He-Ne Research Articles

Holographic Mixed Reality Ultra-High-Definition Traffic Signs to Increase Safety and Inclusivity in Transportation

Current 2D windshield head-up displays can lead to driver distractions due to a shift of gaze from the road towards a small area of the windshield. Customizable mixed reality real-time head-up displays can increase safety in transportation due to the holographic road obstacles being aligned with the road scene. Based on accelerated parallel processing algorithms, a 4K spatial light modulator, virtual Gabor lenses and a He-Ne laser, 3D holographic road signs appear within 1.15 seconds in the driver’s gaze on the road.

Simulation and Characterization of Optical Cavity for Iodine Stabilized Helium Neon Laser

Simulation and Characterization of Optical Cavity for Iodine Stabilized Helium Neon Laser

Influence of Laser Irradiation on the Mechanism of Viscous Flow of Aqueous Sodium Chloride Solution

The effect of 632.8-nm radiation of a helium–neon laser on the viscosity of an aqueous sodium chloride solution has been studied. It has been shown that irradiation changes the nature and numerical values of the concentration dependence of viscosity. The concentration dependences of the viscous-flow activation energy for unirradiated and irradiated aqueous sodium chloride solutions have been determined. The influence of irradiation on the parameters of the power-law dependence of the solution viscosity on concentration has been analyzed, and the temperature dependences of these parameters have been determined. It has been concluded that laser irradiation alters the structural organization of the aqueous system and reduces

Assessment the effect of He-Ne laser treatment of Balanites aegyptiaca seeds on the amelioration of active constituents, antioxidant capacity, and anticancer impact in vitro

Background and objective Cancer is still a major health problem worldwide, with an estimated 18.1 million new cases in 2018, and it is expected to increase by 75% by 2030. Chemotherapeutic drugs have disadvantages such as toxicity to noncancerous tissues, drug resistance, and recurrence of cancer. Medicinal plants with their active components have great potential as an important source for novel drug discovery owing to their availability, efficiency, and safety. Searching for new strategies to obtain new drugs with higher efficiency and more safety represents an urgent need. Laser light treatment for seeds is known to improve germination, plant growth, and bioactive substance. The goal of this study was to investigate the effect of laser irradiation on improvement of the phytochemicals compounds and biological activities of Balanites aegyptiaca seeds.Materials and methods The effect of laser pretreatment was investigated at different powers, that is, 25, 50, 100, and 200 mW, with two-time intervals for each power (2 and 4 min), on B. aegyptiaca seeds to enhance the germination and antioxidant activity of the methanolic extracts of their dry plant material through different assays and select the most powerful laser pretreatment extract to evaluate the anticarcinogenic activity on different cell lines.Results and conclusion The results bring to light that the most efficient laser treatment for seeds of B. aegyptiaca was at 200 mW/4 min, which induces the highest yield percentage, total phenolic and flavonoid contents, metal chelating, reducing power, as well as free diphenylpicrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activities. Based on these outcomes, the antiproliferative screening assay of the methanolic extracts for the shoots (S) and roots (R) dry plant material of B. aegyptiaca after helium-neon laser treatment at 200 mW for 4 min compared with control was performed on a panel of three cancer cell lines (HepG2, HCT116, and MCF-7) using the sulphorhodamine-B assay, and cytotoxicity was determined using normal BHK fibroblast cell line. Obtained results indicated that these extracts should be regarded as potential anticarcinogenic resources against the HepG2 cell line, displayed moderate activity against MCF-7 and HCT116 cell lines, and exhibited no activity against the growth of the normal BHK cell line. Furthermore, a comparison between these laser-treated extracts, and their mixtures against their control extracts and their mixtures, using the doxorubicin as the reference drug on the HepG2 cell line was in favor of the laser-treated roots and shoots extracts, respectively.

Influence of gaseous laser in continuous-wave and pulse regimes on biomaterial characteristics

Aromatic plants and laser beam wavelength in the red range of visible spectra (623.8 nm), most commonly used for treating plant species, were selected. As there is not much information in the references, it is necessary to set a scale with qualitative and partially quantitative evaluations of the results. Specimens of thyme seed (Thymus vulgaris) were selected as aromatic plants for studying the effect of low-power lasers on plant development, and continuous He-Ne laser, with irradiation times in the range of minutes.

