Intensity Of Light Source Research Articles

О ВЫХОДАХ ВОЗБУЖДЕНИЯ И ЛЮМИНЕСЦЕНЦИИ ТРЕХВАЛЕНТНЫХ ИОНОВ ЛАНТАНИДОВ ПРИ ОДНОПУЗЫРЬКОВОМ СОНОЛИЗЕ РАСТВОРОВ В СЕРНОЙ КИСЛОТЕ

The light yields of luminescence (Glum) and the yields of excited ion production (yields of excitation, Gext) were measured for the first time for a number of trivalent lanthanide ions (Ln3+) during moving single-bubble sonoluminescence in solutions of 10-2 M Ln3+ in 70% H2SO4. The luminescence yields were determined by comparing the integrated sonoluminescence intensity of the test solution with the radioluminescence intensity of the reference light source, and the excitation yields were found from the relation Gext = Glum/φ, where φ are the photoluminescence quantum yields of Ln3+ ions in the solution, which were also measured experimentally in the work. Determined yields Glum = (0.63, 0.96, 1.8, 5.1, 0.49)´107 photon/100 eV and Gext = (0.066, 1.6, 0.7, 1.5, 0.7)´108 excited ions/100 eV for Ce3+, Eu3+, Gd3+, Tb3+ ions, Dy3+, respectively. It was confirmed that, as previously shown in the case of radiation-excited luminescence of lanthanide ions (Kazakov V.P., Sharipov G.L. Radioluminescence of aqueous solutions. M.: Nauka, 1986. p. 116), transition with a change in the principal quantum number (4f→5d, Ce3+ ion) is an order of magnitude or less lower than the excitation yield in a transition without its change (4f→4f, Eu3+, Tb3+ , and others ions).

One-Dimensional Coordinated Polymers of Tetraphenylethene Pyridine and Copper-Iodide for Fluorescence Detection of Nitroaromatic Explosives.

The spatial arrangement of molecules plays a crucial role in determining the macroscopic properties of functional materials. Coordinated polymers (CPs) formed by self-assembly of organic isomeric ligands and metals offer unique performance characteristics. In this study, we present the investigation of a one-dimensional CP, named CIT-E, composed of tetraphenylethene pyridine derivative (TPE-2by-2-E) ligands and cuprous iodide. The resulting CP exhibits a one-dimensional bead chain structure with exceptional thermal and chemical stability. By leveraging the competitive absorption between CIT-E and the explosive analog 2,4-dinitroaniline, we achieve detection of the explosive through changes in the absorption intensity of the excitation light source and subsequent fluorescence response. The CP demonstrates high selectivity and anti-interference ability in detecting 2,4-dinitroaniline in aqueous solution, with a detection linear range of 0.1 μM to 300 μM and a detection limit of 0.05 μM, surpassing the national third-level emission standard. These findings highlight the potential of CP CIT-E as a promising material for the detection of explosive nitroaromatic compounds.

Effect of Background Color and Light Source Intensity on Lightness Discrimination Thresholds

Effect of Background Color and Light Source Intensity on Lightness Discrimination Thresholds

Methodology and implementation of a tunable deep-ultraviolet laser source for photoemission electron microscopy

Photoemission electron microscopy (PEEM) is a unique and powerful tool for studying the electronic properties of materials and surfaces. However, it requires intense and well-controlled light sources with photon energies ranging from the UV to soft X-rays for achieving high spatial resolution and image contrast. Traditionally, many PEEMs were installed at synchrotron light sources to access intense and tunable soft X-rays. More recently, the maturation of solid-state lasers has opened a new avenue for laboratory-based PEEMs using laser-based UV light at lower photon energies. Here, we report on the characteristics of a laser-based UV light source that was recently integrated with a PEEM instrument. The system consists of a high repetition rate, tunable wavelength laser coupled to a harmonics generation module, which generates deep-UV radiation from 192 nm to 210 nm. We comment on the spectral characteristics and overall laser system stability, as well as on the effects of space charge within the PEEM microscope at high UV laser fluxes. Further, we show an example of imaging on gallium nitride, where the higher UV photon energy and flux of the laser provides considerably improved image quality, compared to a conventional light source. These results demonstrate the capabilities of laser-based UV light sources for advancing laboratory-based PEEMs.

