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Our recent advancement employs lead sulfide (PbS) quantum dots (QDs) in short‐wave infrared (SWIR) photodetector towards low light night vision (LLNV). The as prepared QD SWIR photodetector showcases low dark current density(< 200 nA/cm2) and high efficiency (EQE > 50%), demonstrating QDs' potential for superior LLNV in mobile devices. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this publication is to present the usage of smart doorbells in smart homes. Design/methodology/approach: Critical literature analysis. Analysis of international literature from main databases and polish literature and legal acts connecting with researched topic. Findings: The integration of smart doorbells into the fabric of smart homes signifies a substantial leap forward in the realms of home automation and security. Originally conceived as a means to alert homeowners to visitors, smart doorbells have undergone a remarkable evolution, emerging as sophisticated devices that significantly contribute to heightened security, convenience, and overall peace of mind. These vigilant guardians offer real-time video surveillance, incorporating features like two-way audio communication, motion detection, and night vision for comprehensive security coverage. Beyond security functions, smart doorbells extend unparalleled convenience through remote access and seamless integration with other smart home devices, allowing users to engage in remote communication, manage settings, and automate various tasks. The incorporation of artificial intelligence and machine learning further enhances their capabilities, introducing features like facial recognition and adaptive learning. Table 1 details the key features, highlighting their diverse contributions to modern smart home environments. The multifaceted advantages of smart doorbells, encompassing security enhancements, convenience, and increased property value, are outlined in Table 2. While acknowledging potential challenges outlined in Table 3, such as privacy concerns and dependence on internet connection, practical solutions are presented, underscoring the ongoing potential for smart doorbells to redefine the management of living spaces as they become increasingly interconnected, secure, and intelligent. Originality/Value: Detailed analysis of all subjects related to the problems connected with the usage of smart doorbells in smart home. [ABSTRACT FROM AUTHOR]

Transition metal chromium (Cr) ion‐doped inorganic materials exhibit distinct tunable broadband near‐infrared luminescence, and they have promising applications including nondestructive composition analysis, night vision, biomedicine, plant illumination, and afterglow anticounterfeiting. Currently, the most critical issue is to optimize their full width at half maxima, thermal stability, and internal/external quantum efficiency. This review systematically summarizes strategies to effectively improve the photoluminescence performance of near‐infrared‐emitting materials with transition metal chromium ions. Key examples of the design and preparation of Cr ion‐doped luminescence with different transition modes, a detailed discussion of strategies to effectively improve the photoluminescence properties of near‐infrared luminescent materials, and a summary of generic strategies to help explore novel and efficient Cr‐doped phosphor materials are provided. Next, the latest developments and trends in these Cr ion‐doped phosphor materials are presented for a variety of application scenarios. Finally, future research directions and new challenges faced are also discussed. [ABSTRACT FROM AUTHOR]

The rapid growth in phosphor‐converted near‐infrared light‐emission diodes (NIR‐LEDs) has led to the development of NIR emitter with high efficiency, broadband emission and high thermal stability. In this work, an efficient broad NIR emission of Cr3+ in novel Ca3Sc2Ge3O12 (CSGO) garnet‐based host was developed for the first time, which located at 700 to 1000 nm peaking at 817 nm with a broad bandwidth of ~128 nm. Such a broadband NIR emission originated from the preferential occupancy of Cr3+ in Sc3+ sites with weak octahedral field, which was manifested by the luminescence spectrum and decay behaviors. The Cr3+‐doping concentration was regulated to achieve a good internal quantum efficiency (IQE) of 72.1 % and a fantastic thermal stability (at 423 K, sustained approximately 85 % of the initial intensity). The mechanism for concentration and thermal quenching was further investigated. Benefiting from the excellent luminescence features, a prototype NIR‐LEDs was assembled via integrating the optimized samples with commercial blue InGaN LED chips, which exhibited a satisfactory photoelectric property and a brilliant performance in night vision. These results demonstrated the as‐obtained sample to be a great potential candidate for NIR‐LEDs. [ABSTRACT FROM AUTHOR]

Modulation of the octahedral crystal field environment of Cr3+ is an effective approach to achieve tunable emission. Here, we prepared a series of broadband MP3O9:Cr3+ (M = Al, Ga, In) near-infrared (NIR) phosphors, and cubic AlP3O9:Cr3+ (APO-c:Cr3+) and monoclinic AlP3O9:Cr3+ (APO-m:Cr3+) phosphors were prepared by controlling the synthesis temperature. The emission wavelength was tuned from 787 nm for APO-c:Cr3+ to 894 nm for monoclinic InP3O9:Cr3+ (IPO:Cr3+) by regulating the M ion and reducing the crystal field intensity. Excitingly, the MP3O9:Cr3+ (M = Al, Ga, In) family shows excellent thermal stability; the emission intensity of APO-c:Cr3+, APO-m:Cr3+ and monoclinic GaP3O9:Cr3+ (GPO:Cr3+) can still maintain 95.6%, 86% and 86% of that at room temperature when heating to 423 K, respectively. An NIR LED device was prepared by incorporating GPO:Cr3+ and a blue light LED, demonstrating the potential application in night vision and non-destructive testing. [ABSTRACT FROM AUTHOR]

