A detail diagram for the phenomena of convergent polarized light passing through a uniaxial crystal

1995 ◽  
Vol 26 (2) ◽  
pp. 65-66
Author(s):  
Chen Mao-Ding
2010 ◽  
Vol 39 (8) ◽  
pp. 1481-1486
Author(s):  
万玲玉 WAN Ling-yu ◽  
谷巍 GU Wei ◽  
班卫华 BAN Wei-hua ◽  
刘立人 LIU li-ren

The retina of Dytiscus is tiered, with proximal and distal layers of receptors at different levels. Photoreceptor units of the proximal retina of the eye of Dytiscus have fields of view so wide that light entering by any facet is able to excite a receptor belonging virtually to any ommatidium in the light- or dark-adapted eye. Although the distal rhabdomeres may have small fields of view, the proximal retina is clearly not adapted for perception of form or movement. The sensitivity of proximal retinula units is compatible with the observations that light passing through many facets sums upon them and that their rhabdomeres are relatively large and jointly occupy the whole cross-sectional area of the eye. The lack of polarized light sensitivity of the proximal retinula units can be attributed to electrical coupling between cells with tubules oriented in different directions within each ommatidium.


1857 ◽  
Vol 8 ◽  
pp. 150-158 ◽  

The elastic reaction of a homogeneously strained solid has a character essentially devoid of all heliçoidal and of all dipolar asymmetry. Hence the rotation of the plane of polarization of light passing through bodies which either intrinsically possess the heliçoidal property (syrup, oil of turpentine, quartz crystals, &c.), or have the magnetic property induced in them, must be due to elastic reactions dependent on the heterogeneousness of the strain through the space of a wave, or to some heterogeneousness of the luminous motions dependent on a heterogeneousness of parts of the matter of lineal dimensions not infinitely small in comparison with the wave length.


Author(s):  
A. G. Anisovich

The optical effects which appeared on internal defects of optically transparent materials by use of various methods of optical staining, i. e. dark-field illumination and polarized light were researched. It was shown that methods of optical staining support to determine spherical defects under a surface of optically transparent materials. Formation of optical effects on materials defects in dark background are partially determined by design features of microscope objective and it was found out. It was defined that the investigation using polarized light the image formation of spherical defects occurs similar to uniaxial crystal. 


2018 ◽  
Vol 52 (3 (247)) ◽  
pp. 213-216
Author(s):  
K.A. Petrosyan

In this work we study the influence of hydrodynamic flows on the optical properties of hybrid aligned nematic liquid crystals (NLC) structure caused by direct volume expansion mechanism for the case, when the direction of flow velocity is perpendicular to the angular distribution of the molecules in the cell. It has been shown that the hydrodynamic flow leads to reorientation of NLC molecules. The behavior of the polarized light passing through the NLC layer for two opposite directions of the flow was observed.


Author(s):  
Eric Scerri

One of the most remarkable things about element 87 is the number of times that people claimed to have discovered it after it was predicted by Mendeleev in 1871 and given the provisional name of eka-caesium . It was recognized early on that the periodic table more or less fizzles out after element 83, or bismuth. All subsequent elements are radioactive and therefore unstable, with a few exceptions like uranium and thorium. But this fact did not deter a number of scientists from searching for element 87 among natural sources and in many cases from claiming to have isolated it. For example, Druce and Loring in England thought they had identified the element by using the classic method developed by Moseley for measuring the K α and K β lines of any element’s X-ray spectrum. But it was not to be. In the 1930s, it was the turn of Professor Fred Allison from the Alabama Polytechnic Institute (now Auburn University). Allison developed what he called a magneto-optical method for detecting elements and compounds based on a supposed time lag in the development of the Faraday effect, whereby the application of a magnetic field causes a beam of polarized light passing through a liquid solution to be rotated. Allison mistakenly thought that every element gave a particular time lag, which he claimed was observed with the naked eye, and that this effect could be used to identify each substance. He boldly claimed in a number of journal articles, and even a special feature in Time Magazine, that he had observed elements 87 and also 85, both of which were still missing at the time. Literally hundreds of papers were published on this effect, including a number of studies arguing that it was spurious. But these days the Allison effect is often featured in accounts of pathological science, alongside the claims for N-rays and cold fusion.


1996 ◽  
Vol 199 (4) ◽  
pp. 999-1004 ◽  
Author(s):  
N Shashar ◽  
T W Cronin

While the ability to analyze polarized light is widespread among animals, its contribution to form vision has not yet been documented. We tested the hypothesis that polarization vision can be used for object discrimination, by training octopuses to distinguish between targets on the basis of the presence or absence of a pattern produced by a 90 degrees polarization contrast within the target. Octopuses recognized a 90 degrees contrast pattern within a single target, when presented either on a horizontal/vertical axis or on a 45 degrees/135 degrees axis. They were able to transfer their learning to new situations and to detect a polarization contrast when the orientations of the e-vector of light passing through the target center and background differed by as little as 20 degrees. Polarization vision may provide information similar to that available from color vision and thus serve to enhance the detection and recognition of objects.


1974 ◽  
Vol 53 ◽  
pp. 265-285 ◽  
Author(s):  
F. K. Lamb ◽  
P. G. Sutherland

We discuss some of the effects which magnetic fields in the range 104–108 G have on the continuum emission of white dwarfs. In order to show how atomic processes are related to the transport of radiation in an anisotropic medium we introduce the radiative transfer equation for polarized light. Using this transfer equation as a guide we develop a greatly simplified model of a white dwarf atmosphere: anisotropic absorption of unpolarized light passing through a cold, optically-thin layer. Two possible sources of continuum polarization in white dwarfs with strong magnetic fields are explored, namely bound-free transitions and cyclotron absorption. Within the hydrogenic approximation we develop a further approximation which is valid for bound-free transitions when B is in the range 104–107 G. Using this approximation it is possible to obtain simple expressions for the net circular and linear polarization in terms of the zero-field opacity. In the case of cyclotron absorption, the cross section is large and strongly peaked at the cyclotron frequency, which falls in the infrared or optical for B ⩾ 108 G. This process can lead to net circular and linear polarization of comparable magnitude. For stars with non-uniform magnetic fields, the cyclotron absorption effects are spread over considerable wavelength ranges, with possibly quite complicated wavelength-dependent polarization.


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