Development and characterization of pH-responsive nanocarriers for chemo-photothermal combination therapy of acidic tumors.

The combination of photothermal therapy and chemotherapy has been considered a promising strategy for improving the excellent antitumor activities of these treatments. In this study, we developed a new simple type of pH-sensitive chemo-photothermal combination agent capable of repeated exposures to a near-infrared (NIR) laser and evaluated its anticancer efficacy in vitro and in vivo. Doxorubicin (Dox) and gold nanoclusters (GNCs) were successfully co-loaded into pH-sensitive nanoparticles (poly(ethylene glycol)-poly[(benzyl-l-aspartate)-co-(N-(3-aminopropyl)imidazole-L-aspartamide)] (PEG-PABI)), resulting in a particle size of approximately120 nm with a narrow size distribution. The dual drug-loaded nanoparticles (Dox/GNC-loaded PEG-PABI micelles (Dox/GNC-Ms)) showed consistent pH-sensitive properties and heat generation efficiency after repeated NIR laser exposure. In particular, GNC-M has improved photothermal stability while maintaining high photothermal conversion efficiency, addressing the shortcomings of previous gold nanoparticles. As the concentration of GNC-Ms, irradiation light exposure time, and light source intensity increased, the amount of heat generated and the anticancer effect increased. When Dox was encapsulated with GNCs (Dox/GNC-Ms), a faster drug release rate under acidic pH conditions and a strong synergistic effect against U87MG cells were observed. When the Dox/GNC-M system was extended to in vivo studies, it effectively increased the temperature of the tumor tissue under near-infrared irradiation and showed excellent anticancer efficacy. Therefore, the Dox/GNC-M system could be a simple but promising strategy for chemo-photothermal combination treatment capable of targeting acidic tumors.

Enhanced photocatalytic activity in BaBi4Ti4O15 with excess Bi2O3

The photocatalytic activity of BaBi4Ti4O15 with excess bismuth oxide (0–10 wt%) and the parametric study of photocatalysis are investigated in this article. BaBi4Ti4O15 with excess bismuth oxide was synthesized via a solid-state route followed by calcination at 950 °C for 4 h. All BaBi4Ti4O15 samples were characterized by X-ray diffractometer, scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and direct optical bandgap. Synthesized BaBi4Ti4O15 with excess bismuth oxide has an orthorhombic perovskite crystal structure with A21am space group. Excess bismuth varies in the concentration of oxygen vacancies, and 8 wt% excess BaBi4Ti4O15 has maximum oxygen vacancy. Excess bismuth also changes direct bandgap; the lowest bandgap is 2.33 eV for 8 wt% excess bismuth. The photocatalytic activity of BaBi4Ti4O15 with excess bismuth oxide (0–10 wt%) showed that 8 wt% excess bismuth has the highest photocatalytic activity. The parametric study of photocatalysis used the initial concentration, volume, and light source intensity as variables. The parametric study suggested that initial concentration, intensity, and volume were correlated with the degradation rate. Indoor dye cleaning in normal room light was also tested for real-life demonstration. BaBi4Ti4O15 was also characterized by an X-ray diffractometer and X-ray photoelectron spectroscopy to investigate the effect of photocatalysis.

Public exposure to artificial optical radiation in the aesthetics and the entertainment sector in Greece. Risk management actions.

Safety issues are raised from the use of low- and high-power optical radiation sources, both laser and non-laser, by non-experts for aesthetic and entertainment purposes. The Greek Atomic Energy Commission relied on the ISO 31000:2018 framework to manage the public exposure risk to such cases. Risk was evaluated as (1) intolerable for lasers and intense pulsed light sources at aesthetic procedures and in the case of laser pointers, (2) severe for lasers at laser shows and (3) moderate for light-emitting diodes (LEDs) at aesthetic procedures, home-use intense pulsed light sources/LEDs and laser/LED projectors. Operators' training, public awareness campaigns, intensive market surveillance actions and the enhancement of the regulatory framework have been proposed as risk treatment/control measures and have been prioritised in this order, according to their effectiveness in reducing the exposure risk and their urgency of implementation. The Greek Atomic Energy Commission developed public awareness campaigns regarding exposure safety to laser and non-laser light sources at aesthetic procedures and the use of laser pointers.

