Laser Intensity Parameters Research Articles

Burning Mouth Syndrome Treated with Low-Level Laser and Clonazepam: A Randomized, Single-Blind Clinical Trial.

Burning mouth syndrome (BMS) is a chronic pain disorder characterized by intraoral burning or dysaesthetic sensation, with the absence of any identifiable lesions. Numerous treatments for BMS have been investigated, though without conclusive results. An analysis was conducted of the efficacy of treatment with a low-level diode laser and clonazepam in patients with BMS, and a study was carried out on the levels of different salivary biomarkers before and after treatment. A randomized, single-blind clinical trial was carried out involving 89 patients divided into the following groups: group 1 (laser, The Helbo® Theralite Laser 3D Pocket Probe + clonazepam) (n = 20), group 2 (sham laser placebo) (n = 19), group 3 (laser) (n = 21) and group 4 (clonazepam) (n = 18). Symptom intensity was scored based on a visual analogue scale (VAS). Sialometry was performed before and after treatment, and the Xerostomia Inventory, Oral Health Impact Profile-14 (OHIP-14) and Mini-Nutritional Assessment (MNA) questionnaires were administered. The following markers were measured in saliva samples: interleukins (IL2, IL4, IL5, IL6, IL7, IL8, IL1β, IL10, IL12, IL13, IL17, IL21 and IL23), proteins (MIP-3α, MIP-1α and MIP-1β), GM-CSF, interferon gamma (IFNγ), interferon-inducible T-cell alpha chemoattractant (ITAC), fractalkine and tumor necrosis factor α (TNFα). A significant decrease in the VAS scores was observed after treatment in group 1 (laser + clonazepam) (p = 0.029) and group 3 (laser) (p = 0.005). In turn, group 3 (laser) showed a decrease in the salivary concentration of fractalkine (p = 0.025); interleukins IL12 (p = 0.048), IL17 (p = 0.020), IL21 (p = 0.008), IL7 (p = 0.001) and IL8 (p = 0.007); proteins MIP1α (p = 0.048) and MIP1β (p = 0.047); and TNFα (p = 0.047) versus baseline. Following treatment, group 1 (laser + clonazepam) showed significant differences in IL21 (p = 0.045) and IL7 (p = 0.009) versus baseline, while group 4 (clonazepam) showed significant differences in IL13 (p = 0.036), IL2 (p = 0.020) and IL4 (p = 0.001). No significant differences were recorded in group 2 (sham laser placebo). The low-level diode laser is a good treatment option in BMS, resulting in a decrease in patient symptoms and in salivary biomarkers. However, standardization of the intervention protocols and laser intensity parameters is needed in order to draw more firm conclusions.

3D Printing of Personalised Carvedilol Tablets Using Selective Laser Sintering.

Selective laser sintering (SLS) has drawn attention for the fabrication of three-dimensional oral dosage forms due to the plurality of drug formulations that can be processed. The aim of this work was to employ SLS with a CO2 laser for the manufacturing of carvedilol personalised dosage forms of various strengths. Carvedilol (CVD) and vinylpyrrolidone-vinyl acetate copolymer (Kollidon VA64) blends of various ratios were sintered to produce CVD tablets of 3.125, 6.25, and 12.5 mg. The tuning of the SLS processing laser intensity parameter improved printability and impacted the tablet hardness, friability, CVD dissolution rate, and the total amount of drug released. Physicochemical characterization showed the presence of CVD in the amorphous state. X-ray micro-CT analysis demonstrated that the applied CO2 intensity affected the total tablet porosity, which was reduced with increased laser intensity. The study demonstrated that SLS is a suitable technology for the development of personalised medicines that meet the required specifications and patient needs.

