Visible Imaging System Research Articles

Three-dimensional reconstruction of asphalt road surface texture based on binocular stereo vision

The texture of asphalt pavement plays a pivotal role in ensuring the safe operation of roads. This paper presents a binocular stereo vision hardware system that is designed to acquire asphalt pavement texture features in an economical and efficient manner. The system comprises an image acquisition device, a micro meter, and a camera bracket. The binocular camera baseline length is first determined according to the adjusted camera parameters, with the objective of enhancing the quality of the acquired images. Secondly, the camera calibration was carried out using Matlab and Python software, and the camera parameters were obtained to perform aberration and stereo corrections on the binocular image pairs. Finally, based on Python software, the sum of absolute differences, symmetric diagonal dominance, zero-mean normalised cross-correlation and semi-global block matching algorithms were applied to stereo-match the texture information image set and reconstructed the 3D asphalt pavement point cloud based on parallax mapping. However, it should be noted that the experiment does not consider the effect of light intensity in indoor and outdoor environments. This paper provides a preliminary summary of the current structural design and experiments, and further discusses ideas for subsequent research and improvement. Research and experiments show that the binocular stereo vision imaging system proposed in this paper can effectively match binocular images and present 3D information of asphalt pavement texture. When the binocular camera baseline distance is 40 mm, the maximum calibration error and the average calibration error are both the smallest, which enhances the stability of binocular matching. Furthermore, the camera parameters calculated by the Matlab toolbox calibration are more stable than those obtained by OpenCV calibration. In the indoor experimental environment, the running speeds of the four stereo matching algorithms were compared. In the indoor test environment, the SGBM algorithm was the fastest, with a running speed of 3 seconds, in the order of SGBM>SAD>SSD>ZNCC. The SGBM algorithm demonstrated the most effective parallax mapping reconstruction of asphalt pavement point clouds. The reconstruction of pavement texture may be employed in the future for the real-time monitoring of asphalt pavement skid resistance.

Synthetic measurements of runaway electron synchrotron emission in the SPARC tokamak.

With plasma currents up to 8.7 MA, the SPARC tokamak runs the risk of forming multi-MA beams of relativistic "runaway" electrons (REs), which could damage plasma facing components if unmitigated. The infrared (IR) and visible imaging and visible spectroscopy systems in SPARC are designed with measurements of synchrotron emission from REs in mind. Synchrotron radiation is emitted by REs along their direction of motion, opposite the plasma current. Matched clockwise and counterclockwise wide views are proposed to detect synchrotron and background radiation, allowing observation of RE synchrotron emission in both plasma current configurations. Due to SPARC's high toroidal magnetic field strength, 12.2T on axis, the synchrotron light spectrum is expected to peak in the visible-IR wavelength range. The synthetic diagnostic tool, Synchrotron Orbit-Following Toolkit, is used to model synchrotron images and spectra for three scenarios, with appropriate magnetic equilibria for each: REs generated during plasma current ramp-up, steady-state flat-top (although unlikely, but serving as a reference), and disruptions. Required time resolutions, achievable spatial coverage, and appropriate spectral ranges for various RE energies are assessed.

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.

Near-infrared in vivo imaging system for dynamic visualization of lung-colonizing bacteria in mouse pneumonia.

Conventional animal models of infectious diseases have traditionally relied upon average assessments involving numerous individuals, meaning they do not directly reflect changes in the pathology of an individual. Moreover, in recent years, ethical concerns have resulted in the demand to reduce the number of animals used in such models. Although in vivo imaging offers an effective approach for longitudinally evaluating the pathogenesis of infectious diseases in individual animals, a standardized method has not yet been established. To our knowledge, this study is the first to develop a highly versatile in vivo pulmonary bacterial quantification system utilizing near-infrared luminescence, plasmid-mediated expression of firefly luciferase in bacteria, and a scientific complementary metal-oxide semiconductor camera. Our research holds promise as a useful tool for assessing the efficacy of therapeutic drugs and pathogenesis of infectious diseases.

Design of an infrared/visible endoscope system for HL-3 divertor observation

This paper presents the design and test results of an infrared/visible endoscope system for diagnosing divertor in HL-3 tokamak. The system is designed to view the plasmas tangentially with multi-imaging systems including two infrared imaging systems and three visible imaging systems. Several filters based visible imaging measurements are thus available simultaneously for divertor physics investigation. The performance of the optical design is explored, and the manufacture of the system and the test results are presented. The characteristics of the advanced divertor configurations, such as multi-strike points and two X-points, are observed clearly with the endoscope system.

