Incoherent Radiation Research Articles

Effects of the Interaction of Microwave Radiation with the Atmosphere on the Passive Remote Sensing of the Earth’s Surface: Problems and Solutions (Review)

The main problems in the remote passive location of positions on the Earth’s surface are reviewed in detail. The first is related to the source of incoherent microwave radiation represented by a layer of two-temperature nonequilibrium ionospheric plasma at an altitude of ca. 80–110 km, which is located below a low Earth-orbiting satellite and formed under the influence of solar activity. As a result, the satellite receives direct radiation from this layer as well as reflected radiation from the Earth’s surface. The next problem is the attenuation of the intensity of the incident radiation as a result of the scattering of radio waves by charged aerosol layers located below the luminous layer. Aerosol particles are affected by solar and cosmic radiation and electronic and ionic attacks, due to which they become charged. Aerosol particles directly take part in the formation of a complete balance of charges in the atmosphere and are an effective catalyst for many physicochemical processes in neutral gaseous media. The processes related to the formation of aerosol particles, the kinetics of formation of their charge, and the processes of their interaction with incoherent microwave radiation are considered. This gives rise to the need to develop a fundamentally new scheme of passive location. Three possible versions of the arrangement of measurements are analyzed. In the first version, a complete set of measurements is implemented when the receiving equipment is simultaneously installed on the Earth, an aircraft, and a low Earth-orbiting satellite; in the second version, the receiving equipment is simultaneously installed on an aircraft and a satellite; in the third version, only on one satellite. The separation of the contributions of direct and reflected incoherent radiation received by the satellite can be achieved only using a special mathematical approach to the information processing (wavelet analysis), which has been under actively development in recent years. We fully show its broad possibilities for solving geophysical problems and discuss the problems of the calibration of the measuring equipment, which are associated with taking into account the superposition of two types of radiation coming to a satellite and with variation of the main parameters (concentration, flux density, and temperature of electrons) of the nonequilibrium two-temperature plasma in time.

A theoretical model of fuselage pressure levels due to fan tones radiated from the intake of an installed turbofan aero-engine.

An existing theoretical model to predict the pressure levels on an aircraft's fuselage is improved by incorporating a more physically realistic method to predict fan tone radiation from the intake of an installed turbofan aero-engine. Such a model can be used as part of a method to assess cabin noise. Fan tone radiation from a turbofan intake is modelled using the exact solution for the radiated pressure from a spinning mode exiting a semi-infinite cylindrical duct immersed in a uniform flow. This approach for a spinning duct mode incorporates scattering/diffraction by the intake lip, enabling predictions of the radiated pressure valid in both the forward and aft directions. The aircraft's fuselage is represented by an infinitely long, rigid cylinder. There is uniform flow aligned with the cylinder, except close to the cylinder's surface where there is a constant-thickness boundary layer. In addition to single mode calculations it is shown how the model may be used to rapidly calculate a multi-mode incoherent radiation from the engine intake. Illustrative results are presented which demonstrate the relative importance of boundary-layer shielding both upstream and downstream of the source, as well as examples of the fuselage pressure levels due to a multi-mode tonal source at high Helmholtz number.

Shedding (Incoherent) Light on Quantum Effects in Light-Induced Biological Processes.

Light-induced processes that occur in nature, such as photosynthesis and photoisomerization in the first steps in vision, are often studied in the laboratory using coherent pulsed laser sources, which induce time-dependent coherent wavepacket molecule dynamics. Nature, however, uses stationary incoherent thermal radiation, such as sunlight, leading to a totally different molecular response, the time-independent steady state. It is vital to appreciate this difference in order to assess the role of quantum coherence effects in biological systems. Developments in this area are discussed in detail.

