Laser Cone Research Articles

Optical Interferometric Device for Rapid and Specific Detection of Biological Cells.

Here, we report a rapid and accurate optical method for detecting cells from liquid samples in a label-free manner. The working principle of the method is based on the interference of parts of a conical laser beam, coming from a single-mode optical fiber directly, and reflected from a flat glass surface. The glass is functionalized by antibodies against the cells to be detected from the liquid sample. Cells bound to that surface modify the reflected beam, and hence, change the resulting interference pattern, too. By registering and interpreting the variation in the image, the presence of cells from the sample can be detected. As for a demonstration, cell suspensions from a U937 cell line were used in glass chambers functionalized by antibodies (TMG6-5 (mIgG1)) to which the cells specifically bind. The limit of detection (LOD) of the method was also estimated. This proof-of-concept setup offers a cost-effective and easy-to-use way of rapid and specific detection of any type of cells (including pathogens) from suspensions (e.g., body fluids). The possible portability of the device predicts its applicability as a rapid test in clinical diagnostics.

Demonstration of low-mode shape control in indirect-drive double shell implosions at the NIF

Double shell inertial confinement fusion is a concept for achieving robust thermonuclear burn that uses dense metal shells to compress deuterium-tritium (DT) fuel to fusion conditions. Double shell implosions are typically indirectly driven and involve a target that consists of a low-Z ablator, a foam layer, and a high-Z pusher surrounding the DT fuel. The goal of the campaign is to achieve a volumetric burn as radiation losses from the DT fuel are trapped by the opaque high-Z shell. The overall performance of double shell implosions relies on the efficient collisional transfer of kinetic energy between layers. The efficiency of this transfer (and therefore the overall performance of a given implosion) is degraded by the presence of low-mode asymmetries. P2 asymmetries are often observed in spatially resolved 2D radiographs of nominal double shell implosions. This work discusses three such experiments: one with an oblate P2 asymmetry, one with a prolate P2 asymmetry, and one with an approximate spherical symmetry. After performing a shape analysis of the oblate and prolate implosions to quantify asymmetries, these experimental results were compared with the results of hydrodynamic simulations for the two experiments. Differences between the experiment and simulation were then used to design an approximately spherical implosion by altering the incident laser cone fraction. Radiographs from the experiment that implemented the modified cone fraction show evidence of an implosion that is approximately spherical until bang time. This design is intended to serve as a point design for future studies that will seek to optimize various aspects of the double shell target.

Efficient laser methods for producing spherical powders

A new process of laser gas atomization has been developed to obtain a spherical metal powder with a particle size of 30-100 μm using laser beams of conical geometry. A process for obtaining a spherical powder in a wide size range of 50 nm - 100 μm, in which a continuous near-surface optical discharge with a temperature of 20 kK is formed using conical laser beams in an inert gas flow, into which the material is introduced in the form of a wire or a powder flow has been designed. Particle condensation is strongly and rapidly quenched by the inert gas flow, resulting in high supersaturation. The efficiency of the proposed laser methods for producing powders is up to 0.5 kg/kWh at an electric power of 16 kW, while the existing, most efficient methods of plasma and gas spraying provide an efficiency of no better than 0.1-0.25 kg/h kW. The method can be used to obtain powders from various materials - metals, ceramics, plastics, suspensions. The new process of laser centrifugal atomization has been elaborated. Melting or evaporation of the end of a rotating hollow cylinder by a laser system ensures a highly efficient process for obtaining spherical powder in the nano and micro size range

Thermal characterization of acrylonitrile butadiene styrene-ABS obtained with different manufacturing processes

