The effect of the angle of incidence of the exposing light rays upon the resolving powers of photographic materials

1946 ◽  
Vol 58 (6) ◽  
pp. 769-774 ◽  
Author(s):  
J M Gregory
Keyword(s):  
Angle Of Incidence ◽  
Light Rays

Orientational Movements of the Foot of Littorina Species in Relation to the Plane of Vibration of Polarized Light

1961 ◽  
Vol 38 (1) ◽  
pp. 213-224
Author(s):  
G. H. CHARLES
Keyword(s):  
Polarized Light ◽  
Angle Of Incidence ◽  
Virtual Absence ◽  
Lens Aperture ◽  
Light Rays ◽  
Stimulation Of

1. Littorina littoralis (L.), L. saxatilis (L.), L. neritoides (L.) and L. littorea (L.) responded to the plane of vibration (e vector) of polarized light directly incident upon their eyes in the virtual absence of any substrate reflexions. Photonegative winkles orientated parallel with the plane of vibration and photopositive individuals at right angles to this plane. 2. Decrease of the angle of incidence towards zero of polarized light rays incident upon the lens aperture of Littorina littoralis completely destroyed the ability to orientate to the plane of vibration. This can be explained on the basis of a Fresnel reflexion/refraction mechanism of orientation. 3. Unilaterally blinded Littorina littoralis gave just as good an orientation to vertical rays of polarized light as winkles with intact vision. 4. It is concluded that the eyes of Littorina species are capable of detecting the plane of vibration of polarized light directly incident from above by means of a Fresnel reflexion/refraction mechanism, and that orientation does not depend on balanced stimulation of the two eyes.

II. Geometrical optics of variable-frequency light rays in special relativistic and nonrelativistic situations:The general law of reflection

2000 ◽  
Vol 78 (8) ◽  
pp. 747-754 ◽  
Author(s):  
W T Chyla
Keyword(s):  
Coherent Scattering ◽  
Skin Depth ◽  
Variable Frequency ◽  
Angle Of Incidence ◽  
X Rays ◽  
Reflection Point ◽  
General Law ◽  
Light Rays ◽  
Relativistic Treatment ◽  
Angle Of Reflection

The general law of reflection concerns situations when the light ray undergoes a shift of frequency at the reflection point. For example, it governs reflection of light rays from a moving mirror (either in a vacuum or in a transparent medium), reflection from a motionless mirror coated with a layer of Raman-active molecules in the coherent-scattering regime, or external reflection of X-rays from the surface of a condensed matter sample, with partial dissipation of energy within the skin depth. The general law of reflection is derived from the extremum principle for propagation of variable-frequency light rays. It states that the angle of reflection depends not only on the angle of incidence but also on the frequency shift in the reflection point and dispersion of the refractive index of the medium in contact with the mirror. The compatibility of the general law of reflection and the special relativistic treatment of reflection is examined in detail. Applications of the new law of reflection are discussed in the special relativistic and the nonrelativistic regime. PACS Nos.: 42.15-i, 03.30+p

scholarly journals A FOTOPOLIMERIZAÇÃO DE COMPÓSITOS ODONTOLÓGICOS ALÉM DA POTÊNCIA LUMINOSA

2020 ◽  
Author(s):  
Thales Ribeiro de Magalhães Filho
Keyword(s):  
Great Power ◽  
Dental Composites ◽  
Angle Of Incidence ◽  
Scientific Evaluation ◽  
Light Power ◽  
Regular Distribution ◽  
Light Rays ◽  
Light Curing ◽  
The Difference ◽  
Regular Mode

O objetivo deste estudo foi mostrar que a potência da luz das unidades de fotopolimerização (LED) não é a única ou a propriedade mais importante para uma polimerização satisfatória de compósitos dentários. A distribuição regular e o ângulo de incidência dos raios de luz também são igualmente responsáveis por uma polimerização mais completa e profunda. Esta revisão de literatura mostra que avançamos o suficiente na potência da luz emitida pelos LEDs, mas no que diz respeito à regularidade e ângulo dos raios emitidos, ainda temos muito a avançar. Novos compósitos com cargas reflexivas e preocupações com a diferença de índice de refração entre as cargas e a matriz são importantes para melhorar essa polimerização, mas os LEDs com vários comprimentos de onda podem complicar ainda mais a distribuição regular dos raios de luz emitidos. Dispositivos com diferentes LEDs emitindo raios de luz com diferentes comprimentos de onda não distribuem essas ondas no modo regular. Portanto, parte da restauração pode estar sub polimerizada, tornando-se menos resistente aos esforços mastigatórios e à infiltração. O estudo também relembra propostas de avaliação científica dessa distribuição regular e conclui que os LEDs modernos emitem raios de luz com grande potência e irradiância, mas ainda são irregulares na distribuição dos raios de luz emitidos.Palavras-chave: fotopolimerização, conprimento de onda, irradiância, resina composta.PHOTOPOLIMERIZATION OF DENTAL COMPOSITES BEYOND THE LIGHT POWER EMITED BY LED LIGHT CURING UNITSABSTRACT:            The objective of this study was to show that light power of light curing units (LCU) is not the only or the most important property for a satisfactory polymerization of dental composites. Regular distribution and angle of incidence of the light rays are also equally responsible for a fuller and deeper polymerization. This literature review shows that we advanced enough in the power of light emitted by LCUs, but as regards the regularity and angle of the emitted rays, we still have much to advance. New composites with reflective fillers and concerns about the difference of refractive index between the fillers and the matrixare important help to improve this polymerization, but LCUs with several wavelengths can further complicate the regular distribution of emitted light rays. Devices with different LEDs emitting light rays with different wavelengths does not distribute these waves in a regular mode. Therefore, part of the restoration can be under polymerized, becoming less resistant to masticatory efforts and infiltration as well. The study also recalls proposals for scientific evaluation of this regular distribution and concludes that modern LCUs emit light rays with great power and irradiance, but are still irregular in the distribution of emitted light rays.Keywords: photopolymerization, wavelength, Irradiance, composite.

