Intense Laser Light Research Articles

Flange-type liquid-level sensor based on laser light reflection

We report a liquid-level sensor composed of a laser, prism, and photodiode array. The sensor does not require components, such as a sensor head, inside the container that stores liquid. The sensor detects the liquid level based on the difference between the intensities of laser light reflected at the liquid/glass and air/glass interfaces. As the detected liquid level shows a shift from the correct liquid level owing to surface tension and the broadening of the laser light, we correct the shift through calculations. The sensor can be attached to a flange-type glass viewport, providing compatibility with broad-ranging containers for industrial use. The sensor can accurately detect the liquid level with a maximum error of 0.3875 ​mm. We demonstrate the implementation and operation of the liquid-level sensor using a wireless system comprising a sensor head and wireless voltmeter. The reported sensor allows accurate measurement of the liquid level in a tank inside which foreign objects such as sensor heads cannot be installed.

A folded π-system with supramolecularly oriented dipoles: single-component piezoelectric relaxor with NLO activity.

Organic molecules with an active dipole moment have a natural propensity to align in an antiparallel fashion in the solid state, resulting in zero macroscopic polarization. This primary limitation makes the material unresponsive to switching with electric fields, mechanical forces, and to intense laser light. A single-component organic material that bestows macroscopic dipole-driven electro-mechanical and optical functions, e.g., piezoelectric, ferroelectric and nonlinear optical (NLO) activity, is unprecedented due to the design challenges imparted by crystal symmetry and dipole orientations. Herein we report a crystalline organic material that self-assembles with a polar order (P 1), and is endowed with a high piezoelectric coefficient (d 33-47 pm V-1), as well as ferroelectric and Debye-type relaxor properties. In addition, it shows second harmonic generation (SHG) activity, which is more than five times that of the benchmark potassium dihydrogen phosphate. Piezoelectric force microscopy (PFM) images validated electro-mechanical deformations. Piezoresponse force spectroscopy (PFS) studies confirmed a signature butterfly-like amplitude and a phase loop. To the best of our knowledge, this is the first report of a folded supramolecular π-system that manifests unidirectionally oriented dipoles and exhibits piezoelectricity, ferroelectricity, and has excellent ability to generate second harmonic light. These findings can herald new design possibilities based on folded architectures to explore opto-, electro- and mechano-responsive multifaceted functions.

Optical Nonlinearity and Optical Limiting Performance of Disperse Blue 1/Dioxane via Z-Scan Technique

The absorption performance and evolution of the organic dye disperse blue 1 (DB1) in dioxane at different concentrations was investigated. The nonlinear absorption coefficient has been measured through the open aperture Z-scan technique, whose values increased exponentially from 0.997×10-3 to 11.7×10-3 cm/W as the dye concentration increased from 3.7×10-5 to 74.6×10-5 M. Also, DB1 optical power limiting characteristics appeared at high laser light intensities, whereby very dilute solution of the order of ~10-4 M was sufficient to limit the transmitted ‎power of the incident laser light by ~90%.

The Potential Impact of Laser Pointers on Aviation Safety

Introduction: Although aviation is considered the safest mode of transportation, the annual number of pilots blinded by laser light cannot be understated. An analysis of the available statistics indicates that it is a widespread phenomenon. The stories told by the pilots show the consequences of these incidents, ranging from temporary sight loss to months of vision problems. The article also describes the current penalties for dazzling a pilot by laser light. Moreover, limited research has been conducted on the intensity of laser light of different wavelengths passing through the fairing and through standard glasses used by pilots. Understanding the effects of laser glare on pilots can help reduce adverse events and improve the ability of safety managers to develop safety procedures. Correctly designed transport systems enable effective route planning and order processing. Methods: Two types of easily available laser pointers, drawn at different distances from the aircraft, were analyzed and the intensity of the transmitted light was examined. Results: The results showed that the intensity decreases with distance and that the intensity is too low to harm the eye. In addition, it should not be forgotten that the light propagates in a cone which strengthens the illumination effect in the cabin and causes pilots to lose orientation. Practical application of the findings: They enable the identification of areas around the airport where the use of lasers should be prohibited. Practical Application: The possibility of determining the transition of laser light through the windscreen of the aircraft as well as its intensity under near real-life conditions.