High-order harmonic generation in a strongly overdriven regime

High-order harmonic generation (HHG) normally requires a careful adjustment of the driving laser intensity (typically ${10}^{14}--{10}^{15}$ W/${\mathrm{cm}}^{2}$) and gas medium parameters to obtain a microscopically and macroscopically optimized output. In contrast to conventional wisdom, we present experimental results indicating efficient HHG in all rare gases, using a high-density medium and a driving laser intensity of around ${10}^{16}$ W/${\mathrm{cm}}^{2}$. The experimental results are corroborated by theoretical simulations, which indicate that ionization-induced self-phase modulation and plasma defocusing self-regulate the driver laser intensity to a level that allows efficient HHG. A tenfold broadening of the driving near-infrared spectrum is observed, which results in the generation of continuous spectra from 18 to 140 eV in spite of using 50-fs-long driving pulses. The presented scheme represents a simple and versatile concept for the generation of extreme-ultraviolet and soft-x-ray continua, which could be used for transient absorption and reflection spectroscopy.

Comparison of different laser pulse envelopes with frequency chirp for efficient electron acceleration in vacuum

In the present manuscript, we have investigated the effect of chirped laser pulse envelope to study electron acceleration in vacuum. For this purpose, we have chosen two different pulse shapes, i.e trapezoidal pulse envelope and Sin4 pulse envelope. Electron has been injected axially to the front of the tested envelopes. In all calculations, the front end of each pulse is presumed to have caught up with the electron at t = 0 at the coordinate origin. The relativistic Newton-Lorentz equations of motion of electron in the field of the laser pulse have been analytically and numerically solved. By optimizing laser and frequency chirp parameters, the energy gain of the order of GeV is obtained, and it has been noticed that under the similar range of phases (0 to 2π) and laser intensity parameter (a0 = 3), trapezoidal pulse envelope shows better result than Sin4 pulse envelope on effective electron acceleration in vacuum.

Rise and fall of laser-intensity effects in spectrally resolved Compton process

The laser intensity dependence of nonlinear Compton scattering is discussed in some detail. For sufficiently hard photons with energy ω′, the spectrally resolved differential cross section dσ/dω′| ω′=const, rises from small toward larger laser intensity parameter ξ, reaches a maximum, and falls toward the asymptotic strong-field region. Such a rise and fall of a differential observable is to be contrasted with the monotonously increasing laser intensity dependence of the total probability, which is governed by the soft spectral part. We combine that hard-photon yield from Compton scattering with the seeded Breit–Wheeler pair production in a folding model and obtain a rapidly increasing e + e − pair number at ξ ≲ 4. Laser bandwidth effects are quantified in the weak-field limit of the related trident pair production.

Impact of laser polarization on q -exponential photon tails in nonlinear Compton scattering

Non-linear Compton scattering of ultra-relativistic electrons traversing high-intensity laser pulses generates also hard photons. These photon high-energy tails are considered for parameters in reach at the forthcoming experiments LUXE and E-320. We consider the invariant differential cross sections $d \sigma / du$ between the IR and UV regions and analyze the impact of the laser polarization and find q-deformed exponential shapes. (The variable $u$ is the light-cone momentum-transfer from initial electron to final photon.) Optical laser pulses of various durations are compared with the monochromatic laser beam model which uncovers the laser intensity parameter in the range $\xi = 1 \cdots 10$. Some supplementary information is provided for the azimuthal final-electron/photon distributions and the photon energy-differential cross sections.

Terahertz radiation generation from short-pulse laser interaction with electron-hole plasmas

In semiconductors, electrons and their corresponding holes exist as free carriers that are created in pairs in inter-band transitions. At very high carrier densities, the carrier-carrier collisions dominate over carrier-lattice collisions and these carriers begin to behave collectively to form a plasma. In this study, we present phase-matched terahertz (THz) radiation generation from laser interaction with electron-hole plasmas. Two collinear laser pulses of finite spot size propagate in an electron-hole plasma to generate THz radiation. The lasers beat and exert a ponderomotive force on electrons and holes. The carriers oscillate with oscillatory velocity at the laser beat frequency. The laser beat wave interacts with the plasma density perturbation and produces a nonlinear transverse current with nonzero curl. This nonlinear current drives coherent THz radiation. Spacial density modulation of hole density is considered to satisfy the phase-matching condition for resonant interaction. The systematic analysis of this mechanism shows an efficient and tunable source of THz radiation, which varies with various parameters such as the density modulation, laser intensity and other laser parameters.