Characterization of the He-Ne laser beam with the Michelson interpherometer and tracker program

En este trabajo de investigación se reporta la caracterización de un láser de He-Ne usando un interferómetro de Michelson y el programa tracker, donde también fueron analizados los fundamentos teóricos y el funcionamiento del láser gaseoso y del interferómetro. Fueron encontrados valores para la longitud de onda usando el interferómetro por dos métodos, con una medición manual y con una técnica de análisis del video de la medición con el programa tracker, encontrándose errores relativos menores al 1 % respecto a valor de referencia de 632,8 nm. Con un método simple asistido por el programa tracker fue medida la longitud de coherencia o componente temporal de la coherencia, para la cual no se encontró un valor de referencia con este método para su comparación. Para el ensanchamiento del haz, con mediciones del diámetro del haz a diferentes distancias se encontró un valor de ángulo promedio mayor que el del valor teórico calculado. Los resultados de las mediciones muestran el estado de funcionamiento relativamente bueno del láser antiguo, de más de 50 años de uso en las prácticas docentes de la carrera de Física.

Lock-in range in a semiconductor ring laser gyroscope.

A locking range in a semiconductor ring laser (SRL) is theoretically analyzed. The simplified model accounting for the specific features of a SRL uses the carrier diffusion and the linewidth enhancement factor. For stabilization of the steady-state bidirectional lasing, we introduce in this model an active feedback loop that creates the intracavity losses proportional to the intensity difference between the counterpropagating waves. Frequency locking of the counterpropagating waves in the region of stability of steady-state bidirectional lasing is considered. Specific features inherent in the locking range in a SRL are discussed. When backscattering coupling is strong, the frequency locking of the counterpropagating waves does not switch to a beat regime at any rotation rate. In the case of weak backscattering coupling, analytical expressions for the locking range are derived. It is shown that an active feedback loop has a strong impact on a locking range. In a He-Ne laser, the locking range is determined by dissipative backscattering, and there is no locking with conservative scattering. Unlike a He-Ne laser, conservative backscattering in a SRL has a strong impact on the locking range.

Design and synthesis of polyindole - ZnO nano composite for NLO applications

Present paper mainly focuses on the synthesis, characterization polyindole-ZnO nano composites for third order nonlinear optical applications. Polyindole was synthesized through oxidative polymerization technique and its composites were prepared with different ZnO concentration. Structural morphology of the polymer composite was studied using FESEM, XRD and UV Visible spectroscopic technique. Polymer showed broad absorption with absorption maxima of 395 nm. Newly prepared thin films showed excellent nonlinear absorption with very good optical limiting behaviour when it is exposed to He-Ne laser with maximum optical limiting power of 11 mW along with third-order nonlinear susceptibility χ(3) of 2.72 × 10−3 esu. Hence these polymer composites may be potential candidate for optical limiting applications.

Интерференционный метод контроля выпуклых гиперболических поверхностей с использованием дифракционного оптического элемента

Interference control methods are making it possible to evaluate with high accuracy errors in the shape of the optical part surface profile. The interference pattern processing allows obtaining a map of the surface deviations at each of its points with an accuracy of half the wavelength. An interference method is proposed for testing the convex hyperbolic surfaces, which could be introduced to control mirrors with large aperture angles in the imaginary geometric focus. The proposed auto-collimation control scheme consists of a helium-neon laser with the wavelength of 632.8 nm, a meniscus lens and a planar axisymmetric diffractive optical element to correct the meniscus spherical aberration. Numerical method is presented for calculating the optical diffraction element using a phase profile on the example of the secondary hyperbolic mirror of the Millimetron space telescope. The developed scheme was simulated in the Zemax OpticStudio program. The approximation error of the calculated phase profile was evaluated depending on the number of phase coefficients. The Fizeau interferometer optical system is proposed to implement the developed method. The influence of errors in installing a controlled mirror on the interference pattern for axial displacement, transverse displacement and tilt was determined. The residual wave aberration was evaluated in the control system