Applications in near‐infrared (NIR) have been explored significantly in many fields, including bioimaging, night vision, plant growth, and chemical analysis. Different emission profiles are required within the same industry. Developing luminescent materials with different tuning methods is reliable for controlling the NIR regions (NIR‐I, 700–1000 nm; NIR‐II, 1000–1700 nm). Spinel phosphors are promising candidates due to their ability to modulate the crystal field. Understanding the parameters that influence the degree of inversion in spinel compounds is crucial to harness the variability of the spinel structure. Cr3+ and Ni2+ are ideal activators for NIR‐I and NIR‐II emissions, respectively. However, there is a need for phosphors that emit in the NIR‐II region when excited by visible light. Although the energy transfer method combining two activators is considered, this review focuses on different types of spinel structures, discussing their types and common strategies to tune the host structure. The goal is to achieve desired shift and broadness of the entire NIR spectrum, highlighting the importance of spectrum tuning for practical applications. [ABSTRACT FROM AUTHOR]

Ultrathin optical components with giant circular dichroism hold great promise for polarization‐sensitive nanophotonics. However, existing chiral metamaterials often rely on complex‐shaped nanoinclusions, and there remains a paucity of designs active in the shortwave infrared (SWIR) useful for telecommunication and night vision. Here a detailed numerical analysis of the chiroptical response of a simple twisted stacked variant of gap‐plasmon metasurface is presented based on periodic nanohole arrays. Impressively, the 100‐nm free‐standing plasmonic metasurface can attain a thickness‐normalized ellipticity of up to 74.2° µm−1 with tunable bands in the SWIR. Strong and robust optical activity is achieved through energy confinement by gap surface plasmons and effective inter‐nanohole coupling, resulting in an intense superchiral near field. The ultrathin plasmonic metasurface serves as an excellent platform for refractive index sensing with a sensitivity Sn of up to 648.1 nm RIU−1 and field‐enhanced enantiodiscrimination. The simple metasurface with strong SWIR chirality can enjoy a multitude of potential applications including polarization‐sensitive photodetection, optical telecommunication, machine vision, medical imaging, and spectroscopy. These findings also offer insights into some fundamental design principles for twisted stacked aperture‐based metasurfaces and should facilitate the development of new chiral metamaterials with exceptional performance. [ABSTRACT FROM AUTHOR]

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Broadband near‐infrared (NIR) photonic materials have wide applications. Although extensive studies on rare‐earth, transition‐metal, and even semiconductor‐activated materials have enabled the development of a rich NIR material pool, developing broadband and efficient photonic candidates covering the NIR I and II regions from 750 to 1500 nm has been met with limited success. Here, it is reported that a subnano Te cluster with a characteristic configuration different from that of the ion state may fill the aforementioned gap. Further, a strategy is proposed for the in situ generation and stabilization of Te clusters by tuning the cluster evolution in glass. A novel active photonic glass embedded with a Te cluster is fabricated; it exhibits intense and broadband short‐wave NIR luminescence with a central wavelength at 1030 nm and a bandwidth exceeding 330 nm. Interestingly, the glass exhibited a full visible‐spectrum conversion ability from 300 to 800 nm. The application of this unique broadband excitation feature for night vision and tissue penetration is demonstrated using a smartphone as the excitation source. These findings demonstrate a fundamental principle of cluster design in glass for creating new properties and provide a new direction for developing novel cluster‐derived functional composite materials. [ABSTRACT FROM AUTHOR]

A novel near-infrared (NIR) emitting Cr3+-doped clinopyroxene NaInSi 2 O 6 phosphor is designed and synthesized by solid-state method. There are three absorption bands in the NaInSi 2 O 6 : 0.04Cr3+ phosphor, peaking at ∼300 nm, ∼470 nm and ∼690 nm, respectively. A broad emission band ranging from 700 nm to 1300 nm is detected at 466 nm excitation, peaking at 936 nm with a full width at half maximum (FWHM) of 151 nm. At the same time, the calculated weak crystal field strength of Cr3+ is 1.93 in the NaInSi 2 O 6 host, resulting in its characteristic broadband emission. Furthermore, the internal quantum efficiency (IQE) and external quantum efficiency (EQE) of NaInSi 2 O 6 : 0.04Cr3+ are 68.9% and 27.4%. The integrated emission intensity of NaInSi 2 O 6 : 0.04Cr3+ at 423 K retains 55.2% of that at 293 K. By contrast, the NaInSi 2 O 6 : 0.04Cr3+-based phosphor-in-glass (PiG) exhibits better thermal stability (64.9%@423 K). A NIR phosphor-converted light emitting diode (pc-LED) was manufactured using a InGaN chip and NaInSi 2 O 6 : 0.04Cr3+, presenting the NIR output power of 30.47 mW@200 mA. Used as a NIR light source, the prepared pc-LED shows good promise in the fields of biological tissue imaging and night vision. [ABSTRACT FROM AUTHOR]