Assessing the Performance of ICESat-2/ATLAS Multi-Channel Photon Data for Estimating Ground Topography in Forested Terrain

As a continuation of Ice, Cloud, and Land Elevation Satellite-1 (ICESat-1), the ICESat-2/Advanced Topographic Laser Altimeter System (ATLAS) employs a micro-pulse multi-beam photon counting approach to produce photon data for measuring global terrain. Few studies have assessed the accuracy of different ATLAS channels in retrieving ground topography in forested terrain. This study aims to assess the accuracy of measuring ground topography in forested terrain using different ATLAS channels and the correlation between laser intensity parameters, laser pointing angle parameters, and elevation error. The accuracy of ground topography measured by the ATLAS footprints is evaluated by comparing the derived Digital Terrain Model (DTM) from the ATL03 (Global Geolocated Photon Data) and ATL08 (Land and Vegetation Height) products with that from the airborne Light Detection And Ranging (LiDAR). Results show that the ATLAS product performed well in the study area at all laser intensities and laser pointing angles, and correlations were found between the ATLAS DTM and airborne LiDAR DTM (coefficient of determination––R2 = 1.00, root mean squared error––RMSE = 0.75 m). Considering different laser intensities, there is a significant correlation between the tx_pulse_energy parameter and elevation error. With different laser pointing angles, there is no significant correlation between the tx_pulse_skew_est, tx_pulse_width_lower, tx_pulse_width_upper parameters and the elevation error.

Electron acceleration by cosh-Gaussian laser beam in the presence of axial magnetic field

The present study was conducted to determine electron acceleration by cosh-Gaussian laser beam (CGLB) and axial magnetic field. CGLB possesses higher power and has ability to focus earlier than the Gaussian beam. Nonlinear differential equations are derived for CGLB for energy and velocity. The dependence of electron energy gained for different values of laser intensity parameter ‘ao’ has been graphically plotted. It is examined that both laser and axial magnetic field significantly affects the electron energy.

Electron Injection for Direct Acceleration by A Gaussian Laser Field Under the Influence of Azimuth Magnetic Field

Electron injection for direct acceleration by a circularly polarized Gaussian laser field under the influence of azimuth magnetic field is studied. The electron energy gain, \(\gamma\) versus electron's injection angle \(\delta\) at different values laser intensity parameters and laser spot size shows the energy enhancement on increasing the parameters. For a small change in angle of injection then there appears a significant change in electron energy gain also for the variation of energy gain and magnetic field energy gain increases when value of \(\delta\) $ is 8.5, 8.0, 13.5 and 13, respectively. It is observed that \(\delta\) should be small and optimized for appropriate momentum to maximize the electron energy gain due to a relativistic longitudinal momentum and the variation of the scattering angle of the electron \(\theta\) with respect to electron's injection angle \(\delta\) in the presence of magnetic field shows a relatively lower scattering is observed with optimized values of injection angle in the presence of magnetic field.

Brilliant keV–MeV x-ray emission through weakly unbalanced quasi-static electric and magnetic fields

We proposed a new method to yield brilliant keV–MeV x-ray emission, inspired by Cao et al (2010 Phys. Plasma 17 043103). When a short femtosecond pulse is coupling into a microwire array target, due to the weakly unbalanced quasi-static electric and magnetic fields, the energetic electrons accelerated by the laser will emit a large amount of photons per shot, comparable to that from the laser-wake betatron radiation. It was found that the critical energy of the photons and the total photon yields are strongly dependent on the laser intensity and structure parameters of the target. The peak spectral brightness of the radiation in our scheme was estimated to be 4 × 1019 at the laser intensity 3 × 1020 W cm−2. More important, the photon energies can be extended to hundreds of keV to MeV readily if electron beam accelerated by the laser is in the range of MeV to GeV.

