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This document provides a simplified solution to the problem of calculation of laser hazard distances defined in the Advisory Circular 70-1B by the U.S. Federal Aviation Administration regarding atmospheric attenuation (assuming its constant value) and measurement uncertainties. The calculation approaches and examples presented in this document do not specify the procedure that should be followed in the case of atmospheric attenuation, nor do they take into account the uncertainties associated with the measured parameters. The analysis presented in the article complements to some extent AC 70-1B and can be used by those who need such a simplified solution regarding illumination of landing or taking off aircrafts. The article presents a sample analysis for a typical laser pointer, where the necessary parameters of the laser beam along with the appropriate uncertainties were determined in accordance with the methods accredited by the Polish Centre for Accreditation while the appropriate laser hazard distances were calculated taking into account different atmospheric attenuation coefficients.

The nanoscale photothermal effect and the optofluidic convection around plasmonic nanoparticles drive the application of such nanoparticles in micro-environment. In this work, heat transfer and fluid flow around Au nanospheres and nanorods in water medium under continuous and pulsed wave laser irradiance was investigated using an FEM based numerical framework. Au nanospheres of a wide range of diameter: 40 nm ≤ Diameter (D) ≤ 180 nm and relatively large nanorods (diameter: 50 nm) with varying aspect ratio (1 ≤ Aspect ratio (A) ≤ 5) and orientation (0° ≤ θ ≤ 90°, ϕ = 0°, 90°) with respect to the incident EM radiation were investigated for continuous wave (CW) and pulsed wave laser. It was found that although nanorods can attain much higher temperature than nanospheres, orientation of a nanorod is an important factor to be carefully considered in applications. In micro-scale spherical and hemispherical confinements (diameter < 14.4 μm), the convective velocity fields around nanoparticles is in the order of 10–9 m/s, with only a weak effect of the slip or no-slip boundary condition on the confining walls. Importantly, the size of the confinement has a strong effect leading to an order of magnitude stronger convection for 14.4 μm (diameter) spherical confinement as compared to 3.6 μm confinement. Additionally close proximity of the nanoparticles to the confining walls strongly reduces (by an order of magnitude) the convective currents. The results reported herein provides important insights for the use of photothermal nanoparticles in microscale confined space (e.g. cellular environment) for applications such as optical tweezers, photoporation, etc. [ABSTRACT FROM AUTHOR]

This document provides a simplified solution to the problem of calculation of laser hazard distances defined in the Advisory Circular 70-1B by the U.S. Federal Aviation Administration regarding atmospheric attenuation (assuming its constant value) and measurement uncertainties. The calculation approaches and examples presented in this document do not specify the procedure that should be followed in the case of atmospheric attenuation, nor do they take into account the uncertainties associated with the measured parameters. The analysis presented in the article complements to some extent AC 70-1B and can be used by those who need such a simplified solution regarding illumination of landing or taking off aircrafts. The article presents a sample analysis for a typical laser pointer, where the necessary parameters of the laser beam along with the appropriate uncertainties were determined in accordance with the methods accredited by the Polish Centre for Accreditation while the appropriate laser hazard distances were calculated taking into account different atmospheric attenuation coefficients. [ABSTRACT FROM AUTHOR]

Laser pointers directed at commercial aircraft by individuals in the vicinity of airports and flight routes are a growing threat to the safety of air travel. During a critical phase of flight, such as landing or takeoff, a laser strike can cause significant distraction or visual impairment to the pilot. This paper investigates laser-related incidents and injury in the United States over the last decade. Using daily data on laser exposure reported by pilots and crew members, and controlling for laser color, hour of the day, day of the week, among other controls, we find that the likelihood of suffering a laser-induced injury is inversely proportional to altitude, but positively related to laser incident frequency. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) have been applied to solid lighting because of their excellent fluorescent properties, good chemical stability, easy functionalization, and other advantages. However, the low thermal stability of most CDs limits the wide application of CDs as phosphors in laser illumination field. Aiming at CDs with high thermal stability and low cost, Y-CDs with fluorescent quantum yield of 49% were prepared by one-step hydrothermal method using citric acid and 2，7-dihydroxynaphthalene as raw materials and adjusting the concentration of reactants. The YG-CDs after annealing only lost 10% of weight at 250 ℃, while their thermal stability was greatly improved. The fluorescent films with good transmittance, fluorescent property, and thermal stability were obtained by combining the annealed YG-CDs with three film-forming agents (polymethyl methacrylate, polyvinyl alcohol, and silane coupling agent). This research provides a theoretical and practical basis for the application of CDs-based fluorescent films for laser illumination.