Simultaneous detection for storage condition and storage time of yellow peach under different storage conditions using hyperspectral imaging with multi-target characteristic selection and multi-task model

The detection for storage condition and storage time can ensure quality and safety of yellow peaches, and optimize storage management. This study explored the feasibility of simultaneously detecting the storage condition and storage time of yellow peach under different storage conditions using hyperspectral imaging technology combined with multi-target characteristic selection and multi-task model. Firstly, a total of 1080 hyperspectral images of 120 yellow peach samples under different storage conditions and different storage time were acquired using visible near-infrared hyperspectral imaging system. Subsequently, Savitzky-Golay first derivative was used to preprocess the raw spectra to improve the signal-to-noise ratio of the spectra. Distinguished index modified competitive adaptive reweighted sampling (DI-CARS) was proposed to select characteristic wavelengths that simultaneously characterize information of storage condition and storage time. Wild horse optimizer optimized support vector machine (WHO-SVM) was proposed for the multi-task modeling analysis. The results showed that multi-target characteristic selection and multi-task model not only reduced 66.67 % in computational cost, but also improved the accuracy, and multi-task WHO-SVM model based on multi-target DI-CARS achieved the optimal result with the overall accuracy reached 98.06 % and the number of characteristic wavelengths being 99. In conclusion, hyperspectral imaging combined with multi-target DI-CARS and multi-task WHO-SVM is feasible to simultaneously detect storage condition and storage time of yellow peach under different storage conditions.

The visual image system of the city of Saratov

The visual image system of the city of Saratov

Enhanced near infrared and gate tunable photoresponse of MoSe2 transistor enabled by 2D hetero contact engineering

The excellent physical features of two-dimensional (2D) layered materials make them very promising for electronic and optoelectronic applications. Here, we investigated the gate-tunable and broadband (220, 365, 460, 510, 840 and 1020 nm) photoresponse of MoSe2 transistor with metallic (Cr–Au/MoSe2) and van der Waals (vdWs) hetero MoSe2/WTe2 contacts. Our study intends to investigate the underlying mechanism of photogeneration and carrier's transport process by Cr–Au/MoSe2 and hetero MoSe2/WTe2 contacts in the MoSe2 transistor. Since, our research revealed that MoSe2 devices with hetero MoSe2/WTe2 contacts exhibited remarkable performance, including high responsivity (R) of about 11.23 × 105 mA/W, exceptional external quantum efficiency (EQE) of 6.3 × 105 %, and detectivity (D*) of 4.61 × 1010 Jones compared to metallic contacts. This implies that the enhanced performance of our devices with 2D hetero-contacts could be attributed to reduced contact resistance, interlayer charge transfer and interlayer excitons in MoSe2/WTe2 heterostructure. Also, the gate-controlled response and broadband capabilities of van der Waals 2D heterostructures hold significant promises for a wide range of optoelectronic applications, including photodetectors, optical sensors, and visual imaging systems.

Vision System for the Mars Sample Return Capture Containment and Return System (CCRS)

The successful 2020 launch and 2021 landing of the National Aeronautics and Space Administration’s (NASA) Perseverance Mars rover initiated the first phase of the NASA and European Space Agency (ESA) Mars Sample Return (MSR) campaign. The goal of the MSR campaign is to collect scientifically interesting samples from the Martian surface and return them to Earth for further study in terrestrial laboratories. The MSR campaign consists of three major spacecraft components to accomplish this objective: the Perseverance Mars rover, the Sample Retrieval Lander (SRL) and the Earth Return Orbiter (ERO). Onboard the ERO spacecraft is the Capture, Containment and Return System (CCRS). CCRS will capture, process and return to Earth the samples that have been collected after they are launched into Mars orbit by the Mars Ascent Vehicle (MAV), which is delivered to Mars onboard the SRL. To facilitate the processing of the orbiting sample (OS) via the CCRS, we have designed and developed a vision system to determine the OS capture orientation. The vision system is composed of two cameras sensitive to the visible portion of the electromagnetic spectrum and two illumination modules constructed from broadband light emitting diodes (LED). Vision system laboratory tests and physics-based optical simulations predict CCRS ground processing will be able to correctly identify the OS post-capture orientation using only a single vision system image that is transmitted to Earth from Mars orbit.