The Prism Illusion: A Function of Dislocated Equivalence Classes

1966 ◽  
Vol 22 (1) ◽  
pp. 219-232 ◽  
Author(s):  
James G. Taylor
Keyword(s):  
Mathematical Analysis ◽  
Retinal Image ◽  
Equivalence Classes ◽  
Angle Of Incidence ◽  
Perceptual Process ◽  
Tabular Form ◽  
Binocular Fusion ◽  
Vertical Disparity ◽  
Light Rays ◽  
Wedge Prism

A mathematical analysis of the transformation of the direction of light rays passing through a wedge prism is presented. It is shown that if ( x, y) is the angle of incidence and ( x′, y′) the angle of emergence, y′ = y and x′ = f ( x, y). The main properties of this function are displayed, and a numerical example is presented in tabular form. Looking through a prism gives the impression that, in general, y′ ≠ y, vertical dimensions being enlarged at the base end and contracted at the apex end of the prism. The function x′ = f ( x, y) shows that horizontal dimensions are contracted at the base end and expanded at the apex. It is suggested that the perceptual process resists this deformation, so that horizontal dimensions are less contracted and less expanded than the function would indicate. Since this does not affect the dimensions of the retinal image, perceptual expansion (or contraction) of contracted (or expanded) horizontal dimensions entails expansion (or contraction) of vertical dimensions as well. The conclusion that y′ = y may be tested by looking through binocular prisms with bases on the temporal sides. If y′ ≠ y, vertical disparity will make binocular fusion difficult. No failure of fusion has been reported.

Electron Channeling Patterns

1977 ◽  
Vol 35 ◽  
pp. 12-13
Author(s):  
David C. Joy
Keyword(s):  
Electron Diffraction ◽  
Incidence Angle ◽  
Photographic Plate ◽  
Diffraction Effect ◽  
Angle Of Incidence ◽  
Bulk Single Crystal ◽  
Time Resolved ◽  
Electron Channeling ◽  
Spatially Resolved ◽  
Large Bulk

Electron channeling patterns (ECP) were first found by Coates (1967) while observing a large bulk, single crystal of silicon in a scanning electron microscope. The geometric pattern visible was shown to be produced as a result of the changes in the angle of incidence, between the beam and the specimen surface normal, which occur when the sample is examined at low magnification (Booker, Shaw, Whelan and Hirsch 1967).A conventional electron diffraction pattern consists of an angularly resolved intensity distribution in space which may be directly viewed on a fluorescent screen or recorded on a photographic plate. An ECP, on the other hand, is produced as the result of changes in the signal collected by a suitable electron detector as the incidence angle is varied. If an integrating detector is used, or if the beam traverses the surface at a fixed angle, then no channeling contrast will be observed. The ECP is thus a time resolved electron diffraction effect. It can therefore be related to spatially resolved diffraction phenomena by an application of the concepts of reciprocity (Cowley 1969).

Electron-Channelling Patterns: Principles and Techniques

1976 ◽  
Vol 34 ◽  
pp. 400-401
Author(s):  
David C. Joy
Keyword(s):  
Crystal Structure ◽  
Electron Flux ◽  
Lattice Structure ◽  
Incident Beam ◽  
Bloch Wave ◽  
Crystalline Solid ◽  
Angle Of Incidence ◽  
Electron Channelling ◽  
Regular Arrangement ◽  
Backscattered Signals

In a crystalline solid the regular arrangement of the lattice structure influences the interaction of the incident beam with the specimen, leading to changes in both the transmitted and backscattered signals when the angle of incidence of the beam to the specimen is changed. For the simplest case the electron flux inside the specimen can be visualized as the sum of two, standing wave distributions of electrons (Fig. 1). Bloch wave 1 is concentrated mainly between the atom rows and so only interacts weakly with them. It is therefore transmitted well and backscattered weakly. Bloch wave 2 is concentrated on the line of atom centers and is therefore transmitted poorly and backscattered strongly. The ratio of the excitation of wave 1 to wave 2 varies with the angle between the incident beam and the crystal structure.