High speed broadband photodetectors (PDs) have attracted significant interest for many applications such as imaging, gas sensing, and night vision. In this study, the widest reported detection range is achieved from 254 nm to 1800 nm by integrating CsPb(BrCl)3: Yb3+ nanocrystals (NCs) with Germanium (Ge) on a Si substrate. To overcome the persistent photoconductance (PPC) effect that limits the detector response speed in the UV region, this study proposes a down conversion technology to convert UV light to 980 nm infrared light by applying a CsPb(BrCl)3: Yb3+ NCs. The response time of the hybrid PD at 275 nm decreased significantly from several hundred seconds to 1.21 µs. Moreover, benefiting from the CsPb(BrCl)3: Yb3+ NCs antireflection layer, the responsivity of a hybrid CsPb(BrCl)3: Yb3+ NCs /Ge metal semiconductor metal (MSM) PD has enhanced the whole detection band, especially at 1310 nm, which increased by 80% from 0.16 to 0.29 A W−1. This work promotes the development of perovskite integrated optoelectronic devices and provides a feasible route for broad‐band PD from the UV to near infrared (NIR) band. [ABSTRACT FROM AUTHOR]

The retina is an intricately organized neural tissue built on cone and rod pathways for color and night vision. Genetic mutations that disrupt the proper function of the rod circuit contribute to blinding diseases including retinitis pigmentosa and congenital stationary night blindness (CSNB). Down Syndrome cell adhesion molecule like 1 (Dscaml1) is expressed by rods, rod bipolar cells (RBCs), and sub-populations of amacrine cells, and has been linked to a middle age onset of CSNB in humans. However, how Dscaml1 contributes to this visual deficit remains unexplored. Here, we probed Dscaml1's role in the maintenance of the rod-to-RBC synapse using a loss of function mouse model. We used immunohistochemistry to investigate the anatomical formation and maintenance of the rod-to-RBC synapse in the young, adult, and aging retina. We generated 3D reconstructions, using serial electron micrographs, of rod spherules and RBCs to measure the number of invaginating neurites, RBC dendritic tip number, and RBC mitochondrial morphology. We find that while rod-to-RBC synapses form and are maintained, similar to wildtype, that there is an increase in the number of invaginating neurites in rod spherules, a reduction in RBC dendritic tips, and reduced mitochondrial volume and complexity in the Dscaml1 mutant retina compared to controls. We also observed precocious sprouting of RBC dendrites into the outer nuclear layer (ONL) of the Dscaml1 mutant retina compared to controls. These results contribute to our knowledge of Dscaml1's role in rod circuit development and maintenance and give additional insight into possible genetic therapy targets for blinding diseases and disorders like CSNB. [ABSTRACT FROM AUTHOR]

Literature and popular media in the past decade have served to introduce the broader public to the infra-red night vision developments of the Second World War, yet focus has primarily fallen upon those devices made and used by Germany and the USA. Through archival research this paper explores the British perspective, detailing the history and design of an infra-red weapon sight produced experimentally before the war's end, as well as the organisations and companies involved in the process. This is followed by an assessment of Britain's immediate post-war efforts in the field, showing why it was instead American equipment which was used in Britain's first martial deployments of infra-red weapon sights in the early 1950s. [ABSTRACT FROM AUTHOR]

Several studies on distance and size estimation have focused on normal and night vision goggles (NVGs), but none of them have been performed during the twilight period. Hence, in this study, distance was estimated for the first time during nautical twilight. According to the findings, the accuracy of distance estimation reduces as visibility decreases and is restricted. When compared with Day Limited Helmet Mounted Display Vision (M = 5.27, SD = .59), Twilight Normal Vision (M = 5.33, SD = .69) and Twilight Helmet Mounted Display Vision (M = 5.20, SD = .61), NVG (M = 4.79, SD = .57) appears to have a lower error rate. In this study, distance was estimated considering objects determined during the helicopter flight by the pilots in different visibility conditions, which are significant in the field of aviation. This work is unique owing to its coverage of helicopter pilots and the estimation during the twilight period. In view of our findings, it may be reasonable to postpone the planned helicopter flights during poor visibility conditions. [ABSTRACT FROM AUTHOR]

The recent prominence of using infrared technology for human detection has garnered attention, particularly for applications in intelligent video surveillance and self-driving systems. This technology offers advantages in adverse weather conditions and night vision. However, within deep learning, the challenge of variable illumination during human detection persists. This study presents a novel method for identifying individuals in thermal images by enhancing the you only look once (YOLOv5s) algorithm. The approach incorporates the Bi-directional feature pyramid network (BiFPN) and the convolutional block attention module (CBAM) to improve the model’s feature integration and extraction capabilities. Evaluation on established thermal imaging datasets confirms the method’s superiority over state-of-the-art convolutional neural networks (CNN) based techniques, achieving remarkable precision 99.1% and recall 96.9%. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Military personnel extensively use night vision goggles (NVGs) in contemporary scenarios. Since NVGs may induce or increase injuries from falls or vehicular accidents, biomechanical risk assessments would aid design goal or mitigation strategy development. METHODS: This study assesses injury risks from NVG impact on cadaver heads using impactors modeled on the PVS-14 NVG. Impacts to the zygoma and maxilla were performed at 20° or 40° angles. Risks of facial fracture, neurotrauma, and neck injury were assessed. Acoustic sensors and accelerometers assessed time of fracture and provided input variables for injury risk functions. Injuries were assessed using the Abbreviated Injury Scale (AIS); injury severity was assessed using the Rhee and Donat scales. Risk functions were developed for the input variables using censored survival analyses. RESULTS: The effects of impact angle and bone geometry on injury characteristics were determined with loading area, axial force, energy attenuation, and stress at fracture. Probabilities of facial fracture were quantified through survival analysis and injury risk functions. These risk functions determined a 50% risk of facial bone fracture at 1148 N (axial force) at a 20° maxillary impact, 588 N at a 40° maxillary impact, and 677 N at a 20° zygomatic impact. A cumulative distribution function indicates 769 N corresponds to 50% risk of fracture overall. DISCUSSION: Results found smaller impact areas on the maxilla are correlated with higher angles of impact increasing risk of facial fracture, neck injuries are unlikely to occur before fracture or neurotrauma, and a potential trade-off mechanism between fracture and brain injury. [ABSTRACT FROM AUTHOR]

