Diffuse reflectance of retinal tapeta lucida, with special reference to drums (Sciaenidae)

1981 ◽  
Vol 59 (2) ◽  
pp. 271-284 ◽  
Author(s):  
R. Wang ◽  
J. A. C. Nicol ◽  
H. J. Arnott
Keyword(s):  
Refractive Index ◽  
Light Absorption ◽  
Visual Pigment ◽  
Diffuse Reflectance ◽  
Pigment Epithelium ◽  
Incident Light ◽  
Model System ◽  
Maximal Absorption ◽  
Reflection Of Light ◽  
Good Agreement

Reflection of light by ocular tapeta lucida of drums (Sciaenidae) was studied in Cynoscion arenarius Ginsburg, C. nebulosus (Cuvier), Micropogon undulatus (L.) and Leiostomus xanthurus Lacèpéde. The tapetum is located in the pigment epithelium of the eye, is matt white, and behaves as a uniform diffuser. The pigment epithelium contains densely packed tapetal spheres; these are randomly arranged, have a diameter of about 0.4 μm and contain a lipid that has a refractive index of 1.50. Because of their dense packing they backscatter much of the incident light. Diffuse reflectance is about 50%. Measured values of reflectance are compared with those computed for a model system having the same physical characteristics, and they are in good agreement. The optical density of the visual pigment at the wavelength of maximal absorption (λ 510 nm) is 0.33, and the tapetum increases light absorption in the dark-adapted eye by a factor of 1.3. Reflectance of croaker tapetum is compared with reflectances of tapeta of Lepisosteus, Arius, and Notopterus afer, which contain different reflecting materials.

Optical Interference Filters By Sol-Gel Processing

1990 ◽  
Vol 180 ◽  
Author(s):  
J.L. Keddie ◽  
E.P. Giannelis
Keyword(s):  
Refractive Index ◽  
Rutherford Backscattering Spectrometry ◽  
Incident Light ◽  
Sol Gel ◽  
Theoretical Modeling ◽  
Optical Interference ◽  
Interference Filters ◽  
The Individual ◽  
Gel Processing ◽  
Good Agreement

ABSTRACTOptical interference filters have been synthesized by sol-gel. The selected filter is a multilayer of alternating TiO2 and SiO2 films. In transmission, the filter edge depends on the angle of incident light, which can be tailored through control of thickness and refractive index of the individual films. Theoretical modeling of the filter with film thicknesses obtained by Rutherford backscattering spectrometry is in good agreement with the experimental optical response.

Investigating the Nonlinear Optical Response of Pepper Oil under Low Power Irradiation with Continuous Wave Visible Laser Beam

2020 ◽  
pp. 131-138
Keyword(s):  
Refractive Index ◽  
Nonlinear Refractive Index ◽  
Nonlinear Optical ◽  
Continuous Wave ◽  
Diffraction Integral ◽  
Visible Laser ◽  
Limiting Property ◽  
Kirchhoff Diffraction Integral ◽  
Theoretical Results ◽  
Good Agreement

The nonlinear optical properties of pepper oil are studied by diffraction ring patterns and Z-scan techniques with continuous wave beam from solid state laser at 473 nm wavelength. The nonlinear refractive index of the sample is calculated by both techniques. The sample show high nonlinear refractive index. Based on Fresnel-Kirchhoff diffraction integral, the far-field intensity distributions of ring patterns have been calculated. It is found that the experimental results are in good agreement with the theoretical results. Also the optical limiting property of pepper oil is reported. The results obtained in this study prove that the pepper oil has applications in nonlinear optical devices.

Stress Whitening in Polypropylene. I. Light Scattering Theory and Model Experiments

1995 ◽  
Vol 60 (11) ◽  
pp. 1875-1887 ◽  
Author(s):  
Jaroslav Holoubek ◽  
Miroslav Raab
Keyword(s):  
Refractive Index ◽  
Light Scattering ◽  
Incident Light ◽  
Polymeric Materials ◽  
Wavelength Dependence ◽  
Theoretical Background ◽  
Surrounding Matrix ◽  
Embedded Particles ◽  
The One ◽  
Stress Whitening

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.

scholarly journals Direct Action of Light in Naturally Pigmented Muscle Fibers

1962 ◽  
Vol 46 (2) ◽  
pp. 333-342 ◽  
Author(s):  
Howard H. Seliger
Keyword(s):  
Visual Pigment ◽  
Absorption Maximum ◽  
Pupil Diameter ◽  
Direct Action ◽  
Pigment Epithelium ◽  
Action Spectrum ◽  
Square Root ◽  
Light Reaction ◽  
First Order ◽  
Iris Sphincter

Contraction due to light in excised eel irises appears to follow a simple first order law. The action spectrum for contraction has a maximum which agrees with the eel rhodopsin absorption maximum. Inasmuch as rhodopsin is the rod pigment-opsin complex and the iris sphincter pupillae evolves from the pigment epithelium of the retina in the region of the iris, the muscle pigment might be the same as the visual pigment. In the human eye the contraction of the iris sphincter is activated only by light incident on the retina and the pupil diameter varies inversely with the square root of the light intensity. The inverse first power relation observed in the present experiments suggests a more primitive origin for the light reaction in eel irises. Relaxation is a much slower process and can be approximated as the sum of two first order processes.

scholarly journals Peropsin, a novel visual pigment-like protein located in the apical microvilli of the retinal pigment epithelium