Utilization of Laser Turbidimeter to Measure the Concentration of Starch Suspension as a Model for Measurement of Sperm Turbidity

Introduction: Turbidimeter is a tool that serves to determine or measure the level of turbidity of water. Based on the similarity in composition between starch and sperm fluid composition, such as protein, carbohydrates, fat, iron, starch suspension was chosen as a model for measuring sperm turbidity. By using a laser turbidimeter to measure the concentration of starch suspension, it is hoped that it will provide an alternative model that is appropriate for measuring sperm turbidity in the future. Methods: The data were processed using pearson correlation analysis by looking for the relationship between starch concentration and laser light intensity. Then performed linear regression analysis by looking for the equation of the regression line. Objective: This study aims to see the effectiveness of the laser Turbidimeter to measure the level of turbidity of sperm Results: The highest laser intensity value is at a starch concentration of 20%, with an intensity value of 0.071. While the lowest laser intensity value is at a starch concentration of 80%, with an intensity value of 0.032. The cloudier the starch, the harder it is for the laser light to penetrate it, resulting in a lower intensity value. The results also show that the results of the pearson correlation statistic test are -0.901 and with a significance value of 0.006, or it can be interpreted as less than 0.05. Conclusion: With these results it can be explained that there is a relationship between starch concentration and laser light intensity. However, this study also has many shortcomings in terms of research and analysis methods. We hope that there will be further research that can be better in terms of research methods and analysis so as to produce better results

Adjacent Frame Difference with Dynamic Threshold Method in Underwater Flash Imaging LiDAR

During the underwater LiDAR imaging process, the images achieved by the conventional constant threshold adjacent frame difference (AFD) method normally loses the distance information of targets. This is mainly due to the Gaussian distribution of the laser light intensity field, which leads to the inhomogeneous intensity distribution in the frame from the target acquired by intensity charge-coupled devices (ICCD). In order to overcome this issue, the novel dynamic threshold adjacent frame difference (DTAFD) method was proposed in this paper. The DTAFD method modifies the intensity threshold following the pixel intensities in the different parts of the single frame intensity image acquired by ICCD. After the detailed theoretical demonstration of the DTAFD method, with the purpose of verifying its feasibility, the self-developed range-gated flash imaging LiDAR has been employed to construct the distance images of the rectangular and circular shaped targets at different distances. The distance between the rectangular target and the LiDAR system is 25.7 m, and the circular target is 70 cm further away from the rectangular target. The full distance information of these two targets is obtained by the DTAFD method with an effectively suppressing noise and the PSNR is increased from 6.95±0.0426 dB to 7.62±0.0264 dB. The experimental results indicate that the DTAFD method efficiently solves the AFD method’s drawback on the target information loss caused by the unequal optical field distribution, which makes it more suitable for the scenarios with uneven laser distribution such as the underwater imaging environment.

Transient optically induced grating and underlying transport process in bent-core nematics

In this paper, we have applied a holographic time-of-flight technique with a nanosecond laser pulse to perform time-resolved measurements of optically induced gratings in bent-core nematics formed by a new kind of liquid crystal (LC). The effects of the electric field, laser pulse energy, temperature, and light intensity pattern on the photocharge transport process were investigated systematically. The results indicate that some peculiar features, such as high photosensitivity, relatively large mobility, and negative conductivity anisotropy, were present in the studied soft-matter system. Furthermore, a coupling between the optically induced grating and electrically induced convection was observed, which revealed a competitive state between them via the transport process. Thus, a better understanding of the carrier transport process involving photosensitivity and response time will help to tailor LC devices toward novel optical applications.

