Night Vision Technology Research Articles

Broadband near-infrared emission of Cr3+ doped Zn7Sb2O12 phosphors for night vision imaging system sources

Near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) are highly promising for various applications, including food analysis, night vision, and biological detection. In this work, we report a Cr3+-doped Zn7Sb2O12 phosphor, which was prepared through a high-temperature solid-phase method. Under excitation at 400 nm, the phosphor reveals an emission spectrum that extends from 700 to 1400 nm, peaking at 950 nm with a full width at half maximum (FWHM) of 179 nm. In addition, the internal quantum efficiency (IQE) of the Zn7Sb2O12: 0.01Cr3+ phosphor is recorded at 33.13%. When encapsulated in pc-LEDs, the phosphor achieves a near-infrared (NIR) output power of 18.90 mW at 160 mA, along with a photoelectric conversion efficiency (PCE) of 15.45% at 20 mA. The developed pc-LED shows promise in non-destructive testing and night vision technologies.

Recent Advancements in Nanomaterials for Near‐Infrared to Long‐Wave Infrared Photodetectors

AbstractNanomaterials have superior electronic, optical, and mechanical properties making them highly suitable for a range of applications in optoelectronics, biomedical fields, and photonics. Nanomaterials‐based IR detectors are rapidly growing due to enhanced sensitivity, wide spectral range, and device miniaturization compared to commercial photodetectors. This review paper focuses on the significant role of nanomaterials in infrared detection, an area critical for enhancing night vision and health monitoring technologies. The latest advancements in IR photodetectors that employ various nanomaterials and their hybrids are discussed. The manuscript covers the operational mechanisms, device designing, performance optimization strategies, and material challenges. This review aims to provide a comprehensive overview of the current developments in nanomaterial‐based IR photodetectors and to identify key directions for future research and technological advancements.

Performance testing of a novel short axis photomultiplier tube for the HUNT project

Photomultiplier tubes (PMTs) with large-area cathodes are increasingly being used in cosmic-ray experiments to enhance detection efficiency. The optical modules (OMs) of the High-Energy Underwater Neutrino Telescope (HUNT) have employed a brand new N6205 20-inch microchannel plate photomultiplier tube (MCP-PMT) developed by the North Night Vision Science & Technology (Nanjing) Research Institute Co. Ltd. (NNVT). In order to make the 20-inch PMT fit into the 23-inch diameter pressure-resistant glass sphere, NNVT improved the internal structure of PMT and shortened the height of PMT by more than 10 cm. The first batch of these PMTs has been delivered for preliminary research work. This paper describes a specific PMT testing platform built for the first batch of 15 MCP-PMTs, and some performance parameters of PMT, such as peak-to-valley ratio, TTS and nonliniearity, are measured. The measurement results show that the new PMT still has good performance and can meet the requirements of HUNT project.

High-Sensitive Uncooled Mid-Wave Infrared Detector Based on TiS3 Nanoribbon.

High-sensitive uncooled mid-wave infrared (MWIR) photodetection with fast speed is highly desired for biomedical imaging, optical communication, and night vision technology. Low-dimensional materials with low dark current and broadband photoresponse hold great promise for use in MWIR detection. Here, this study reports a high-performance MWIR photodetector based on a titanium trisulfide (TiS3) nanoribbon. This device demonstrates an ultra-broadband photoresponse ranging from the visible spectrum to the MWIR spectrum (405-4275nm). In the MWIR spectral range, the photodetector achieves competitive high photoresponsivity (R) of 21.1 AW-1, and an impressive specific detectivity (D*) of 5.9× 1010 cmHz1/2W-1 in ambient air. Remarkably, the photoresponse speed in the MWIR with τr = 1.3ms and τd = 1.5ms is realized which is much faster than the thermal time constant of 15ms. These findings pave the way for highly sensitive, room-temperature MWIR photodetectors with exceptionally fast response speed.