Multipoint-projection x-ray microscopy

Point projection is a mature geometry of x-ray imaging that is implemented in scientific and industrial applications. Objects to be imaged are placed near a microscopic x-ray source, and the magnification is accomplished by x-ray propagation towards a distant detector. The source size is a trade-off between the signal level and the spatial resolution. In this work, we demonstrate multipoint-projection x-ray imaging realized with an x-ray tube and compound structured microcapillary optics that generates nearly one thousand submicrometer secondary x-ray sources. The generated microbeams are multiplexed at the object. Demultiplexing of the transmitted beams, magnification, and phase contrast are achieved by the free-space propagation. A massive improvement in the signal-to-noise ratio, relative to a single secondary source, was achieved without a loss in spatial resolution. Hence, x-ray projections of highly absorbing samples at submicrometer spatial resolution could be recorded with only a few photons per detector pixel. For weakly absorbing samples, the multipoint-projection method enabled us to record, in a parallel way, replicated in-line x-ray holograms with incoherent radiation from an x-ray tube. Our method may enrich the panel of x-ray nanoscale imaging techniques and may be adopted for on-chip x-ray photonic devices.

Distribution of Solar Energy in Optical, Radio and X-ray Region Due to Solar Flare on 15th April 2017

We analyzed solar burst type III occurred on 15th of April 2017 and compare with optical and X-ray region using the high time resolution hard-X-ray data from space weather and 45 MHz-85 MHz dynamic spectra from CALLISTO network. The eruption mechanism of solar flares and type III has been observed intermittently in the last a few hours since 09:30 UT. The burst consequences from the ejection of plasma oscillations localized disturbance due to excited in the plasma frequency incoherent radiations such as gyro synchrotron and free–free emissions. Significant results of the flaring becoming more intense at 3:00 UT. During this event, the electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 1427 pfu. Solar wind speed reached a peak of 375 km/s at 14/2246Z. Total IMF reached 6 nT at 14/2123Z with 73 sfu of radio flux. The electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 1427 pfu. It was found that radiation from the flare created waves of ionization in the upper atmosphere over Asia and Australia and possibly HF radio blackouts at high latitudes. We believed these data represent the first direct evidence of high-speed flows will be exploded on 20th April 2017 due to this pattern of eruption.

Highly Uniform White Light-Based Visible Light Communication Using Red, Green, and Blue Laser Diodes

With the development of wireless optical communication and solid-state lighting, the high efficiency, large bandwidth, and high uniform white light source becomes more and more important. In this paper, a white light source generated by red, green, and blue laser diodes (RGB LDs) was synthetized according to the calculated power ratio of RGB LDs based on the chromaticity theory. The high coherence of the lasers normally leads to the nonuniform white light. Thus, it is to improve the illumination quality of the lighting source by employing micro lens for the purpose of homogenization. The simulation results showed that the uniformity of the white light incoherent radiation was above 90% which proves that the coherence of the lasers was destroyed. In addition, the photoelectric parameters of the RGB-LD mixed white light after homogenization was characterized. Meanwhile, the modulation bandwidth of RGB LDs before and after homogenization was analyzed, respectively, and it shows that the bandwidth was more than 1 GHz, which is limited by the photodetector cut-off frequency. Such a high-uniformity and high-speed RGB-LD mixed white light can be deployed for illumination and wireless communication simultaneously.

Quantitatively consistent computation of coherent and incoherent radiation in particle-in-cell codes—A general form factor formalism for macro-particles

Quantitative predictions from synthetic radiation diagnostics often have to consider all accelerated particles. For particle-in-cell (PIC) codes, this not only means including all macro-particles but also taking into account the discrete electron distribution associated with them. This paper presents a general form factor formalism that allows to determine the radiation from this discrete electron distribution in order to compute the coherent and incoherent radiation self-consistently. Furthermore, we discuss a memory-efficient implementation that allows PIC simulations with billions of macro-particles. The impact on the radiation spectra is demonstrated on a large scale LWFA simulation.

Ultrabroadband Nanospectroscopy with a Laser-Driven Plasma Source

Scattering-type scanning near-field optical microscopy (s-SNOM) enables infrared spectroscopy at 10–20 nm spatial resolution through elastic light scattering. Coupled with an infrared light source, s-SNOM characterizes chemical compositions or probes nanoscale photonic phenomena on length scales 2 orders of magnitude below the diffraction limit. However, widespread use of s-SNOM as an analytical standard tool has been restrained to a large extent by the lack of a bright and affordable broadband light source. Here we present a turnkey thermal emitter based on a laser-driven plasma that offers incoherent radiation of a broader bandwidth (>1000 cm–1) and ∼40-fold higher brilliance than previous blackbody radiators in addition to a compact size and at a fraction of the cost of alternative coherent laser systems or synchrotrons. We demonstrate a nearly 1 order of magnitude increase in signal-to-noise in near-field spectra compared to existing incoherent emitters, which allows probing of not only inorganic mate...

