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Glancing Angle (optics)
The angle of incidence, in geometric optics, is the angle between a ray incident on a surface and the line perpendicular (at 90 degree angle) to the surface at the point of incidence, called the normal. The ray can be formed by any waves, such as optical, acoustic, microwave, and X-ray. In the figure below, the line representing a ray makes an angle θ with the normal (dotted line). The angle of incidence at which light is first totally internally reflected is known as the critical angle. The angle of reflection and angle of refraction are other angles related to beams. In computer graphics and geography, the angle of incidence is also known as the illumination angle of a surface with a light source, such as the Earth's surface and the Sun. It can also be equivalently described as the angle between the tangent plane of the surface and another plane at right angles to the light rays. This means that the illumination angle of a certain point on Earth's surface is 0° if the Sun i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geometric Optics
Geometry (; ) is a branch of mathematics concerned with properties of space such as the distance, shape, size, and relative position of figures. Geometry is, along with arithmetic, one of the oldest branches of mathematics. A mathematician who works in the field of geometry is called a '' geometer''. Until the 19th century, geometry was almost exclusively devoted to Euclidean geometry, which includes the notions of point, line, plane, distance, angle, surface, and curve, as fundamental concepts. Originally developed to model the physical world, geometry has applications in almost all sciences, and also in art, architecture, and other activities that are related to graphics. Geometry also has applications in areas of mathematics that are apparently unrelated. For example, methods of algebraic geometry are fundamental in Wiles's proof of Fermat's Last Theorem, a problem that was stated in terms of elementary arithmetic, and remained unsolved for several centuries. Duri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sunset
Sunset (or sundown) is the disappearance of the Sun at the end of the Sun path, below the horizon of the Earth (or any other astronomical object in the Solar System) due to its Earth's rotation, rotation. As viewed from everywhere on Earth, it is a phenomenon that happens approximately once every 24 hours, except in areas close to the Geographical pole, poles. The equinox Sun sets due west at the moment of both the spring and autumn equinoxes. As viewed from the Northern Hemisphere, the Sun sets to the northwest (or not at all) in the spring and summer, and to the southwest in the autumn and winter; these seasons are reversed for the Southern Hemisphere. The sunset is defined in astronomy the moment the upper limb of the Sun disappears below the horizon. Near the horizon, atmospheric refraction causes sunlight rays to be distorted to such an extent that geometrically the solar disk is already about one diameter below the horizon when a sunset is observed. Sunset is distinct from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Illumination Angle
The angle of incidence, in geometric optics, is the angle between a ray incident on a surface and the line perpendicular (at 90 degree angle) to the surface at the point of incidence, called the normal. The ray can be formed by any waves, such as optical, acoustic, microwave, and X-ray. In the figure below, the line representing a ray makes an angle θ with the normal (dotted line). The angle of incidence at which light is first totally internally reflected is known as the critical angle. The angle of reflection and angle of refraction are other angles related to beams. In computer graphics and geography, the angle of incidence is also known as the illumination angle of a surface with a light source, such as the Earth's surface and the Sun. It can also be equivalently described as the angle between the tangent plane of the surface and another plane at right angles to the light rays. This means that the illumination angle of a certain point on Earth's surface is 0° if the Sun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effect Of Sun Angle On Climate
The amount of heat energy received at any location on the globe is a direct effect of Sun angle on climate, as the angle of incidence (optics), angle at which sunlight strikes Earth varies by location, time of day, and season due to Earth's orbit around the Sun and Earth's rotation around its axial tilt, tilted axis. Seasonal change in the angle of sunlight, caused by the tilt of Earth's rotation around a fixed axis, axis, is the basic mechanism that results in warmer weather in summer than in winter.Windows to the UniverseEarth's Tilt Is the Reason for the Seasons! Retrieved on 2008-06-28. Change in daytime, day length is another factor (albeit lesser). Geometry of Sun angle Figure 1 presents a case when sunlight shines on Earth at a lower angle of incidence (optics), angle (Sun closer to the horizon), the energy of the sunlight is spread over a larger area, and is therefore weaker than if the Sun is higher overhead and the energy is concentrated on a smaller area. Figure 2 d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lloyd's Mirror
Lloyd's mirror is an optics experiment that was first described in 1834 by Humphrey Lloyd (physicist), Humphrey Lloyd in the ''Transactions of the Royal Irish Academy''. Its original goal was to provide further evidence for the Light#Wave theory, wave nature of light, beyond those provided by Thomas Young (scientist), Thomas Young and Augustin-Jean Fresnel. In the experiment, light from a monochromatic slit source reflection (optics), reflects from a glass surface at a small angle and appears to come from a virtual image, virtual source as a result. The reflected light interferes with the direct light from the source, forming interference (wave propagation), interference fringes. It is the optical wave analogue to a sea interferometer. Setup Lloyd’s Mirror is used to produce two-source interference patterns that have important differences from the interference patterns seen in Young's experiment. In a modern implementation of Lloyd's mirror, a diverging laser beam strikes a fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milliradian