In this study, two kinds of composite ceramic phosphors, Ce3+:YAG/Al 2 O 3 and Ce3+:Y(Gd)AG/Al 2 O 3 were prepared via solid state reaction sintering in flowing pure oxygen at atmospheric pressure. The ceramic phosphors were packaged into chip-scale white light emitting diodes (w-LEDs), and laser assisted w-LED automobile headlight prototypes were assembled. The luminous flux output of the w-LEDs was significantly improved through additional blue diode laser excitation. Notably, the Al 2 O 3 phase is able to impart an improvement in the luminescence saturation exhibited by Ce3+:Y(Gd)AG, which typically reaches saturation prior to Ce3+:YAG. [ABSTRACT FROM AUTHOR]

Keywords: aviation safety; laser hazard distance; laser hazard distances in navigable airspace; laser illumination; laser safety EN aviation safety laser hazard distance laser hazard distances in navigable airspace laser illumination laser safety 33 46 14 07/05/22 20220101 NES 220101 1 Introduction Scientific and technological progress is becoming more and more noticed by every person. Aviation safety, laser hazard distance, laser hazard distances in navigable airspace, laser illumination, laser safety The influence of ellipticity HT ht on the distances was also analyzed. [Extracted from the article]

A reliable yellow phosphor converter that can be efficiently excited by a 405 nm bluish violet laser is in high demand for laser illumination applications. A NaAlSiO 4 :Eu2+ phosphor with a quantum efficiency reaching 92% was obtained using LTA zeolite as the raw material. NaAlSiO 4 :Eu2+ ceramics with suitable porosities for laser illumination were prepared from the phosphor powders via spark plasma sintering. The ceramics lost only 2% of the quantum efficiency compared to the powders, maintained good thermal quenching properties (30% drop at 150 °C), and showed good thermal conductivity (2.02 W‧m−1‧K−1). The NaAlSiO 4 :Eu2+ ceramic with 405 nm bluish violet lasers, with the increase in laser power density to 9.15 W/mm2, exhibited an increasing luminous flux (23.83–70.26 lm) and maintained a stable luminous efficacy (47.7–46.8 lm/W), and the temperature distribution of the ceramic remained uniform and stable under long-time laser irradiation. This indicates that the nepheline-phase NaAlSiO 4 :Eu2+ ceramic is a promising material for laser illumination. [ABSTRACT FROM AUTHOR]

The formation of semiconductor heterostructures is an effective approach to achieve high performance in electrical gas sensing. However, such heterostructures are usually prepared via multi‐step procedures. In this contribution, by taking advantage of the crystal phase‐dependent electronic property of SnSex based materials, we report a one‐step colloid method for the preparation of SnSe(x%)/SnSe2(100−x%) p–n heterostructures, with x ≈30, 50, and 70. The obtained materials with solution processability were successfully fabricated into NO2 sensors. Among them, the SnSe(50 %)/SnSe2(50 %) based sensor with an active layer thickness of 2 μm exhibited the highest sensitivity to NO2 (30 % at 0.1 ppm) with a limit of detection (LOD) down to 69 ppb at room temperature (25 °C). This was mainly attributed to the formation of p–n junctions that allowed for gas‐induced modification of the junction barriers. Under 405 nm laser illumination, the sensor performance was further enhanced, exhibiting a 3.5 times increased response toward 0.1 ppm NO2, along with a recovery time of 4.6 min. [ABSTRACT FROM AUTHOR]

Measurements of high-pressure sprays and particle fields in high-speed flows have been very challenging for the existing instrumentation. Deformed drops or solid particles significantly limit the range of experimental methods that can be applied for detailed, quantitative measurements. We developed advanced microscope imaging equipment and diagnostic methods to characterize fast-moving droplets or particles. We designed illumination systems based on high-power light-emitting diode (LED) and incoherent laser devices capable of short, intense light pulses. We compared their characteristics and performance separately, as well as their interaction within a complete line-of-sight microscope imaging system. The optical design of the microscope setup was optimized via ray tracing simulations showing high energy losses for LED illumination compared to laser radiation, as confirmed experimentally. The energy transmission measurements provided guidance about the pulse energy density necessary to maximize camera response and signal-to-noise ratio. Characterization testing supported that both illumination systems are valid options for microscopy applications, with an advantage to LED for image quality and resolution performance, but a strong limitation to distance, where the multi-beam laser system demonstrated its superiority. [ABSTRACT FROM AUTHOR]

