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Borate
Published in S. K. Omanwar, R. P. Sonekar, N. S. Bajaj, Borate Phosphors, 2022
Light is absorbed when it passes through the atmosphere and at the same time it undergoes scattering process. One of the mechanisms for light scattering in the atmosphere is known as Rayleigh scattering, which is caused by molecules in the atmosphere. Rayleigh scattering is particularly effective for short wavelength light since it has λ−4 dependence. Other than the Rayleigh scattering, aerosols and dust particles contribute to the scattering of incident light known as Mie scattering. Scattered light is undirected and it appears to be coming from any region of the sky. This light is called diffuse light. Since diffuse light is primarily “blue” light, the light that comes from regions of the sky other than where the sun is, appears blue. In the absence of scattering in the atmosphere, the sky would appear black, and the sun would appear as a disk light source. On a clear day, about 10% of the total incident solar radiation is diffused.
Radiometry and Photometry
Published in Antoni Rogalski, Zbigniew Bielecki, Detection of Optical Signals, 2022
Antoni Rogalski, Zbigniew Bielecki
The scattering process causes a redirected radiation beam to propagate in various directions away from the original direction [9]. There are three main types of scattering: Rayleigh, Mie and non-selective. The scattering type depends on a relationship between both scattering particles’ size and the wavelength of the propagating light. Rayleigh scattering is caused by particles with a size much smaller than the light wavelength. In this case, the scattering intensity decreases with the wavelength as ~λ-4. When the particle size is comparable or as large as a radiation wavelength, Mie scattering is observed. Non-selective scattering occurs for a particle with a size larger than the beam wavelength. In this case, Mie theory is approximated by the principles of reflection, refraction and diffraction. The scattering coefficient depends on the concentration Nscat and the effective cross section parameters σscat of the particles and can be described byβscat=σscatNscat.
Particles and Radiation
Published in Rob Appleby, Graeme Burt, James Clarke, Hywel Owen, The Science and Technology of Particle Accelerators, 2020
Rob Appleby, Graeme Burt, James Clarke, Hywel Owen
where λ is the wavelength of the incident/scattered radiation. We use the subscript R since this cross section (and the phenomenon that goes with it) is known as Rayleigh scattering. We see that shorter wavelengths are scattered much more than longer wavelengths. Consider the scattering of visible photons in air, which is an example of Rayleigh scattering. The relative rate of scattering of e.g. red and blue photons is given by (λredλblue)4≃(780nm390nm)4=16.
Preconceptual Design of Multifunctional Gas-Cooled Cartridge Loop for the Versatile Test Reactor: Instrumentation and Measurement—Part II
Published in Nuclear Science and Engineering, 2022
Piyush Sabharwall, Kevan Weaver, N. K. Anand, Chris Ellis, Xiaodong Sun, Hangbok Choi, Di Chen, Rich Christensen, Brian M. Fronk, Joshua Gess, Yassin Hassan, Igor Jovanovic, Annalisa Manera, Victor Petrov, Rodolfo Vaghetto, Silvino Balderrama-Prieto, Adam J. Burak, Milos Burger, Alberto Cardenas-Melgar, Daniel Orea, Reynaldo Chavez, Byunghee Choi, Londrea Garrett, Genevieve L. Gaudin, Noah Sutton, Ken William Ssennyimba, Josh Young
Fiber sensors for measuring distributed strain (and temperature) generally rely on an interferometry technique. Light (from either a tunable laser or broadband source) is sent into the fiber under test. Rayleigh scattering is an elastic scattering of light due to the presence of scattering sites that are much smaller than the wavelength of the light. In an elastic scattering process, the wavelength is conserved, and only direction changes. The scattering amplitude is inversely proportional to the wavelength to the fourth power λ−4. This implies that shorter-wavelength light is scattered more intensely. Scattering sites in fiber-optic cables arise due to microscopic local density differences or other inhomogeneity arising from the fiber manufacturing process. When light is transmitted through the cable, some fraction is scattered in a direction 180 deg to the propagation axis (Rayleigh backscatter) and can be analyzed as it returns to the source. Backscattered light is then detected, and changes in the backscattered characteristics can be used to understand quasi-local strain and, in turn, temperature.
The unique asymmetric nano-cluster formation by the uneven hockey-stick-shaped mesogen based on 1,3,4-oxadiazole in Langmuir–Blodgett thin film
Published in Journal of Dispersion Science and Technology, 2022
Alpana Baidya, Bandana Das, Santanu Majumder, Sandip K. Saha, Ranendu K. Nath, Manoj K. Paul
When a photon interacts with a particle it scatters, that is, reflection, refraction, or diffraction. The elastic collision generates two types of scattering, the Rayleigh scattering, and the Mie scattering, depending on the size of the particles. The Rayleigh scattering happens when the particle size is very minute, below the one-tenth of the wavelength of incident radiation and it remains below 50 nm, like air molecules, because the visible light is between 400 and 700 nm. The amount of light that is scattered in Rayleigh scattering is expressed as the extinction coefficient, Q, which is proportional to the ratio between the radius of the particle and the wavelength. The forward and backscattering are almost equal. But Mie scattering occurs when the particle diameter is one-tenth or the full size of the wavelength of incident radiation. Most of the scattering is in the forward direction and little in the backward direction.[25] In Mie scattering the extinction coefficient, Q depends on
Crack monitoring in reinforced concrete beams by distributed optical fiber sensors
Published in Structure and Infrastructure Engineering, 2021
Carlos G. Berrocal, Ignasi Fernandez, Rasmus Rempling
Raman scattering arises from the thermal vibration of the glass molecules in the fiber core as light travels through the fiber and is highly sensitive to temperature variations (Rodriguez, Casas, & Villalba, 2015b). Brillouin scattering is produced by the interaction of backscattered light and acoustic waves generated when changes in the density of the material occur as a result of thermal effects. Brillouin scattering is sensitive to external changes of both mechanical strain and temperature and despite its measuring range can reach lengths of up to more than 300 km (Gyger, Rochat, Chin, Niklès, & Thévenaz, 2014), the spatial resolution that can be achieved is often limited to several centimetres (Güemes, Fernández-López, & Soller, 2010). Rayleigh scattering, on the other hand, refers to the elastic distribution of light in all directions that happens when light interferes with local inhomogeneities in the fiber core that are smaller than the wavelength of the light itself. These inhomogeneities are caused by fluctuations in the density and composition of the fiber core, which makes Rayleigh scattering sensitive to both mechanical strain and temperature changes (Palmieri, 2013). Systems based on Rayleigh scattering are currently limited to a measuring range of up to 2 km, but in exchange they provide an unprecedented spatial resolution that can go down to the the sub-millimetric scale, thereby offering new possibilities for the development of damage detection systems (Rodriguez et al., 2015b).