Polymers are widely employed in many areas, e.g. transport, packaging, electronic devices, etcetera. Among them, acrylonitrile–butadiene–styrene (ABS) is one of the most employed polymers due to its mechanical properties, its ease to mechanize and recyclability. Nevertheless, according to the fire properties, ABS behaviour is usually worse than other polymers, therefore, they have to be upgraded with flame retardant additives. To characterize the fire behaviour of a certain material is necessary to address several typology of tests, providing relevant properties such as thermal conductivity, flammability and heat released. However, researchers may not always be able to run all tests due to the lack of apparatus or samples. Therefore, it is necessary to seek bibliographic sources. As one might expect, for a given material, the property values should be similar, regardless of who performs the test. However, sometimes slightly different results are obtained, which may be due to different causes, such as differences in test set-up and in material composition/manufacture. These differences in properties may lead researcher to doubt which data to use. This paper presents the results of different types of tests using neat ABS polymer. Additionally, these results are compared with the data from literature, discussing the similarities/differences and offering a more comprehensive characterization of ABS. The laboratory techniques included in this work are: thermogravimetric analysis, differential scanning calorimetry, laser flash analysis, smoke density, cone calorimeter, fire propagation and flammability.

Diffraction and thermal effect of a Bessel-Gaussian laser for Ag nanoparticle deposition

Nanoparticles are known to sinter at much lower temperatures than the corresponding bulk or micro size particles. A laser-assisted sintering process is considered in this study to sinter Ag nanoparticles by dispensing Ag paste onto an indium tin oxide-coated Si substrate. The Gaussian beam of a CO2 laser source is propagated through axicon and biconvex lenses, and the resulting hollow beam is focused on the Ag paste with a hollow parabolic mirror. A Bessel-Gaussian irradiance distribution is obtained at the focal plane of the parabolic mirror due to the interference of the hollow laser cone. The Fresnel diffraction approximation is considered to determine the phasor of the laser and an analytical approach is implemented to calculate the irradiance distribution of the Bessel-Gaussian beam. This irradiance distribution is utilized as a heat source in a heat conduction model and the temperature distribution is analyzed for thin Ag films formed during the laser sintering of Ag nanoparticles. An analytical expression is obtained for the temperature distribution by solving the heat conduction equation using Fourier transform for finite media. The widths of the deposited Ag lines are predicted from the temperature profiles and the model predictions compare well with the experimental results. The isotherms are found to be geometrically noncongruent with convex and concave tips depending on the locally maximum and minimum irradiances of the Bessel-Gaussian beam, respectively. The convex and concave tips, however, appear in the same isotherm for sufficiently high substrate speed relative to the laser beam.

Evaluation of Dose Accuracy in the Near-Surface Region for Whole Breast Irradiation Techniques in a Multi-institutional Consortium

PurposeTo assess the accuracy of dose calculations in the near-surface region for different treatment planning systems (TPSs), treatment techniques, and energies to improve clinical decisions for patients receiving whole breast irradiation (WBI). Methods and MaterialsA portable custom breast phantom was designed for dose measurements in the near-surface regions. Treatment plans of varying complexities were created at 8 institutions using 4 different TPSs on an anonymized patient data set (50 Gy in 25 fractions) and peer reviewed by participants. The plans were recalculated on the phantom data set. The phantom was aligned with predetermined shifts and laser marks or cone beam computed tomography, and the irradiation was performed using a variety of linear accelerators at the participating institutions. Dose was measured with radiochromic film placed at 0.5 and 1.0 cm depth and 3 locations per depth within the phantom. The film was scanned and analyzed >24 hours postirradiation. ResultsThe percentage difference between the mean of the measured and calculated dose across the participating centers was -0.2 % ± 2.9%, with 95% of measurements within 6% agreement. No significant differences were found between the mean of the calculated and measured dose for all TPSs, treatment techniques, and energies at all depths and laterality investigated. Furthermore, no significant differences were observed between the mean of measured dose and the prescription dose of 2 Gy per fraction. ConclusionThese results demonstrate that dose calculations for clinically relevant WBI plans are accurate to within 6% of measurements in the near-surface region for various complexities, TPSs, linear accelerators, and beam energies. This work lays the necessary foundation for future studies investigating the correlation between near-surface dose and acute skin toxicities.

