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Forensic document examination has been considered one of the most important fields in the forensic science. For this, a quick, effective, and cheap techniques for evaluation of forensic evidence is highly required. This study explores the comparison of A4 document paper by chemical and physical analysis. 16 of white A4 paper from different brands were analyzed by FTIR for investigation of structural characteristics. Video Spectral Comparator 8000 has been used to compare the A4 papers under different light source. The inorganic filler composition in the paper is also explored by ICP‐OES. The calcium carbonate content in document papers play a discriminant role which found to be between 16.02 % and 35.54 %. Also, water contact angle has been utilized in order to examine the surface of paper which is generally related to the inorganic filler and other additives. The WCA results ranged between 83° and 111° that enable quick and easy way to compare A4 document papers. The experimental results have demonstrated that besides FTIR methods, other methods such as ICP‐OES for elemental composition, WCA for wetting test, VSC for visualization under different light of source could have been applied for comparison of document papers in case of criminal cases. [ABSTRACT FROM AUTHOR]

This study introduces the development of a photothermal-based microfluidic paper analytical device (PT-µPAD) integrated with near-field communication (NFC) technology and smartphone readout for enzyme-free glucose quantification in human samples. With the properties of gold nanoparticles (AuNPs) both as a nanozyme and as a photothermal substrate, there is no need for costly reagents like enzymes or a readout instrumentation for the selective and sensitive detection of glucose. In PT-µPADs, AuNPs are etched by hydrogen peroxide (H2O2) generated from glucose catalysis. Photothermal detection from the plasmonic heating of these AuNPs when illuminated by a 533nm LED light source is achieved by inserting the PT-µPAD sensor into a portable NFC platform suitable for smartphone readout. Temperature variation is directly proportional to the glucose concentration. After optimization, we acquired a linear range between 5.0 and 20.0 µmol L−1 (R2 = 0.9967) and a limit of detection (LOD) of 25.0 nmol L−1 for glucose. Additionally, while our sensor does not utilize any enzyme, it is remarkably selective to glucose with no effects from interferences. Recovery studies in various human control samples indicated a range of 99.73–102.66% with the highest RSD of 3.53%, making it highly accurate and precise. Moreover, our method is more sensitive than other methods relying on conventional µPADs for glucose sensing. By integrating the potential benefits of microfluidics, nanomaterials as nanozymes, and NFC technology for wireless readout, our sensor demonstrates great promise as an accessible, affordable, and shelf-stable device for glucose quantification. Moreover, this concept can be extended to detect other molecules of interest as a point-of-care (POC) diagnostics device. [ABSTRACT FROM AUTHOR]

As an important substrate of traditional Chinese cultural relics in museums, paper is the material with highly light sensitivity, which is susceptible to irreversible lighting damage. To provide high-quality viewing, it is vital to study the parameters of light sources in consideration of paper substrates' long-term conservation. As an important factor affecting both conservation and viewing, there are some issues concerning correlated color temperature (CCT) in the relevant standards, namely, the inconsistent recommended values. In this research, paper samples were subjected to accelerated irradiation experiments for 1440 h by 10 narrow-band lights in the visible range, and the infrared spectra were measured periodically. The calculated oxidation index was used to obtain the damage response function to different spectral wavelengths and exposures. Subsequently, using the method of exhaustion, 9477 spectra with a CCT range of 2650–4150 K that met the viewing requirements were screened, and lighting damage to paper substrates was calculated using this function. Based on that, the correlation between CCT and lighting damage to paper substrates and their standard deviations was obtained. Combining the previous research on recommended for CCT pigments, a preliminary recommended CCT of 3100–3200 K in selecting light sources for traditional Chinese paper relics was proposed. It is worth emphasizing that it is still necessary to use the spectral power distribution of light sources, as the underlying independent variable that leads to damage, to further calculate the lighting damage using the function mentioned above to achieve protective lighting. [ABSTRACT FROM AUTHOR]

The text provides a summary of various articles related to air quality, climate change, and environmental initiatives. It mentions a report from the World Meteorological Organization (WMO) highlighting record-breaking climate change indicators in 2023, the use of pulp and paper waste to reduce carbon emissions, the development of national indoor quality standards for public buildings, the establishment of a hydrogen hub in the Pilbara region of Australia, and the U.S. Environmental Protection Agency's new tailpipe rules to reduce pollution from cars and light trucks. These articles offer insights into the current state of the environment and efforts to address climate change. [Extracted from the article]

This document is a letter to the editor of the PM World Journal, written by Crispin Piney in response to Stephen Devaux's paper on the Program-Level Breakdown Structure. Piney agrees with Devaux's ideas but offers some additional perspectives. Piney suggests that the confusion around the term "project" could have been avoided if more thought had been given to naming the categories of project management. Piney also discusses his own approach to program scheduling, which involves defining the overall objective of the program and using a "benefits map" to determine the schedule and evaluate options. Piney emphasizes the importance of visual tools, such as benefits maps, in allowing stakeholders to see the big picture and optimize the realization of benefits. Overall, Piney believes that combining Devaux's concepts with his own approach could improve the success rate of programs in various domains. [Extracted from the article]

Cholesteric liquid crystal (ChLC) is a reflective display technology that utilizes ambient light sources to display images, eliminating the need for a backlight. With its bistable characteristics, ChLC displays only require voltage supply during screen updates, resulting in significant energy savings. To cater to various application scenarios, we have developed ChLC reflective displays with different functionalities and sizes. The 7.9‐ inch passive matrix ChLC reflective display offers features such as full‐color capability, wide viewing angles, and fast refreshing rate, making it suitable for electronic book applications. The 24.5‐ inch and 13.3‐inch displays are respectively the largest passive matrix ChLC reflective display and active matrix ChLC reflective display in the world. They incorporate wide temperature range materials and high contrast ratio driving methods, making them highly suitable for outdoor public information display applications. [ABSTRACT FROM AUTHOR]

This document discusses the optimization of display systems for augmented reality glasses. The author categorizes augmented reality devices into three groups based on field of view (FOV): small FOV (15-30 degrees), medium FOV (~50 degrees), and large FOV (>65 degrees). The author explores different choices and consequences for projectors, combiners, and dimmers in each category. They also discuss the use of different technologies, such as microLED panels, LCoS, OLED, and laser beam scanning. The document emphasizes the importance of optimizing the overall system, including illumination, projectors, displays, and waveguides, to achieve desired performance metrics such as resolution, efficiency, contrast, brightness, volume, and weight. [Extracted from the article]

