Polarized Light Studies of the Cornea

1953 ◽  
Vol 30 (2) ◽  
pp. 164-169
Author(s):  
A. STANWORTH
Keyword(s):  
Intraocular Pressure ◽  
Human Subject ◽  
Reasonable Agreement ◽  
Polarized Light ◽  
Transmitted Light ◽  
Posterior Surface ◽  
Photographic Image ◽  
Reflected Light

A method is described of measuring the birefringence of the intact cornea using light reflected obliquely from its posterior surface. The value obtained (0.0037) is in reasonable agreement with the results obtained by using transmitted light and from corneal sections. The change in birefringence with an increase in intraocular pressure from 10 to 40 mm. Hg is about 7% of this. The change in birefringence was also assessed by changes in the density of the photographic image of the reflected light from the surface, and this affords a possible way in which the intraocular pressure could be measured in the human subject without touching the eye.

scholarly journals On certain peculiarities in the double refraction, and absorption of light, exhibited in the oxalate of chromium and potash

1837 ◽  
Vol 3 ◽  
pp. 322-323
Keyword(s):  
Polarized Light ◽  
Transmitted Light ◽  
Double Refraction ◽  
Small Thickness ◽  
Reflected Light ◽  
Absorption Of Light ◽  
General Action ◽  
Bright Green ◽  
The Difference ◽  
Bright Blue

The crystals of the oxalate of chromium and potash are, generally speaking, opake; for at thicknesses not much greater than the 25th of an inch, they are absolutely impervious to the sun’s rays, and their colour, seen by reflected light, is nearly black; but when powdered, they are green; and the colour of the smaller crystals, viewed either by reflected or by transmitted daylight, is blue. One of the most remarkable of the properties of this salt is the difference of colour in the two images formed by double refraction. At a certain small thickness, the least refracted image is bright blue, and the most refracted image bright green. The blue is found by analysis with the prism to contain an admixture of green, and the green an admixture of red; and by candlelight this red predominating over the green, gives the crystal a pink hue. At greater thicknesses the blue becomes purer and fainter, and the green passes into red; and at a certain thickness the least refracted blue image disappears altogether, and the most refracted image is alone seen. At still greater thicknesses this image also disappears, and absolute opacity ensues. When the crystal is exposed to polarized light, with its axis in the plane of polarization, the transmitted light is green; but when the axis is perpendicular to that plane, the transmitted light is blue. A solution of the salt exhibits the same general action upon light as the solid, with the exception of double refraction. This salt has also the peculiar property of exciting a specific action upon a definite red ray, situated near the extremity of the red portion of the spectrum.

Dalnegroite, Tl5–xPb2x(As,Sb)2l–xS34, a new thallium sulphosalt from Lengenbach quarry, Binntal, Switzerland

2009 ◽  
Vol 73 (6) ◽  
pp. 1027-1032 ◽  
Author(s):  
F. Nestola ◽  
A. Guastoni ◽  
L. Bindi ◽  
L. Secco
Keyword(s):  
Polarized Light ◽  
New Mineral ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elemental Concentrations ◽  
Reflected Light ◽  
Mohs Hardness ◽  
The Mean ◽  
The University ◽  
Probable Space

AbstractDalnegroite, ideally Tl4Pb2(As12Sb8)Σ20S34, is a new mineral from Lengenbach, Binntal, Switzerland. It occurs as anhedral to subhedral grains up to 200 μm across, closely associated with realgar, pyrite, Sb-rich seligmanite in a gangue of dolomite. Dalnegroite is opaque with a submetallic lustre and shows a brownish-red streak. It is brittle; the Vickers hardness (VHN25) is 87 kg mm-2(range: 69—101) (Mohs hardness ∼3—3½). In reflected light, dalnegroite is highly bireflectant and weakly pleochroic, from white to a slightly greenish-grey. In cross-polarized light, it is highly anisotropic with bluish to green rotation tints and red internal reflections.According to chemical and X-ray diffraction data, dalnegroite appears to be isotypic with chabournéite, Tl5-xPb2x(Sb,As)21-xS34. It is triclinic, probable space groupP1, witha= 16.217(7) Å,b= 42.544(9) Å,c= 8.557(4) Å, α = 95.72(4)°, β = 90.25(4)°, γ = 96.78(4)°,V= 5832(4) Å3,Z= 4.The nine strongest powder-diffraction lines [d(Å) (I/I0) (hkl)] are: 3.927 (100) (10 0); 3.775 (45) (22); 3.685 (45) (60); 3.620 (50) (440); 3.124 (50) (2); 2.929 (60) (42); 2.850 (70) (42); 2.579 (45) (02); 2.097 (60) (024). The mean of 11 electron microprobe analyses gave elemental concentrations as follows: Pb 10.09(1) wt.%, Tl 20.36(1), Sb 23.95(1), As 21.33(8), S 26.16(8), totalling 101.95 wt.%, corresponding to Tl4.15Pb2.03(As11.86Sb8.20)S34. The new mineral is named for Alberto Dal Negro, Professor in Mineralogy and Crystallography at the University of Padova since 1976.