Laser induced electron drift in the magnetized quantum plasma: electron spin effects

The spin effect on accumulation of the electron density profile in the presence of an external magnetic field is investigated. In this regard, the two-fluid quantum hydrodynamic model is used to derive the interaction of intense laser light with magnetized quantum plasma. The results emphasize that the initial laser intensity and external magnetic field play significant roles in the accumulation of electron density. Moreover, the behavior of spin-up and spin-down electrons in the same spatial position is completely different. In a way, where spin-up electrons accumulate, spin-down electron density is rarefied. This fact provides a useful recipe for spintronics applications.

Onco-preventive management of oral leukoplakia lesions by topical 5-ALA-mediated photodynamic therapy: A systematic review of clinical trials

Oral leukoplakia is the most prevalent potentially malignant disorder of the oral mucosa globally and its management remains a challenge. Photodynamic therapy is a minimally invasive alternative method in the treatment of premalignant lesions; and the use of the topical 5-ALA photosensitizer plus irradiation with light emitting diode (LED) or laser light has been one of the most recommended approaches for the treatments of oral leukoplakia by photodynamic therapy. The present study was carried out to determine its clinical efficacy as a chemoprevention alternative in the different clinical forms of oral leukoplakia. An exhaustive search of scientific articles published in the last 30 years in English was carried out, using keywords with the MeSH guideline, about the use of topical 5-ALA-mediated photodynamic therapy as a photosensitizer and under low intensity laser radiation or light LED as a source of illumination, in different digital bases. The systematic review under PRISMA guidance recognized an efficacy of 88.6% for this mode of phototherapy in the management of oral leukoplakia, with a greater effect size in the homogeneous clinical forms with dysplastic changes, regardless of the type of light source. However, the evidence used in this analysis was moderate. Based on the results of the present study, we can conclude that topical 5-ALA-mediated photodynamic therapy appears to be a high-performance alternative in the oncopreventive management of oral leukoplakia lesions. However, we recommend running controlled and randomized clinical trials with homogeneous methodologies that allow us to generate a met analysis with a high level of evidence.

Simulation and Analysis of Mie-Scattering Lidar-Measuring Atmospheric Turbulence Profile.

Based on the residual turbulent scintillation theory, the Mie-scattering lidar can measure the intensity of atmospheric turbulence by detecting the light intensity scintillation index of the laser return signal. In order to evaluate and optimize the reliability of the Mie-scattering lidar system for detecting atmospheric turbulence, the appropriate parameters of the Mie-scattering lidar system are selected and optimized using the residual turbulent scintillation theory. Then, the Fourier transform method is employed to perform the numerical simulation of the phase screen of the laser light intensity transformation on the vertical transmission path of atmospheric turbulence. The phase screen simulation, low-frequency optimization, and scintillation index calculation methods are provided in detail, respectively. Based on the phase distribution of the laser beam, the scintillation index is obtained. Through the relationship between the scintillation index and the atmospheric turbulent refractive index structure constant, the atmospheric turbulence profile is inverted. The simulation results show that the atmospheric refractive index structure constant profile obtained by the iterative method is consistent with the input HV5/7 model below 6500 m, which has great guiding significance to carry out actual experiments to measure atmospheric turbulence using the Mie lidar.

Real-Time Measurement of Photodissociation with a Static Modulated Fourier Transform Spectrometer