Methods of total spectral radiant flux realization at VNIIOFI

VNIIOFI carries out works on realization of independent methods for realization of the total spectral radiant flux (TSRF) of incoherent optical radiation sources - reference high-temperature blackbodies (BB), halogen lamps, and LED with quasi-Lambert spatial distribution of radiance. The paper describes three schemes for measuring facilities using photometers, spectroradiometers and computer-controlled high class goniometer. The paper describes different approaches for TSRF realization at the VNIIOFI National radiometric standard on the basis of high-temperature BB and LED sources, and gonio-spectroradiometer. Further, they are planned to be compared, and the use of fixed-point cells (in particular, based on the high-temperature δ(MoC)-C metal-carbon eutectic with a phase transition temperature of 2583 °C corresponding to the metrological optical “source-A”) as an option instead of the BB is considered in order to enhance calibration accuracy.

Does Light from Steady Sources Bear Any Observable Imprint of the Dispersive Intergalactic Medium?

Abstract There has recently been some interest in the prospect of detecting ionized intergalactic baryons by examining the properties of incoherent light from background cosmological sources, namely quasars. Although the paper by Lieu et al. proposed a way forward, it was refuted by the later theoretical work of Hirata & McQuinn and the observational study of Hales et al. In this paper we investigate in detail the manner in which incoherent radiation passes through a dispersive medium both from the frameworks of classical and quantum electrodynamics, leading us to conclude that the premise of Lieu et al. would only work if the pulses involved are genuinely classical ones containing many photons per pulse; unfortunately, each photon must not be treated as a pulse that is susceptible to dispersive broadening. We are nevertheless able to change the tone of the paper at this juncture by pointing out that because current technology allows one to measure the phase of individual modes of radio waves from a distant source, the most reliable way of obtaining irrefutable evidence of dispersion, namely via the detection of its unique signature of a quadratic spectral phase, may well be already accessible. We demonstrate how this technique is only applied to measure the column density of the ionized intergalactic medium.

Secular versus nonsecular Redfield dynamics and Fano coherences in incoherent excitation: An experimental proposal

Two different Master Equation approaches have been formally derived to address the dynamics of open quantum systems interacting with a thermal environment (such as sunlight). They have led to two different physical results: non-secular equations that show noise-induced (Fano) coherences and secular equations that do not. An experimental test for the appearance of non-secular terms is proposed using Ca atoms in magnetic fields excited by broadband incoherent radiation. Significantly different patterns of fluorescence are predicted, allowing for a clear test for the validity of the secular and non-secular approach and for the observation of Fano coherences.

Экспериментальная ячейка приемника радиосвета

AbstractThe problem of creating a receiver for incoherent microwave radiation from sources realized on the basis of ultra-wideband oscillators of chaotic oscillations and objects and surfaces “illuminated” by these sources has been considered. The structure of the device is proposed, the experimental sample is described, and its ability to register sources of incoherent microwave radiation with an integrated output power of ~2 mW at a distance of more than 100 m is shown.

A non-coherent holographic correlator based on a digital micromirror device

The possibility of application of a digital micromirror device (DMD) as a spatial light modulator for outputting holographic filters in an optical correlator illuminated by quasi-monochromatic spatially incoherent radiation was discussed. The experimental setup of the optical correlator was assembled using a one-lens scheme. Experiments on the recognition of test objects with the synthesized dynamic holographic filters being output onto the DMD were performed. The results obtained allow one to conclude that object recognition can be successfully performed using the proposed scheme of a non-coherent correlator containing a digital micromirror device.