Real-time identification and visualization of Egyptian blue using modified night vision goggles

The possibility to use light in the visible spectrum to induce near-infrared luminescence in some materials, particularly Egyptian blue and related pigments, offers a significant advantage in terms of their detection. Since 2008, this property has been exploited to reveal the presence of those pigments even in tiny amounts on ancient and decayed surfaces, using a technical-photography method. This paper presents a new type of imaging device that enables real-time, easy, and inexpensive identification and mapping of Egyptian blue and related materials. The potential of the new tool is demonstrated by its effectiveness in detecting Egyptian blue within some prestigious sites: (a) Egyptian findings at Museo Egizio, Turin; (b) underground Roman frescoes at Domus Aurea, Rome; and (c) Renaissance frescoes by Raphael, Triumph of Galatea and Loggia of Cupid and Psyche, at Villa Farnesina, Rome. The device is based on night vision technology and allows an unprecedented fast, versatile, and user-friendly approach. It is employable by professionals including archeologists, conservators, and conservation scientists, as well as by untrained individuals such as students or tourists at museums and sites. The overall aim is not to replace existing photographic techniques but to develop a tool that enables rapid preliminary recognition, useful for planning the work to be carried out with conventional methods. The ability to immediately track Egyptian blue and related pigments, through real-time vision, photos, and videos, also provides a new kind of immersive experience (Blue Vision) and can foster the modern use of these materials in innovative applications and future technologies.

Proton and muon beam tests for ultra-fast MCP-PMT detectors

In collaboration with the North Night Vision Science and Technology (Nanjing) Research Institute Co. Ltd, researchers at the Institute of High Energy of Physics in China have successfully developed the 20-inch micro-channel-plate photomultiplier tube (MCP-PMT) that exhibits high detection efficiency (DE) for use in the Jiangmen Underground Neutrino Observatory (JUNO). Due to the long drift path of electrons from photocathode to MCP, the 20-inch MCP-PMT has a time resolution on the order of nanoseconds. Recently, the team has made advancements in ultra-fast MCP-PMTs (FPMTs), achieving picosecond-level time resolution with both 1-inch and 2-inch types. By now, prototypes featuring single-anode, 2 × 2 anodes, 4 × 4 anodes, and 8 × 8 anodes have been successfully manufactured and tested. The 8 × 8 anode FPMT, in particular, demonstrates a transit time spread (TTS) of 36 ps (Sigma) in single photon mode, thanks to its meticulously engineered structure. To assess the FPMT’s time performance under beam conditions, two beam tests were conducted at Fermi Lab and CERN. In these tests, the 8 × 8 pixel arrays of four distinct radiators, including LYSO, BGO, Pb glass and quartz glass, were paired with the 8 × 8 anodes FPMT. This setup involved the use of two radiator-coupled FPMT detectors for particle detection. The best coincidence time resolution recorded was 64 ps (Sigma) with a 120 GeV proton beam and 56 ps (Sigma) with a 108 GeV muon beam.

Development of Multi Modal Image Fusion Techniques in Night Vision Technology Using Deep Learning

This study is aimed at exploring new development in nighttime image processing based on nighttime photography/night vision. We use various learning methodologies based on neural networks to develop multisensor data processing techniques. The ability of Convolutional Neural Networks (CNN) to enhance image quality and clarity under conditions of low light or at night is the focus of our research. To do this A large database has been created, containing 3200 images both taken from the internet as well as our own. This data is preprocessed, normalized and features expanded using some common methods of data augmentation in order to optimize model performance. We compared our proposed CNN model with existing literature through a series of experiments. Performance was measured using Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Index (SSIM), and Feature Similarity Index (FSIM). The Results are now in. They showed that our model can improve various metrics with higher scores. And they show the real-time monitoring capabilities in urban streets for our model. This research brings multisensor image fusion based on night-adjacent techniques forward from night vision technology and provides insight into practical and potential future directions for using deep learning techniques to improve safety and security in many different environments.

Guided CdTe Nanowires Integrated into Fast Near-Infrared Photodetectors.

