Light scattering by bubbles in liquids: comments and application of results to circularly polarized incident light

1983 ◽  
Vol 40 (1) ◽  
pp. 3-5 ◽  
Author(s):  
Philip L. Marston
1995 ◽  
Vol 60 (11) ◽  
pp. 1875-1887 ◽  
Author(s):  
Jaroslav Holoubek ◽  
Miroslav Raab

Theoretical background for an optical method is presented which makes it possible to distinguish unambiguously between voids and particles as light scattering sites in polymeric materials. Typical dependences of turbidity as a function of diameter of scattering elements, their volume fractions and also turbidity curves as a function of the wavelength of the incident light were calculated, based both on the Lorenz-Mie theory and the fluctuation theory. Such dependences calculated for polypropylene-containing voids on the one hand and particles, differing only slightly from the surrounding matrix in their refractive index, on the other hand, are markedly different. The most significant results are: (i) Turbidity is at least by two orders of magnitude larger for voids in comparison to embedded particles of ethylene-propylene (EPDM) rubber of the same size, concentration and at the same wavelength. (ii) The wavelength dependence of turbidity for EPDM particles and the inherent refractive index fluctuations in the polypropylene matrix is much steeper as compared to voids for all considered diameters (0.1-10 μm). Thus, the nature of stress whitening in complex polymeric materials can be determined from turbidity measurements.


2022 ◽  
Author(s):  
Atefeh Fazel Najafabadi ◽  
Baptiste Auguié

The optical properties of nanoparticle clusters vary with the spatial arrangement of the constituent particles, but also the overall orientation of the cluster with respect to the incident light. This...


The iridescent cuticle of certain Rutelino scarab beetles, which is a form optically active and selectively reflects circularly polarized light, incorporates an NH 4 OH -extractable component The ultraviolet absorption spectrum of this component, together with its chromatographic and refractive properties, identify it as uric acid (2,6,8-trihydroxypurine). All species of Plusiotis examined have uric acid in their reflecting layers, as do several species of Anoplognathus. Plusiotis resplendens has a reflecting layer with a uric acid volume fraction of 0.7, P . optima a volume fraction of 0.6. The reflecting layer of P . resplenden s has an anticlockwise helicoidal architecture, the optical thickness of the helicoidal p itch being such that it constructively interferes with visible light wavelengths. An anticlockwise helicoid constructively interferes with only the left circularly polarized component of incident light, right circularly polarized light being transmitted without attenuation. P. resplendens has a 1.8 /xm thick unidirectional layer embedded within the helicoid which functions as a perfect halfwave retardation plate for wavelength 590 nm . This halfwave plate enables the helicoidal reflector in this species to reflect both left and right circularly polarized components of incident light. After passing through the halfwave plate, transmitted right circularly polarized light becomes left circularly polarized ; this light is now reflected and emerges from the cuticle right circularly polarized, after passing back through the halfwave plate. Consequently the total reflectivity of circularly polarized incident light is greater in P. resplendens than in any other species examined; the plate also reduces multiple internal reflexions. Interferometric analysis of the refractive properties of the helicoidal reflectors in species of Plusiotis showed that the ordered incorporation of uric acid increases the birefringence of the system by a factor of five times, e.g. the in tact birefringence of the unidirectional layer of P . resplendens is 0.166 at wavelength 560 nm ; after uric acid extraction the birefringence is reduced to 0.034. As the coefficient of reflexion of a helicoidal reflector is directly proportional to the birefringence of the individual planes comprising the helicoid, beetles incorporating uric acid into their reflecting surfaces reflect circularly polarized light far more efficiently than beetles lacking uric acid. Refractive index values for a single multicomponent plane of the helicoid have been summarized as a biaxial indicatrix, with the Z axis tilte dat 45° to the plane of the epicuticle. Beetle reflecting layers which incorporate uric acid have twenty times greater optical rotatory power compared with reflecting layers lacking this component. Mathematical treatments dealing with helicoidal reflectors predict the form optical rotatory power to be a function of the square of the birefringence, which is in agreement with the experimental observations. To enable uric acid to have the optical effects mentioned above, an epitaxial incorporation into the helicoidal framework is necessary. Although uric acid is a common cytoplasmic reflecting material in arthropods, this is the first record of its presence in an extracellular (cuticular) reflector.


1977 ◽  
Vol 1977 (1) ◽  
pp. 153-156 ◽  
Author(s):  
Bruce Friedman

ABSTRACT Light scattering techniques are used in several oil-in-water monitors, proposed or in existence. Particulate matter which may interfere with these monitors is also frequently found in oily wastes. An analysis is made of the potential of using measurements of the angular intensity distribution of scattered light in conjunction with determination of the state of polarization of the scattered light for discriminating between oil and particulates. The size conditions which apply to the oil droplets and particulates relative to the incident light allow the scattered light angular intensity distribution to be treated as a consequence of a combination of classical diffraction and of geometrical refraction and reflection. The state of polarization of the scattered light for oil droplets is investigated using expressions for the electric field which are approximations to the expressions of the Mie theory. For the particulate matter, the state of polarization is probed on the basis of light reflected from a plane. It is found that it would be difficult to discriminate between oil and particulates using measurements of the angular intensity distribution of scattered light even in conjunction with the determination of the state of polarization of the scattered light in a real life situation.


2009 ◽  
Vol 1208 ◽  
Author(s):  
Erdem Ogut ◽  
Gullu Kiziltas ◽  
Kursat Sendur

AbstractWith advances in nanotechnology, emerging plasmonic nano-optical applications, such as all-optical magnetic recording, require circularly-polarized electromagnetic radiation beyond the diffraction limit. In this study, a plasmonic cross-dipole nano-antenna is investigated to obtain a circularly polarized near-field optical spot with a size smaller than the diffraction limit of light. The performance of the nano-antenna is investigated through numerical simulations. In the first part of this study, the nano-antenna is illuminated with a diffraction-limited circularly-polarized radiation to obtain circularly polarized optical spots at nanoscale. In the second part, diffraction limited linearly polarized radiation is used. An optimal configuration for the nano-antenna and the polarization angle of the incident light is identified to obtain a circularly polarized optical spot beyond the diffraction limit from a linearly polarized diffraction limited radiation.


2016 ◽  
Author(s):  
Dongsheng Chen ◽  
Nan Zeng ◽  
Yunfei Wang ◽  
Honghui He ◽  
Valery V. Tuchin ◽  
...  

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