A museum is a historical and cultural center with important conservation significance. In this work, the minimum light damage spectrum of paper cultural relics and solar spectrum are mixed in 11 different proportions by MATLAB software. In addition, REDOX index and the full-spectrum index are used as evaluation indices to calculate the damage degree and comfort level of the mixed 11 spectra. The monochrome light emitting diodes (LEDs) on the market are investigated, and a simulation database of 109 monochromatic LEDs is established by using the state joint state density function as the spectral radiation model. The nine mixed spectra with solar spectral weights from 0.1 to 0.9 are used as the target spectra. The monochromatic LEDs and 2850 K warm white LED in the database are fitted to calculate the optimal solution, and the spectral combination scheme is obtained by parameter comparison. A hybrid light source is designed by LIGHTTOOLS simulation software, and chromaticity analyses are carried out for the five light sources with solar spectral weights of 0.1, 0.3, 0.5, 0.7, and 0.9. The results prove the feasibility of the theory of mixing the solar spectrum with the minimum light damage spectrum to improve the comfort and color rendering of the light source. This will have a certain guiding significance for the lighting of the museum. [ABSTRACT FROM AUTHOR]

Because the human eye cannot visually detect the results of direct bilirubin test papers accurately and quantitatively, this study proposes four different highly collimated mini light-emitting diodes (HC mini-LEDs) as light sources for detection. First, different concentrations of bilirubin were oxidized to biliverdin by FeCl3 on the test paper, and pictures were obtained with a smartphone. Next, the red, green, and blue (RGB) channels of the pictures were separated to average grayscale values, and their linear relationship with the direct bilirubin concentration was analyzed to detect bilirubin on the test paper noninvasively and quantitatively. The experimental results showed that when green HC mini-LEDs were used as the light sources and image analysis was performed using the G channel, for a direct bilirubin concentration range of 0.1–2 mg/dL, the G channel determination coefficient (R2) reached 0.9523 and limit of detection was 0.459 mg/dL. The detection method proposed herein has advantages such as rapid analysis, noninvasive detection, and digitization according to RGB grayscale changes in the images of the detection test paper. [ABSTRACT FROM AUTHOR]

People's interest in health care has increased these days. As various health care platforms are emerging, the corresponding market is also expanding. In order to monitor health conditions in everyday life, no physical damage should be made. One of the non‐invasive method, using light for sensing, is preferred due to this effect. In general, as the wavelength increases, light can penetrate deeper into the skin, leading to different bio‐signals. For example, All‐in‐One Sensor Display, which was announced by Samsung Display at SID 2023, used green light to selectively sense fingerprints on the skin surface by reducing the depth of skin penetration. To apply this progress to health care, red light can also be used for OPDs in the All‐in‐One Sensor Display. In this case, red light from red pixel is used as the light source. The light can reach blood vessels under the epidermis because the skin penetration depth is deeper than green light. The light reaching the blood vessel becomes a signal to gather biometric information. This biometric information is then collected at OPD as the signal reaches the OPD in the panel again. For these series of processes, an OPD capable of effective detecting of light in the 625 nm region emitted by red pixels is required. In this study, OPD was fabricated using RD‐01, a high absorption donor material suitable for red light absorption, and RA‐01, a non‐fullerene acceptor for mass production, to respond to red light near 625 nm. The EQE of the OPD was 25% at wavelength of 625 nm. In addition, absorption spectrum of the OPD covers the Red emission effectively. Our results represent that OLED panel can be used for not only fingerprint recognition but also health care platform. [ABSTRACT FROM AUTHOR]

Chronic Kidney Disease (CKD) is becoming one of the major causes of morbidity and mortalities in 21st century. We have developed a bioengineered cellulosic paper device for the quantification of albumin (ALB) in physiological samples. The paper surface was activated and antibodies specific to target biomarker was immobilized on engineered paper surface. Every step after modification was characterized by FTIR, XPS, SPM and optical analysis. Further, the device model was designed using CAD file, and a 3-D cascade device was fabricated with in-built constant light source to provide proper and controlled environment for in-situ image analysis. After adding the sample on the bioengineered paper, the antigen-antibody reaction takes place, after that addition of dye results in change of color from yellow to blueish-green within 40 s. An optical method was employed for the analysis of the images by recognizing the specific area and the color intensity. Additionally, the immunosensor specificity was evaluated on number of molecules that are usually found in the serum sample. The linear dynamic range of the developed immunosensor has been reported to be 1–60 mg/mL, covering the normal as well as clinical range of ALB in physiological samples with a detection limit of 0.049(±0.002) mg/mL. With good precision and recovery, the device was able to successfully determine the ALB concentrations in serum sample. The developed device has simple and user-friendly interface and it may also help diagnosing CKD in personalized settings. [ABSTRACT FROM AUTHOR]

Background: The quality of low-light endoscopic images involves applications in medical disciplines such as physiology and anatomy for the identification and judgement of tissue structures. Due to the use of point light sources and the constraints of narrow physiological structures, medical endoscopic images display uneven brightness, low contrast, and a lack of texture information, presenting diagnostic challenges for physicians. Methods: In this paper, a nonlinear brightness enhancement and denoising network based on Retinex theory is designed to improve the brightness and details of low-light endoscopic images. The nonlinear luminance enhancement module uses higher-order curvilinear functions to improve overall brightness; the dual-attention denoising module captures detailed features of anatomical structures; and the color loss function mitigates color distortion. Results: Experimental results on the Endo4IE dataset demonstrate that the proposed method outperforms existing state-of-the-art methods in terms of Peak Signal-to-Noise Ratio (PSNR), Structural Similarity (SSIM), and Learned Perceptual Image Patch Similarity (LPIPS). The PSNR is 27.2202, SSIM is 0.8342, and the LPIPS is 0.1492. It provides a method to enhance image quality in clinical diagnosis and treatment. Conclusions: It offers an efficient method to enhance images captured by endoscopes and offers valuable insights into intricate human physiological structures, which can effectively assist clinical diagnosis and treatment. [ABSTRACT FROM AUTHOR]

This paper proposes a novel data-enhanced virtual texture generation network for use in deep learning detection systems. The current methods of data enhancement, such as image flipping, scaling ratios, or Generative Adversarial Networks, have limitations as they cannot determine characteristics beyond the training data. The proposed system uses the texture characteristics of a learning surface to generate surface textures through the Open Graphics Library, which can simulate material textures, light sources, and shadow effects. This enables the generation of required texture parameters for the Reinforcement Learning Network to conduct parameter search. The generated image is authenticated by a discriminator, and the reward score is fed back into the critic network to update the value network. The proposed system can complement the imbalance of defective data types, generate large quantities of random and non-defective data, and automatically classify and label during the generation process, reducing labor consumption and improving labeling accuracy. The study found that the proposed data enhancement method can increase the diversity of data characteristics, and the generated data can increase the recall rate of test and verification data sets. Specifically, the proposed system increased the recall rate of test data sets with different distributions from 78.21% to 82.40% and the recall rate of verification data sets with the same distribution from 81.64 to 91.94%. [ABSTRACT FROM AUTHOR]