Infrared photodetectors are essential devices for telecommunication and night vision technologies. Two frequently used materials groups for this technology are III-V and II-VI semiconductors, notably, mercury-cadmium-telluride alloys (MCT). However, growing them usually requires expensive substrates that can only be provided on small scales, and their large-scale production as crystalline nanostructures is challenging. In this paper, we present a two-stage process for creating aligned MCT nanowires (NWs). First, we report the growth of planar CdTe nanowires with controlled orientations on flat and faceted sapphire substrates via the vapor-liquid-solid (VLS) mechanism. We utilize this guided growth approach to parallelly integrate the NWs into fast near-infrared photodetectors with characteristic rise and fall times of ∼100 μs at room temperature. An epitaxial effect of the planar growth and the unique structure of the NWs, including size and composition, are suggested to explain the high performance of the devices. In the second stage, we show that cation exchange with mercury can be applied, resulting in a band gap narrowing of up to 55 meV, corresponding to an exchange of 2% Cd with Hg. This work opens new opportunities for creating small, fast, and sensitive infrared detectors with an engineered band gap operating at room temperature.

Highly efficient deep-red to near-infrared thermally activated delayed fluorescence organic light-emitting diodes using a 2,3-bis(4-cyanophenyl)quinoxaline-6,7-dicarbonitrile acceptor

The demand for deep-red (DR) or near-infrared (NIR) emitters has grown markedly owing to their essential roles in optical telecommunications, night vision-technologies, flat panel displays, bioimaging, photodynamic therapy, and sensors,...

Bifunctional near-infrared-emitting phosphors of chromium (III)-activated antimonates for NIR light-emitting diodes and low-temperature thermometry

Owing to the development of near-infrared phosphor-converted light-emitting diodes (NIR pc-LED), researchers have paid lots of attention to investigating broad-band NIR phosphors. A broadband NIR phosphor of chromium (III)-doped Sr2InSbO6 (SISO: Cr3+) was comprehensively introduced in terms of X-ray diffractometer (XRD), Rietveld refinement, and X-ray photoelectron spectroscopy (XPS), electronic structure, diffuse reflection, crystal field strength, photoluminescence performances and so on. Additionally, Cr3+ was successfully incorporated into the SISO lattice by substituting the In3+ site while the critical concentration was determined to be 3 mol%. The LED device was fabricated to better identify its practical application in the field of NIR solid-state lighting. On the other hand, the decay curves were recorded in the range of 10–460 K, which is used to analyze the luminescence lifetime sensing behaviors based on the Struck and Fonger models. Especially, the favorable relative sensitivity reached 0.73% K−1 at 280 K, which is rarely affected by the doping concentration. Briefly, this work synthesized a late-model luminescent material for potential NIR low-temperature measurement and NIR night vision technology.

Regulating Eu2+ Multisite Occupation through Structural Disorder toward Broadband Near-Infrared Emission

To promote the development of near-infrared (NIR) light sources in optoelectronic and biomedical applications, the discovery of NIR-emitting phosphor materials and their design principles are essential. Herein, we report a novel Eu2+-activated broadband NIR-emitting phosphor, BaSrGa4O8:Eu2+, which features multisite occupation due to Ba/Sr and oxygen site occupancy disorder. With an increase in the Ba/Sr atomic ratio from 1:1 to 1.7:0.3, the Eu2+ emission band maximum red-shifts from 670 to 775 nm, along with an enlargement of the full width at half-maximum (FWHM) from 140 to 230 nm. The underlying mechanism for the structure–property relationship is elucidated using density functional theory calculations. The application of the NIR phosphor-converted light-emitting diodes (pc-LEDs) is demonstrated, showing their potential in night-vision technology. Our results can initiate further exploitation of the host structural disorder toward Eu2+ broadband NIR luminescence for applications in pc-LEDs.

An efficient LiSrGaF6:Cr3+ fluoride phosphor with broadband NIR emission towards sunlight-like full-spectrum lighting.

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.