Fractal Laser Cone Structures Proposed to Confine Antimatter

Flat, straight sheets of paper, standing vertically on edge cannot support any load placed upon their top edge, but once formed into fractal tube conic sections, they have been measured to support up to 97.52 (± 2.27) kilograms (215 (± 5) pounds) of weight with strength-per-weight ratio up to 10,336 (± 240). So, strength has been discovered to be an emergent characteristic arising solely from addition of intelligent order. It is proposed to impose such intelligent order upon, preferably, at least 6 laser beams by focusing each of them to form cones of light, arranging the cones to form a wall of a larger fractal cone, and converging all of them to a common focal point inside a vacuum chamber to give them sufficient strength near this focal point to attract, hold, and move neutral antimatter, preferably anti-lithium. This opens the new field of structural engineering of light and re-defines the concept of strength. Means of cancelling out radiation pressure by reflection of laser beams back to the common focal point are proposed to enable laser confinement of particles having low polarizability, such as anti-hydrogen. Counter-circulation of light by reflection at grazing incidence is proposed as a means of returning escaping antimatter back to the common focal point containment area. Means are proposed to inject a stream of matter into the contained antimatter to create a matter-antimatter reactor and propulsion engine. Since anti-lithium is not available, yet, means are proposed to test these structures by confining ordinary lithium, instead, and by hitting it with anti-protons and/or positrons. Means are proposed to modulate the matter-antimatter reaction with information to create modulated gravitational waves for communication. The proposed structures would enable efficient, stable, safe confinement of antimatter, which would allow better study of antimatter, and make possible renewable, clean, safe, matter-antimatter reactor generators and propulsion engines, antimatter-assisted fusion reactors, and modulated gravitational wave generators.

COVID-19: mask efficacy is dependent on both fabric and fit.

Aim: Face masks are an important addition to our arsenal in the fight against COVID-19. The aim of this study is to present a novel method of measuring mask performance which can simultaneously assess both fabric penetration and leakage due to poor fit. Materials & methods: A synthetic aerosol is introduced into the lung of a medical dummy. A conical laser sheet surrounds the face of the dummy where it illuminates the aerosol emitted during a simulated breath. The system is demonstrated with five mask types. Conclusions: The curved laser sheet highlights both penetration through the mask fabric and leakage around the edges of the mask. A large variation in both material penetration and leakage was observed.

Labor Complicated by Cervical Stenosis Following a Laser Cone Biopsy

A 34-year-old lady, with three previous spontaneous vaginal deliveries, presented in labor at 37 + 0 weeks’ gestation. Following the birth of her third child, she underwent a laser cone biopsy for cervical intraepithelial neoplasia (CIN) 3. Despite sustained regular contractions and augmentation with Syntocinon, progressive cervical dilatation beyond 1 cm failed to occur in this multiparous lady. A delayed diagnosis of cervical stenosis was made. She eventually underwent a cesarean section where her internal cervical os was found to be thin and fibrotic. This case describes an uncommon occurrence of cervical stenosis presenting in labor and seeks to increase awareness of this condition so as to allow preemptive counselling of similar patients, early recognition in a labor with poor progress and a swift, better-informed decision to deliver via an emergency cesarean section. We review the existing literature on cervical stenosis following cervical conization and analyze the various definitions available. J Med Cases. 2021;12(1):13-15 doi: https://doi.org/10.14740/jmc3605