Sooty mold is a common disease found in citrus plants and is characterized by black fungi growth on fruits, leaves, and branches. This mold reduces the plant's ability to carry out photosynthesis. In small leaves, it is very difficult to detect sooty mold at the early stages. Deep learning-based image recognition techniques have the potential to identify and diagnose pest damage and diseases such as sooty mold. Recent studies used advanced and expensive hyperspectral or multispectral cameras attached to UAVs to examine the canopy of the plants and mid-range cameras to capture close-up infected leaf images. To bridge the gap on capturing canopy level images using affordable camera sensors, this study used a low-cost home surveillance camera to monitor and detect sooty mold infection on citrus canopy combined with deep learning algorithms. To overcome the challenges posed by varying light conditions, the main reason for using specialized cameras, images were collected at night, utilizing the camera's built-in night vision feature. A total of 4200 sliced night-captured images were used for training, 200 for validation, and 100 for testing, employed on the YOLOv5m, YOLOv7, and CenterNet models for comparison. The results showed that YOLOv7 was the most accurate in detecting sooty molds at night, with 74.4% mAP compared to YOLOv5m (72%) and CenterNet (70.3%). The models were also tested using preprocessed (unsliced) night images and day-captured sliced and unsliced images. The testing on preprocessed (unsliced) night images demonstrated the same trend as the training results, with YOLOv7 performing best compared to YOLOv5m and CenterNet. In contrast, testing on the day-captured images had underwhelming outcomes for both sliced and unsliced images. In general, YOLOv7 performed best in detecting sooty mold infections at night on citrus canopy and showed promising potential in real-time orchard disease monitoring and detection. Moreover, this study demonstrated that utilizing a cost-effective surveillance camera and deep learning algorithms can accurately detect sooty molds at night, enabling growers to effectively monitor and identify occurrences of the disease at the canopy level. [ABSTRACT FROM AUTHOR]

The broadband near-infrared (NIR) phosphor converted light emitting diode (NIR pc-LED) has garnered unprecedented attention due to its crucial role in NIR applications. However, there remains a scarcity of efficient broadband NIR luminescence materials capable of emitting NIR light with wavelengths greater than 800 nm. This study reports the synthesis, crystal structure and photoluminescence (PL) properties for double perovskite Sr 2 ScTaO 6 :Cr3+ phosphors which exhibit a broadband NIR emission in the 650–1250 nm range, peaking at∼815 nm with the full width at half maximum (FWHM) of 161 nm. The observed broadband emission arises from two distinct Cr3+ centers, namely Sc3+ and Ta5+ octahedral sites within the Sr 2 ScTaO 6 structure, as demonstrated by luminescence and decay kinetic analysis. A significant enhancement of the thermal stability and a remarkable broadening of the FWHM (from 161 to 275 nm) are achieved by employing Yb3+ co-doping strategy. The efficient energy transfer from Cr3+ to Yb3+ was confirmed through emission and excitation spectra, as well as luminescence decay measurements. Finally, Sr 2 ScTaO 6 :Cr3+-Yb3+ phosphor was integrated with a 470 nm blue LED chip to fabricate a NIR pc-LED device, and its potential application in night vision was evaluated. [ABSTRACT FROM AUTHOR]

Ambient temperature long‐wavelength infrared (LWIR) photodetection has many critical applications ranging from thermal imaging and optical communications to night vision cameras. Currently, high performance, low cost, air stability, and ultra‐broadband response still constitute challenges. Here, the study demonstrates a high‐performance uncooled LWIR photodetector using 2D hexagonal α‐Fe2O3 single crystal nanoflakes, which are synthesized via chemical vapor deposition. The 2D α‐Fe2O3 photodetector realizes high specific detectivity (D*) of 3.28×109 cmHz1/2 W−1 and very low noise equivalent power of 8.94×10−14 W Hz−1/2 with 10.6 µm laser. The photo bolometer effect is responsible for the photoresponse in the infrared range with a large temperature coefficient resistance of −241.2% K−1. This study shows a new type of potential broadband response material and provides a promising LWIR optoelectrical device with good air stability. [ABSTRACT FROM AUTHOR]