Afterpulse measurement of JUNO 20-inch PMTs

In this study, we present the large photomultiplier tube (PMT) afterpulse measurement results obtained from the Jiangmen underground neutrino observatory (JUNO) experiment. A total of 11 dynode-PMTs (R12860) from the Hamamatsu company (Hamamatsu Photonics K.K. (HPK)) and 150 micro-channel plate PMTs (MCP-PMTs, GDB-6201) from the NNVT company (North Night Vision Technology Co., Ltd. (NNVT)) were tested. Subsequently, an afterpulse model was built according to the afterpulse time distribution and the probability of occurrence for these two types of PMTs. The average ratio of the total afterpulse charge with a delay between 0.5 \(\upmu\)s and 20 \(\upmu\)s to the primary pulse charge is \(\sim\) 5.7% (13.2%) for the tested MCP-PMTs (dynode-PMTs). The JUNO experiment will deploy 20,012 20-inch PMTs; this study will benefit detector simulation, event reconstruction, and data analysis regarding the JUNO experiment.

Highly efficient near-infrared solid solution phosphors with excellent thermal stability and tunable spectra for pc-LED light sources toward NIR spectroscopy applications.

Near-infrared (NIR) luminescent materials have attracted wide research interest due to their unique photophysical properties for designing NIR light-emitting diodes (NIR LEDs). Here, a series of Cr3+-activated NIR-emitting solid solution phosphors, Gd1-xLux(Al1-xScx)3(BO3)4:0.01Cr3+ (GLASB:Cr3+) (x = 0 to 0.5), are successfully synthesized via a cosubstitution approach. The GLASB:Cr3+ phosphors reveal extraordinary optical performance with a desirable high IQE of 93.6%, considerable broadened FWHM (from 128 nm to 196 nm) and redshift of 119 nm (747 → 866 nm) as the amount of [Lu3+-Sc3+] ion doping increases. Moreover, their photoluminescent thermal stability is substantially improved, maintaining 105.7% of the initial integral intensity up to 150 °C, namely zero-thermal-quenching. The NIR pc-LED fabricated using the GLASB:Cr3+ phosphor generates an NIR output power of 46 mW and an electro-optical efficiency of 37% at a 120 mA input current. Finally, the characteristic NIR emission of this phosphor can not only be utilized in the fields of night-vision technology and biometric identification, but also exhibits a perfect match with the absorption of the bacteriochlorophyll (BChl) and light-harvesting protein (LHP) of photosynthetic bacteria (PSB), presenting a high application prospect for improving PSB photosynthesis.

Mass testing and characterization of 20-inch PMTs for JUNO

Main goal of the JUNO experiment is to determine the neutrino mass ordering using a 20 kt liquid-scintillator detector. Its key feature is an excellent energy resolution of at least 3% at 1 MeV, for which its instruments need to meet a certain quality and thus have to be fully characterized. More than 20,000 20-inch PMTs have been received and assessed by JUNO after a detailed testing program which began in 2017 and elapsed for about four years. Based on this mass characterization and a set of specific requirements, a good quality of all accepted PMTs could be ascertained. This paper presents the performed testing procedure with the designed testing systems as well as the statistical characteristics of all 20-inch PMTs intended to be used in the JUNO experiment, covering more than fifteen performance parameters including the photocathode uniformity. This constitutes the largest sample of 20-inch PMTs ever produced and studied in detail to date, i.e. 15,000 of the newly developed 20-inch MCP-PMTs from Northern Night Vision Technology Co. (NNVT) and 5000 of dynode PMTs from Hamamatsu Photonics K. K.(HPK).

Influencing factors of time resolution for LPMT for JUNO

Large area PMTs (LPMT) are widely used in neutrino experiments and cosmic ray detection. To meet the performance requirements for Jiangmen Underground Neutrino Observatory (JUNO), researchers at IHEP developed 20-inch MCP-PMTs which provide higher collection efficiency at a lower cost. 15k 20-inch PMTs produced by North Night Vision Technology Co., Ltd. (NNVT) has been delivered to Jiangmen and are to be installed as the central liquid scintillator detector of JUNO. Compared with prototype, though the collection efficiency (CE) and the quantum efficiency (QE) of the 15k MCP-PMTs get improved, the time performance gets worse. In this manuscript, the reasons for the deterioration of time resolution of the 15k MCP-PMTs are explored from several aspects. The optimized structure with great TTS of less than 5 ns is also introduced.