Using Scattered Radiation Method in element analysis of sediments by total reflection X-ray fluorescence

A technique for determining Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr and Ba in sediments by total reflection X-ray fluorescence (TXRF) was proposed. Sample preparation procedure consisting of suspending 20 mg of powdered sample in 2 ml of a 0.5% methylcellulose solution and depositing a volume 10 µL of a slurry on the reflector showed to be the most suitable. The sample preparation error did not exceed 10% for most analytes. In order to calculate the concentration of the elements, scattered radiation method was used where the analytical parameter was the ratio between the intensity of the analytical line and the intensity of the scattered incoherent radiation of the MoKα line. Using the intensity of the scattered incoherent radiation allowed taking into the account the variations in the surface density of the dried sample on the reflector. To control accuracy, certified “BIL-1” and “SGH-1” reference materials were used. It was shown that the scattered radiation method does not concede with the internal standard method widely used in TXRF and provides better results than the internal standard method in most cases. The TXRF results obtained for the sediment samples were compared to the results obtained by a conventional X-ray fluorescence spectrometer. It was shown that the changes in the element content along with the core depth obtained by both methods, were consistent and had a common tendency. Key words : X-ray fluorescence analysis, XRF, total reflection X-ray fluorescence, TXRF, sediments, methylcellulose, internal standard, scattered radiation method (Russian) DOI: http://dx.doi.org/10.15826/analitika.2018.22.2.004 G.V. Pashkova 1,2 , М . М . Mukhamedova 1,2 , Т .S. Aisueva 3 , А .L. Finkelshtein 1,3 , А . А . Shchetnikov 1,4 1 Institute of the Earth’s Crust, SB RAS, Lermontov st., 128, Irkutsk, 664033, Russian Federation 2 Irkutsk State University,1 K. Marx St., Irkutsk, 664003, Russian Federation 3 Vinogradov Institute of Geochemistry, SB RAS, Favorsky st., 1A, Irkutsk , 664033, Russian Federation 4 Irkutsk Scientific Center, SB RAS, Lermontov st., 134, Irkutsk, 664033, Russian Federation

On contrast of biological X-ray nanomicroscopy

We analyse the absorption contrast of histological and cytological preparations, which can be achieved in nanomicroscopic studies using monochromatic radiation in the spectral range of 90 – 600 eV (14 – 2 nm). Two types of unstained biological objects are considered: untreated and fixed in paraffin, and optimum wavelengths are determined for the study of samples with a thickness of 0.5 – 10 μm with a spatial resolution of 100 – 20 nm. Taking into account the efficiency of X-ray optics, the number of source photons required to produce a single image is estimated. It is shown that the greatest interest for the study of fixed objects represents the spectral region of 7 – 14 nm, for which, on the basis of rapidly developing compact sources of incoherent and coherent radiation and effective optics, microscopes for scientific and clinical research can be designed.

Mathematical Modeling of Optical Radiation Emission as a Function of Welding Power during Gas Shielded Metal Arc Welding.

Arc welding is accompanied by intense optical radiation emission that can be detrimental not only for the welder himself but also for people working nearby or for passersby. Technological progress advances continuously in the field of joining, so an up-to-date radiation database is necessary. Additionally, many literature irradiance data have been measured for a few welding currents or for parts of the optical spectral region only. Within this paper, a comprehensive study of contemporary metal active gas, metal inert gas, and cold metal transfer welding is presented covering optical radiation emission from 200 up to 2,700 nm by means of (spectro-) radiometric measurements. The investigated welding currents range from 70 to 350 A, reflecting values usually applied in industry. Based upon these new irradiance data, three mathematical models were derived in order to describe optical radiation emission as a function of welding power. The linear, exponential, and sigmoidal emission models depend on the process variant (standard or pulsed) as well as on the welding material (mild and stainless steel, aluminum). In conjunction with the corresponding exposure limit values for incoherent optical radiation maximum permissible exposure durations were calculated as a function of welding power. Typical times are shorter than 1 s for the ultraviolet spectral region and range from 1 to 10 s for visible radiation. For the infrared regime, exposure durations are of the order of minutes to hours. Finally, a validation of the metal active gas emission models was carried out with manual arc welding.