Atmospheric turbulence causes transmitted light to fade randomly, which results in irradiance scintillation fluctuations in the received signal and significantly affects the quality of wireless optical communication systems. In this paper, we investigate the propagation characteristics of a monochromatic light-emitting diode (LED) light beam through weak-to-strong turbulence. Considering the spatial incoherence of a monochromatic LED light source, the emitted light field of a monochromatic LED light source is represented by a random field multiplied by a deterministic field that follows a Gaussian distribution. Then, based on the extended-Rytov theory, a closed expression for the irradiance scintillation index under weak-to-strong turbulence is derived. In addition, the expression for the fading probability governed by the Gamma–Gamma model is given. Finally, the effects of near-earth atmospheric refractive index structural parameters, signal propagation distances, and working light wavelengths on propagation characteristics of the LED-based VLC system are simulated and compared with those of the laser-based one. The results theoretically confirm that laser light sources are more susceptible to atmospheric turbulence along the propagation path than monochromatic LED light sources. The investigation in this paper can provide theoretical support for the design of visible light communication systems in practical applications. [ABSTRACT FROM AUTHOR]

This paper introduces a new safety approach for Optical Wireless Power Transmission (OWPT), a technology that is integral to the new kinds of Wireless Power Transmission technology (WPT). It starts from the fundamental configuration of the current OWPT system, addressing the safety concerns related to lasers by involving laser irradiation hazards, laser exposure regulation and guidelines, and a comparison with other safety methods. A camera-based OWPT safety system focused on the emission control of the light source is proposed, and it utilizes a depth camera and finely tuned computer vision-based control program. Through meticulous system design and experiments, the proposed system can detect moving objects in a limited indoor environment and control the laser/LED light transmission according to the object's velocity dynamically. Various functions and exclusive improvements towards OWPT operation are mentioned, and Dynamic Safety-Distance is proposed as the core mechanism of the safety system. Through on-site experiments, indoor safety control and system operation's evaluation are discussed, acknowledging both the advantages and limitations of the proposed safety system. This paper concludes with suggestions for further developments in camera-based OWPT safety incorporating the concept of Automatic Emission Control. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of fidelity on the capability of digital twins (DT) to detect two common material extrusion (MEX) failures: extrusion error and layer shift. Monitoring of the failures is first explored using an image-based DT to provide a benchmark. The fidelity-performance analysis of DTs with significantly different levels of fidelity ranging from low to high fidelity is then studied and presented. In this paper, digital twin fidelity is defined as the expression of the necessary levels of accuracy in different attributes of the twin. The basis for the DTs employed in this study is image comparison. Consequently, six attributes are selected to describe the fidelity, including image resolution, mesh number, shadow method, illumination model, light source and state threshold. The effects of varying the fidelity of the six attributes on the capability to detect printing failures are then analysed and discussed. It is shown that, for the two failure cases considered, lower-fidelity DTs can deliver comparable capability to what are considered DTs with high or ultra-high fidelity. In addition, benefits in terms of configuration cost, data storage, simulation time, and detection time are demonstrated. [ABSTRACT FROM AUTHOR]

Light is a popular choice as an indoor energy source for Internet of Things (IoT) end devices. However, indoor light sources are intermittent, which can disrupt the operation of IoT end devices, potentially leading to safety concerns or inaccurate data. Therefore, there is a growing need to develop a long‐duration power supply for IoT end devices. The energy from ambient light is harnessed to charge a supercapacitor through an energy manager chip. This supercapacitor serves as the power source for IoT nodes when the ambient light is unavailable. Nevertheless, as the voltage of the supercapacitor drops below the operating threshold, the IoT end node will eventually shut down. This paper proposes a circuit that utilizes a Joule Thief circuit, booster converter, and capacitor stack‐up circuit to extract the remaining energy from the supercapacitor and boost the voltage, thereby extending the operational lifespan of IoT end nodes. Additionally, capacitor stack‐up circuits significantly enhance charging efficiency. PSpice design and simulations confirm circuit feasibility. High‐efficiency charging and long‐duration IoT nodes suggest replacing traditional batteries with supercapacitors, reducing environmental impact. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central European Agriculture is the property of Journal of Central European Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, we present a simple numerical technique based on optical frequency domain reflectometry. Nonlinear Schrödinger having anti-cubic equation is suggested for computing a new solitons-solutions propagation. The dispersion is to be calculated from variations in the frequency chirp rate, when frequency-chirped light is utilized as the light source. We utilize an accurate model of the average dispersion, in fibers up to several tens of kilometers. The numerical simulation is obtained by applying variable perturbation theory on the group velocity dispersion term in nonlinear Schrödinger having anti-cubic equation. The proposed model is used with some particular conditions; to be significantly more accurate for links with strong nonlinearities and high dispersion. [ABSTRACT FROM AUTHOR]

A plane-symmetric optical system with a two-dimensional field light source, such as a soft X-ray and vacuum ultraviolet optical system, is widely used for synchrotron radiation source devices, microscopes and so on. Therefore, this paper studied third-order intrinsic aberration modification with second-order accuracy transfer of pupil coordinates and extrinsic aberration of these kinds of optical systems. First, we discuss the extrinsic aberration calculation method and derive the corresponding aberration expressions; in addition, we apply optical geometric relations and the polynomial fitting method to obtain a second-order accuracy transfer relationship expression of the pupil coordinates between adjacent optical surfaces and derived the modification calculation expressions of the intrinsic aberration caused by the above factor. Finally, the third-order intrinsic aberration modification with second-order accuracy transfer of pupil coordinates and extrinsic aberration expressions derived in this paper are applied to calculate ray spot diagrams of two soft X-ray and vacuum ultraviolet optical systems with meridional and sagittal field angle light sources, and these results are compared with those obtained from the ray-tracing software Shadow; this showed that the calculation accuracy of the aberration expressions is sufficient. [ABSTRACT FROM AUTHOR]

In recent years, China's advanced light sources have entered a period of rapid construction and development. As modern X-ray detectors and data acquisition technologies advance, these facilities are expected to generate massive volumes of data annually, presenting significant challenges in data management and utilization. These challenges encompass data storage, metadata handling, data transfer and user data access. In response, the Data Organization Management Access Software (DOMAS) has been designed as a framework to address these issues. DOMAS encapsulates four fundamental modules of data management software, including metadata catalogue, metadata acquisition, data transfer and data service. For light source facilities, building a data management system only requires parameter configuration and minimal code development within DOMAS. This paper firstly discusses the development of advanced light sources in China and the associated demands and challenges in data management, prompting a reconsideration of data management software framework design. It then outlines the architecture of the framework, detailing its components and functions. Lastly, it highlights the application progress and effectiveness of DOMAS when deployed for the High Energy Photon Source (HEPS) and Beijing Synchrotron Radiation Facility (BSRF). [ABSTRACT FROM AUTHOR]