The recent availability of imaging sensors able to work in accumulation mode in the SWIR spectral range allows the realization of new efficient range-gated viewing systems. Such systems relax the illumination constraint so that the energy required to build an image can be distributed over several laser pulses. Semiconductor or fiber lasers can be used instead of high peak power solid state lasers. Such a system was realized in our laboratory, tested, and compared to a more classical flash system under outdoor conditions. In a first step, images of the same scenes recorded in the same weather conditions were compared to those recorded with a classical system working in flash mode. The MTF analysis shows an improvement of up to 40% with the system working in accumulation mode. In order to remove the influence of two different laser sources as well as of two different cameras, a second experiment was conducted. For this purpose, a shorter range and only one system were employed. Both operating modes, the flash and the accumulation mode, were examined. The second experiment confirms that accumulation mode can decrease significantly the value of the scintillation index resulting in a higher resistance to optical perturbations. These results increase the relevance of the accumulation mode for active imaging applications in the SWIR spectral region. [ABSTRACT FROM AUTHOR]

Transparent ceramics possess highly luminescent and safe for museum lighting and be considered excellent color converters for laser diode (LD) devices. However, the current LD lighting has a low color rendering index for the lack of red component that affects the original appearance of the artwork. Here, a series of Lu 3-x Gd x Al 5 O 12 :Ce3+, Mn2+ (x = 0–1.5) photoluminescent transparent ceramics were prepared with an improvement display index due to the red shift of emission spectrum, the emission peak of Ce3+ and Mn2+ has a red shift by 30 and 20 nm respectively. The transmittance of transparent ceramics is 70 % and the spectrum adjustable from 500 to 800 nm. Their photoluminescence property is retained at 96% of the initial value at 425 K when the doping of Gd3+ is 0.25. The color rendering index of the Lu 1.38 Gd 1.5 Al 5 O 12 :0.02Ce3+, 0.1Mn2+ can reached 81.5, while the correlated-color temperature is 3465 K. These characteristics show the LD system is promising for application in museum lighting. • Lu 3-x Gd x Al 5 O 12 :Ce3+,Mn2+ (x = 0–1.5) photoluminescent transparent ceramics were prepared. • The transmittance of transparent ceramics is 70% and the spectrum adjustable from 500 to 800 nm. • The color rendering index reached 81.5, the correlated-color temperature is 3465 K. [ABSTRACT FROM AUTHOR]

An experimental methodology was developed involving techniques that allow non-intrusive measurement of confined geogrid deformations and soil particle displacements under pullout loading condition, which together are expected to generate a comprehensive volume of data including the entire displacement field in both geogrid and surrounding soil. The techniques involve the use of transparent soil with laser-aided imaging, which allows visualization and facilitates subsequent evaluation of the load-transfer mechanisms that develop between soil particles and the different rib elements in geogrids. A laser beam was employed to track the transparent soil particles in a plane perpendicular to the soil-geogrid interface. The collimated laser beam produced well-defined individual particles in the selected plane of the soil model. Digital cameras were used to track the displacement fields of both the confined geogrid specimen and soil particles within the laser-illuminated plane. Digital image correlation as well as other image-processing techniques were used to define the displacement fields based on images captured during the tests. The field displacements resulting after processing the data gathered from the newly developed experimental system led to well defined manifestations of the load transfer mechanisms, including the deflection patterns in geogrid ribs and shear bands within the soil mass. [ABSTRACT FROM AUTHOR]

Highlights • The number of laser attacks on aircraft has increased during the last two decades. • STAMP and STPA were applied to an exemplary laser incident. • Countermeasures against laser attacks were assessed comprehensively. • Pilot's operational procedures are defined and established in practice quite well. • In reduced-crew operations procedures can be at least as safe as in multi-crew. Abstract Laser attacks in commercial aviation have become headline news worldwide and the frequency of incidents has increased. A review of the research regarding lasers in commercial aviation shows the need for a systematic analysis. By applying a hazard analysis of system theory (both STAMP and STPA) to a practical example it is possible to identify countermeasures and their current state of elaboration. Furthermore, this research considered the concept of reduced-crew operations, and the possible effects of laser strikes. Whereas the pilot operational procedures are established, the legislation lags behind for some nation states. Detection and prevention of lasers operating in the same area as aircraft is critical reduction of attacks. [ABSTRACT FROM AUTHOR]

Measurements of high-pressure sprays and particle fields in high-speed flows have been very challenging for the existing instrumentation. Deformed drops or solid particles significantly limit the range of experimental methods that can be applied for detailed, quantitative measurements. We developed advanced microscope imaging equipment and diagnostic methods to characterize fast-moving droplets or particles. We designed illumination systems based on high-power light-emitting diode (LED) and incoherent laser devices capable of short, intense light pulses. We compared their characteristics and performance separately, as well as their interaction within a complete line-of-sight microscope imaging system. The optical design of the microscope setup was optimized via ray tracing simulations showing high energy losses for LED illumination compared to laser radiation, as confirmed experimentally. The energy transmission measurements provided guidance about the pulse energy density necessary to maximize camera response and signal-to-noise ratio. Characterization testing supported that both illumination systems are valid options for microscopy applications, with an advantage to LED for image quality and resolution performance, but a strong limitation to distance, where the multi-beam laser system demonstrated its superiority.