1997 ◽  
Vol 94 (18) ◽  
pp. 9893-9898 ◽  
Author(s):  
H. Sun ◽  
D. J. Gilbert ◽  
N. G. Copeland ◽  
N. A. Jenkins ◽  
J. Nathans
Keyword(s):  
Retinal Pigment Epithelium ◽  
Visual Pigment ◽  
Pigment Epithelium ◽  
Retinal Pigment

Analysis of Thermal Variation of Length and Refractive Index of Lead Fluoride to Study its Optical Properties

1989 ◽  
Vol 172 ◽  
Author(s):  
T. S. Aurora ◽  
D. O. Pederson ◽  
S. M. Day
Keyword(s):  
Refractive Index ◽  
Room Temperature ◽  
Linear Thermal Expansion ◽  
Small Variation ◽  
Published Data ◽  
Thermal Variation ◽  
Lead Fluoride ◽  
Superionic Phase Transition ◽  
Lorenz Relation ◽  
Good Agreement

AbstractLinear thermal expansion and refractive index variation have been measured in lead fluoride with a laser interferometer as a function of temperature. Data has been analyzed using the Lorentz-Lorenz relation. Molecular polarizability, band gap, variation of refractive index with density, and strain-polarizability parameter have been studied as a function of temperature. They exhibit a small variation with temperature except near the superionic phase transition where the variation appears to be more pronounced. The results are in good agreement with the published data near room temperature.

scholarly journals Aerosol retrieval from multiangle, multispectral photopolarimetric measurements: importance of spectral range and angular resolution

2015 ◽  
Vol 8 (6) ◽  
pp. 2625-2638 ◽  
Author(s):  
L. Wu ◽  
O. Hasekamp ◽  
B. van Diedenhoven ◽  
B. Cairns
Keyword(s):  
Refractive Index ◽  
Spectral Range ◽  
Angular Resolution ◽  
Single Scattering ◽  
Microphysical Properties ◽  
Aerosol Retrieval ◽  
Spectral Ranges ◽  
Shortwave Infrared ◽  
Aerosol Properties ◽  
Good Agreement

Abstract. We investigated the importance of spectral range and angular resolution for aerosol retrieval from multiangle photopolarimetric measurements over land. For this purpose, we use an extensive set of simulated measurements for different spectral ranges and angular resolutions and subsets of real measurements of the airborne Research Scanning Polarimeter (RSP) carried out during the PODEX and SEAC4RS campaigns over the continental USA. Aerosol retrievals performed from RSP measurements show good agreement with ground-based AERONET measurements for aerosol optical depth (AOD), single scattering albedo (SSA) and refractive index. Furthermore, we found that inclusion of shortwave infrared bands (1590 and/or 2250 nm) significantly improves the retrieval of AOD, SSA and coarse mode microphysical properties. However, accuracies of the retrieved aerosol properties do not improve significantly when more than five viewing angles are used in the retrieval.

scholarly journals The scattering of light by turbid media.–Part II

1931 ◽  
Vol 131 (817) ◽  
pp. 464-475 ◽  
Keyword(s):  
Refractive Index ◽  
Absorption Coefficient ◽  
Spherical Shell ◽  
Direct Observation ◽  
Single Particle ◽  
Unit Volume ◽  
Incident Light ◽  
Parallel Beam ◽  
Photometric Observations ◽  
Transmission And Reflection

In Part I it was shown how the values of the transmission and reflection of a sheet of a medium containing particles in suspension can he calculated. First the amounts of light scattered in the forward and forward directions from a single particle were determined; from these results the transmission 1 and rejection R for diffuse incident light were found for a layer of the disusing medium, when the effects of boundary reflections are negligible. At this stage, the expressions developed apply to a mist or fog consisting of particles suspended in air. Finally it was shown how, if the particles are suspended in some other medium, having a different refractive index from that of air, the transmission and reflection ז and p can be expressed in terms of T and R and the surface rejection coefficients. The more general expressions, for the case when the incident light is a parallel beam, were also developed. We shall now show how the absorption coefficient μ can be determined from photometric observations. As a check on the theory, we shall deduce the diameter D of the particles and the number N present per unit volume and compare these calculated values with those found by direct observation, Finally, the necessary modifications of the theory will be made to cover the case when the diffusing medium is in the form of a spherical shell.

Temperaturabhängigkeit der statischen Dielektrizitätskonstante und des optischen Brechungsindexes von Flüssigkeiten

1975 ◽  
Vol 30 (3) ◽  
pp. 287-291 ◽  
Author(s):  
I. Gryczyński ◽  
A. Kawski
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Dipole Moment ◽  
Dipole Moments ◽  
Mixed Solvents ◽  
Temperature Changes ◽  
Temperature Dependences ◽  
Solvent Shifts ◽  
Pure And Mixed Solvents ◽  
Good Agreement

A variation of the temperature changes the static dielectric constant (ε) and the refractive index (n) of solvents and, in conjunction with the measurement of solvent shifts of absorption and fluorescence maxima, allows the investigation of dipole moment changes of solutes in the excited state. For this purpose, investigations of the temperature dependences of ε and n of some pure and mixed solvents of different polarities have been made. It is found that the excited dipole moments of indole, 1,2-dimethylindole, 2,3-dimethylindole and tryptophan obtained from the shifts of the fluorescence maxima in mixed solvents at high temperatures are in good agreement with those obtained in other ways.

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