This paper is dedicated to the investigation of the metrological properties of phase-sensitive reflectometric measurement systems, with a particular focus on addressing the non-uniformity of responses along optical fibers. The authors highlight challenges associated with the stochastic distribution of Rayleigh reflectors in fiber optic systems and propose a methodology for assessing response non-uniformity using both cross-correlation algorithms and machine learning approaches, using chirped-reflectometry as an example. The experimental process involves simulating deformation impact by altering the light source's wavelength and utilizing a chirped-reflectometer to estimate response non-uniformity. This paper also includes a comparison of results obtained from cross-correlation and neural network-based algorithms, revealing that the latter offers more than 34% improvement in accuracy when measuring phase differences. In conclusion, the study demonstrates how this methodology effectively evaluates response non-uniformity along different sections of optical fibers. [ABSTRACT FROM AUTHOR]

Turbidity is one of the crucial parameters of water quality. Even though many commercial devices, low-cost sensors, and remote sensing data can efficiently quantify turbidity, they are not valid tools for the classification it. In this paper, we design, calibrate, and test a novel optical low-cost sensor for turbidity quantification and classification. The sensor is based on an RGB light source and a light detector. The analyzed samples are characterized by turbidity values from 0.02 to 60 NTUs, and have four different sources. These samples were generated to represent natural turbidity sources and leaves in the marine areas close to agricultural lands. The data are gathered using 64 different combinations of light, generating complex matrix data. Machine learning models are compared to analyze this data, including training, validation, and test datasets. Moreover, different alternatives for data preprocessing and feature selection are assessed. Concerning the quantification of turbidity, the best results were obtained using averaged data and principal components analyses in conjunction with exponential gaussian process regression, achieving an R2 of 0.979. Regarding the classification of the turbidity, an accuracy of 91.23% is obtained with the fine K-Nearest-Neighbor classifier. The cases in which data were misclassified are characterized by turbidity values lower than 5 NTUs. The obtained results represent an improvement over the current solutions in terms of turbidity quantification and a completely novel approach to turbidity classification. [ABSTRACT FROM AUTHOR]

Due to the large number of defects at the grain boundaries of nanocomposites, defects have a significant effect on the physico-chemical properties of a material. Therefore, controlling the charging behaviour of functional nanocomposites in a non-contact manner with a light field can improve their physical and chemical properties. Chitosan-derived carbon dots were synthesised by exploiting the abundant N element in chitosan. In order to passivate the defects of chitosan-derived carbon dots, a MoO3/carbon dot nanocomposite was constructed in this study to tailor the band gap and improve the extraction ability of carriers through light induction. The results showed that the strong interfacial interaction between MoO3 and carbon dots enhanced the optical absorption and interfacial charge transfer in the visible and some near-infrared regions. The resulting MoO3/carbon dot heterostructure was coated on A4 printing paper, and electrodes were integrated in the coating film. The photocurrent signals of the thick film were investigated using 405, 532, 650, 808, 980 and 1064 nm light sources. The results indicated that the phenomenon of photocurrent switching to the visible light and some near-infrared light regions was observed. The charge carrier extraction ability of the MoO3/carbon dot nanocomposite through light triggering was much better than that of chitosan-derived carbon dots. The on/off ratio and response speed of the MoO3/carbon dot nanocomposite were significantly improved. The physical mechanism was discussed based on the ordered and disordered structures of polymer-derived carbon nanomaterials. This material could be applicable to the development of broadband flexible photosensors, artificial vision or light-utilising interdisciplinary fields. [ABSTRACT FROM AUTHOR]

There are many possible LED lighting applications where separate regulation of the LED current (luminous flux) of individual LED strings would be desirable—specialized variable correlated color temperature lights for ambient lighting, decorative lighting, surgical lights, horticultural lights, etc. Separate regulation of the current or light flux of individual LED strings is associated with a known problem: the necessity of using a controllable LED driver for each string, which increases the total component count, overall system complexity and costs. One of the possible solutions—a current source mode single-inductor multiple-output LED driver—was discussed in previous different papers. However, the practical implementation of this solution was not discussed in detail. This article aims to correct this omission. [ABSTRACT FROM AUTHOR]

Photoplethysmography (PPG) technology enables the measurement of multiple physiological and psychological parameters with low‐cost wearable sensors and is reshaping modern healthcare. Advanced materials play a vital role in improving reliability and accuracy of PPG sensors. Recently, various advanced materials have been explored to optimize PPG sensor design, while some challenges exist toward large‐scale validation and mass production. This paper focuses on advanced materials applied in the photodetectors, light sources, and circuits of PPG sensors. The materials are categorized into four groups: inorganic, organic, nanomaterials, and hybrid materials. The properties and fabrication processes are summarized. Other technical details including the mode of operation, measurement sites, testing, and validation are discussed. The merits and limitations of the state of the art are highlighted to provide some suggestions for the future development of PPG sensors based on advanced materials. [ABSTRACT FROM AUTHOR]

To enhance the performance of visual SLAM in underwater environments, this paper presents an enhanced front-end method based on visual feature enhancement. The method comprises three modules aimed at optimizing and improving the matching capability of visual features from different perspectives. Firstly, to address issues related to insufficient underwater illumination and uneven distribution of artificial light sources, a brightness-consistency recovery method is proposed. This method employs an adaptive histogram equalization algorithm to balance the brightness of images. Secondly, a method for denoising underwater suspended particulates is introduced to filter out noise from images. After image-level processing, a combined underwater acousto–optic feature-association method is proposed, which associates acoustic features from sonar with visual features, thereby providing distance information for visual features. Finally, utilizing the AFRL dataset, the improved system incorporating the proposed enhancement methods is evaluated for its performance against the OKVIS framework. The system achieves a better trajectory estimation accuracy compared to OKVIS and demonstrates robustness in underwater environments. [ABSTRACT FROM AUTHOR]

An emergent need exists for solid state tunable coherent light emitters in the mid-infrared range for spectroscopy, sensing, and communication applications where current light sources are dominated by spontaneous emitters. This paper demonstrates a distinct class of coherent thermal emitters operating in the mid-infrared wavelength regime. The structure of the light source consists of a dielectric metasurface fabricated on a phononic substrate. In this study, we present the first implementation of off-Γ Friedrich–Wintgen bound states in the continuum at mid-infrared wavelengths suitable for developing the next generation of coherent light emitters. Numerical analysis of the emissivity spectrum reveals the interference of resonances leading to avoided crossings and the formation of Friedrich–Wintgen bound states in the radiation spectrum. Additionally, significant localized field enhancements are observed within the metasurface at operating wavelengths. The emissivity spectra measured by reflectivity and emission experiments exhibit temporally coherent emission peaks in the vicinity of the bound state in the continuum, the first such demonstration in the mid-infrared region for wavelengths longer than 7 µm. These results represent a new approach for significant advancement in realizing mid-infrared coherent light emitters with promising implications for future technologies. [ABSTRACT FROM AUTHOR]