LIDA: The Leiden Ice Database for Astrochemistry

Context. High-quality vibrational spectra of solid-phase molecules in ice mixtures and for temperatures of astrophysical relevance are needed to interpret infrared observations toward protostars and background stars. Such data are collected worldwide by several laboratory groups in support of existing and upcoming astronomical observations. Over the last 25 yr, the Laboratory for Astrophysics at Leiden Observatory has provided more than 1100 (high-resolution) spectra of diverse ice samples. Aims. In time with the recent launch of the James Webb Space Telescope, we have fully upgraded the Leiden Ice Database for Astrochemistry (LIDA) adding recently measured spectra. The goal of this paper is to describe what options exist regarding accessing and working with a large collection of infrared (IR) spectra, and the ultraviolet-visible (UV/vis) to the mid-infrared refractive index of H2O ice. This also includes astronomy-oriented online tools to support the interpretation of IR ice observations. Methods. This ice database is based on open-source Python software, such as Flask and Bokeh, used to generate the web pages and graph visualization, respectively. Structured Query Language (SQL) is used for searching ice analogs within the database and Jmol allows for three-dimensional molecule visualization. The database provides the vibrational modes of molecules known and expected to exist as ice in space. These modes are characterized using density functional theory with the orca software. The IR data in the database are recorded via transmission spectroscopy of ice films condensed on cryogenic substrates. The real UV/vis refractive indices of H2O ice are derived from interference fringes created from the simultaneous use of a monochromatic HeNe laser beam and a broadband Xe-arc lamp, whereas the real and imaginary mid-IR values are theoretically calculated. LIDA not only provides information on fundamental ice properties, but it also offers online tools. The first tool, SPECFY, is directly linked to the data in the database to create a synthetic spectrum of ices towards protostars. The second tool allows the uploading of external files and the calculation of mid-infrared refractive index values. Results. LIDA provides an open-access and user-friendly platform to search, download, and visualize experimental data of astrophysically relevant molecules in the solid phase. It also provides the means to support astronomical observations; in particular, those that will be obtained with the James Webb Space Telescope. As an example, we analysed the Infrared Space Observatory spectrum of the protostar AFGL 989 using the resources available in LIDA and derived the column densities of H2O, CO and CO2 ices.

Optimizing laser induced nonlinear optical, dielectric and microscopic traits of copper sulfate crystal by glycine for photonic device applications

• First comparative article on pure and glycine doped copper sulfate crystal has been reported. • Glycine enhanced optical transmittance of copper sulfate by 8% within 300-698 nm. • Glycine optimized third order nonlinear optical properties of copper sulfate crystal. • Glycine enhanced the laser induced damage threshold energy of copper sulfate by 55 mJ. • Glycine significantly reduced the dielectrics of copper sulfate crystal. Novel investigation reports mono crystal growth of pristine and glycine (C 2 H 5 NO 2 ) doped copper sulfate (CS) by slow solvent evaporation method. The structural analysis has been performed by single crystal X-ray diffraction technique. The presence of various chemical components has been qualitatively established by energy dispersive spectroscopy. The UV-visible spectroscopy has been employed within 200-1000 nm to evaluate the rise in optical transmittance of CS crystal due to glycine. Influence of glycine on third order nonlinear optical response of CS crystal has been examined at 632.8 nm by means of He-Ne laser assisted Z-scan technique. The laser induced surface damage tolerance limit of pure and glycine doped CS crystal has been comparatively investigated at 1064 nm. The impact of glycine and temperature on dielectric traits of CS crystal has been investigated by means of dielectric studies. A comparative etching analysis has been done to investigate surface attributes of pure and glycine doped CS crystal.

Dual-Beam Photothermal Spectroscopy Employing a Mach-Zehnder Interferometer and an External Cavity Quantum Cascade Laser for Detection of Water Traces in Organic Solvents.