Analytical Thomson backscattering spectra and new scaling laws in laser and magnetic fields

The analytical asymptotic expression of Thomson backscattering spectra in arbitrarily polarized laser and uniform magnetic fields is given. It is used to theoretically analyze the spectra structures and properties. The results of asymptotic expression and numerical calculations show good agreement in the large harmonic-order region. The scaling laws about laser intensity and electron initial axial momentum are obtained. Furthermore, the optimal harmonic order corresponding to the maximum radiation intensity can be found, then new scaling laws about this optimal harmonic order with laser intensity and resonance parameter are revealed.

Electron Acceleration by a Chirped Short Intense Laser Pulse in Presence of an External Axial Magnetic Field in Vacuum With Different Phase Values

We investigated electron acceleration by a chirped short intense laser pulse in presence of an external magnetic field. The retained electron energy is very high with frequency chirp on increasing the value of chirp parameter and constant value of laser intensity parameter. Also, the retained electron energy increases on increment of laser intensity parameter. A linear frequency chirp \(\omega (t ) =\omega_0 (1-\alpha t)t\) was considered, here \(\omega _0\) is the laser frequency at \(z=0\) and \(\alpha\) is the frequency chirp parameter. On increasing the chirp parameters corresponding to the magnetic field with phase then the retained electron energy become so high. Also, we study the variation of the relativistic factor gamma \((\gamma)\) and the laser intensity parameter \((a _0 )\); also the variation of the relativistic factor gamma \(( \gamma )\) and the magnetic field \((b_0)\) with different values of the phase, \(\phi=0\), \(\pi /4\) and \(\pi/2\), respectively. As the time duration is increased the energy gain increased.

Response of thermoelastic microbeam with double porosity structure due to pulsed laser heating

Abstract The present investigation is concerned with vibration phenomenon of a homogeneous, isotropic thermoelastic microbeam with double porosity (TDP) structure induced by pulsed laser heating, in the context of Lord– Shulman theory of thermoelasticity with one relaxation time. Laplace transform technique has been applied to obtain the expressions for lateral deflection, axial stress, axial displacement, volume fraction field, and temperature distribution. The resulting quantities are recovered in the physical domain by a numerical inversion technique. Variations of axial displacement, axial stress, lateral deflection, volume fraction field, and temperature distribution with axial distance are depicted graphically to show the effect of porosity and laser intensity parameter. Some particular cases are also deduced.

Turning point temperature of self-focusing at laser–plasma interaction with weak relativistic-ponderomotive nonlinearity: effect of light absorption

In this communication, we have examined the influence of light absorption on turning point temperature of self-focusing in the interaction of Gaussian laser beam in plasma. The dielectric function of plasma introduced herein is under weak relativistic and ponderomotive regime. Differential equation for beam-width parameter has been established by using parabolic equation approach under WKB and paraxial approximations. Numerical analysis shows that light absorption plays an important role on turning point temperature of self-focusing under relativistic and ponderomotive regime. It is also found that variation of normalized plasma density, normalized laser intensity parameter and plasma dielectric function with dimensionless distance of propagation gives reasonably interesting results.

The effect of pulsed laser radiation on a thermoviscoelastic semi-infinite solid under two-temperature theory

AbstractThe purpose of this paper is to study the thermoviscoelastic interactions in a homogeneous, isotropic semi-infinite solid under two-temperature theory with heat source. The Kelvin-Voigt model of linear viscoelasticity which describes the viscoelastic nature of the material is used. The bounding plane surface of the medium is subjected to a non-Gaussian laser pulse. The generalized thermoelasticity theory with dual phase lags model is used to solve this problem. Laplace transform technique is used to obtain the general solution for a suitable set of boundary conditions. Some comparisons have been shown in figures to estimate the effects of the phase lags, viscosity, temperature discrepancy, laser-pulse and the laser intensity parameters on all the studied fields. A comparison was also made with the results obtained in the case of one temperature thermoelasticity theory.