This paper explores the photocatalytic degradation of Reactive Orange 16 (RO16) dye in textile wastewater employing a novel CuO@A-TiO2/Ro-TiO2 nanocomposite. The nanocomposite was synthesized via a hydrothermal technique, resulting in a monoclinic phase of leaf-shaped CuO loaded on a hexagonal wurtzite structure of rod-shaped ZnO, as confirmed by FE-SEM and XRD analyses. Optical experiments revealed band gap energies of 1.99 eV for CuO, 2.19 eV for ZnO, and 3.34 eV for the CuO@A-TiO2/Ro-TiO2 nanocomposite. Photocatalytic degradation experiments showcased complete elimination of a 100 mg/L RO16 solution (150 mL) after 120 min of UV light illumination and 100 min of sunlight illumination, emphasizing the nanocomposite's efficiency under both light sources. The study further delves into the application of the CuO@A-TiO2/Ro-TiO2 nanocomposite for the degradation of actual textile wastewater samples under sunlight irradiation. The results underscore the nanocomposite's remarkable efficacy in treating RO16 in textile wastewater, positioning it as a promising candidate for sustainable and efficient wastewater treatment applications. This research contributes valuable insights into the development of advanced photocatalytic materials for textile dye degradation in wastewater treatment. [ABSTRACT FROM AUTHOR]

Quantum emitters, such as the negatively charged nitrogen-vacancy center in diamond, are attractive for quantum technologies, such as nano-sensing, quantum information processing, and as a non-classical light source. However, it is still challenging to position individual emitters in photonic structures while preserving the spin coherence properties of the defect. In this paper, we investigate single and ensemble waveguide-integrated nitrogen-vacancy centers in diamond fabricated by femtosecond laser writing followed by thermal annealing. Their spin coherence properties are systematically investigated and are shown to be comparable to native nitrogen-vacancy centers in diamond. This method paves the way for the fabrication of coherent spins integrated within photonic devices. [ABSTRACT FROM AUTHOR]

This paper presents a number of lessons learned while designing a proposed sterilization system for Mars Sample Return. This sterilization system is needed to inactivate any potentially hazardous Mars material on the exterior surface of the vessel containing sealed sample tubes filled with Mars rock cores, regolith and atmosphere. These returned samples would provide information on the geologic history of Mars, the evolution of its climate and the potential for ancient life. Mars Sample Return is categorized at Planetary Protection Category V Restricted Earth Return, so it is required to protect the Earth–Moon system from the biological impact of returning samples from Mars to Earth. This article reviews lessons learned in the development of a particular engineering implementation to support the protection of the Earth–Moon biosphere: the use of in situ ultraviolet LED illumination. The details of the biological efficacy of this approach or the policy-related impacts are outside of the scope of this manuscript. The lessons learned presented here include establishing design requirements for the system, the selection of a light source, optical design options, contamination control and approaches to thermal and power management. [ABSTRACT FROM AUTHOR]

Ambient temperature has a significant effect on the electrical and luminous parameters of light-emitting diodes (LEDs), which include forward and reverse current, forward voltage, and luminous flux. This paper gives insight into the influence of ambient temperature on the electrical and luminous parameters of LEDs powered by a rectangular pulsed voltage source versus those powered by a constant voltage source. The characteristics of LEDs in LED lighting devices were studied to determine their optimal operating conditions. To this end, rectangular pulse voltages with different pulse filling factors D were considered against the DC voltage source. Characteristics were obtained for the current stabilization mode and for the LED voltage stabilization mode. In both modes, the temperature dependence of the luminous flux, current, voltage, power consumption, and luminous efficiency of the LEDs was studied in the 20 °C to 60 °C range. The optimal LED operating conditions were determined, of which their luminous flux and luminous efficiency are least dependent on ambient temperature. When powered by a rectangular pulse voltage, the LED device drivers' optimal pulse filling factor and operating frequency were determined. [ABSTRACT FROM AUTHOR]

To address the technical challenge of identifying tiny defects, especially dust and point defects, on mobile phone flat glass, an automatic optical inspection system is established. The system investigates algorithms including imaging principles, target detection models, data augmentation, foreground segmentation, and image fusion. The system builds an automatic optical inspection platform to collect glass defect samples. It illuminates the glass samples with a combined total reflection–grazing light source, collects the defect sample data, segments the background and defects of the collected data, generates the defect mask, and extracts the complete defects of the cell phone flat glass. The system then seamlessly integrates the extracted defects with a flawless background using Poisson editing and outputs the location information of the defects and the label output to automatically generate the dataset. The deep learning network YOLOv5 works as the core algorithm framework, into which the Constructive Block Attention Module and the small target detection layer are specifically added to enhance the capability of the model to detect small defects. According to the experimental results, the combined lighting effectively improves the precision of detecting dust and bright spots. Additionally, with the adoption of novel data augmentation techniques, the enhanced YOLOv5 model is capable of effectively addressing the challenges posed by inefficient sample data and non-uniform distribution, thus mitigating network generalization issues. Furthermore, this data augmentation approach facilitates the rapid adaptation of the same detection tasks to diverse environmental scenarios, enabling the expedited and efficient deployment of the model across various industrial settings. The mean average precision (MAP) of the optimal model in the validation set reached 98.36%, 2.62% higher than that of the original YOLOv5. In addition, its false acceptance rate (FAR) is 1.27%, its false rejection rate (FRR) was 2.47%, its detection speed was 64 fps, and its correct detection rate in the validation set was 98.75%, which meets the current industrial detection requirements by and large. In this way, this paper achieved the automated inspection of mobile phone flat glass with high robustness, high precision, and a low false acceptance rate and false rejection rate, significantly reducing material losses in the factories and the likelihood of error occurrence in follow-on products. This method can be applied to the multi-scale and multi-type detection of glass defects. [ABSTRACT FROM AUTHOR]

Dark-and-weak-target simulators are used as ground-based calibration devices to test and calibrate the performance metrics of star sensors. However, these simulators are affected by full-field-of-view energy nonuniformity. This problem impacts the quality of output images and the calibration accuracy of sensors and inhibits further improvements in navigational accuracy. In the study reported in this paper, we sought to analyze the factors which affect full-field-of-view energy uniformity in dark-and-weak-target simulators. These include uneven irradiation in backlight sources, the leakage of light from LCD display panels, and the vignetting of collimating optical systems. We then established an energy transfer model of a dark-and-weak-target simulator based on the propagation of a point light source and proposed a self-adaptive compensation algorithm based on pixel-by-pixel fitting. This algorithm used a sensor to capture the output image of a dark-and-weak-target simulator and iteratively calculated the response error matrix of the simulator. Finally, we validated the feasibility and effectiveness of the compensation algorithm by acquiring images using a self-built test system. The results showed that, after compensating an output image of the dark-and-weak-target simulator, the grayscale standard display function (SDF) of the acquired sensor image was reduced by about 50% overall, so the acquisition image was more accurately compensated, and the desired level of grayscale distribution was obtained. This study provides a reference for improving the quality of output images from dark-and-weak-target simulators, so that the working environments of star sensors may be more realistically simulated, and their detection performance improved. [ABSTRACT FROM AUTHOR]