We report on a mid-infrared (mid-IR) photothermal spectrometer for liquid-phase samples for the detection of water in organic solvents, such as ethanol or chloroform, and in complex mixtures, such as jet fuel. The spectrometer is based on a Mach-Zehnder interferometer (MZI) employing a He-Ne laser, a mini-flow cell with two embedded channels placed in the interferometer's arms, and a tunable external cavity quantum cascade laser (EC-QCL) for selective analyte excitation in a collinear arrangement. In this study, the bending vibration of water in the spectral range 1565-1725 cm-1 is targeted. The interferometer is locked to its quadrature point (QP) for most stable and automated operation. It provides a linear response with respect to the water content in the studied solvents and photothermal analyte spectra, which are in good agreement with FTIR absorbance spectra. The method is calibrated and validated against coulometric Karl Fischer (KF) titration, showing comparable performance and sensitivity. Limits of detection (LODs) for water detection in the single-digit ppm range were obtained for chloroform and jet fuel due to their low background absorption, whereas lower sensitivity has been observed for water detection in ethanol due to pronounced background absorption from the solvent. In contrast to KF titration, which requires toxic reagents and produces waste, the developed method works reagent-free. It can be applied in an online format in the chemical industry as well as for fuel quality control, being industrial applications where traces of water need to be accurately determined, preferably in real-time. It thus holds great promise as a green alternative to the offline KF titration method, which is the current standard method for this application.

Is the targeted approach for vitiligo satisfactory?

Vitiligo is also known as Safed Daagh, Safed Kodh, Phuleri and Savitra in vernacular. Vitiligo causes social and psychological distress, affecting 0.1 to 2 Percent global population. The pathology demonstrates depigmentation of the skin, with loss of melanocytes by autoreactive cytotoxic T cells. The vitiligo-infiltrating lymphocytes were T lymphocytes, and most were CD8+The elevated levels of H2O2 in the skin mediate the production of proinflammatory cytokines like IL-1β, IL6, and IL-8 indirectly by activating the calreticulin pathway. Autoimmunity in vitiligo is driven by the IFN-γ-CXCL10 cytokine (motif chemokine ligand) signaling pathway. No drug can stop the process of vitiligo. Most of the drugs are used in combination. Light therapy can help to restore some color. Topical steroids, calcineurin inhibitors, and narrow-band ultraviolet (UV)–B phototherapy are widely used. New depigmenting therapies are emerging such as helium-neon (He–Ne) lasers and prostaglandin E2 analogs. In cases of stable disease, surgical procedures such as skin grafting, blister grafting, orCellular suspension transplant are often tried. Ruxolitinib is the first medication that can restore pigment in patients with nonsegmental vitiligo. Tildrakizumab is also being evaluated in form of Topical Cream. Unfortunately, vitiligo is life long condition which is difficult to treat with satisfaction.

Online monitoring and active control of alignment errors in a tiled grating assembly using single wedge plate

With reference to application in chirped pulse amplification (CPA) based high-energy, ultra-short laser systems, online monitoring of alignment errors and active coherent locking of gratings in a tiled grating assembly (TGA) consisting of two gratings, each of size 140 mm x 120 mm and groove density 1740 grooves/mm, is presented. All the tiling alignment errors present in the TGA have been monitored simultaneously using a single wedge plate based lateral shearing interferometry and corrected using piezo motor driven 6-axis aligner stage. As a novelty, to have further advantages in the wedge plate based method for TGA alignment, the He-Ne laser beam diffracted/ reflected from the TGA has been folded back towards the source, which facilitated measurement sensitivity enhancement by a factor of two, and also generation and simultaneously capturing of both reflected and diffracted beam's interferograms using comparatively smaller dimension single wedge plate and CCD camera. The angular and translational alignment errors of the TGA have been actively locked in the range of ± 0.5 µrad and ± 50 nm respectively.