Robust and adaptive star identification algorithm based on linear assignment for multiple large field of view visual imaging systems

The integration of the visual imaging system and the self-attitude determination system in on-orbit space projects necessitates robust star identification algorithms. However, disturbances in the on-orbit environment pose a challenge to the accuracy and efficiency of star identification algorithms. This paper introduces a novel star identification algorithm, to the best of our knowledge, designed for multiple large field of view (FOV) visual imaging systems, providing stability in the presence of the noise types, including position noise, lost-star noise, and fake-star noise. We employ the dynamic simulated star images generation method to construct simulated star image libraries suitable for various cameras with different FOV angles. Our algorithm comprises two parts: the star edge matching for coarse matching of interstellar angular distances based on linear assignment, and the star point registration for precise matching of star vectors. This innovative combination of local edge generation and global matching approach achieves an impressive 97.83% identification accuracy, maintaining this performance even with a standard deviation of one pixel in image plane errors and up to five missing stars. A comprehensive approach involving both simulated and empirical experiments was employed to validate the algorithm’s effectiveness. This integration of the visual imaging system and the self-attitude determination system offers potential benefits such as reduced space equipment weight, simplified satellite launch processes, and decreased maintenance costs.

Enhanced YOLO- and Wearable-Based Inspection System for Automotive Wire Harness Assembly

In response to the challenges associated with the misassembly, omission, and low manual inspection efficiency in automobile wiring harness relay assemblies, a novel online detection system has been engineered. This system consists of a mobile-based visual imaging system and an improved YOLOv5-based detection algorithm that tracks human movement to acquire images and videos. The system is coupled with deep learning for real-time detection and recognition for error-proofing the installation process of automotive wiring harness relays. This innovation aims to facilitate error-proof inspection during the assembly process of automotive wiring harness relays. The YOLOv5s model is augmented with an Adaptive Spatial Feature Fusion (ASFF) module, enhancing multi-scale feature integration capabilities. A Global Context Network (GCNet) is incorporated into the C3 module to emphasize target information from a global perspective. Additionally, the replacement of standard Convolution (Conv) modules with Global Sparse Convolution (GSConv) modules in the Neck section effectively reduces computational costs while sustaining overall performance efficacy. The experimental results show that the detection system achieved a comprehensive accuracy rate of 99.2% and an F1 score of 99.29. The system possesses high accuracy and stability, enabling flexible and intelligent target detection applications in the automotive industry.

Integrative Research on Visible Light Full-Color and Near-Infrared Co-Aperture Single-Pixel Imaging System (Invited)

Integrative Research on Visible Light Full-Color and Near-Infrared Co-Aperture Single-Pixel Imaging System (Invited)

Design and optimization of the performance of self-powered Sb2S3 photodetector by SCAPS-1D simulation and potential application in imaging

Antimony sulfide (Sb2S3) is considered an excellent semiconductor material for visible light photodetectors (PDs) due to the non-toxicity, stability and high visible photon absorption coefficient. However, the deep physical cascade relationship between Sb2S3 devices and key parameters, such as the thickness, the doping density, the defect density, and the inverse contact of the figure of merit, has not been thoroughly investigated. In order to systematically explore the impact of parameters on Sb2S3 device performance, self-powered optoelectronic devices of TiO2/Sb2S3 p-n heterojunction were simulated by using one-dimensional (SCAPS-1D) software. Base on simulation, we learned that the optimum thickness of Sb2S3 is about 400 nm, the donor and acceptor densities of TiO2 and Sb2S3 layers are 1020 and 1016 cm−3, respectively. In addition, Au was chosen as the back electrode, and the high-quality Sb2S3 functional layer required a defect density of less than 1016 cm−3. Based on the guidance of simulation results, we finally fabricated the FTO/TiO2/Sb2S3/Au self-powered photodetectors. Under an illumination intensity of 3 μW/cm2 at 530 nm, the responsivity (R) and specific detectivity (D*) of the device can be up to 0.357 A/W and 5.1 × 1011 Jones, respectively. Particularly, the device exhibits a fast response with a response time of 1.4 μs and 3 dB bandwidth of 383 kHz. In this regard, we constructed a single-pixel scanning imaging system around the Sb2S3 detector and showed excellent imaging results, which provided a new path for us to develop a new type of visible light detector and imaging system.