Luminescent metal halides have attracted increasing attention because of their tunable emission and superior photoelectric properties. However, it is still challenging to achieve near‐infrared (NIR) emission from metal halides, which is important in applications such as food quality analysis and night vision. In this work, the broadband NIR emission is achieved by alloying Sn2+ into zero‐dimensional (0D) Cs2ZnBr4. The incorporating of Sn2+ cations enables the originally weakly luminescent Cs2ZnBr4 to exhibit an efficient broadband NIR emission. Upon photoexication, the optimized Sn2+ alloyed Cs2ZnBr4 (Cs2Zn0.875Sn0.125Br4) exhibits a highly efficient broadband NIR emission peaked around 700 nm, with a large Stokes shift of 323 nm, a full width at maximum of 177 nm, and a high quantum efficiency of around 41%. Spectroscopic and theoretical calculations unveil that the efficient NIR emission originates from the self‐trapping emission introduced by the Sn alloying. In addition to the high efficient broadband emission, the Sn2+ alloyed Cs2ZnBr4 also exhibits high thermal stability, retaining 78% of its initial intensity at 150 °C. The night vision application is demonstrated by using a light source fabricated by combining Sn2+ alloyed Cs2ZnBr4 phosphor with a 365 nm LED chip in the dark. [ABSTRACT FROM AUTHOR]

In recent years, the prevalence of cardiovascular diseases has been growing geometrically, especially among the elderly. Real-time heart rate monitoring becomes an effective measure for preventing cardiovascular diseases. Traditional contact-based real-time heart rate measurement methods require long-term wearing of contact electrodes, which can cause inconvenience to the elderly population. In this study, a wide spectrum full color night vision elderly face video heart rate automatic measurement and early warning system was designed and developed by combining imaging photoplethysmography (IPPG), video acquisition equipment based on starlight wide spectrum camera and high-speed face recognition signal processing algorithm based on deep learning. By constructing a software and hardware platform, a comprehensive evaluation of the system's application in elderly facial video heart rate measurement experiments was conducted. [ABSTRACT FROM AUTHOR]

Organic near‐infrared (NIR) photodetectors with essential applications in medical diagnostics, night vision, remote sensing, and optical communications have attracted intensive research interest. Compared with most conventional inorganic counterparts, organic semiconductors usually have higher absorption coefficients, and their thin active layer could be sufficient to absorb most incident light for effective photogeneration. However, due to the relatively poor charge mobility of organic materials, it remains challenging to inhibit the photogenerated exciton recombination and effectively extract carriers to their respective electrodes. Herein, this challenge was addressed by increasing matrix conductivities of a ternary active layer (D–A–D structure NIR absorber [2TT‐oC6B]:poly(N,N′‐bis‐4‐butylphenyl‐N,N′‐bisphenyl)benzidin [PolyTPD]:[6,6]‐phenyl‐C61‐butyric acid methyl ester [PCBM] = 1:1:1) upon in situ incident light illumination, significantly accelerating charge transport through percolated interpenetrating paths. The greatly enhanced photoconductivity under illumination is intrinsically related to the unique donor–acceptor molecular structures of PolyTPD and 2TT‐oC6B, whereas stable intermolecular interaction has been verified by systematic molecular dynamics simulation. In addition, an ultrafast charge transfer time of 0.56 ps from the NIR aggregation‐induced luminogens of 2TT‐oC6B absorber to PolyTPD and PCBM measured by femtosecond transient absorption spectroscopy is beneficial for effective exciton dissociation. The solution‐processed organic NIR photodetector exhibits a fast response time of 83 μs and a linear dynamic range value of 111 dB under illumination of 830 nm. Therefore, our work has opened up a pioneering window to enhance photoconductivity through in situ photoirradiation and benefit NIR photodetectors as well as other optoelectronic devices. [ABSTRACT FROM AUTHOR]

Infrared and visible light image fusion combines infrared and visible light images by extracting the main information from each image and fusing it together to provide a more comprehensive image with more features from the two photos. Infrared and visible image fusion has gained popularity in recent years and is increasingly being employed in sectors such as target recognition and tracking, night vision, scene segmentation, and others. In order to provide a concise overview of infrared and visible picture fusion, this paper first explores its historical context before outlining current domestic and international research efforts. Then, conventional approaches for infrared and visible picture fusion, such as the multi-scale decomposition method and the sparse representation method, are thoroughly introduced. The advancement of deep learning in recent years has greatly aided the field of picture fusion. The outcomes of the fusion have a wide range of potential applications due to the neural networks' strong feature extraction and reconstruction skills. As a result, this research also evaluates deep learning techniques. After that, some common objective evaluation indexes are provided, and the performance evaluation of infrared and visible image fusion is introduced. The common datasets in the areas of infrared and visible image fusion are also sorted out at the same time. Datasets play a significant role in the advancement of infrared and visible image fusion and are an essential component of infrared and visible image fusion testing. The application of infrared and visible image fusion in many domains is then simply studied with practical examples, particularly in developing fields, used to show its application. Finally, the prospect of the current infrared and visible image fusion field is presented, and the full text is summarized. [ABSTRACT FROM AUTHOR]

Ambient temperature long‐wavelength infrared (LWIR) photodetection has many critical applications ranging from thermal imaging and optical communications to night vision cameras. Currently, high performance, low cost, air stability, and ultra‐broadband response still constitute challenges. Here, the study demonstrates a high‐performance uncooled LWIR photodetector using 2D hexagonal α‐Fe2O3 single crystal nanoflakes, which are synthesized via chemical vapor deposition. The 2D α‐Fe2O3 photodetector realizes high specific detectivity (D*) of 3.28×109 cmHz1/2 W−1 and very low noise equivalent power of 8.94×10−14 W Hz−1/2 with 10.6 µm laser. The photo bolometer effect is responsible for the photoresponse in the infrared range with a large temperature coefficient resistance of −241.2% K−1. This study shows a new type of potential broadband response material and provides a promising LWIR optoelectrical device with good air stability. [ABSTRACT FROM AUTHOR]