A Cervical Smear Scare due to Monsel’s Solution: A Case Report

Monsel’s solution has been in use since the end of the 19th century for its valuable property of creating hemostasis in minor disruptions of the epithelium. Its styptic effect was first described by Leon Monsel, a pharmacist in the French army, in a letter dated on October 13, 1852. Containing ferric subsulphate, it is used as a topical hemostatic agent in minor procedures such as biopsies in gynecology, proctology, dermatology, otorhinolaryngology and odontology. A 28-year-old nulliparous woman, with a known history of adenomyosis, had presented for sudden heavy intermenstrual vaginal bleeding. Examination revealed a bleeding Nabothian cyst. Monsel’s solution application helped stop the bleeding. She returned 3 days later with persistent heavy vaginal bleeding. Examination showed active oozing from the Nabothian cyst. A cervical smear and a human papillomavirus (HPV) swab were taken, and vaginal packing was inserted. The cervical smear result was reported as atypical cells, suspicious for malignancy. Colposcopy performed showed a grade 2 acetowhite lesion, suspicious for cervical intraepithelial neoplasia (CIN) III/microinvasive disease. However, punch biopsies of the cervix revealed only CIN I/koilocytosis. The patient was counselled and subsequently underwent a laser cone biopsy, which showed CIN I with clear margins. The discrepant results between the cervical smear and the cone biopsy prompted a review of the cervical smear and cervical histology; and a relook at the chronology of events. The cytological features observed in the initial cervical smear could be explained by the interference from the Monsel’s solution, which was applied just 3 days before the cervical smear. In cases where Monsel’s solution has been used for hemostasis, it is best to delay taking a cervical smear or a biopsy for at least 3 weeks as the histologic effect of Monsel’s solution may persist for up to that duration of time in tissues. J Med Cases. 2020;11(10):324-326 doi: https://doi.org/10.14740/jmc3556

Comparative efficacy and complication rates after local treatment for cervical intraepithelial neoplasia and stage 1a1 cervical cancer: protocol for a systematic review and network meta-analysis from the CIRCLE Group

IntroductionLocal treatments for cervical intraepithelial neoplasia (CIN) and microinvasive disease remove or ablate a cone-shaped part of the uterine cervix containing the abnormal cells. A trend toward less radical techniques...

Ultra-high (>30%) coupling efficiency designs for demonstrating central hot-spot ignition on the National Ignition Facility using a Frustraum

A new hohlraum geometry or “Frustraum” is proposed that may enable 2–3× higher capsule absorbed x-ray energy than for nominally sized capsules in standard cylinders. The Frustraum geometry comprises two truncated conical halves (or “frusta”) joined at the waist. An associated larger waist volume above the capsule allows fielding ∼50% larger capsules than the nominal 1 mm (radius) scale. A key feature of the Frustraum is that the outer laser cones strike the Frustraum ends at a higher glancing angle (by ∼23°) compared with a cylinder and generate more specular reflection. A scenario for boosted symmetry control from the outer cones reflecting off a glancing angle hohlraum wall depends on the choice of electron flux limit in the simulations. Recent data from the National Ignition Facility using oversized aluminum shells in rugby-shaped hohlraums [Ping et al., Nat. Phys. 15, 138 (2019)] come closest to approximating a Frustraum and are consistent with a flux limit of 0.03–0.04 in matching the simulated Dante drive history, the backlit trajectory of the Al shell, neutron yield, and implosion time. Applying this simulation methodology to hot-spot ignition designs in a Frustraum shows effective symmetry control and sufficient drive (∼290 eV) to enable high yield, moderate convergence implosions. Simulations suggest that adjusting the obliquity of the Frustraum wall is a robust lever for symmetry tuning. A high adiabat (α = 4.6) ignition design with a shortened laser pulse (<7 ns) is proposed to provide further margin to potential late-time loss of symmetry control from hohlraum filling and anomalous sources of fuel preheat.