A static modulated Fourier transform spectrometer composed of a modified Sagnac interferometer was implemented for real-time remote sensing of the spectral property changes in a solid dye. In the spectrum obtained from the implemented spectrometer, the relationship between spectral resolution and dependent factors was discussed to prevent aliasing. As a target material, a solid-state dye of rhodamine-6G was fabricated in the laboratory. When an intense pumping laser light was irradiated to a solid dye, with increasing irradiating time, photodissociation occurred due to the accumulated heat and the fluorescence intensity decreased rapidly. The fast change in the fluorescence spectrum of the solid dye due to photodissociation could be measured and analyzed in real time using a static modulated Fourier transform spectrometer implemented in the laboratory. As the pumping light source, a diode laser of 1 W output power at 530 nm, in which pulse width modulation was possible, was used. When the solid-state dye sample was irradiated with a 10 Hz pulse repetition rate and 2.5 ms pulse duration for 900 s, the fluorescence intensity decreased by 44%, the fluorescence peak wavelength shifted from 590 to 586 nm, and the maximum temperature of the irradiated portion rose up to 45 °C. Under the same conditions, when the pulse duration was increased by 4 times to 10 ms, the fluorescence intensity decreased by 65%, the fluorescence peak wavelength shifted from 590 to 580 nm, and the maximum temperature of the irradiated portion rose up to 76 °C. The spectrometer proposed in this study was effective in measuring and analyzing the spectral properties of rapidly changing materials in real time.

Superior optical Kerr effects induced by two-dimensional excitons

Materials with strong optical Kerr effects (OKEs) are crucial for a broad range of applications, such as all-optical data processing and quantum information. However, the underlying OKE mechanism is not clear in 2D materials. Here, we reveal key insights of the OKE associated with 2D excitons. An admirably succinct formalism is derived for predicting the spectra and the magnitude of the nonlinear refractive index ( n 2 ) of 2D materials. The predicted n 2 spectra are consistent with reported experimental data and exhibit pronounced excitonic resonances, which is distinctively different from bulk semiconductors. The n 2 value is predicted to be 3 × 10 − 10 cm 2 / W for a 2D layered perovskite at low temperature as 7 K, which is four orders of magnitude larger than those of bulk semiconductors. The superior OKE induced by 2D excitons would give rise to a narrow refractive index-near-zero region for intense laser light. Furthermore, we demonstrate that the 2D layered perovskite should exhibit the best OKE efficiency ( W FOM = 1.02 , T FOM = 0.14 ) at 1550 nm, meeting the material requirements for all-optical switching. Our findings deepen the understanding of the OKE of 2D semiconducting materials and pave the way for highly efficient all-optical excitonic devices.

Laser Light Durability and Nonlinear Optical Properties of Acrylate Polymer−Chalcogenide Glass−Gold Nanocomposites

Synthesis of acrylate‐based nanocomposites (NCs) for photonic applications is performed, and the influence of gold and chalcogenide glass nanoparticles (NPs) on optical parameters of NC layers at high laser intensities is investigated, whereas the polymerization, recording of optical gratings or other elements, and variations of their functional parameters in As2S3 and Au‐containing NC layers are possible at low, 532 nm laser light intensities in the absorption edge range; optical stability under high intensity illumination and threshold laser damage intensities in NIR optical transmission range are important for nonlinear optical experiments, measurements of n2. Hence, these parameters are determined and show the increase in NCs’ stability due to the addition of Au NPs, as well as increase in n2 in gold‐ and chalcogenide‐containing NCs. Thus, the functionality of such NCs and optical elements on their basis can be extended to high‐intensity applications and nonlinear optics.

High-Intensity Illuminated Annealing of Industrial SHJ Solar Cells: A Pilot Study

Here, we demonstrate the effectiveness of illuminated annealing using high-intensity light to improve the efficiency of industrial n-type silicon heterojunction (SHJ) solar cells. The application of high intensity laser light during annealing at 200 °C led to efficiency improvements as large as 0.7% <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">abs</sub> and final efficiencies as high as 24.5%. This was demonstrated on industrial SHJ solar cells from five different manufacturers, indicating the robust application of this technique. We show that the annealing process with high-intensity light leads to significant efficiency enhancements compared to previous observations using light soaking under 1-sun conditions, meaning the process can be completed in 30 s, rather than hours. The observed enhancements were related to increased V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OC</sub> and fill factor. If this approach can be tailored to time scales amenable with mass production, the associated efficiency enhancements could drive reductions in the levelized cost of electricity for SHJ solar cells, making them more competitive in the face of existing technologies.