Phase Detection for Nanometer Scale Metal Film’s Thickness Based on SPR Effect

2011 ◽  
Vol 320 ◽  
pp. 377-381 ◽  
Author(s):  
Jin Dong Xin ◽  
Qing Gang Liu ◽  
Chao Liu ◽  
Ting Ting Li ◽  
Shi Yi Liu
Keyword(s):  
Film Thickness ◽  
Resonance Effect ◽  
Polarized Light ◽  
Nanometer Scale ◽  
Phase Detection ◽  
Surface Plasmon Resonance Effect ◽  
Interference Fringes ◽  
Reflected Light ◽  
Phase Data ◽  
Spr Effect

It is found that the phase position of p-component of reflected light changes with the metal film thickness, while the phase position of s-component almost doesn’t change in the Surface Plasmon Resonance effect. S-polarized light is taken as reference and interferometry is adopted to turn the change of the phase position into the change of interference fringes position in the paper, and the film thickness can be derived from it. The simulation results indicated that, through making use of piecewise quadratic fitting on the phase data, the inaccuracy with the range of film thickness is between 30 and 80 nanometers is not more than 0.33 nm.

Reduction of Reflected Light On Fluorescence Emission for Indocyanine Green

2021 ◽  
Author(s):  
So Yoon Kwon ◽  
Ki-Cheol Yoon ◽  
Kwang Gi Kim
Keyword(s):  
Blood Vessel ◽  
Indocyanine Green ◽  
Blood Vessels ◽  
Light Emitting Diode ◽  
Polarized Light ◽  
Fluorescence Emission ◽  
Light Reflection ◽  
Light Emitting ◽  
Surgical Microscope ◽  
Reflected Light

Abstract Inside the brain tumor, the blood vessels are intricately composed, and the tumors and blood vessels are similar in color. Therefore, when observing tumors and blood vessels with the naked eye or a surgical microscope, it is difficult to distinguish between tumors and blood vessels. Fluorescence staining with indocyanine green (ICG) is performed to distinguish between brain tumors and blood vessels using a surgical microscope. However, when observing the blood circulation state of a tumor or blood vessel through a surgical microscope, light reflection occurs from the camera. In the process of observing the state of the blood vessel, due to the occurrence of light reflection, an obstruction phenomenon in which the observation field is blocked by the blood vessel of the object to be observed occurs. Therefore, it is difficult to diagnose the vascular condition. In this experiment, the 780nm light-emitting diode (LED) was irradiated to the ICG phantom, and then, when the fluorescence expression image was observed, the polarizing filter such as circular polarized light (CPL) filter and linear polarized light (LPL) filter were inserted into the camera and the reflected light was reduced. Therefore, it is possible to reduce the reflected light from the fluorescence expression image by using a polarizing filter, and it is expected to be applicable to surgery and diagnostic fields of cancer such as surgery.

Wood identification of charcoal with 3D-reflected light microscopy

IAWA Journal ◽  
2020 ◽  
Vol 41 (4) ◽  
pp. 478-489 ◽  
Author(s):  
Valentina Zemke ◽  
Volker Haag ◽  
Gerald Koch
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Light Microscopy ◽  
Field Emission ◽  
Polarized Light ◽  
Structural Features ◽  
Light Illumination ◽  
Reflected Light ◽  
Carbonized Wood ◽  
Scanning Electron