In order to meet the high uniformity calibration requirements for scientific-grade, large-size space detectors used in the CHES Extrasolar Planet Exploration Mission, this paper presents the design of a wide dynamic range, high uniformity spectral irradiance source (WHUIS). Utilizing a cascade integrating sphere design, and optimizing the overlapping area radiant flux adjustment structure and illumination light path, we achieve a wide dynamic range and high uniformity irradiance output. We established an irradiance transmission model based on the new assumption and analyzed the influence of factors such as illumination distance, stray light, and non-uniform radiance on the uniformity of irradiance output. The model is then validated by building experimental equipment. The findings show that in a circular area of 40 mm, the irradiance uniformity of our light source system exceeds 99.9%, and constant color temperature is adjustable within six orders of magnitude, consistent with the uniformity level predicted by the model. [ABSTRACT FROM AUTHOR]

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High-average-power narrow-linewidth tunable solid-state lasers in the wavelength region between 2 and 3 μm are attractive light sources for many applications. This paper reports a narrow-linewidth widely tunable laser system based on the polycrystalline Cr2+:ZnSe elements pumped by repetitively pulsed 2.1 µm Ho3+:YAG laser operating at a pulse rate of tens of kilohertz. An advanced procedure of ZnSe element doping and surface improvement was applied to increase the laser-induced damage threshold, which resulted in an increase in the output power of the Cr2+:ZnSe laser system. The high-average-power laser system comprised double master oscillators and power amplifiers: Ho3+:YAG and Cr2+:ZnSe laser oscillators, and Ho3+:YAG and Cr2+:ZnSe power amplifiers. The output wavelength was widely tuned within 2.3–2.7 µm by means of an acousto-optical tunable filter inside a Cr2+:ZnSe master oscillator cavity. The narrow-linewidth operation at the pulse repetition rate of 20–40 kHz in a high-quality beam with an average output power of up to 9.7 W was demonstrated. [ABSTRACT FROM AUTHOR]

A vehicle-mounted solar occultation flux–Fourier transform infrared spectrometer uses the sun as an infrared light source to quantify molecular absorption in the atmosphere. It can be used for the rapid three-dimensional monitoring of pollutant emissions and the column concentration monitoring of greenhouse gases. The system has the advantages of high mobility and a capacity for noncontact measurement and measurement over long distances. However, in vehicle-mounted applications, vehicle bumps and obstacles introduce aberrations in the measured spectra, affecting the accuracy of gas concentration inversion results and flux calculations. In this paper, we propose a spectral data preprocessing method that combines a self-organizing mapping neural network and correlation analysis to reject anomalous spectral data measured by the solar occultation flux–Fourier transform infrared spectrometer during mobile observations. Compared to the traditional method, this method does not need to adjust the comparison threshold and obtain the training spectra in advance and has the advantage of automatically updating the weights without the need to set fixed correlation comparison coefficients. The accurate identification of all anomalous simulated spectra in the simulation experiments proved the effectiveness of the method. In the vehicle-mounted application experiment, 342 anomalous spectra were successfully screened from 1739 spectral data points. The experimental results show that the method can improve the accuracy of gas concentration measurement results and can be applied to a vehicle-mounted solar occultation flux–Fourier transform infrared spectrometer system to meet the preprocessing needs of a high number of spectral data in mobile monitoring. [ABSTRACT FROM AUTHOR]

Advanced glycation end-products (AGEs) are complex compounds closely associated with several chronic diseases, especially diabetes mellitus (DM). Current methods for detecting AGEs are not suitable for screening large populations, or for long-term monitoring. This paper introduces a portable autofluorescence detection system that measures the concentration of AGEs in the skin based on the fluorescence characteristics of AGEs in biological tissues. The system employs a 395 nm laser LED to excite the fluorescence of AGEs, and uses a photodetector to capture the fluorescence intensity. A model correlating fluorescence intensity with AGEs concentration facilitates the detection of AGEs levels. To account for the variation in optical properties of different individuals' skin, the system includes a 520 nm light source for calibration. The system features a compact design, measuring only 60 mm × 50 mm × 20 mm, and is equipped with a miniature STM32 module for control and a battery for extended operation, making it easy for subjects to wear. To validate the system's effectiveness, it was tested on 14 volunteers to examine the correlation between AGEs and glycated hemoglobin, revealing a correlation coefficient of 0.49. Additionally, long-term monitoring of AGEs' fluorescence and blood sugar levels showed a correlation trend exceeding 0.95, indicating that AGEs reflect changes in blood sugar levels to some extent. Further, by constructing a multivariate predictive model, the study also found that AGEs levels are correlated with age, BMI, gender, and a physical activity index, providing new insights for predicting AGEs content and blood sugar levels. This research supports the early diagnosis and treatment of chronic diseases such as diabetes, and offers a potentially useful tool for future clinical applications. [ABSTRACT FROM AUTHOR]

Thanks to the line-scanning camera, the measurement method based on line-scanning stereo vision has high optical accuracy, data transmission efficiency, and a wide field of vision. It is more suitable for continuous operation and high-speed transmission of industrial product detection sites. However, the one-dimensional imaging characteristics of the line-scanning camera cause motion distortion during image data acquisition, which directly affects the accuracy of detection. Effectively reducing the influence of motion distortion is the primary problem to ensure detection accuracy. To obtain the two-dimensional color image and three-dimensional contour data of the heavy rail surface at the same time, a binocular color line-scanning stereo vision system is designed to collect the heavy rail surface data combined with the bright field illumination of the symmetrical linear light source. Aiming at the image motion distortion caused by system installation error and collaborative acquisition frame rate mismatch, this paper uses the checkerboard target and two-step cubature Kalman filter algorithm to solve the nonlinear parameters in the motion distortion model, estimate the real motion, and correct the image information. The experiments show that the accuracy of the data contained in the image is improved by 57.3% after correction. [ABSTRACT FROM AUTHOR]