In the autonomous driving industry, there is a growing trend to employ long-wave infrared (LWIR)-based uncooled thermal-imaging cameras, capable of robustly collecting data even in extreme environments. Consequently, both industry and academia are actively researching contrast-enhancement techniques to improve the quality of LWIR-based thermal-imaging cameras. However, most research results only showcase experimental outcomes using mass-produced products that already incorporate contrast-enhancement techniques. Put differently, there is a lack of experimental data on contrast enhancement post-non-uniformity (NUC) and temperature compensation (TC) processes, which generate the images seen in the final products. To bridge this gap, we propose a histogram equalization (HE)-based contrast enhancement method that incorporates a region-based clipping technique. Furthermore, we present experimental results on the images obtained after applying NUC and TC processes. We simultaneously conducted visual and qualitative performance evaluations on images acquired after NUC and TC processes. In the visual evaluation, it was confirmed that the proposed method improves image clarity and contrast ratio compared to conventional HE-based methods, even in challenging driving scenarios such as tunnels. In the qualitative evaluation, the proposed method demonstrated upper-middle-class rankings in both image quality and processing speed metrics. Therefore, our proposed method proves to be effective for the essential contrast enhancement process in LWIR-based uncooled thermal-imaging cameras intended for autonomous driving platforms.

The helmet plays an important role in protection of pilot's head and enhances the pilot's capabilities and performance significantly with the use of mounted devices such as the Night Vision Goggle (NVG). However, the use of helmet-mounted devices might increase the risk of injury due to the increased helmet weight and change in the centre of gravity of head. In this study, four helmets with different combinations of mounted devices were modelled in a validated human head–neck multi-body model to analyse their effects on the pilot's neck injury during simulated ejection. The probability of neck injury was evaluated and predicted using the N i j neck injury criteria and human injury risk curves, considering the tolerance of injury for upper and lower cervical segment. It was demonstrated that the helmet-mounted devices would increase the compression force and bending moment on cervical spine, especially for the lower cervical segments with higher N i j . In the cases with Night Vision Goggle, N i j of the lower cervical segment reached 0.54, which exceeded the requirement in aviation filed. For the cases with Visor, excessive extension occurred, resulting in a high N i j . The simulation results of this study could provide a reference for helmet and mounted devices design and offer a proposal for the protection of pilots during ejection. [ABSTRACT FROM AUTHOR]

Sunlight-like full-spectrum phosphor-converted light-emitting diodes (pc-LEDs) require near-infrared (NIR) emission bands to fill the spectrum gap and consequently propel their widespread applications. Although fluoride NIR phosphors have been increasingly investigated, balancing high quantum efficiency (QE), high thermal stability, and wideband NIR emission to obtain excellent overall performance in a single system is still a challenge for Cr3+-doped fluoride NIR phosphor and is significant for direct utilization. Herein, a high-efficiency and thermally stable broadband NIR emission was realized in a novel LiSrGaF6:Cr3+ fluoride phosphor benefitting from a relatively weak crystal field and electron–phonon coupling effect. Upon blue light excitation, the ultra-broad NIR luminescence ranging from 650 to 1150 nm can be achieved with an FWHM of 149 nm peaking at ∼813 nm. Furthermore, this system possesses a high QE of up to 76.88% and its emission intensity at 423 K still maintains 61.62% of its initial intensity at room temperature. An NIR output power of 42.82 mW and photoelectric conversion efficiency of 14.27% of NIR pc-LED devices have also been presented based on this NIR phosphor, demonstrating its possible application in compact nonvisible light sources. In addition, a highly continuous sunlight-like vis-NIR pc-LED was further constructed by employing a blue chip with commercial cyan (BaSi2O2N2:Eu2+), yellow (Y3Al5O12:Ce3+), red (CaAlSiN3:Eu2+), and this LiSrGaF6:Cr3+ NIR phosphor. The as-obtained pc-LED exhibits an ultra-broad spectrum ranging from 400 nm to 1000 nm, exhibiting a higher color reproduction with a color rendering index (CRI) of 95.1 and luminous efficiency (LE) of 50.22 lm W−1. These results indicate that LiSrGaF6:Cr3+ phosphor can be a promising NIR phosphor candidate for high-quality sunlight-like full-spectrum lighting and infrared night vision technology. [ABSTRACT FROM AUTHOR]

SiC ceramic is an excellent infrared source material that can be used in a wide range of fields, like infrared heating, night vision and communication, but its poor electrical properties limit it. In this work, carbon nanotubes (CNTs) were selected as conductive phase filler, and SiC-CNT composite ceramics were prepared by SPS method. The effects of CNT content on the microstructures, electrical properties and infrared radiation performance of the composites were studied. The introduction of CNT effectively reduced the height of Schottky barrier at grain boundary, thus weakening the grain boundary effect, reducing the grain boundary resistance, further weakening the nonlinear characteristics and bulk resistivity of the composite ceramics. When the content of CNT was 1 wt%, electrical percolation was achieved, and the bulk resistivity of SiC ceramics dropped by nearly 3 orders of magnitude. The preferred orientation distribution of CNT made the bulk resistivity perpendicular to the pressure direction R ⊥ always lower than that parallel to the pressure direction R //. The sample with 5 wt% CNT assumed linear conductivity characteristics, with bulk resistivity in different direction of 16.5 Ω cm (R //) and 11.8 Ω cm (R ⊥), respectively. CNT addition slightly increased the infrared radiation performance of SiC ceramics, and the sample with 5 wt% CNT possessed the highest total emissivity of 0.675. The excellent electrical conductivity and infrared radiation performance of SiC-CNT composite ceramic confirmed this class as a promising infrared source material. [ABSTRACT FROM AUTHOR]