The Microstructure of Steatite (Protoenstatite)

1985 ◽  
Vol 43 ◽  
pp. 236-237
Author(s):  
W. E. Lee ◽  
A. H. Heuer
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Magnesium Silicate ◽  
Beam Current ◽  
Glassy Matrix ◽  
Angle Of Incidence ◽  
X Ray ◽  
Mechanical And Electrical Properties ◽  
Argon Ions ◽  
High Temperature Polymorph

IntroductionTraditional steatite ceramics, made by firing (vitrifying) hydrous magnesium silicate, have long been used as insulators for high frequency applications due to their excellent mechanical and electrical properties. Early x-ray and optical analysis of steatites showed that they were composed largely of protoenstatite (MgSiO3) in a glassy matrix. Recent studies of enstatite-containing glass ceramics have revived interest in the polymorphism of enstatite. Three polymorphs exist, two with orthorhombic and one with monoclinic symmetry (ortho, proto and clino enstatite, respectively). Steatite ceramics are of particular interest a they contain the normally unstable high-temperature polymorph, protoenstatite.Experimental3mm diameter discs cut from steatite rods (∼10” long and 0.5” dia.) were ground, polished, dimpled, and ion-thinned to electron transparency using 6KV Argon ions at a beam current of 1 x 10-3 A and a 12° angle of incidence. The discs were coated with carbon prior to TEM examination to minimize charging effects.

On resolving fine periodic microstructures in the optical microscope

1989 ◽  
Vol 47 ◽  
pp. 364-365
Author(s):  
W.S. Putnam ◽  
C. Viney
Keyword(s):  
Liquid Crystalline ◽  
Numerical Aperture ◽  
Polarized Light ◽  
Normal Incidence ◽  
Optical Microscope ◽  
Angle Of Incidence ◽  
Resolution Limit ◽  
Crystalline Materials ◽  
Periodic Microstructures ◽  
Liquid Crystalline Materials

Many sheared liquid crystalline materials (fibers, films and moldings) exhibit a fine banded microstructure when observed in the polarized light microscope. In some cases, for example Kevlar® fiber, the periodicity is close to the resolution limit of even the highest numerical aperture objectives. The periodic microstructure reflects a non-uniform alignment of the constituent molecules, and consequently is an indication that the mechanical properties will be less than optimal. Thus it is necessary to obtain quality micrographs for characterization, which in turn requires that fine detail should contribute significantly to image formation.It is textbook knowledge that the resolution achievable with a given microscope objective (numerical aperture NA) and a given wavelength of light (λ) increases as the angle of incidence of light at the specimen surface is increased. Stated in terms of the Abbe resolution criterion, resolution improves from λ/NA to λ/2NA with increasing departure from normal incidence.

Sun Load Analysis and Testing on Automotive Front Lighting Products

2020 ◽  
pp. 116-122
Author(s):  
Emre Öztürk ◽  
Mehmet Aktaş ◽  
Tunç Şenyüz
Keyword(s):  
Prolonged Exposure ◽  
Hot Spot ◽  
Load Test ◽  
Angle Of Incidence ◽  
The Sun ◽  
Solar Simulator ◽  
Automotive Lighting ◽  
Inclination Angles ◽  
Plastic Parts ◽  
Load Simulation

The purpose of this research is to reach good correlation between sun load simulation and solar focusing test for exterior automotive lighting products. Light coming from sun is highly collimated (parallel rays) and focusable from lenses with concave structure. Focusing incidence leads to a hot spot on lens surrounding plastic parts which may cause melting failures at high temperature zones. Sun load simulation is performing to eliminate risk of discoloration, deformation, out gassing, coating failures and fire with prolonged exposure from field. Irradiance values in W/m2 defined in simulation as heat source depending of an angle of incidence of the sun radiation. At first step, simulation is performing with 5 degree intervals to define the critical zones then intervals decreased to 2 degree to detect the critical azimuth and inclination angles. Critical azimuth and inclination angles is checking with ray trace analysis to check the bouncing of sun rays and possible solution to eliminate focuses with design solutions. After numerical analysis to release and validate the automotive lighting products regarding the sun load test, measurement with first parts is necessary. Measurement is performing for all critical angles which have been detected at simulation with thermal camera under ultra high-collimation solar simulator. Measured temperatures are settled according to environment conditions and correlation is checking with simulations.

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