Improved ellipse-fitting phase demodulation technique to suppress the effect of light source intensity noise in interferometric system.

An improved ellipse-fitting algorithm phase demodulation (EFAPD) technique is proposed to reduce the influence of light source intensity noise on a system. In the original EFAPD, the sum of the intensities of coherent light (ICLS) is an important part of the interference signal noise, which makes the demodulation results suffer. The improved EFAPD corrects the ICLS and fringe contrast quantity of the interference signal by an ellipse-fitting algorithm, and then calculates the ICLS based on the structure of pull-cone 3 × 3 coupler, so as to remove it in the algorithm. Experimental results show that the noise of the improved EFAPD system is significantly reduced compared with that of the original EFAPD, with a maximum reduction of 35.57 dB. The improved EFAPD makes up for the deficiency of the original EFAPD in suppressing light source intensity noise, and promotes the application and popularization of EFAPD.

Intense Lyman-alpha light source for ultra-slow muon generation

A small-momentum-width muon beam, so-called ultra-slow muon beam, can be generated by laser ionization of muonium. To realize efficient ultra-slow muon generation, the Lyman-alpha and below 360 nm coherent light are required to resonantly excite the muonium from the ground state to 2p and sequentially ionizes excited muonium to the unbound state. At the J-PARC MLF Ultra-Slow Muon beamline, we have successfully generated Lyman-alpha coherent light exceeding 10 μJ using an all-solid-state laser and high-efficiency vacuum ultraviolet light generation technologies. In this paper, we will describe the intense Lyman-alpha light source.

Pyrite (FeS2)‐decorated 1D TiO2 nanotubes in a bilayer as a sustainable photoanode for photoelectrochemical water splitting activity

AbstractHerein, FeS2@TiO2 nanotubes photocatalyst was prepared by electrochemical anodization method followed by successive ionic layer adsorption and reaction method, and then finally annealed in a tube furnace for homogenous crystallization. The surface morphology, elemental composition, optical properties, and crystalline structure of the prepared FeS2@TiO2 nanocomposite were found out by performing scanning electron microscopy, energy dispersive X‐ray spectroscopy, X‐ray diffraction, UV–Vis diffuse reflectance spectroscopy, and fluorescence spectroscopy, respectively, while bonds vibrations and various functional groups' presence were analyzed using Raman and Fourier transform infrared spectroscopy. A higher photocurrent density of 1.59 mA/cm2 at 0.3 V versus reference electrode of Ag/AgCl (1.23 V versus reversible hydrogen electrode) using 100 mW/cm2 intensive light source was shown by 15‐FeS2@TiO2 nanotubes (uniformly loaded photoanode) while donor density (ND) of 3.68 × 10−13 cm−3 as compared to pure TiO2 NTs (0.09 mA/cm2), 05‐FeS2@TiO2 NTs (0.19 mA/cm2), 10‐FeS2@TiO2 NTs (0.53 mA/cm2) and 20‐FeS2@TiO2 NTs (0.61 mA/cm2), respectively. The exceptional photoelectrochemical activity results were attributed to the homogenous integration of FeS2 that not only increase the charge separation but also, intensively interacted with the substrate (TiO2 nanotubes), which results in an excellent photoelectrochemical activity.

Optimization of novel exoscopic blue light filter during fluorescence-guided resection of Glioblastoma.