Analysis and development on general structure and characteristics of laser interferometry systems

The laser interferometry systems have been developed for scientific studies, industrial operations, artworks investigation, etc. They present common generic elements, such as laser, optics, beam, polarization, splitting, interferometry, etc., but also diverse specific components and features,such as He-Ne or femtosecond laser, quantum cascade lasers, non-polarising beam splitter, collimating lens, high reflecting mirror, photodetector, attosecond pulse train, etc., as the case. The paper presents, also, a development on general structure and characteristics of laser interferometry systems. Analytical descriptors are introduced for the main implied entities, as well as some qualitative features referring to measurement object, coordinate system, lasers, laser beams, optics, output beams, detectors, environmental sensors and compensation modules, electronics, process software and computer, assembly, calibration, etc. The conclusions accord attention to further laser interferometry development regarding the interacting processes, analytical modelling, simulation, operational characteristics, etc.

Electrically controlled continuous laser beam steering in a liquid crystal based electro-optic waveguide

Non-mechanical and continuous beam steering devices are highly desirable in recent laser scanning applications and telecommunication advancements. We report a liquid crystal (LC) core waveguide-based electrically controlled, non-mechanical, and continuous laser beam steering device. The waveguide uses nematic 5CB (4-cyano-4′-pentylbiphenyl) LC as a propagation medium surrounded by PVA (polyvinyl alcohol) polymer cladding, which is realized on ITO coated glass substrates. A pattern of five triangular electrodes is transferred on the substrate using photolithography to create prisms of tunable refractive index in the LC core of the waveguide. The beam steering for transverse electric (TE) and transverse magnetic (TM) polarization is theoretically studied and experimentally characterized using a He-Ne laser of λ = 633 nm. A steering angle of −5.4° and +5.7° at 7 Vpp is obtained for TE and TM polarization, respectively, in a waveguide with the prism’s apex angle of 13°. Similarly, a higher steering angle up to 7.3° for TM polarization is demonstrated in the waveguide with an apex angle of 22°. The device is developed using ease of fabrication process and cost-effective materials that operate at relatively low voltages.

Reliable estimation of wavenumbers for peaks of benzonitrile and cyclohexane

AbstractOne of the most important parameters in Raman spectroscopy is the wavenumber (Raman shift), which is calculated from the difference between the excitation and Raman scattering absolute wavenumbers. Because the observed wavenumbers are strongly dependent on the spectrometer and measurement conditions, it is essential to calibrate the system by using a well‐characterised material. We therefore reliably estimated the wavenumbers and evaluated their uncertainty for the peaks of benzonitrile and cyclohexane by using a HeNe laser and Raman‐scattered light calibrated with Ne/Ar emission lines. We considered the uncertainties originating from the fitting and repeatability of both the Ne/Ar emission lines and the Rayleigh/Raman‐scattered lights, as well as the unstabilised HeNe laser, and the pixel and spectral resolutions. We also considered the uncertainty originating from the differences in results among the grades and manufacturers (four for benzonitrile and seven for cyclohexane). The estimated wavenumbers of 12 peaks for benzonitrile and 11 peaks for cyclohexane were comparable with those described in ASTM E1840 with an expanded uncertainty from 1.3 to 1.6 cm−1 (k = 2, coverage factor). It was also confirmed that the wavenumbers at 10°C and 35°C were within the expanded uncertainty; thus, these values should be widely useful for the calibration of Raman systems.

Absolute distance measurement using sinusoidal phase modulating frequency sweeping interferometry with a reference interferometer.

Frequency sweeping interferometry with reference interferometer based on sinusoidal phase modulating technique is proposed in this paper for absolute distance measurement. With the frequency of the external cavity diode laser (ECDL) swept continuously in sinusoidal, a HeNe laser was employed to monitor the drifts of the target and the reference length, and influences caused by drifts during the measurement were compensated in real time. Sinusoidal phase modulation with non-overlapping frequencies were applied to the two laser lights individually by two electro-optic modulators (EOM), and the interference phases corresponding to the two laser lights were extracted simultaneously using the phase generated carrier (PGC) demodulation based on frequency-division multiplex technique. Performance of the phase detection method has been verified by nanometer displacement measurements. Experimental results show that the measurement uncertainty can be considerably reduced by compensating the influences of drifts and by applying linear regression to get the ratio of interference phase changes between the measurement interferometer and the reference interferometer. Comparison of the absolute distance measurement with an incremental interferometer yields a measurement uncertainty of 10-5, which is in good agreement with the estimation of the measurement uncertainty.

