehicle detection;image enhancement;attention mechanism
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发布时间：2024-06-27 - “在遥感图像目标检测领域，专家提出了基于相似目标替换的增广方法，通过样本库建立、相似类划分、少数样本补偿和替换样本预处理等步骤，有效提升了模型的泛化能力和检测准确率。”摘要：Nowadays remote sensing image object detection algorithms are highly relied on the development of deep learning technology. Data augmentation to dataset images is an important way to enhance model’s generalization ability. Current augmentation methods of remote sensing object detection algorithms still use general object detection methods. There is an urge need to develop methods that focus on the properties of remote sensing objects. This paper raised a data augmentation method named Similar Targets Replacement （STR） that based on remote sensing images and designed the STR process. First， the sample library is built to collect statistics of samples’ categories. Second， categories of the dataset is divided into several similar target categories. Then， to solve the problem of disbalanced sample amounts， minority sample compensation is designed to balance the proportion of samples from different categories by controlling the probability of input samples. Finally， sample replacing preprocess mechanics is designed by using appropriate transforms for each different categories as the preprocess methods. Experiments on DOTA dataset shows the mAP of DCL detection algorithm using STR augmentation raises 1.34 compared to baseline. Model’s detection accuracy to similar categories raises and ability to categories with fewer number of samples is strengthened.关键词：Remote sensing images;object detection;Data augmentation;Similar target replacement
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发布时间：2024-06-27 - “在图像去雾技术领域，研究者提出了一种基于多尺度残差特征融合的去雾算法，有效提升了图像清晰度，降低了背景噪声干扰，为解决雾霾天气下图像质量退化问题提供了新方案。”摘要：Aiming at the problems of dim color， poor visual fidelity and loss of detail features of the image after processing by existing defogging algorithms， this paper proposes an image defogging algorithm based on multi-scale residual feature fusion. Firstly， a multi-scale parallel feature layer is designed to extract image features from different scales to improve the robustness of the network. Then， the residual network connection layer is designed to realize the transmission and connection of information between multiple convolutional layers， improve the feature utilization rate and speed up feature extraction. The depth feature information fusion layer embedded in the attention mechanism is designed to focus on the key information of the image. It can effectively improve the clarity of the image and reduce the background noise interference. Finally， a color correction and enhancement method based on fog removal theory and exposure fusion is designed to solve the problem of dim image color after network defogging. The experimental results show that the proposed defogging enhancement algorithm achieves the peak signal-to-noise ratio （PSNR）， structural similarity （SSIM） and mean square error （MSE） of 21.37 dB， 82% and 473.6 on the public data sets SOTS， OTS and RTTS， respectively， which effectively improves the image quality degradation caused by foggy weather with better performance.关键词：image defogging;Multiscale convolution;Residual connection;attention mechanism;image fusion
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发布时间：2024-06-27 -
Hyperspectral image classification based on spatial pyramid attention mechanism combined with ResNet AI导读
“在高光谱图像分类领域，研究者提出了一种基于改进的空间金字塔注意力机制残差网络模型，有效提升了分类精度和收敛速度。”摘要：In order to extract spatial-spectral joint features of hyperspectral images， this paper proposes a hyperspectral image classification model based on an improved spatial pyramid attention mechanism residual network. Firstly， principal component analysis is used to remove spectral redundancy， and combined with spatial pyramid attention mechanism， a residual network based hyperspectral image classification model is improved to obtain refined features. Then， the spatial pyramid attention model is used to achieve multi-scale joint feature attention， improve sensitivity to joint features， and effectively emphasize and focus on spatial and spectral information for information exchange. Finally， the classification label is obtained through the Softmax classifier. The proposed method in this paper is tested on MUUFL and Trento datasets， and the experimental results show that the overall classification accuracy of the proposed algorithm reaches 94.08% and 98.32%， respectively. Compared to other hyperspectral classification models， the convergence speed of this model is faster， and it achieves significant improvement in classification performance with higher ground object classification accuracy.关键词：Hyperspectral image;image classification;attention mechanism;spatial-spectral feature- 186
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发布时间：2024-06-27 - “在高光谱图像分类领域，研究者提出了一种新型模型SSFE-MBACNN，通过多分支特征提取和注意力机制，有效提升了分类精度，为解决噪声干扰和样本不足问题提供了创新解决方案。”摘要：To solve the problems of high noise interference in the hyperspectral image itself and the process of classification， insufficient extraction of spatial-spectral feature information， and poor classification performance under limited samples， a hyperspectral image classification model SSFE-MBACNN based on multi-branched spatial-spectral feature enhancement is proposed. First， shallow spatial-spectral feature information and deep spatial feature information are extracted separately using multi-branch feature extraction modules， and attention mechanism are introduced to suppress noise interference. Second， an improved fusion module for multi-scale spatial-spectral feature extraction and a spatial feature enhancement module combining dual pooling and dilated convolution are designed to achieve spatial-spectral feature enhancement， reduce the number of model parameters and improve classification performance. Finally， the global average pooling layer is used instead of the fully connected layer to further reduce the number of parameters and alleviate the model overfitting problem. The experimental results show that the overall classification accuracies of 0.990 7， 0.997 5 and 0.994 7 are achieved for the Indian Pines （10% training sample）， Pavia University （5% training sample） and Salinas （1% training sample） datasets. SSFE-MBACNN makes full use of the spatial-spectral feature information and achieves excellent classification performance with limited samples， which is significantly higher than other comparative methods.关键词：Hyperspectral image classification;feature enhancement;Multi-branch feature extraction;attention mechanism;Multi-scale features;Dual pooling;Dilated convolution
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发布时间：2024-06-27 - “在图像处理领域，专家提出了一种低照度图像增强算法，通过跨级特征自适应融合，有效提升了图像亮度和对比度，为低照度环境下的图像质量改善提供了新方案。”摘要：Aiming at the problems of low brightness， low contrast and poor visual effect in images collected in low-light environment， a low-light image enhancement algorithm based on cross-level adaptive feature fusion is proposed. Firstly， a network frontend is built by combining hierarchical sampling and large receptive field convolution to generate multi-scale features of large-area receptive fields， so that shallow information mining can be fully carried out. Secondly， a multi-head transposed attention module embedded in the middle of the network is introduced， the cross-covariance between channels is calculated to generate attention maps， and global context information associations are implicitly established. Thirdly， a joint loss function is constructed to correct the convergence direction of the model， assist the model optimized from the perspective of contrast and structure， and improve the robustness of the algorithm. Relevant experiments are carried out on the LOL and LOLv2 datasets. The experimental results show that the proposed algorithm outperforms most advanced algorithms in terms of objective indicators such as peak signal-to-noise ratio （PSNR） and structural similarity （SSIM）. Subjectively， the image brightness is natural and the noise is low， and artifacts are effectively suppressed.关键词：Low-Light image;Large receptive field convolution;multi-scale;Transformer;Joint loss function
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发布时间：2024-06-27
Image Processing
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