High-sensitivity fluorescence monitoring has been widely used in agriculture and environmental science. However, the active fluorescence detection information of leaf segments mainly focuses on total chlorophyll, and the fluorescence information of chlorophyll a, chlorophyll b, and some other pigments has not been explored. This only considers the fluorescence spectrum characteristics at a single wavelength or the fluorescence integral from a range of wavelength regions and does not completely consider the linkage relation between the excitation, emission, and interference information. In this paper, the three-dimensional fluorescence spectrum, containing the excitation and emission fluorescence spectra, and the corresponding multiple pigment characteristics from the upgraded LOPEX_ZJU database were collected. The linkages of excitation and emission of the three-dimensional fluorescence spectra of these pigments were analyzed for the newly built multiple pigment 3-D fluorescence spectral indices (3-D FSIs), including those of chlorophyll a, chlorophyll b, carotenoid, anthocyanin, and flavonoid 3-D FSIs. Then, these pigment inversion models were established and validated. The results show that the 3-D FSIs performances for the photosynthetic pigment content inversion (including chlorophyll a and b, and carotenoids) were much better than those for the photo-protective pigments (including anthocyanins and flavonoids) from the 3-D fluorescence spectra of these plant leaves. Here, the 3-D fluorescence normalization index (FNI ((F430,690 − F430,763)/(F430,690 + F430,763))) for the chlorophyll a inversion model has a high accuracy, the RMSE is 2.96 μg/cm2, and the 3-D fluorescence reciprocal difference index (FRI (F650,704/F650,668) for the chlorophyll b model has an encouraging RMSE (2.01 μg/cm2). The RMSE of the 3-D fluorescence ratio index (FRI (F500,748/F500,717)) for the carotenoid inversion is 3.77 μg/cm2 RMSE. Only FRI (F370,615/F370,438) was selected for the modeling and validating evaluation of the leaf Flas content inversion, but the evaluation metrics were not good, with an RMSE (151.13 μg/cm2). For Ants, although there was a 3-D FSI (FRDI (1/F540,679 − 1/F540,557)), and its evaluation metrics, with an RMSE (2.8 μg/cm2), were at or over 0.05 level, the validating evaluation metric VC (98.3577%) was not encouraging. These results showed that fluorescence, as a nondestructive and efficient detection method, could determine the contents of chlorophyll a, chlorophyll b, and carotenoid in plant leaves, providing a new method to detect plant information. It can also provide a potential chance for the fluorescence images of fine photo-protective pigments, especially chlorophyll a and b, using the special active fluorescence excitation light source and a few fluorescence imaging channels from the optimal FSIs. [ABSTRACT FROM AUTHOR]

Time-Resolved Serial Femtosecond Crystallography (TR-SFX) conducted at X-ray Free Electron Lasers (XFELs) has become a powerful tool for capturing macromolecular structural movies of light-initiated processes. As the capabilities of XFELs advance, we anticipate that a new range of coherent control and structural Raman measurements will become achievable. Shorter optical and x-ray pulse durations and increasingly more exotic pulse regimes are becoming available at free electron lasers. Moreover, with high repetition enabled by the superconducting technology of European XFEL (EuXFEL) and Linac Coherent Light Source (LCLS-II) , it will be possible to improve the signal-to-noise ratio of the light-induced differences, allowing for the observation of vibronic motion on the sub-Angstrom level. To predict and assign this coherent motion, which is measurable with a structural technique, new theoretical approaches must be developed. In this paper, we present a theoretical density matrix approach to model the various population and coherent dynamics of a system, which considers molecular system parameters and excitation conditions. We emphasize the use of the Wigner transform of the time-dependent density matrix, which provides a phase space representation that can be directly compared to the experimental positional displacements measured in a TR-SFX experiment. Here, we extend the results from simple models to include more realistic schemes that include large relaxation terms. We explore a variety of pulse schemes using multiple model systems using realistic parameters. An open-source software package is provided to perform the density matrix simulation and Wigner transformations. The open-source software allows us to define any arbitrary level schemes as well as any arbitrary electric field in the interaction Hamiltonian. [ABSTRACT FROM AUTHOR]

The application of terahertz (THz) radiation in scientific research as well as in applied and commercial technology has expanded rapidly in recent years. One example is the progress in high-resolution THz spectroscopy based on quantum cascade lasers, which has enabled new observations in astronomy, atmospheric research, and plasma diagnostics. However, the lack of easy-to-use and miniaturised detectors has hampered the development of compact THz spectroscopy systems out of the laboratory environment. In this paper, we introduce a new high-speed pyroelectric receiver as a cryogen-free detector for THz absorption spectroscopy. Its performance is characterised by absorption spectroscopy measurements on a reference gas cell (RGC) with ammonia using a tunable THz quantum cascade laser at approximately 4.75 THz as the light source. It is shown that the receiver can record spectra up to 281 Hz without any artefacts to the observed spectral absorption profile, and the results reproduce the known pressure of ammonia in the RGC. This demonstrates that the pyroelectric receiver can be reliably used as an alternative to helium-cooled bolometers for absorption spectroscopy measurements in the THz range, with its main advantages being the high bandwidth, compactness, relatively low cost, and room-temperature operation. Its simplicity and high sensitivity make this receiver a key component for compact THz spectroscopy systems. [ABSTRACT FROM AUTHOR]

The ability to study chemical dynamics on ultrafast timescales has greatly advanced with the introduction of X-ray free electron lasers (XFELs) providing short pulses of intense X-rays tailored to probe atomic structure and electronic configuration. Fully exploiting the full potential of XFELs requires specialized experimental endstations along with the development of techniques and methods to successfully carry out experiments. The liquid jet endstation (LJE) at the Linac Coherent Light Source (LCLS) has been developed to study photochemistry and biochemistry in solution systems using a combination of X-ray solution scattering (XSS), X-ray absorption spectroscopy (XAS), and X-ray emission spectroscopy (XES). The pump–probe setup utilizes an optical laser to excite the sample, which is subsequently probed by a hard X-ray pulse to resolve structural and electronic dynamics at their intrinsic femtosecond timescales. The LJE ensures reliable sample delivery to the X-ray interaction point via various liquid jets, enabling rapid replenishment of thin samples with millimolar concentrations and low sample volumes at the 120 Hz repetition rate of the LCLS beam. This paper provides a detailed description of the LJE design and of the techniques it enables, with an emphasis on the diagnostics required for real-time monitoring of the liquid jet and on the spatiotemporal overlap methods used to optimize the signal. Additionally, various scientific examples are discussed, highlighting the versatility of the LJE. [ABSTRACT FROM AUTHOR]

To solve the problem of pixel light intensity information distortion caused by camera vignetting in optical devices such as CMOS or CCD cameras, existing studies mainly focus on small spatial light fields and point light sources and adopt an integrating sphere and function model for vignetting correction, but it is not suitable for large LED optical composite display devices. Under this background, this paper innovatively proposes a camera vigneting compensation method based on an LED spatial array, independently develops a two-dimensional translation device driven by a high-precision guide rail, uses spatial array technology to obtain the brightness distribution of the corrected display screen to quantify its camera vigneting distortion characteristics, and adopts systematic mathematical operations and iterative compensation strategies. Industry standard tests show that the brightness uniformity of the display has been improved by 5.06%. The above research results have been applied to mass production and industrialization. [ABSTRACT FROM AUTHOR]