Potential Energies of the Orbitally Degenerate Atmospheric Rydberg Complexes

A method was developed for calculating the vibronic potential energy surfaces (PESs) of atmospheric complexes consisting of orbitally degenerate Rydberg nitrogen and oxygen molecules and the molecules of a neutral medium in the ground electronic state. The degenerate states are formed as a result of l-mixing in the D and E layers of the atmosphere during the periods of increased solar activity. The complexes are populated in the nonequilibrium two-temperature plasma and are responsible for the incoherent additional background radiation in the decimeter (microwave) and terahertz (IR) bands at an altitude of 80–110 km from the Earth’s surface. To describe the interaction of a weakly bound electron with a singly charged molecular ion and a neutral molecule of a gas medium, the formalism of the multichannel quantum defect (MCD) theory was used. Quantum-chemical calculations of the dependences of the scattering lengths, polarizabilities, and quadrupole moments of the main atmospheric molecules N2 and O2 on the interatomic distance were performed. The specific features of the behavior of vibronic PESs of Rydberg complexes for large values of the principal quantum number (n ≫ 1) were analyzed. The vibronic PESs of orbitally degenerate states were constructed. They are necessary for determining the positions and shape of the vibronic minima of the l-mixing cross sections of the N2 and O2 Rydberg molecules in the D and E layers of the Earth’s atmosphere, where the delay times of satellite positioning signals should be minimum. The possibility of “quantum chaos” appearing in the Rydberg complexes at sufficiently large n values and angular momenta of the weakly bound electron was noted.

Unified Analysis for Calculating the Incoherent Spontaneous Emission of Cooperative Radiations**Supported by the ASRT-INFN Joint Project between the Academy of Scientific Research and Technology in Egypt and INFN in Italy.

A unified analysis is presented to calculate the incoherent spontaneous power of cooperative radiations based on self-amplified spontaneous emission. Using quantum mechanical tools, we derive analytical expressions for the incoherent spontaneous power of undulator and Cherenkov free-electron lasers (FELs). The undulator and Cherenkov FELs are considered as two different examples for the radiation that accumulate cooperatively. In the case of the undulator FEL, we show an excellent agreement between an expression for the incoherent radiation power derived in the present work and that obtained using a completely different approach [Phys. Rev. E 65 (2002) 026501]. For the Cherenkov radiation, we demonstrate a satisfactory agreement between the incoherent power predicted in our analysis and previous experimental results.

Ultraviolet germicidal efficacy as a function of pulsed radiation parameters studied by spore film dosimetry

Disinfection by pulsed ultraviolet (UV) radiation is a commonly used method, e.g. in industry or medicine and can be carried out either with lasers or broadband UV radiation sources. Detrimental effects to biological materials depending on parameters such as pulse duration τ or pulse repetition frequency fp are well-understood for pulsed coherent UV radiation, however, relatively little is known for its incoherent variant. Therefore, within this work, it is the first time that disinfection rates of pulsed and continuous (cw) incoherent UV radiation studied by means of spore film dosimetry are presented, compared with each other, and in a second step further investigated regarding two pulse parameters. After analyzing the dynamic range of the Bacillus subtilis spore films with variable cw radiant exposures H=5–100Jm−2 a validation of the Bunsen-Roscoe law revealed its restricted applicability and a 28% enhanced detrimental effect of pulsed compared to cw incoherent UV radiation. A radiant exposure H=50Jm−2 and an irradiance E=0.5Wm−2 were found to be suitable parameters for an analysis of the disinfection rate as a function of τ=0.5–10ms and fp=25–500Hz unveiling that shorter pulses and lower frequencies inactivate more spores. Finally, the number of applied pulses as well as the experiment time were considered with regard to spore film disinfection.

COMPLEX APPLICATION OF POLYCHROMATIC INCOHERENT RADIATION AND SURFACE ENZYME-ACTIVE PUMP TISSUE PAM-T IN THE PURULENT PROCESSES OF THE MAXILLOFACIAL REGION

The results of complex application of polychromatic incoherent radiation and surface enzyme-active pump tissue PAM-T in purulent processes of the maxillofacial region are reflected. Studies were carried out on 120 patients with suppurative processes of the maxillofacial region. The authors proved that the complex of polychromatic incoherent radiation and PAM-T in purulent processes of the maxillofacial region has a pronounced anti-inflammatory, analgesic and anti-edematous effects, more pronounced compared with the use of polychromatic incoherent radiation and especially standard treatment, which is confirmed by the coping of all the main complaints and objective signs of the disease and the data of the clinic boron research.