Determination of the Detection Limit of the Detection of GMO in Food Using the Isothermal Solid-Phase Recombinase Polymerase Amplification on Microfluidic DVDs

A major drawback of the current literature on bioassay development is that these tests are not made using statistically robust methods for establishing the limit of detection. As an alternative, researchers often make use of simple detection-limit methods that are only roughly indicative of the actual detection limit. We can only assume that this is due to a practical need for simplified processes, in addition to the notion that the limit of detection theory has already been lowered to practice for bioassays. A DNA sensor based on light intensity of the scanning laser on a DVD drive with microfluidic layer etched onto the polycarbonate surface of an ordinary DVD has been previously developed for fast screening of genetically modified organisms (GMOs). The resultant calibration curve showed a sigmoidal calibration curve but was not modelled according to any of the sigmoidal models available. The objective of this study is the remodel the data using the standard 4-PL model and to determine the Limits of Detection (LOD) based on the standard method. The LOD value obtained through the 4PL modelling exercise based on a pooled standard deviation method yielded an LOD value of 62 mg/g (95% confidence interval of 17 to 158), which was quite similar to the classical three standard deviation of the blank method but was lower than the rough estimation employed in the original publication.

Modeling of spontaneous Raman scattering for detonation wave imaging

To determine if spontaneous Raman scattering can be employed to perform temperature measurements in detonation waves propagating in a stoichiometric hydrogen–air mixture, a detailed rotational–vibrational Raman scattering model for nitrogen has been implemented. The Raman scattering cross-sections were calculated over the wavelength range 337–532 nm and show reasonable agreement with experimental data. The Raman model was coupled to steady one-dimensional and unsteady two-dimensional simulations of detonation to determine under which conditions temperature measurement can be performed with an appropriate signal-to-noise ratio. Based on the calculated Raman signal and signal-to-noise ratio fields, it was concluded that, through an integrated intensity ratio of Stokes Raman scattering and anti-Stokes Raman scattering, the Raman scattering temperature measurement might be possible for large incident laser light intensity and minimized background emission noise.

Hemorheological study on erythrocyte aggregation in patients with type 2 diabetes mellitus without cholesterol and with hyper cholesterol

BackgroundThe aggregation of erythrocytes has been studied in many pathological conditions like diabetes mellitus, malaria, jaundice, hyper cholesterol, etc. Different types of erythrocyte aggregation occur in different pathological conditions. Enhanced aggregation was found in pathological conditions compared to control subjects. ObjectiveThis research aims to study the aggregation of erythrocytes in type 2 diabetes mellitus subjects without cholesterol and with cholesterol and to compare such subjects with healthy subjects. MethodsAggregation of erythrocytes was determined using an online erythrocyte aggregometer based on sequential analysis of transmitted laser light intensity after passing through the erythrocyte suspension in plasma. The aggregation mechanism was determined in terms of several aggregation parameters such as aggregation size index (ASI), aggregation sedimentation time index (ASTI), and the total number of fluctuations (TNF) of erythrocyte aggregates. These parameters were used to describe the dynamic nature of the aggregation process under gravitation quantitatively. There were a total of 45 subjects (control subjects (n = 10)), diabetes with normal cholesterol (n = 24), and diabetes with hyper cholesterol (n = 21) in this study. ResultsThe aggregation parameter total number of fluctuations (TNF) was 1634 ± 397 in normal subjects, 1539 ± 197 in group 1, and 1096 ± 180 in group 2. The aggregation sedimentation time index (ASTI, Fig. 2) indicates the time taken by the aggregates to sediment (28–32 min for normal, 24–28 min for group 1, and 16–20 min for group 2 subjects). The aggregation parameters decreased in diabetes with normal cholesterol and were significantly decreased in diabetes with hyper cholesterol compared to controls. The results show that in patients with diabetes with normal cholesterol, the aggregation of erythrocytes is increased and in patients with diabetes with hyper cholesterol, the aggregation increased significantly. ConclusionsThe significant increase in aggregation in diabetes with hypercholesterol may increase the microcirculatory complications compared to diabetes with normal cholesterol.