A milliradian (International System of Units, SI-symbol mrad, sometimes also abbreviated mil) is an SI derived unit for angular measurement which is defined as a thousandth of a radian (0.001 radian). Milliradians are used in adjustment of firearm sights by adjusting the angle of the sight compared to the barrel (up, down, left, or right). Milliradians are also used for comparing shot groupings, or to compare the difficulty of hitting different sized shooting targets at different distances. When using a scope with both mrad adjustment and a reticle with mrad markings (called an "mrad/mrad scope"), the shooter can use the reticle as a ruler to count the number of mrads a shot was off-target, which directly translates to the sight adjustment needed to hit the target with a follow-up shot. Optics with mrad markings in the reticle can also be used to make a stadiametric rangefinding, range estimation of a known size target, or vice versa, to determine a target size if the distan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ridged Mirror
In atomic physics, a ridged mirror (or ridged atomic mirror, or Fresnel diffraction mirror) is a kind of atomic mirror, designed for the specular reflection of neutral particles (atoms) coming at a grazing incidence angle. In order to reduce the mean attraction of particles to the surface and increase the reflectivity, this surface has narrow ridges. Reflectivity of ridged atomic mirrors Various estimates for the efficiency of quantum reflection of waves from ridged mirror were discussed in the literature. All the estimates explicitly use the de Broglie theory about wave properties of reflected atoms. Scaling of the van der Waals force The ridges enhance the quantum reflection from the surface, reducing the effective constant ~C~ of the van der Waals attraction of atoms to the surface. Such interpretation leads to the estimate of the reflectivity : \displaystyle r \approx r_0\!\left( \frac \ell L C,\!~K\sin(\theta)\right), where ~\ell~ is width of the ridges, ~L~ is distan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atom Optics
Atom optics (or atomic optics) "refers to techniques to manipulate the trajectories and exploit the wave properties of neutral atoms". Typical experiments employ beams of cold, slowly moving neutral atoms, as a special case of a particle beam. Like an optical beam, the atomic beam may exhibit diffraction and interference, and can be focused with a Fresnel zone plate or a concave atomic mirror. For comprehensive overviews of atom optics, see the 1994 review by Adams, Sigel, and Mlynek or the 2009 review by Cronin, Jörg, and Pritchard. More bibliography about Atom Optics can be found in the 2017 Resource Letter in the American Journal of Physics. For quantum atom optics see the 2018 review by Pezzè et al. History Interference of atom matter waves was first observed by Esterman and Stern in 1930, when a Na beam was diffracted off a surface of NaCl. The short de Broglie wavelength of atoms prevented progress for many years until two technological breakthroughs revived interes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Spectroscopy
X-ray spectroscopy is a general term for several Spectroscopy, spectroscopic techniques for characterization of materials by using x-ray radiation. Characteristic X-ray spectroscopy When an electron from the inner shell of an atom is excited by the energy of a photon, it moves to a higher energy level. When it returns to the low energy level, the energy it previously gained by excitation is emitted as a photon of one of the wavelengths uniquely characteristic of the element. Analysis of the X-ray emission spectrum produces qualitative results about the elemental composition of the specimen. Comparison of the specimen's spectrum with the spectra of samples of known composition produces quantitative results (after some mathematical corrections for absorption, fluorescence and atomic number). Atoms can be excited by a high-energy beam of charged particles such as electrons (in an electron microscope for example), protons (see PIXE) or a beam of X-rays (see X-ray fluorescence, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grazing Incidence Diffraction
Grazing incidence diffraction (GID) is a technique for interrogating a material using small incidence angles for an incoming wave, often leading to the diffraction being surface sensitive. It occurs in many different areas: * Reflection high-energy electron diffraction (RHEED), where electrons of relatively high energy diffract at small angles from a surface. RHEED is used to interrogate surface structure. * Surface X-ray diffraction (SXRD), which is similar to RHEED but uses X-rays, and is also used to interrogate surface structure. * X-ray standing waves, another X-ray variant where the intensity decay into a sample from diffraction is used to analyze chemistry. * Grazing-incidence small-angle scattering (GISAS) a hybrid approach using small scattering (diffraction) angles with X-rays or neutrons. * X-ray reflectivity, yet another related technique, but here the intensity of the specular reflected beam is measured.J. Als-Nielsen, D. McMorrow, ''Elements of Modern X-Ray Phys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Complementary Angle
In Euclidean geometry, an angle can refer to a number of concepts relating to the intersection of two straight lines at a point. Formally, an angle is a figure lying in a plane formed by two rays, called the '' sides'' of the angle, sharing a common endpoint, called the '' vertex'' of the angle. More generally angles are also formed wherever two lines, rays or line segments come together, such as at the corners of triangles and other polygons. An angle can be considered as the region of the plane bounded by the sides. Angles can also be formed by the intersection of two planes or by two intersecting curves, in which case the rays lying tangent to each curve at the point of intersection define the angle. The term ''angle'' is also used for the size, magnitude or quantity of these types of geometric figures and in this context an angle consists of a number and unit of measurement. Angular measure or measure of angle are sometimes used to distinguish between the measurement an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Tangent
In geometry, the tangent line (or simply tangent) to a plane curve at a given point is, intuitively, the straight line that "just touches" the curve at that point. Leibniz defined it as the line through a pair of infinitely close points on the curve. More precisely, a straight line is tangent to the curve at a point if the line passes through the point on the curve and has slope , where ''f'' is the derivative of ''f''. A similar definition applies to space curves and curves in ''n''-dimensional Euclidean space. The point where the tangent line and the curve meet or intersect is called the ''point of tangency''. The tangent line is said to be "going in the same direction" as the curve, and is thus the best straight-line approximation to the curve at that point. The tangent line to a point on a differentiable curve can also be thought of as a ''tangent line approximation'', the graph of the affine function that best approximates the original function at the given point. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