Achieving the ultra-broadband near-infrared La3SnGa5O14:Cr3+ phosphor via multiple lattice sites occupation for biological nondestructive detection and night-vision technology

Currently, near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have become a research hotspot, however, the NIR phosphors continue to face the problems of narrowband emission and poor thermal stability. Therefore, in order to solve these problems, La3SnGa5O14:xCr3+ phosphors with ultra-broadband NIR emission were obtained by multiple lattice sites occupation, featuring ultra-broadband emission in the range of 650–1300 nm with full width at half-maximum (FWHM) up to 333 nm under 437 nm excitation. By tuning the concentration of Cr3+, the FWHM value can reach 333–417 nm La3SnGa5O14:Cr3+ also exhibits favorable thermal stability, maintaining 90.5% and 67% of the initial intensity at 373 K and 423 K, respectively. The NIR pc-LEDs were manufactured by combining the blue light chip with La3SnGa5O14:Cr3+ phosphor. When the NIR pc-LED was switched off, no image could be generated from the infrared camera. Instead, the image captured by the infrared camera was visible in the light of the NIR pc-LED lamp. Such results imply that La3SnGa5O14:Cr3+ may be a prospective candidate for future biological accurate nondestructive detection and night-vision technology.

(Digital Presentation) Red and Near-Infrared Emission of Eu2+ Doped Solid-State Phosphors for LED Applications

Owing to the unique 4f-5d transition, Eu2+ is one of the most commonly used activators in luminescent materials for phosphor-converted light-emitting diodes (pc-LEDs), and Eu2+-doped phosphors exhibit outstanding luminescence properties, including multi-color emission, adjustable bandwidth, excellent thermal stability as well as high luminescence efficiency. These attributes motivate scientists to find Eu2+ doped phosphors that can practically meet the various LED application requirements. In this talk, I will summrize our recent progresses to manipulate Eu2+ emission exhibiting red and near-infrared emissions under blue light excitation. One can expect and further adopt proper structural engineering strategies to tune the Eu2+ luminescence. Moreover, the state-of-the-art LED application including solid-state lighting and near infrared night-vision technologies will be also introduced based on these Eu2+ doped phosphors. We hope this talk will be helpful for controlling the photoluminescence by theory-structure-property relationships and guide scientists discover the next generation of Eu2+ doped phosphors for emerging applications.

P‐7.16: Design of ORGB LED array based BLU for Night Vision Compatible Application

P‐7.16: Design of ORGB LED array based BLU for Night Vision Compatible Application

INTELLIGENT VIDEO SURVEILLANCE USING DEEP LEARNING

Video surveillance, also known as CCTV (closed-circuit television), is a rapidly growing industry that has been around for more than 30 years and has seen its fair share of technological advancements. In today's world, video surveillance has become an essential component for ensuring public safety. Security can be defined in a variety of ways depending on the context, such as theft detection, violence detection, explosion risk, and so on. The term "security" in crowded public places refers to almost any type of abnormal event.Intelligent video surveillance delivers cutting-edge smart security by recording unexpected activities in homes, offices, and public locations based on the preferences of the user. In the event of an abnormal incident, the video surveillance system will actively respond to detect actions in advance through real-time monitoring and promptly communicate data. The primary focus is on the use of deep learning techniques to provide tracking of a moving target, high-definition picture quality, and night vision technology triggered by motion sensors, which means the system isn't running when nothing is happening at your location, automatic audio and visual detection, video recording initiation, and detection of suspicious activities that can trigger and alert the systems in all climate conditions.Deep learning technology will be used in the data processing model design to visualise data for abnormal activities, and this design also proposes an intelligent surveillance system to quickly and effectively detect activities by sending a video image and an alert message to the web via real-time processing. Recent improvements in computer vision, particularly deep learning approaches, have opened up new possibilities for these systems, enhancing their capabilities and launching new research areas in this field.