Influence of Lighting and Laser Irradiation on the Germination of Caper Seeds

Caper seeds present difficulties in their germination, which has been studied by several research teams. It is known that light can release dormancy in some seeds, but its effect on caper seed germination has not yet been deeply studied. The main aim of this study was to analyze the response of caper seeds germination to light exposure. The study analyzed the germination response of seeds to lighting with different wavelengths (white, red, blue, red + blue and darkness) and to the He-Ne laser light, using both dry seeds and seeds that had been previously soaked in water. Overall, it could be stated that caper seeds are insensitive to light during the germination process. Thus, germination could be carried out in lightness or darkness, so germination in nurseries could be carried out in the darkness, leading to substantial energy savings. Caper seed irradiation with a He-Ne laser during short exposure times improved the germination percentage for the seeds previously soaked in water, germinating all viable seeds. However, applying a solution of gibberellic acid was always required in all the cases studied.

Optical properties of planar plasmon active surfaces modified with gold nanostars

The article discusses the experimental and theoretical results of studying the optical properties for planar quartz surfaces modified with gold nanostars using Surface-Enhanced Raman Spectroscopy (SERS). Surfaces functionalized with nanoparticles, prototypes of optical sensors, have been obtained. It is shown that the obtained experimental Raman signal enhancement from the dye rhodamine 6G (R6G) can be at least order 104. The paper presents the results of calculation, synthesis and study of the optical and morphological properties of such structures. A complex method for creating and evaluating the optical properties of planar nanostructures and evaluating their optical properties is proposed. The method includes the approaches based on mathematical modeling using finite differences in the time domain (FDTD - Finite-Difference Time-Domain) evaluating electromagnetic field strengths near the surfaces of star-shaped gold nanoparticles in colloidal solutions and on a silicon surface. During the simulation, we studied such parameters as the particle size, the wavelength of the exciting radiation, and the dependence of the effective amplification of the electromagnetic field on the morphological parameters of the star. The theoretical approach to the calculation of such structures is shown to be promising for the subsequent chemical synthesis described in the article and the study of optical properties. In this paper, a theoretical calculation of the parameters of the electric field and optical properties is carried out near star-shaped nanoparticles of varying sizes. These parameters were calculated by the finite difference method in the time domain. The task included finding the optimal sizes of nanoparticles as well as varying the thickness of the surface layers in order to obtain the maximum scattering values and further use of similar structures in SERS experiments. Also, within the framework of this work, syntheses of star-shaped nanoparticles was carried out, their optical and morphological properties were studied, quartz surfaces were functionalized with nanoparticles, and sensor prototypes were created in order to further assess the Raman signal amplification. Based on the results of mathematical modeling, the optimal sizes for the synthesis of star-shaped NPs were determined. Synthesis of NPs was carried out by a chemical method using seeds. To carry out the experimental part, SERS spectra were obtained using Centaur U spectrometer (OOO NanoScanTechnology, Russia). The spectrometer was equipped with three different laser sources: 632.8 nm He-Ne laser (17 mW), 532 nm and 473 nm DPSS lasers (45 mW). During the experiment, a He-Ne laser with λ = 632 nm and DPSS laser with λ = 532 nm were used to match the excitation of the plasmon maximum for the nanostars. The optical scheme of the spectrometer included an Olympus BX41 microscope (Olympus, Japan) with a 100× objective (NA 0.9) for positioning the beam and collecting scattered photons. The monochromator of the spectrometer had a focal length of 800 mm. A holographic diffraction grating of 300 gr/mm, and was equipped with a 1024×256 pixel thermoelectric cooled CCD detector (Andor Tech., UK). As a result of the paper, surfaces functionalized by nanoparticles were obtained prototypes of optical sensors. It is shown that the experimental gain of the Raman signal can be no less than 104 times. The presented data will serve as the basis for obtaining the required sizes of nanostars in the methods of the controlled chemical synthesis of colloidal nanoparticles. The results presented in the article can be applied to the development of biocompatible and highly sensitive optical sensors based on the effect of Raman scattering of light.