Realization of a filter-free wavelength image sensor and imaging system for visualization of wavelength information

In this study, we fabricated a filter-free wavelength image sensor for the two-dimensional visualization of wavelength information, in addition to light intensity, and realized an imaging system. In this sensor, the electrons generated in silicon in different distributions at each wavelength are divided into two parts by the potential peaks. The wavelength can be identified from the current ratio, and the light intensity can be determined from the total current. In the proposed structure, the pixel current is sequentially output by controlling the rows and columns. The layout was designed based on the proposed structure and was fabricated at the Toyohashi University of Technology LSI factory. An imaging system was constructed using operational amplifiers, A/D converters, and a microcontroller. The ratio and sum of the two signals obtained from the sensor responded linearly to the wavelength and light intensity. The wavelength response was independent of changes in the light intensity. Even when the spot was narrowed down, the response was obtained only at the corresponding pixel and succeeded in the simultaneous imaging of the intensity and wavelength. The above results can be applied to cell analysis, such as multiple fluorescence staining, where multiple fluorescence signals are detected simultaneously.

Racially fair pupillometry measurements for RGB smartphone cameras using the far red spectrum

Pupillometry is a measurement of pupil dilation commonly performed as part of neurological assessments. Prior work have demonstrated the potential for pupillometry in screening or diagnosing a number of neurological disorders including Alzheimer’s Disease, Schizophrenia, and Traumatic Brain Injury. Unfortunately, the expense and inaccessibility of specialized pupilometers that image in the near infrared spectrum limit the measurement to high resource clinics or institutions. Ideally, this measurement could be available via ubiquitous devices like smartphones or tablets with integrated visible spectrum imaging systems. In the visible spectrum of RGB cameras, the melanin in the iris absorbs light such that it is difficult to distinguish the pupil aperature that appears black. In this paper, we propose a novel pupillometry technique to enable smartphone RGB cameras to effectively differentiate the pupil from the iris. The proposed system utilizes a 630 nm long-pass filter to image in the far red (630–700 nm) spectrum, where the melanin in the iris reflects light to appear brighter in constrast to the dark pupil. Using a convolutional neural network, the proposed system measures pupil diameter as it dynamically changes in a frame by frame video. Comparing across 4 different smartphone models, the pupil-iris contrast of N = 12 participants increases by an average of 451% with the proposed system. In a validation study of N = 11 participants comparing the relative pupil change in the proposed system to a Neuroptics PLR-3000 Pupillometer during a pupillary light response test, the prototype system acheived a mean absolute error of 2.4%.

Efficient Ultra‐Broadband Phosphors for High-Power Near-infrared LED and night vision imaging system sources

Broadband near-infrared (NIR)-emitting materials have critical applications in biology, medical detection, and NIR night-vision. However, developing NIR phosphors with promising optical properties and excellent thermal stability is a great challenge for research. In this work, a novel NIR phosphor Cr3+ and Yb3+ doped CaSc2O4 (CSO) is an evolving NIR emitting phosphor with decent optical properties, boosted emission intensity, and thermal stability that makes it a promising candidate with potential applications in NIR-LED and infrared night-vision. The implications of the fundamental electronic structure of CSO, including valence-band (VB) and conduction-band (CB) orbital character, are investigated. Under blue light excitation, CSO:Cr3+ is settled with pure broadband NIR emissions (max = 920 nm, FWHM (full width at half maximum) = ∼310 nm) and good thermal stability. The occupation of two selectable lattice sites of Cr3+ in CSO is discussed in detail. Furthermore, emission enhancements of samples are done by Cr3+ and Yb3+ codoping, effectively broadening FWHM to 351 nm and reducing thermal quenching. The energy transfer (ET) routes in CSO:Cr3+,Yb3+ are investigated based on PL lifetime and comprehensive kinetic ET model, revealing that the PL enhancements by Cr3+ and Yb3+ codoping mainly originate from the ET from Cr3+ to Yb3+ emitters with more efficient and thermally stable. Finally, an InGaN-LED device encapsulated using CSO:0.01Cr3+ and CSO:0.01Cr3+,0.01 Yb3+ phosphor was fabricated. The fabricated NIR pc-LEDs are excellent candidates for NIR light sources in biological imaging and NIR night vision.

