Circularly and elliptically polarized light under water and the Umov effect

Total internal reflection occurs when light is incident on the interface of high- and low-refractive-index materials at an angle greater than the critical angle. Sunlight with high degree of linear polarization, such as atmospheric scattered skylight, can be converted with a high efficiency up to 53% to circular and elliptical polarizations by total internal reflection under water in the region outside Snell's window. The degree of circular polarization is observed to be inversely dependent on the albedo of underwater objects and is shown to be a direct consequence of the Umov effect. Our results are important for underwater polarimetry, surveillance applications and studies of marine animals' polarized vision near the water-air interface.NSF [1607358]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Comets: Gases, ices, grains and plasma

The program and abstracts of the 97 papers delivered at the colloquium are presented. Cometary nuclei, comet dust, the coma, ion tails, several comet missions, and cometary origin and evolution were discussed

Plasmon-assisted direction-and polarization-sensitive organic thin-film detector

Utilizing Bragg surface plasmon polaritons (SPPs) on metal nanostructures for the use in optical devices has been intensively investigated in recent years. Here, we demonstrate the integration of nanostructured metal electrodes into an ITO-free thin film bulk heterojunction organic solar cell, by direct fabrication on a nanoimprinted substrate. The nanostructured device shows interesting optical and electrical behavior, depending on angle and polarization of incidence and the side of excitation. Remarkably, for incidence through the top electrode, a dependency on linear polarization and angle of incidence can be observed. We show that these peculiar characteristics can be attributed to the excitation of dispersive and non-dispersive Bragg SPPs on the metal–dielectric interface on the top electrode and compare it with incidence through the bottom electrode. Furthermore, the optical and electrical response can be controlled by the organic photoactive material, the nanostructures, the materials used for the electrodes and the epoxy encapsulation. Our device can be used as a detector, which generates a direct electrical readout and therefore enables the measuring of the angle of incidence of up to 60\ub0 or the linear polarization state of light, in a spectral region, which is determined by the active material. Our results could furthermore lead to novel organic Bragg SPP-based sensor for a number of applications

The rings of Saturn

The upcoming Mariner Jupiter-Saturn '77 space project is discussed. The variations in radar and radio observations are evaluated, along with particle distribution within the Saturn rings

Moon Water

Water was discovered on the Moon in October 2009 by the Chandrayaan-1 mission. The conditions on the Moon such as no atmosphere and low temperatures, made the water in the form of ice. The origins of this water were determined to be meteorites and winds. The location of the water was determined to be affected by the diurnal cycle and cold traps in craters. The goals of this report were to estimate the amount of water ice present on the Moon, the location and to detail methods to obtain this water for human use. It was calculated that approximately 3.76 X 10^12 grams of water ice is present within the cold traps of the permanently shadowed regions at the lunar poles

The Voyager flights to Jupiter and Saturn

The results of the mini-Grand Tour to Jupiter and Saturn by the Voyager 1 and 2 spacecraft are highlighted. Features of the spacecraft are depicted including the 11 instruments designed to probe the planets and their magnetic environments, the rings of Saturn, the fleets of satellites escorting the planets, and the interplanetary medium. Major scientific discoveries relating to these phenomena are summarized

Das beobachtbare Erscheinungsbild von Trümmerscheiben

Debris disks are dusty circumstellar disks around main-sequence stars and natural by-products of the planet formation process. With an almost gas-free environment, dust-replenishing parent bodies orbit their host star and most likely continuously supply fine dust through mutual collisions. Thus, debris disks comprise solids ranging from kilometer-sized planetesimals down to micrometer-sized dust. Due to the large surface to volume ratio, dust grains are efficient radiators of thermal re-emission and scatterers of incident radiation from the stellar source. Dust grains are, therefore, readily detectable in a planetary system. Consequently, debris disk observables mainly depend on dust properties and the disk structure, as well as stellar properties. In this dissertation, an observational appearance of debris disks is investigated. This allows the verification of predictions made concerning the spatial structure, underlying dynamical processes, and optical properties of the dust in the debris disk system. In particular, the potential for multi-wavelength and spatially resolved observations in numerical studies are conducted to constrain the observational appearance of debris disks with the physical properties and dynamics of dust grains. To develop observational strategies of disk observations, a new tool has been developed for analytical modeling of debris disks and the interpretation of results from the collisional approach. The dependence of the observational appearance of debris disks on essential collisional parameters, such as the eccentricity of the parent belt, the dispersion of the eccentricities of parent belt bodies, and the critical specific energy for fragmentation of dust particles, is investigated. Furthermore, the feasibility of detecting water ice in typical debris disk systems, assuming various ice destruction mechanisms and dust mixtures with various internal structures, is investigated. Additionally, the multi-wavelength modeling of debris disks in η Chameleontis cluster is investigated to constrain the physical parameters and properties of the disks, such as the range of possible radial locations and total dust mass, based on observation from the APEX/LABOCA and the archival Gaia/DR2 data. Finally, a model based on a planetesimal mass distribution function is investigated to discuss the flattening of the spectral energy distribution of HD 107146 at mm wavelength with the NIKA2 observation

NASA Tech Briefs, December 1989

Topics include: Electronic Components and Circuits. Electronic Systems, Physical Sciences, Materials, Computer Programs, Mechanics, Machinery, Fabrication Technology, Mathematics and Information Sciences, and Life Sciences

Modern Observational Techniques for Comets

Techniques are discussed in the following areas: astrometry, photometry, infrared observations, radio observations, spectroscopy, imaging of coma and tail, image processing of observation. The determination of the chemical composition and physical structure of comets is highlighted