Operative guidelines and use optimization for new surgical exoscopes are not well described in the literature. In this study, we evaluated use of the ORBEYE (Olympus) surgical exoscope system during 5-ALA fluorescence-guided resection of GBMs to optimize workflow and exoscope settings. The ORBEYE exoscope system was fitted with a blue light filter for 5-ALA mediated fluorescence-guided surgery (FGS). Intraoperative images were obtained during 5-ALA FGS in 9 patients with primary or recurrent GBM. The exoscope was set up at constant, increasing focal distances from the target tissue, and light source intensity varied. High-resolution 4K images were captured and analyzed. Comparisons of fluorescence to background were then generated for use optimization. Light intensity did not significantly influence tumor fluorescence (P = 0.878). However, focal distance significantly impacted relative fluorescent intensity (P = 0.007). Maximum average fluorescence was seen consistently at a focal length of 220mm and a light intensity of approximately 75% maximum. Decreasing focal distance from 400mm to 220mm significantly increased visualized fluorescence (P = 0.0038). The ORBEYE surgical exoscope system with blue light filter is a powerful imaging tool for 5-ALA FGS in GBM. The ORBEYE blue filter performs optimally at shorter focal distance with moderate light intensity. Similar to microscope systems, decreasing focal distance significantly influences visualized fluorescence.

The Effect of Inverse Square Law of Light on ENF in Videos Exposed by Rolling Shutter

Due to a constant imbalance between demand and supply of power, ENF (Electric Network Frequency) fluctuates around a nominal value of 50 or 60 Hz. These variations in ENF cause the luminance intensity of a mains-powered light source, having no AC/DC converter inside, also to fluctuate. As a result, a video of a scene illuminated by a mains-powered light source can be used to estimate these fluctuations. As a consequence, the ENF signal within the time period when the video was captured can be estimated. This work explores the effects of frame rate harmonics that emerge when a rolling shutter based approach is used for ENF estimation from videos captured using CMOS cameras. These harmonics are a problem, especially for videos whose frame rate is a divisor of the nominal ENF because the frame rate harmonics and the ENF harmonics overlap. It is discovered that a key reason for the presence of the harmonics is the inverse square law of light that results in some repeating patterns of luminance variation across frames. This paper presents an analysis of the effect of the inverse square law of light on ENF estimation. A technique for refined ENF-related luminance signal estimation is proposed that attenuates these frame rate harmonics. This enables more accurate ENF estimates. The work also proposes an approach to estimate ENF-related luminance waveform cycles within each video frame, and a method to compute the confidence score for the estimated cycles. It provides insight into the reliability of the extracted ENF signal from a video, in the sense of its usefulness for ENF forensics, and consequently for ENF detection, which is an important precursor to ENF-based video forensics.

Multi-color luminescence and anticounterfeiting application of upconversion nanoparticle.

Multi-color luminescence materials are important in the illumination, solid-state three-dimensional display, information storage, biological labelling and anticounterfeiting fields. Herein, we designed a novel core-shell structure upconversion nanoparticle (UCNP) material (NaYF4) with lanthanide ion doping to achieve multi-color luminescence under a single NIR excitation laser. Different from the typical single-sensitizer materials, the core-shell structure utilizes Nd3+, Yb3+, Tm3+ and Er3+ ions to obtain tuning of the color and brightness. The doping of Nd3+ ions enhances the weak color (red) light source to maintain the light color balance. Benefiting from the color adjustment of the sensitizers and the change of the core-shell coating, bright-white emission and flexible color emission from red to green, cyan and blue can be achieved via the diverse doped rare earth ions in a single UCNP under continuous-wave laser excitation (980 nm). Simultaneously, the emission color of the UCNPs can change with the intensity of the excitation light source and the wavelength. The bright-white emission can be used for lighting displays, and the flexible full-color emission can be applied in the anticounterfeiting and information storage fields.

Intense and Superflat White Laser with 700-nm 3-dB Bandwidth and 1-mJ Pulse Energy Enabling Single-Shot Subpicosecond Pulse Laser Spectroscopy.