Automation of Dosimetric Control for Laser Radiation

The wide application of laser systems and the increase in the values of their energy characteristics, which may hazard to the health of staff and other people in the area of direct and reflected laser radia­tion, necessitates a permanent dosimetric monito­ring in these areas. However, the methods of mea­suring the parameters of laser radiation at a given point in space to determine the degree of radiation safety for the human body, established in the stan­dard DSTU EN 60825-1: 2016, are difficult to implement when using obsolete monitoring equipment. Therefore, the development of an automated method for determining the characteristics of a laser system and the rapid detection and determination of the direction and coordinates of laser radiation is relevant.
 The proposed method for automated determination of the laser system characteristics differs by applying an additional measurement channel with a photodetector, as in the main channel, and a compensated filter to ensure the difference of the rea­dings in the channels, so that each difference of measured channel values corresponds to the one wavelength value. For the formation of a compensation filter with a constant spectral characteristic in the most demanded wavelength range from 0.4 microns to 1.1 microns are used by known methods of calculation and manufacturing. A combination of optical glass NSNU 13 and SZS-9 with varying thickness as a compensation filter is permitting measure of laser irradia­tion doze for radiation in this range with an error that does not exceed 15%.
 It is necessary to perform the tasks of quickly finding and estimating the angular coordinates of the laser sources for monitoring the parameters of laser radiation in the working area. Improving the design of the device for detecting and determining the angular coordinates of laser radiation is made by using an optical system that directs laser radiation to a photodetector of radiation and an information processing unit, in front of which a volume matted screen is installed so that the distance from the middle of the optical system to the nearest point of the screen is greater distance of the optical system. The photodetector matrix installed in the optical system focus is used as a photodetector of laser radiation.
 The application of spherical screens for direct laser radiation and cones for diffused and diffused reflec­ted radiation is proposed for the effective and rapid determination of radiation corners in the working zone.
 Dosimeters with automated wavelength monitoring and detection and determination of the angular coordinates of laser radiation will facilitate and reduce the cost of conducting dosimetry monitoring.

A New Method of Selective Laser Cladding

A new approach to selective laser cladding using conical laser beams has been elaborated. The initial round laser beam is divided into two or more circular beams with regulated distribution of the laser power between them. The circular beams are converted into conical beams that are focused separately on the surface and on different areas of the deposited material for their efficient heating. The delivery of laser energy into the powder stream is very effective because it provides a complete uniform absorption of laser energy in a dense powder stream (104–106 cm–3). Under wire deposition, substrate heating reduces residual stresses due to temperature gradients and compensates for heat loss from the deposition zone by thermal conduction. The required power density for melt contact formation is significantly reduced.

Новый метод селективной лазерной наплавки

AbstractA new approach to selective laser cladding using conical laser beams has been elaborated. The initial round laser beam is divided into two or more circular beams with regulated distribution of the laser power between them. The circular beams are converted into conical beams that are focused separately on the surface and on different areas of the deposited material for their efficient heating. The delivery of laser energy into the powder stream is very effective because it provides a complete uniform absorption of laser energy in a dense powder stream (10^4–10^6 cm^–3). Under wire deposition, substrate heating reduces residual stresses due to temperature gradients and compensates for heat loss from the deposition zone by thermal conduction. The required power density for melt contact formation is significantly reduced.

New approach in selective laser cladding

The new approach in selective laser cladding using conical laser beams has been elaborated. Initial round laser beam is divided into 2 circular beams with regulated distribution of the laser power throughout the circular beams. Circular beams are transformed to conical beams, which are focused separately on the surface and on the deposited material for heating. The laser energy delivery to powder stream is very efficient because a total uniform absorption of laser energy in the dense powder stream (104-105 1/cm3). Under wire deposition the heating of substrate reduces the residual stresses due the reduction temperature gradients and compensates heat losses from deposition zone by thermal conduction. The required power density for melt contact formation is significantly reduced.

Examining the radiation drive asymmetries present in the high foot series of implosion experiments at the National Ignition Facility

This paper details and examines the origins of radiation drive asymmetries present during the initial High Foot implosion experiments. Such asymmetries are expected to reduce the stagnation pressure and the resulting yield of these experiments by several times. Analysis of reemission and dual axis shock timing experiments indicates that a flux asymmetry, with a P2/P0 amplitude that varies from −10% to −5%, is present during the first shock of the implosion. This first shock asymmetry can be corrected through adjustments to the laser cone fraction. A thin shell model and more detailed radiation hydrodynamic calculations indicate that an additional negative P2/P0 asymmetry during the second or portions of the third shock is required to reach the observed amount of asymmetry in the shape of the ablator at peak implosion velocity. In conjunction with symmetry data from the x-ray self emission produced at stagnation, these models also indicate that after the initially negative P2/P0 flux asymmetry, the capsule experiences a positive P2/P0 flux asymmetry that develops at or before ∼2 ns into the peak of the laser power. Here, direct evidence for this inference, using measurements of the x-ray emission produced by the lasers irradiating the hohlraum, is presented. These data indicate that the reduction in the transmitted inner laser cone energy results from impeded propagation through the plasma associated with the ablation of the capsule target. This paper also correlates measurements of the outer cone laser deposition location with variations in the observed x-ray self emission shape from experiments conducted with nominally the same input conditions.