High-performance photodetectors based on two-dimensional perovskite crystals with alternating interlayer cations

Organic-inorganic halide perovskite, as a low-cost, solution-processable material with remarkable optoelectronic properties, is ideal candidate to fabricate high-performance photodetectors and is expected to significantly reduce device costs. Compared to the common Dion-Jacobson and Ruddlesden-Popper two-dimensional (2D) layered hybrid perovskite compounds, the perovskites with alternating cations in the interlayer (ACI) phase show higher crystal symmetry and narrower optical bandgaps, which exhibit great potential for excellent photodetection performance. Herein, we report a high-performance photodetector based on the 2D bilayered hybrid lead halide perovskite single crystal with the ACI phase (GAMA2Pb2I7; GA = C(NH2)3 and MA = CH3NH3). The single-crystal photodetector exhibits high photoresponsivity of 1.56, 2.54, and 2.60 A/W for incident light wavelengths of 405, 532, and 635 nm under 9.82 nW, respectively, together with the correspondingly high detectivity values of 1.86 × 1012, 3.04 × 1012, and 3.11 × 1012 Jones under the same operating conditions. Meanwhile, a high-resolution imaging sensor is built based on the GAMA2Pb2I7 single-crystal photodetector, confirming the high stability and photosensitivity of the imaging system. These results show that the 2D hybrid lead halide perovskites with alternating interlayer cations are promising for high-performance visible light photodetectors and imaging systems.

Vision-Based Support for the Detection and Recognition of Drones with Small Radar Cross Sections

Drones are increasingly vital in numerous fields, such as commerce, delivery services, and military operations. Therefore, it is essential to develop advanced systems for detecting and recognizing drones to ensure the safety and security of airspace. This paper aimed to develop a robust solution for detecting and recognizing drones and birds in airspace by combining a radar system and a visual imaging system, and contributed to this effort by demonstrating the potential of combining the two systems for drone detection and recognition. The results showed that this approach was highly effective, with a high overall precision and accuracy of 88.82% and 71.43%, respectively, and the high F1 score of 76.27% indicates that the proposed combination approach has great effectiveness in the performance. The outcome of this study has significant practical implications for developing more advanced and effective drone and bird detection systems. The proposed algorithm is benchmarked with other related works, which show acceptable performance compared with other counterparts.

Imaging system aberrations through optical windows with nonuniform laser heating.

An optical window is a critical component of an imaging system. When operating in harsh environments with extreme heating, nonuniform temperature changes occur throughout the window and cause nonuniform refractive index changes and mechanical deformations due to thermal expansion, which can degrade the imaging system's performance. In this paper, we present results collected from an experimental setup developed to characterize these aberrations. This setup includes a C O 2 laser for sample heating, an infrared camera for measuring front and back surface temperatures, and a visible imaging system and a wavefront sensor for measuring degradations of a collimated beam from a point source transmitted through the heated window. Sapphire samples are laser heated with a Gaussian profile to temperatures in excess of 500K with surface temperature gradients in excess of 15K/mm. These measurements are compared with first principles models, which show quantitative agreement for window temperatures and qualitative agreement with the transmitted wavefront and imaged point source.

In vivo imaging system for cellular level visualization of immune responses in various animal models

Abstract Immune cells have a variety of functions to defend against pathogens under certain circumstances. It is not until recently, However, that these miscellaneous responses can be observed in vivo. Herein, we optimized some solutions of researchers keeping track of the changes of the immune response by utilizing the IVM-C intravital imaging system and in vivo fluorescence labeling for target cells. It is possible to successfully acquire a crystal-clear cellular level images of immune cells in the different animal model including RNA adjuvant-injected mouse and sepsis-induced one by using intravital microscope, respectively. In case of the RNA adjuvant injection, it is obvious that retention of the antigen presenting cells in draining lymph node is on the rise to promote T/B cell activation. A dramatic increase in the number of the infiltrated dendritic cells into the organ was observed at the same time. Moreover, Pathogenesis of sepsis by monitoring of pulmonary capillary circulation was investigated. In order to visualize pulmonary microcirculation, we’ve established a pulmonary imaging window which makes it feasible to image the real-time dynamics of rapidly circulating neutrophils in live mouse. We found out that many clusters of neutrophils aggregates in the pulmonary vasculature or, even in the arteriole of the sepsis-induced mouse, thereby disturbing the microcirculation of that region and generating dead space in the pulmonary structure. Taking everything into account, we make certain it is appropriate to utilize the intravital imaging method for cellular level visualization of the immune system under various pathological conditions. we believe that it could be an invaluable tool for a comprehensive understanding of immunology.