An optical spectrometer is a basic spectral instrument that probes microscopic physical and chemical properties of macroscopic objects but generally suffers from difficulty in broadband time-resolved measurement. In this work, we report the creation of ultrabroadband white-light laser with a 3-dB bandwidth covering 385 to 1,080 nm, pulse energy of 1.07 mJ, and pulse duration of several hundred femtoseconds by passing 3-mJ pulse energy, 50-fs pulse duration Ti:Sapphire pulse laser through a cascaded fused silica plate and chirped periodically poled lithium niobate crystal. We utilize this unprecedented superflat, ultrabroadband, and intense femtosecond laser light source to build a single-shot (i.e., single-pulse) subpicosecond pulse laser ultraviolet-visible-near-infrared spectrometer and successfully measure various atomic and molecular absorption spectra. The single-shot ultrafast spectrometer may open up a frontier to monitor simultaneously the ultrafast dynamics of multiple physical and chemical processes in various microscopic systems.

A tensile stage for high resolution synchrotron-based infrared microspectroscopy at MIRAS

For the study of thin films and fibres under load, a uniaxial tensile stage has been developed for synchrotron-based polarized Fourier-transform infrared (FTIR) microspectroscopy. One of the advantages compared to commercial available stages is its compact design at the sample position (<20 mm thickness) and the large field of view on the sample for transmission and reflection geometry. In addition, the stage is mounted on a base plate, which can be rotated between -15° and +193° in the sample plane, in order to rotate the sample relative to the inherent polarization of the incoming infrared light from the synchrotron light source. Preliminary in situ tensile load experiments conducted at MIRAS beamline of the ALBA synchrotron were done on 3D printed thermoplastic polyurethane (TPU) polymer thin films. The samples could be mapped in transmission geometry under tensile load achieving high spatial resolution up to 10 micros using the intense IR source of the synchrotron light. Making use of polarized synchrotron-based infrared light, it was possible to show the alignment of different vibrational bands parallel and orthogonal to the stretching direction. The v(C=O) absorbance bands decrease upon stretching using parallel polarized infrared light, while the v(C=C) bands are increasing in intensity, revealing the orientation of v(C=O) bonds orthogonal to the stretching direction during stretching. The experiments highlight the unique instrumentation capabilities of the tensile stage for in situ measurement of molecular distributions and chemical bond orientations as a function of sample displacement and applied load.

Abnormal handling mechanism and improvement measures of optical DC current transformer in smart grid environment.

An optical DC current transformer anomaly handling mechanism is proposed to address the problem that the conventional DC current transformer anomaly handling mechanism cannot compensate for the defect of capacitor anomaly blocking. First, the implementation principle, modulation loop, demodulation method and its anomaly warning mechanism of the sine-wave modulated all-fibre-optic current transformer (FOCT) are investigated, and the effects of light source intensity and modulation voltage on current decoding are explained. The modulation loop is then simulated and modelled and a FOCT anomaly handling mechanism is proposed based on the Bessel function with real-time dynamic current compensation for small changes in modulation depth. Finally, an integrated dynamic test system for DC current transformers and DC protection is designed, and the actual system operation and fault model is established using the RTDS simulation system. The experiments demonstrate that the proposed FOCT anomaly handling and improvement measures can effectively improve the transient performance of FOCT, and at the same time provide a complete set of testing means for the engineering application and later upgrade and replacement of FOCT.

Research on the Characteristics of Light Sources in Machine Vision

A machine vision system as eyes, through image taking device will get signal converted into image signal, and then through computer processing, get the useful information for subsequent research. In the machine vision system, the stand or fall of lighting light source directly affects the system input. A good lighting solution can greatly reduce the later image processing of the computing workload, and can also reduce the cost of the system to a certain extent, so for machine vision system, the light source properties research is particularly important. Light source characteristics research mainly around the type of light source, light source, the intensity of the light source, the number of the layout of the light source and the color of the light source study of five aspects. These five factors will directly affect the lighting effect is good or bad, or even to a certain extent determines the success or failure of a complete set of machine vision system. Combine five factors analysis, find a lighting effect is the best plan combination, light source characteristics research of machine vision system is the key. In this paper, it chooses the best lighting scheme for the school logo box, use the control variable method to carry out research, respectively find the best light source type, quantity, intensity, layout and color, and then combine a set of best lighting scheme. In the lighting scheme studied in this paper, the best combination of lighting scheme is to use two red LED bulbs with 7W power to illuminate in the forward lighting position.