Two-sided conical laser target for a neutron source of a hybrid nuclear-thermonuclear reactor

Numerical simulations suggest that a source of thermonuclear neutrons with a high pulse repetition rate and the number of neutrons of ~1017 per pulse, which is required for the development of nuclear-thermonuclear reactors, can be realised in the irradiation of a two-sided conical target simultaneously by a long and short laser pulses with energies of ~1 MJ and 50 kJ and durations of 100 – 250 ns and 0.1 – 1 ns. We consider the feasibility of verifying separate propositions of the proposed conception with the use of existing laser facilities.

A new ignition hohlraum design for indirect-drive inertial confinement fusion**Project supported by the National Natural Science Foundation of China (Grant Nos. 11435011 and 11575034).

In this paper, a six-cylinder-port hohlraum is proposed to provide high symmetry flux on capsule. It is designed to ignite a capsule with 1.2-mm radius in indirect-drive inertial confinement fusion (ICF). Flux symmetry and laser energy are calculated by using three-dimensional view factor method and laser energy balance in hohlraum. Plasma conditions are analyzed based on the two-dimensional radiation-hydrodynamic simulations. There is no Ylm (l ⩽ 4) asymmetry in the six-cylinder-port hohlraum when the influences of laser entrance holes (LEHs) and laser spots cancel each other out with suitable target parameters. A radiation drive with 300 eV and good flux symmetry can be achieved by using a laser energy of 2.3 MJ and peak power of 500 TW. According to the simulations, the electron temperature and the electron density on the wall of laser cone are high and low, respectively, which are similar to those of outer cones in the hohlraums on National Ignition Facility (NIF). And the laser intensity is also as low as those of NIF outer cones. So the backscattering due to laser plasma interaction (LPI) is considered to be negligible. The six-cyliner-port hohlraum could be superior to the traditional cylindrical hohlraum and the octahedral hohlraum in both higher symmetry and lower backscattering without supplementary technology at an acceptable laser energy level. It is undoubted that the hohlraum will add to the diversity of ICF approaches.

First beryllium capsule implosions on the National Ignition Facility

The first indirect drive implosion experiments using Beryllium (Be) capsules at the National Ignition Facility confirm the superior ablation properties and elucidate possible Be-ablator issues such as hohlraum filling by ablator material. Since the 1990s, Be has been the preferred Inertial Confinement Fusion (ICF) ablator because of its higher mass ablation rate compared to that of carbon-based ablators. This enables ICF target designs with higher implosion velocities at lower radiation temperatures and improved hydrodynamic stability through greater ablative stabilization. Recent experiments to demonstrate the viability of Be ablator target designs measured the backscattered laser energy, capsule implosion velocity, core implosion shape from self-emission, and in-flight capsule shape from backlit imaging. The laser backscatter is similar to that from comparable plastic (CH) targets under the same hohlraum conditions. Implosion velocity measurements from backlit streaked radiography show that laser energy coupling to the hohlraum wall is comparable to plastic ablators. The measured implosion shape indicates no significant reduction of laser energy from the inner laser cone beams reaching the hohlraum wall as compared with plastic and high-density carbon ablators. These results indicate that the high mass ablation rate for beryllium capsules does not significantly alter hohlraum energetics. In addition, these data, together with data for low fill-density hohlraum performance, indicate that laser power multipliers, required to reconcile simulations with experimental observations, are likely due to our limited understanding of the hohlraum rather than the capsule physics since similar multipliers are needed for both Be and CH capsules as seen in experiments.