Abstract The present study focusses on the application of 3D-reflected light microscopy (3D-RLM) for the wood anatomical identification of charcoal specimens produced from domestic and tropical timbers. This special microscopic technique offers a detailed investigation of anatomical features in charcoal directly compared with the quality of field emission scanning electron microscopy (FESEM). The advantages of using the 3D-RLM technology are that fresh fracture planes of charcoal can be directly observed under the microscope without further preparation or surface treatment. Furthermore, the 3D-technique with integrated polarized light illumination creates high-contrast images of uneven and black charcoal surfaces. Important diagnostic structural features such as septate fibres and intercellular canals can be clearly detected and intervessel pits are directly measured. The comparison of the microscopic analyses reveals that 3D-reflected light microscopy (3D-RLM) provides an effective alternative technique to conventional field emission scanning electron microscopy for the identification of carbonized wood.

scholarly journals Multipole Radiations from Large Gold Nanospheres Excited by Evanescent Wave

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 175
Author(s):  
Jingdong Chen ◽  
Jin Xiang ◽  
Shuai Jiang ◽  
Qiaofeng Dai ◽  
Shaolong Tie ◽  
...  
Keyword(s):  
Evanescent Wave ◽  
Polarized Light ◽  
Electric Quadrupole ◽  
Photonic Devices ◽  
High Order ◽  
Gold Nanospheres ◽  
Reflected Light ◽  
Gold Nanosphere ◽  
Scattering Light ◽  
Plasmon Modes

We proposed the use of the evanescent wave generated in a total internal reflection configuration to excite large gold nanospheres and investigated the radiations of the high-order plasmon modes supported in gold nanospheres. It was revealed that the evanescent wave excitation is equivalent to the excitation by using both the incident and reflected light, offering us the opportunity to control the orientation of the electric field used to excite nanoparticles. In addition, it was found that the scattering light intensity is greatly enhanced and the background noise is considerably suppressed, making it possible to detect the radiations from high-order plasmon modes. Moreover, the influence of the mirror images on the scattering induced by a metal substrate is eliminated as compared with the surface plasmon polariton excitation. By exciting a gold nanosphere with s-polarized light and detecting the scattering light with a p-polarized analyzer, we were able to reveal the radiation from the electric quadrupole mode of the gold nanosphere in both the spatial and the frequency domains. Our findings are important for characterizing the radiations from the high-order modes of large nanoparticles and useful for designing nanoscale photonic devices.

scholarly journals Polarization Controlled Dual Functional Reflective Planar Metalens in Near Infrared Regime

Coatings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 389 ◽  
Author(s):  
Yuhui Zhang ◽  
Bowei Yang ◽  
Zhiying Liu ◽  
Yuegang Fu
Keyword(s):  
Near Infrared ◽  
Polarized Light ◽  
New Method ◽  
Dual Functional ◽  
Light Manipulation ◽  
Reflected Light ◽  
Polarization States ◽  
Dual Functions

The metalens has been a hotspot in scientific communications in recent years. The polarization-controlled functional metalens is appealing in metalens investigation. We propose a metalens with dual functions that are controlled by polarization states. In the first design, when applied with x- and y-polarized light, two focal spots with different focal lengths are acquired, respectively. The proposed metalens performs well when illuminated with adjacent wavelengths. In the second design, the reflected light is focused when applied with x-polarized light, and when applied with y-polarized light, the reflected light is split into two oblique paths. We believe that the results will provide a new method in light manipulation.

Visualization of the posterior surface of the lens nucleus with triamcinolone acetonide in phacoemulsification

2020 ◽  
pp. 112067212097735
Author(s):  
Tadashi Mizuguchi ◽  
Masayuki Horiguchi ◽  
Atsuhiro Tanikawa
Keyword(s):  
Intraocular Pressure ◽  
Endothelial Cell ◽  
Triamcinolone Acetonide ◽  
Corneal Endothelial Cell ◽  
Posterior Surface ◽  
Evaluation Technique ◽  
Novel Technique ◽  
Corneal Endothelial Cell Density ◽  
Cell Densities ◽  
Phaco Time