Innovative Contactless Palmprint Recognition System Based on Dual-Camera Alignment

Recently, contactless bimodal palmprint recognition technology has attracted increased attention due to the COVID-19 pandemic. Many dual-camera-based sensors have been proposed to capture palm vein and palmprint images synchronously. However, translations between captured palmprint and palm vein images differ depending on the distance between the hand and the sensors. To address this issue, we designed a low-cost method to align the bimodal palm regions for current dual-camera systems. In this study, we first implemented a contactless palm image acquisition device with a dual-camera module and a single-point time of flight (TOF) ranging sensor. Using this device, we collected a dataset named DCPD under different distances and light source intensities from 271 different palms. Then, a bimodal palm image alignment method is proposed based on the imaging and ranging models. After the system model is calibrated, the translation between the visible light and infrared light palm regions can be estimated quickly based on the palm distance. Finally, we designed a convolutional neural network (CNN) to effectively extract the fine- and coarse-grained palm features. Compared to widely used existing methods, the proposed networks achieved the lowest equal error rate (EER) on the Tongji, IITD, and DCPD datasets, and the average time cost of the system to perform one-time identification is approximately 0.15 s. The experimental results indicate that the proposed methods achieved high efficiency and comparable accuracy. In addition, the system’s EER and rank-1 on the DCPD dataset were 0.304% and 98.66%, respectively.

YOLOv4-Driven Appearance Grading Filing Mechanism: Toward a High-Accuracy Tomato Grading Model through a Deep-Learning Framework

In traditional agricultural quality control, agricultural products are screened manually and then packaged and transported. However, long-term fruit storage is challenging in tropical climates, especially in the case of cherry tomatoes. Cherry tomatoes that appear rotten must be immediately discarded while grading; otherwise, other neighboring cherry tomatoes could rot. An insufficient agricultural workforce is one of the reasons for an increasing number of rotten tomatoes. The development of smart-technology agriculture has become a primary trend. This study proposed a You Only Look Once version 4 (YOLOv4)-driven appearance grading filing mechanism to grade cherry tomatoes. Images of different cherry-tomato appearance grades and different light sources were used as training sets, and the cherry tomatoes were divided into four categories according to appearance (perfect (pedicled head), good (not pedicled head), defective, and discardable). The AI server ran the YOLOv4 deep-learning framework for deep image learning training. Each dataset group was calculated by considering 100 of the four categories as the difference, and the total numbers of images were 400, 800, 1200, 1600, and 2000. Each dataset group was split into an 80% training set, 10% verification set, and 10% test set to overcome the identification complexity of different appearances and light source intensities. The experimental results revealed that models using 400–2000 images were approximately 99.9% accurate. Thus, we propose a new mechanism for rapidly grading agricultural products.

Observation of Rabi dynamics with a short-wavelength free-electron laser

Rabi oscillations are periodic modulations of populations in two-level systems interacting with a time-varying field1. They are ubiquitous in physics with applications in different areas such as photonics2, nano-electronics3, electron microscopy4 and quantum information5. While the theory developed by Rabi was intended for fermions in gyrating magnetic fields, Autler and Townes realized that it could also be used to describe coherent light–matter interactions within the rotating-wave approximation6. Although intense nanometre-wavelength light sources have been available for more than a decade7–9, Rabi dynamics at such short wavelengths has not been directly observed. Here we show that femtosecond extreme-ultraviolet pulses from a seeded free-electron laser10 can drive Rabi dynamics between the ground state and an excited state in helium atoms. The measured photoelectron signal reveals an Autler–Townes doublet and an avoided crossing, phenomena that are both fundamental to coherent atom–field interactions11. Using an analytical model derived from perturbation theory on top of the Rabi model, we find that the ultrafast build-up of the doublet structure carries the signature of a quantum interference effect between resonant and non-resonant photoionization pathways. Given the recent availability of intense attosecond12 and few-femtosecond13 extreme-ultraviolet pulses, our results unfold opportunities to carry out ultrafast manipulation of coherent processes at short wavelengths using free-electron lasers.