Hot Carrier Photocurrent through MOS Structure

Flow of photocurrent through the metal-oxide-semiconductor structure induced by the pulsed infrared CO2 laser is investigated experimentally. In the case of a perfect insulator, the photocurrent has a photocapacitive character. Its rise is based on the hot carrier phenomenon; no carrier generation is present, only redistribution of laser-heated carriers takes place at the semiconductor surface. The magnitude of this displacement current is related to the capacitance of the structure and is dependent on the rate of the laser pulse change as well as on the laser light intensity. This effect can find application in the detection of fast infrared laser pulses as well as in the development of infrared photovaractors. Operation of such devices would not require cryogenic temperatures what is usually needed by the long-wavelength infrared semiconductor technique.

Macroscopic, layered onion shell like magnetic domain structure generated in YIG films using ultrashort, megagauss magnetic pulses

Study of the formation and evolution of large scale, ordered structures is an enduring theme in science. Generation, evolution and control of large sized magnetic domains are challenging tasks, given the complex nature of competing interactions in a magnetic system. Here, we demonstrate large scale non-coplanar ordering of spins, driven by picosecond, megagauss magnetic pulses derived from a high intensity, femtosecond laser. Our studies on a specially designed yttrium iron garnet (YIG) dielectric/metal film sandwich target, show the creation of complex, large, concentric, elliptical shaped magnetic domains which resemble the layered shell structure of an onion. The largest shell has a major axis over hundreds of micrometers, in stark contrast to sub micrometer scale polygonal, striped or bubble shaped magnetic domains in magnetic materials, or large dumbbell shaped domains produced in magnetic films irradiated with accelerator based relativistic electron beams. Micromagnetic simulations show that the giant magnetic field pulses create ultrafast terahertz (THz) spin waves and a snapshot of these fast-propagating spin waves is stored as the layered onion shell shaped domains in the YIG film. Typically, information transport via spin waves in magnonic devices occurs in the gigahertz regime, where devices are susceptible to thermal disturbances at room temperature. Our intense laser light pulse—YIG sandwich target combination, paves the way for room temperature table-top THz spin wave devices, operating just above or in the range of the thermal noise floor. This dissipation-less device offers ultrafast control of spin information over distances of few hundreds of microns.

Hirshfeld surface analysis, enrichment ratio, energy frameworks and third-order nonlinear optical studies of a hydrazone derivative for optical limiting applications

Organic materials with good third-order nonlinear optical (NLO) properties are used in optoelectronics for protecting human eyes and sensors from high intensity laser light. In this regard, herein we report the synthesis, structural analysis, and third-order NLO properties of an organic molecule N'-[(E)-(4-fluorophenyl)methylidene]biphenyl-4-carbohydrazide (FMBC) containing hydrazone moiety. The formation of the synthesized molecule is confirmed by identifying the functional groups through FTIR spectral analysis. The material possesses good thermal stability before the melting point of 242.5∘C and transparent in the entire visible region of the EM spectrum. The photoluminescence study revealed the blue light-emitting property of FMBC. The crystal structure is stabilized by N-H···O, C-H···O, and C-H···F hydrogen bond interactions. The interconnects in the crystal packing were envisioned quantitatively using Hirshfeld surfaces (HS) by 2D fingerprint plots. The main contribution to the HS comes mainly from C-H, H-H, and O-H interconnects which cover about 80 % of the total HS surface. The enrichment ratios show that the favorable contacts accountable for the crystal packing are C···H, N···H, O···H, and F···H. The breakdown of the interaction energies obtained for various molecular pairs shows the nature and strength of the interactions. The calculation of 3D energy frameworks suggests that contacts formed in the structure are largely due to the dispersion force followed by the electrostatic potential. Third-order NLO coefficients were extracted under the continuous wave (CW) regime using z -scan technique. The material is an excellent optical limiter with a threshold value of 3.42 kJ/cm2. [Display omitted]