Purpose: We report a novel technique for visualizing the posterior surface of the lens nucleus during phacoemulsification. Surgical Technique: Hydro-dissection was performed using a solution of 20 mg triamcinolone acetonide powder without preservatives mixed with 3 ml BSS-plus, and triamcinolone acetonide was clearly identifiable underneath the posterior surface of the lens nucleus. Using a phaco-tip, the nucleus was shaved to the level of the triamcinolone acetonide and could be easily divided. The remnant triamcinolone acetonide was aspirated as much as possible from the lens cortex with an infusion/aspiration tip. Subjects and Evaluation Technique: Twenty-eight eyes in 28 patients with cataracts were enrolled in this study. Triamcinolone acetonide-assisted phacoemulsification was performed in 13 eyes in 13 patients (triamcinolone acetonide-phacoemulsification group), and normal phacoemulsification was performed in 15 eyes in 15 patients (phacoemulsification group). Intraocular pressure was measured in all patients pre-operatively, 1 day after, and 1 week after surgery. Corneal endothelial cell density was measured pre-operatively and 1 month after surgery. The time of surgical phacoemulsification (surgical phaco time) was measured from the video of the surgery. Results: Surgery was successively performed in all eyes. Pre-operative and post-operative intraocular pressures and cell densities did not significantly differ between the two groups. Surgical phaco time was shorter in the triamcinolone acetonide-phacoemulsification group than in the phacoemulsification group (157.1 ± 51.7 s vs 225.3 ± 45.1 s; p = 0.006). Conclusion: The triamcinolone acetonide-assisted phacoemulsification procedure is safe and useful for visualizing the posterior surface of the lens nucleus and facilitates removal of the lens nucleus by phacoemulsification.

The thickness of the helium film

1951 ◽  
Vol 205 (1081) ◽  
pp. 270-285 ◽  
Keyword(s):  
Stainless Steel ◽  
Liquid Helium ◽  
Polarized Light ◽  
Angle Of Incidence ◽  
Helium Film ◽  
Helium Ii ◽  
Reflected Light ◽  
Linearly Polarized ◽  
Barium Stearate

A description is given of an optical method for the determination of the thickness of the helium II film. Linearly polarized light is reflected from a stainless steel mirror, the upper part of which is coated with a layer of barium stearate one molecule thick and the lower part with a similar layer three molecules thick. The reflected light passes through a mica compensating plate and a nicol prism. Adjustment of the mica plate and nicol gives equality of illumination on the ‘1’ and ‘3’ areas. If now a film of helium II covers the mirror the nicol must be rotated to restore equality of illumination. The rotation is a measure of the thickness of the helium film, the relation between the two quantities being calculated in terms of the angle of incidence and the optical constants of liquid helium, barium stearate and stainless steel. The observed thickness at any given height above the liquid helium was found to be nearly independent of the temperature between 1⋅1 and 2⋅18° K but then decreased rapidly to zero at the λ -point. In the formula d = k / h 1/ z for the thickness d at height h cm. for any given temperature, the value of z varies from 3⋅5 at 1⋅1° K to 2⋅5 at 2⋅1° K. The thickness at 1 cm. and 1⋅5° K is provisionally given as 1⋅9 x 10 -6 cm.

scholarly journals Image Segmentation for Reflected-Light Microscopy: Some Theoretical Approaches

2021 ◽  
Vol 906 (1) ◽  
pp. 012121
Author(s):  
Stefano Pagnotta ◽  
Andrea Aquino ◽  
Marco Lezzerini
Keyword(s):  
Image Segmentation ◽  
Light Microscopy ◽  
Urban Environment ◽  
Maximum Size ◽  
Transmitted Light ◽  
Minimal Sample ◽  
Theoretical Approaches ◽  
Reflected Light ◽  
Pass Through ◽  
The One

Abstract Often when we approach the study of lithologies coming from the urban environment, but in general, even from any other environment, be it a quarry, a mine, an outcrop of our interest, the first study we carry out is the one in reflected-light optical-microscopy. Reflected-light microscopy in respect to transmitted-light microscopy requires minimal sample preparation, having to polish a single surface and without the need to thin the samples to allow light to pass through them. It may be useful, already in the first analysis, to try to produce quantitative data on what we are observing. A further advantage of reflected light in an urban environment is that of being able to observe and describe the formation or interaction between opaque minerals and the environment. Information that we lose by passing directly to the transmitted light. The information that can be useful to us and that we can obtain are the relative porosity of the sample, the texture (when easily recognizable in reflected light), the maximum size and shape of the edges of the grains. To all this is added the relationship between the areas of the different crystallites identified and the possible background mass, which cannot be solved on the observation scale. When we are dealing with many samples, we do not always have the time to be able to study individually sample by sample through images, so we resort to the use of image analysis tools for image segmentation and analysis. Among these, the main thresholding method with the Otsu method, the segmentation with the k averages algorithm, and, finally, a neural network of the SOM type. In this short work, we will review the main methods of image segmentation plus an innovative method developed by our group, highlighting its strengths and weaknesses.

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