Laser Pulse Heating of a Semi-Infinite Solid Based on a Two-Temperature Theory with Temperature Dependence

A two-temperature theory of the generalized thermoelasticity is proposed to study the effect of temperature dependence on a semi-infinite medium. The surface of bounding plane of the medium is under a non-Gaussian laser pulse. Lamé’s coefficients and the thermal conductivity are supposed as temperature-dependent linear functions. The dual-phase-lags (DPLs) theory of the generalized thermoelasticity is applied to treat with the present problem. The analytical solution for different boundary conditions may be deduced by using Laplace transform technique. The numerical results are obtained by using the inverse of Laplace transforms. The comparisons have been graphically presented to show the effects of PLs, temperature discrepancy, laser pulse and laser intensity parameters on field quantities. Also, the results are compared with those obtained from the mechanical and thermal material properties with the temperature independence.

Vibration analysis of thermoelastic double porous microbeam subjected to laser pulse

ABSTRACTThe present work deals with vibration phenomenon of a homogeneous, isotropic thermoelastic double porous microbeam induced by laser pulse heating, in context of Lord–Shulman theory of thermoelasticity with one relaxation time. Laplace transform technique has been used to obtain the expressions for lateral deflection, axial stress, axial displacement, volume fraction field and temperature distribution. The resulting quantities are obtained in the physical domain by applying a numerical inversion technique. Variations of axial displacement, axial stress, lateral deflection, volume fraction field and temperature distribution with axial distance are depicted graphically to show the effects of porosity and laser intensity parameter. Some particular cases are also deduced.

A quantitative approach for Cd, Cu, Fe and Mn through laser ablation imaging for evaluating the translocation and accumulation of metals in sunflower seeds

The uptake and accumulation of Cd in sunflower seeds represents an important pathway for imputing potentially toxic metals into human and animal food. In this way, bioimaging of Cd and micronutrients (Cu, Fe and Mn) in the seeds of sunflower grown in soil contaminated with Cd are performed. For this task, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is used in quantitative approach, considering four groups: precursor, control, Cd-low (50mg) and Cd-high (700mg). For attaining our proposals, ICP-MS (nebulizer and auxiliary flow rates and radiofrequency power) and LA (laser intensity, frequency and spot size) parameters were optimized, and the analytical signal improved to 197%, 217%, 232%, and 283%, for 57Fe, 112Cd, 55Mn and 63Cu, respectively. The accuracy of proposed method using LA-ICP-MS is evaluated comparing the CRM results (Tomato leaves, NIST SRM 1573a). No difference is found at 95% confidence level. Regarding Cd accumulation in sunflower seeds, the results indicated that cadmium is translocated to seeds, and the cotyledons showed the highest concentration (Cd-high group), ranging from 10 to 20µgg−1. Considering both total concentration and the distribution in the seeds, Cd uptake is responsible to the homeostasis misbalance of micronutrients, which play an essential role in the sunflower metabolism. Such results highlight the importance of bioimaging evaluation, in the translocation and accumulation of metals, contributing to expand the information available of this culture.

Scale invariance and scaling law of Thomson backscatter spectra of electrons moving in the resonance regime in combined laser and magnetic fields

The Thomson scattering spectra by an electron moving in the laser-magnetic resonance acceleration regime are computed numerically and analytically. The dependence of fundamental frequency on the laser intensity and magnetic resonance parameter is examined carefully. By calculating the emission of a single electron in a circularly polarized plane-wave laser field and constant external magnetic field, the scale invariance of the radiation spectra is evident in terms of harmonic orders. The scaling law of backscattered spectra are exhibited remarkably for the laser intensity as well for the initial axial momentum of the electron when the cyclotron frequency of the electron approaches the laser frequency. The results indicate that the magnetic resonance parameter plays an important role on the strength of emission. And the rich features of scattering spectra found may be applicable to the radiation source tunability.