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Dy 3+ doped fluoroborate (NCZLB) glass phosphors were designed and fabricated, and efficient photon releasing confirms the effectiveness of laser pumping. Quantitative characterization reveals that net emission powers and net emission photon numbers of 1.00 wt% Dy 2 O 3 doped NCZLB glass were identified to be 618.9 μW and 17.2 × 10 14 cps under the excitation of 453 nm laser with 15.81 mW power, respectively, and the quantum yield was solved to be 25.9%. Potential fluorescence color trace was presupposed by change of intensity ratio between residual laser and Dy 3+ emission, and pure white luminescence are expected when the intensity ratio reaches the appropriate range. Optimizing of size and doping concentration for the Dy 3+ -doped NCZLB glass phosphor achieves anticipated white lighting effect under blue laser excitation, and the luminous flux is up to 9.07lm. Effective white fluorescence depended on controllable photon releasing demonstrates that the Dy 3+ doped NCZLB glasses have promising application as laser-driven white light sources for solid-state illumination. [ABSTRACT FROM AUTHOR]

The autofocusing plays a crucial role in various industrial microscopic measurements. However, conventional autofocus methods involve axial scanning and are prone to inaccuracies caused by surface noises, such as defects and texture, making them both time-consuming and unreliable. In this work, a novel high-performance autofocus pipeline with laser illumination was introduced, namely Learning Split-image Prediction Model (LSPM), to accurately predict the defocus distance from a single split image. To effectively reduce the interference of the noises as foregrounds, a lightweight generation network was built to restore the incomplete split images. Furthermore, a new judgment mechanism for split images was proposed to identify the ideal focal plane of each focal stack. The experiment demonstrated LSPM outperforms the state-of-the-art methods, in terms of focusing accuracy, especially when the defocusing amount is relatively small, achieving only 1/15 depth of field. LSPM has the advantages of high accuracy, high speed, and robustness in industrial measurement. • A novel high-performance autofocus method with laser illumination was introduced, namely Learning Split-image Prediction Model (LSPM), which only used a single defocus split image to predict the defocus distance. • A lightweight generation network, namely Pix2pix Split-image-pattern Restoring Network (PSRN), was built to restore incomplete split images caused by complex foregrounds. • A new judgment mechanism for split images was proposed to identify the ideal focal plane of each focal stack. What is more, a paired dataset was made by these ideal focal planes to train the PSRN. [ABSTRACT FROM AUTHOR]

Illumination products using laser source have plenty of advantages, such as high conversion efficiency, more brightness, wide color gamut, long life and so on. However, due to the high energy density of laser, the optical radiation safety of laser used as illumination products should be studied and analyzed. First of all, the characteristics, advantages of laser used as illumination products are introduced. Then the international and national organizations, such as IEC/TC 76, IEC/TC 108, SAC/TC 284, are surveyed. In addition, standards and the corresponding relations related to laser used as illumination products are reviewed, especially for safety of laser products (IEC 60825) series standards, photobiological safety of lamps and lamp systems (IEC 62741) series standards, Audio/video, information and communication technology equipment ‐ Part 1: Safety requirements (IEC 62368‐1:2018), as well as ICNIRP guidelines. Finally, optical radiation safety of some specific illumination products using lasers are discussed. [ABSTRACT FROM AUTHOR]

The use of light pipes is an efficient and low-cost technique to get a homogeneous illumination for laser-gated viewing systems. However, this technique suffers from drawbacks when used with coherent sources like solid-state lasers. Compacting light pipe-based laser illuminators involves working with small light pipe sections, and experiments show that interference fringes appear on the laser illumination profiles. The principle of light pipe homogenization has been reviewed using geometrical optics to understand the phenomenon better, and a pragmatic light pipe design method, based on laser-gated viewing system parameters, is proposed. Another original solution based on optical stepper is studied to reduce both interference fringes and speckle noise to increase the homogeneity of laser illumination profiles. [ABSTRACT FROM AUTHOR]

The phase separation of a thin film of the binary composite of Ni and C60 has been studied using laser illumination of the sample through an array of pinholes (with a diameter of 10-µm and 60-µm × 80-µm spacing). The mesh with pinholes enabled splitting of the probing beam into an array of close-spaced laser micro-beams. The simultaneous illumination of the composite, with a set of micro-beams, resulted in a fast phase separation of the hybrid matter and an occurrence of unusual laser-induced periodic surface structures – a net of complex Ni and C allotropes (C60 and amorphous C) concentric rings and a fine array of the C60 – based islands, regularly distributed over the Ni + C60 thin film matrix. The results confirmed the high proclivity of the hybrid Ni + C60 composites to a correlated separation of the Ni and C-allotrope phases. [ABSTRACT FROM AUTHOR]