The key to realizing a high-performance frequency-modulated continuous wave (FMCW) laser frequency-sweeping light source is how to extend the frequency-swept bandwidth and eliminate the effect of nonlinearity. To solve these issues, this paper designs a broadband high-linear FMCW frequency-sweeping light source system based on the combination of fixed temperature control and digital optoelectronic phase-locked loop (PLL), which controls the temperatures of the two lasers separately and attempts to achieve the coarse spectral stitching based on a time-division multiplexing scheme. Furthermore, we uses the PLL to correct the frequency error more specifically after the coarse stitching, which achieves the spectrum fine stitching and, meanwhile, realizes the nonlinearity correction. The experimental results show that our scheme can successfully achieve bandwidth expansion and nonlinearity correction, and the sweeping bandwidth is twice as much as that of the original single laser. The full-width half-maximum (FWHM) of the FMCW output is reduced from 150 kHz to 6.1 kHz, which exhibits excellent nonlinear correction performance. The relative error of the FMCW ranging system based on this frequency-swept light source is also reduced from 1.628% to 0.673%. Therefore, our frequency-swept light source with excellent performance has a promising application in the FMCW laser ranging system. [ABSTRACT FROM AUTHOR]

The classical wave theory can trace its historical origins to the seminal works of Christian Huygens, Thomas Young, and Augustin Fresnel. To explain some of light's observed properties, such as rectilinear propagation, reflection, and refraction, Huygens proposed a simple geometrical construction of secondary spherical wavelets with centers of disturbance located on a primary wavefront. More than a century later, Young formulated the law of interference to both predict the formation of fringes in his now famous double slit experiment and also to estimate the wavelengths associated with different colors. A decade after that, Fresnel combined Huygens' construction with Young's interference law to qualitatively and quantitatively describe diffraction, which is the bending of light upon encountering an obstacle or an aperture. This grand synthesis, called the Huygens–Fresnel principle, acts as a powerful pictorial aid and conceptual tool that can describe a wide variety of complicated optical phenomena. However, the applications of the principle and its later developments, such as the Kirchhoff–Fresnel integral, are strewn with several simplifying assumptions and approximations that are aimed at minimizing the mathematical challenges involved. Consequently, two distinct formalisms are necessary to account for diffraction effects when the source of light or observation screen is placed nearby and far away from the aperture or obstacle. Recently, a hyperbola framework for analyzing wave interference at a multi-slit barrier was shown to successfully circumvent all conventionally imposed ad hoc conditions. The method commences directly from the Huygens–Fresnel principle and the ensuing predictions pertaining to the distribution of fringe characteristics, namely, positions, widths, and intensities on a detection screen can, therefore, justifiably claim accuracy in both the near field (Fresnel regime) and the far field (Fraunhofer regime). In this paper, the analysis that was previously carried out for the special case of slits of negligible widths is further extended to encompass slits of finite widths as well. [ABSTRACT FROM AUTHOR]

High-Temperature Materials Science Experiment Cabinet on the Chinese Space Station is mainly used to carry out experimental research related to high-temperature materials science in microgravity. It is equipped with an X-ray transmission imaging module, which is applied to realize transmission imaging of material samples under microgravity. However, the X-ray light source is far away from the experimental samples, and the images obtained by the module are blurred, so it is impossible to accurately observe the morphological changes during the melting and solidification processes of high-temperature materials. To address this issue, this paper proposed a contrast enhancement algorithm specifically designed for X-ray images obtained during the experiments of high-temperature materials. The algorithm is based on gradient three-interval equalization, and it is combined with a Gaussian function to expand the gradient histogram. Meanwhile, the local gray level information within each gradient interval is corrected by designing an improved adaptive contrast enhancement algorithm. By comparing with Adaptive Histogram Equalization (AHE) and Contrast Limited Adaptive Histogram Equalization (CLAHE) algorithms, EnlightenGAN, and Wavelet algorithms, the Contrast Enhancement based contrast-changed Image Quality measure (CEIQ) and Measure of Enhancement (EME) are improved by an average of 56.97%, 10.58%, and Measure of Entropy (MOE) are improved by an average of 7.74 times. The experimental results show that the algorithm makes the image details clearer on the basis of image contrast enhancement. The solid-liquid interface in the image can be clearly observed after contrast enhancement. The algorithm provides strong support for the study of interface dynamics during the experiment process of high-temperature materials. [ABSTRACT FROM AUTHOR]

This paper presents a chaotic system based on novel semiconductor nanolasers (NLs), systematically analyzing its chaotic region and investigating the influence of key parameters on the unpredictability of chaotic output. This study found that under optical feedback conditions, NLs generate chaos across a wide range of feedback parameters, with the highly unpredictable region completely overlapping with the chaotic region. Further injection into the slave lasers enhances the chaotic output, expanding the range of unpredictability. Additionally, we analyzed the impact of internal parameter mismatch on the complexity of chaotic signals and found it to be similar to the scenario when parameters are matched. Using this chaotic system as an entropy source, we constructed a random number generator (RNG) and investigated the effects of internal parameters mismatch and differences in the injection parameters on the generator's performance. The simulation results show that the RNG performs well under different parameter settings, and the generated random sequences pass all random number tests successfully. Therefore, this chaotic system can yield a high-complexity chaotic light source with appropriate parameter selection, and when combined with effective post-processing, it can generate high-quality random numbers. This is crucial for advancing the realization of small-sized, high-randomness RNGs. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) bonding technology is widely used across industries. As the curing reaction is initiated via an external light source, the use of fast-curing structural UV acrylates has so far been limited to joint designs with at least one transparent joining part. By introducing a side-emitting polymer optical fiber textile into the adhesive layer, which acts as an embedded light source, the technology can be made accessible for applications with nontransparent substrates such as metals. This paper describes the development of extra thin polymer optical fiber narrow fabrics designed to enable curing of structural adhesive joints. Polymer optical fibers (warp) were combined with different low-titer polyester weft yarns in two fabric design types with different primary out-coupling mechanisms: undulation and surface modification of the polymer optical fibers. The effect of yarn properties, thread densities and weave on fabric quality, geometry and lateral light intensity of each type were investigated. Results showed that narrow fabric production within the tight geometric limits required is feasible. Fabrics manufactured with nontextured yarns at low titers and low weft densities exhibited the highest lateral light intensities for the surface modification type fabric. To compensate for intensity loss over fabric length, investigating light coupling from both sides is recommended for this fabric type. For the undulation type fabric, the lateral light intensity characteristics indicated that the high tenacity yarns are promising candidates for the fabrication of low sidelight attenuation fabrics through modulation of the weft density. [ABSTRACT FROM AUTHOR]