The noise statistics of real-world camera images are challenging for any denoising algorithm. Here, I describe a modified version of a bionic algorithm that improves the quality of real-word noisy camera images from a publicly available image dataset. In the first step, an adaptive local averaging filter was executed for each pixel to remove moderate sensor noise while preserving fine image details and object contours. In the second step, image sharpness was enhanced by means of an unsharp mask filter to generate output images that are close to ground-truth images (multiple averages of static camera images). The performance of this denoising algorithm was compared with five popular denoising methods: bm3d, wavelet, non-local means (NL-means), total variation (TV) denoising and bilateral filter. Results show that the two-step filter had a performance that was similar to NL-means and TV filtering. Bm3d had the best denoising performance but sometimes led to blurry images. This novel two-step filter only depends on a single parameter that can be obtained from global image statistics. To reduce computation time, denoising was restricted to the Y channel of YUV-transformed images and four image segments were simultaneously processed in parallel on a multi-core processor. [ABSTRACT FROM AUTHOR]

In recent years, food detection, plant photosynthesis, night vision, and the identification of biological data have all benefited from near-infrared luminescence. However, developing metal halides emitting near-infrared (NIR) light is still difficult, which restricts further applicability. Here, we propose an insightful methodology to investigate the wideband NIR emission in metal halide Cs 2 ZnCl 4 host by doping Sb3+. The phosphors are successfully synthesized by the coprecipitation method and the photoluminescent properties are explored in detail. Based on the spectroscopic information, experimental data with DFT calculations, and luminescence kinetics investigation of Sb3+ doped Cs 2 ZnCl 4 , the broadband red emission is caused by self-trapped excitons, which can be attributed to the 3P 1 –1S 0 transitions. The spectra under the excitation at 351 nm exhibit an ultra-wideband emission with a center wavelength of 737 nm, an FHWM of 196 nm, and a significant Stokes shift of 386 nm. The NIR LED fabricated by Cs 2 ZnCl 4 : Sb3+ can also be used in night vision devices and biological identification. Our findings in Sb3+ doped Cs 2 ZnCl 4 materials provide light on how doping induces emission centers and expand our understanding of the optical characteristics of doped lead-free metal halides for future research. This work also offers recommendations for broadening the range of uses for luminous metal halides and proposes an efficient method for developing fresh environmentally friendly and wideband emission NIR phosphors. [ABSTRACT FROM AUTHOR]

Trivalent chromium ion-activated broadband near-infrared (NIR) luminescence materials have shown great application prospects as next-generation NIR light sources, but improvement of the luminescence efficiency remains a challenge. Herein, novel K2LiScF6:Cr3+ and K2LiScF6:Cr3+/Mn4+ broadband fluoride NIR phosphors are designed and prepared by a combination of hydrothermal and cation exchange methods for the first time. The crystal structure and photoluminescence (PL) properties of K2LiScF6:Cr3+ are studied in detail, which shows strong absorption in the blue light region (λex = 432 nm) and broadband NIR emission (λem = 770 nm) with a PL quantum efficiency of 77.6%. More importantly, the NIR emission of Cr3+ can be enhanced by co-doping with Mn4+, which may provide an alternative way for improving the PL intensity of Cr3+-activated broadband NIR phosphors. Finally, a NIR phosphor-converted LED (pc-LED) device is fabricated using the as-prepared NIR phosphor and its application in bio-imaging and night vision has been evaluated. [ABSTRACT FROM AUTHOR]

In this paper, a real-time video-stream enhancement scheme is proposed along with a hardware prototype development. The proposed technique employs a multi-linear adaptive gamma correction method to locally enhance the dark video frames in presence of high intensity optical sources. The proposed algorithm employs three linear functions corresponding to low, medium and high intensity regions for proper enhancement of different intensity regions. The slope and range of the linear functions are automatically derived from intensity distribution and hence the overall multi-linear function becomes highly nonlinear and adaptive to varying constraints. Consequently, the input–output mapping function of the algorithm works as a spreading function in the low intensity range for contrast improvement and preserves the information of the high intensity regions to avoid information loss due to over-enhancement. The experimental results show that the proposed algorithm exhibits better performance than various existing algorithms in terms of subjective and objective measures. [ABSTRACT FROM AUTHOR]

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Cr3+ activated near‐infrared (NIR) phosphors are getting unprecedented attention to fabricate the broad band NIR light emitting diodes (NIR‐LEDs) for nondestructive detection, bio‐imaging, and night vision. However, it remains a major challenge to obtain ultrabroadband NIR emitting phosphor with excellent quantum yield (QY). Here, a broadband NIR emitting phosphor Mg7Ga2GeO12:Cr3+ (MGGO: Cr3+) ranging from 600 to 1300 nm with an outstanding QY (93%) and large full width of half maximum (FWHM = 226 nm) is developed, in which the site occupancy tendency of Cr3+ in MGGO host is discussed in detail through combining the structure optimization and the first‐principles theory calculation with luminescent properties at low temperature. After that, the emission intensity of MGGO:Cr3+ is improved through partial substitution of Mg2+ by alkaline‐earth ions Ca2+, Sr2+, or Ba2+, and the luminescence enhancement mechanism is also investigated. Furthermore, the NIR pc‐LED device is fabricated by combining 450 nm blue LED chip with the brightest phosphor MGGO:Cr3+/Ba2+, and its potential applications are evaluated in the field of nondestructive detection, night vision, and bio‐imaging. [ABSTRACT FROM AUTHOR]

An infrared perfect absorber structure is designed based on GaAs/Au/SiO2 metamaterial with numerical simulation, in which gold split ring resonators (SRR) embedded in the GaAs layer. The absorption exceeds 99% at 1360 nm under the plane wave excitation with its polarization perpendicular to the opening direction of the SRR. When the polarization of the plane wave is parallel to the opening direction, the absorption exceeds 97% and 56% at 970 and 2070 nm, respectively, which realize dual-band absorption. The absorption peaks are effectively modulated by controlling surface current density distribution and resonant electromagnetic response. In addition, the resonant wavelengths are further manipulated by optimizing the resonant ring structural parameters, which achieve ultrawide-band absorption ranging from near-infrared to mid-infrared region. The absorber remains absorption peaks above 96% under wide-angle plane wave incidence, and the resonant peak positions are independent of the incident angle. This work exhibits the promise of GaAs-based metamaterial in practical applications in energy harvesting and night vision imaging. [ABSTRACT FROM AUTHOR]

The NIR phosphor-converted light-emitting diode (NIR pc-LED) is a new near-infrared light source that has been widely studied. Among various NIR phosphors, Cr3+ doped gadolinium aluminum gallium garnet (GAGG:Cr3+) ceramic phosphor has shown great potential due to its ultra-high efficiency and thermal stability. Despite its capabilities, its detection range may be limited due to a relatively narrow emission bandwidth. To make the GAGG:Cr3+ ceramic phosphors achieve both high efficiency and broadband emission, a series of Gd 3 Al 2- x - y Sc x Ga 3 O 12 : y Cr3+ (GASGG:Cr3+) ceramic phosphors were prepared. Thanks to the decrease of crystal field strength with the doping of Sc3+, the full width at half maximum (FWHM) of GASGG:Cr3+ ceramic phosphors were extended from 84 nm to 117 nm, and the emission peak exhibited a red-shift of 46 nm. Meanwhile, it still retained extremely high external quantum efficiency (EQE = 47%) and excellent thermal stability (90.7%@150 °C). Then, a NIR pc-LED prototype device was fabricated by combining GASGG:Cr3+ ceramic phosphor with a blue LED chip. The NIR light output power and the photoelectric conversion efficiency of this device achieved 646 mW and 19.2%, respectively. Finally, the application effect in night vision and venography of this prototype device was demonstrated. [ABSTRACT FROM AUTHOR]

Cr3+ activated near‐infrared (NIR) phosphors are getting unprecedented attention to fabricate the broad band NIR light emitting diodes (NIR‐LEDs) for nondestructive detection, bio‐imaging, and night vision. However, it remains a major challenge to obtain ultrabroadband NIR emitting phosphor with excellent quantum yield (QY). Here, a broadband NIR emitting phosphor Mg7Ga2GeO12:Cr3+ (MGGO: Cr3+) ranging from 600 to 1300 nm with an outstanding QY (93%) and large full width of half maximum (FWHM = 226 nm) is developed, in which the site occupancy tendency of Cr3+ in MGGO host is discussed in detail through combining the structure optimization and the first‐principles theory calculation with luminescent properties at low temperature. After that, the emission intensity of MGGO:Cr3+ is improved through partial substitution of Mg2+ by alkaline‐earth ions Ca2+, Sr2+, or Ba2+, and the luminescence enhancement mechanism is also investigated. Furthermore, the NIR pc‐LED device is fabricated by combining 450 nm blue LED chip with the brightest phosphor MGGO:Cr3+/Ba2+, and its potential applications are evaluated in the field of nondestructive detection, night vision, and bio‐imaging. [ABSTRACT FROM AUTHOR]

Neuronal plasticity of the inner retina has been observed in response to photoreceptor degeneration. Typically, this phenomenon has been considered maladaptive and may preclude vision restoration in the blind. However, several recent studies utilizing triggered photoreceptor ablation have shown adaptive responses in bipolar cells expected to support normal vision. Whether such homeostatic plasticity occurs during progressive photoreceptor degenerative disease to help maintain normal visual behavior is unknown. We addressed this issue in an established mouse model of Retinitis Pigmentosa caused by the P23H mutation in rhodopsin. We show robust modulation of the retinal transcriptomic network, reminiscent of the neurodevelopmental state, and potentiation of rod - rod bipolar cell signaling following rod photoreceptor degeneration. Additionally, we found highly sensitive night vision in P23H mice even when more than half of the rod photoreceptors were lost. These results suggest retinal adaptation leading to persistent visual function during photoreceptor degenerative disease.