404 relations: A Dynamical Theory of the Electromagnetic Field, Abbe number, Absorption spectroscopy, Accommodation (eye), Acoustical engineering, Acronym, Adaptive optics, Afterglow, Airborne Laser, Airy disk, Al-Kindi, Albert Einstein, Ames room, Ancient Egypt, Ancient Greece, Ancient Greek, Ancient Greek philosophy, Ancient Rome, Angular resolution, Anterior chamber of eyeball, Anti-reflective coating, Aperture, Aristotle, Ashgate Publishing, Assyria, Astigmatism, Astronomical interferometer, Astronomical seeing, Astronomy, Atmosphere of Earth, Augustin-Jean Fresnel, Averroes, Avicenna, Ångström, Étienne-Louis Malus, Barcode, Beam divergence, Binocular vision, Birefringence, Black-body radiation, Blind spot (vision), Bloodless surgery, Bohr model, Book of Optics, Boundary element method, Bragg's law, Brewster's angle, Brigham Young University, Brillouin scattering, Bubblegram, ..., Café wall illusion, Calcite, Camera, Camera lens, Charge-coupled device, Chemistry, Chirality (chemistry), Chirp, Christiaan Huygens, Chromatic aberration, Ciliary muscle, Circular dichroism, Circular polarization, Classical electromagnetism, Coherence (physics), Color, Color television, Compact disc, Comparison microscope, Compton scattering, Computer engineering, Computer simulation, Conservation of energy, Constantine the African, Contact lens, Cornea, Corner reflector, Corona (optical phenomenon), Corpuscular theory of light, Corrective lens, Correlation and dependence, Cosmogony, Covalent bond, Crepuscular rays, Crystal, Crystal optics, Curved mirror, Cylinder, Daniel Frank Walls, Degree of polarization, Democritus, Depth of field, Diameter, Dichroism, Dielectric, Dielectric mirror, Diffraction, Diffraction grating, Diffraction topography, Diffraction-limited system, Diffuse reflection, Digital image processing, Dioptre, Directional Infrared Counter Measures, Double-slit experiment, E. C. George Sudarshan, Ehrenstein illusion, Electromagnetic radiation, Electromagnetism, Electron multiplier, Electrostatic lens, Ellipse, Elliptical polarization, Emission spectrum, Emission theory (vision), Engineering, Epicurus, Epistemology, Etiology, Euclid, Euclidean vector, European Optical Society, European Photonics Industry Consortium, Exposure (photography), Eyepiece, F-number, Fabrication and testing of optical components, Far point, Far-sightedness, Faraday effect, Fata Morgana (mirage), Fermat's principle, Fiber-optic communication, Film speed, Finite element method, Focal length, Focus (optics), Fourier optics, Fovea centralis, Francesco Maria Grimaldi, Fraser spiral illusion, Fraunhofer diffraction, Fraunhofer diffraction equation, Fresnel diffraction, Fresnel equations, Gaussian beam, Gaussian optics, Geometrical optics, Geometry, Glasses, Gradient-index optics, Greco-Roman world, Group velocity, Halo (optical phenomenon), Hering illusion, History of quantum mechanics, Holography, Horizon, Hot mirror, HRL Laboratories, Huygens–Fresnel principle, Ibn al-Haytham, Ibn Sahl (mathematician), Image, Image sensor, Index of optics articles, Indian philosophy, Infrared, Interface (matter), Interference filter, Interferometry, Internet, Inversion (meteorology), Iran, Isaac Newton, James Clerk Maxwell, James Gregory (mathematician), Johannes Kepler, John William Strutt, 3rd Baron Rayleigh, Jones calculus, Kapitsa–Dirac effect, Kirchhoff's diffraction formula, Lambert's cosine law, Laser, Laser capture microdissection, Laser diode, Laser hair removal, Laser lighting display, Laser pointer, Laser printing, Laser surgery, LaserDisc, Law of superposition, Lens (anatomy), Lens (optics), Leonard Mandel, Lidar, Light, Light-emitting diode, Lighting, Line moiré, Linear polarization, Lissajous curve, Long-focus lens, Luminance, Lunar eclipse, Machine vision, Magnification, Magnifying glass, Maser, Matter, Max Planck, Müller-Lyer illusion, Medicine, Mesopotamia, Metamaterial, Metaphysics, Michelson interferometer, Microscope, Microwave, Middle Ages, Mie scattering, Mineralogy, Mirage, Mirror, Mirror image, Moiré pattern, Molecule, Moon illusion, Multiplicative inverse, Muslim world, Near-sightedness, Newton's rings, Niels Bohr, Night vision, Nimrud lens, Nonimaging optics, Nonlinear optics, Normal (geometry), Normal lens, Novaya Zemlya effect, Number sign, Objective (optics), Ophthalmology, Optic nerve, Optical aberration, Optical communication, Optical computing, Optical engineering, Optical fiber, Optical instrument, Optical lens design, Optical microscope, Optical physics, Optical resolution, Optical rotation, Optical storage, Optical telescope, Optical tweezers, Optical vortex, Optician, Opticks, Optics (Ptolemy), Optoelectronics, Optometry, Orbison illusion, Parabolic reflector, Parallax, Paraxial approximation, Parity (physics), Paul Dirac, Perception, Peripheral vision, Periscope, Perspective (graphical), Phase (waves), Phase velocity, Photodetector, Photoelasticity, Photoelectric effect, Photographic film, Photographic plate, Photography, Photomultiplier, Photon, Photonic integrated circuit, Photonics, Photopic vision, Photoreceptor cell, Physical optics, Physics, Pinhole camera, Plane mirror, Plato, Pleochroism, Poggendorff illusion, Polarimetry, Polarization rotator, Polarizer, Ponzo illusion, Presbyopia, Prism, Propagation constant, Ptolemy, Pupil, Quantum efficiency, Quantum electrodynamics, Quantum field theory, Quantum mechanics, Quantum optics, Quartz, Radio frequency, Radio wave, Radiometry, Rainbow, Raman scattering, Rasmus Bartholin, Ray (optics), Ray tracing (physics), Rayleigh scattering, Real image, Rear-view mirror, Reciprocity (photography), Reference.com, Reflecting telescope, Refracting telescope, Refraction, Refractive index, René Descartes, Retina, Retroreflector, Robert Grosseteste, Robert Hooke, Roger Bacon, Roy J. Glauber, Sander illusion, Scalar (physics), Scattering, Science of photography, Scotopic vision, Sense, Sensitometry, Shot noise, Sign convention, Signal processing, Sky, Snell's law, Solar cell, Solar eclipse, Specular reflection, Speed of light, Spherical aberration, SPIE, Statistical mechanics, Stereoscopy, Stimulated emission, Stokes parameters, Stress (mechanics), Sun dog, Sunny 16 rule, Sunrise, Sunset, Superposition principle, Telephony, Telephoto lens, The Optical Society, Theodore Harold Maiman, Theology, Thin lens, Thin-film optics, Thomas Young (scientist), Thomson scattering, Timaeus (dialogue), Total internal reflection, Transmission-line matrix method, Transparency and translucency, Transverse wave, Twinkling, Tyndall effect, Ultraviolet, Unconscious inference, Vacuum, Vanishing point, Virtual image, Virtual particle, Visual perception, Visual system, Vitello, Vitreous body, Wave, Wave interference, Wave propagation, Wave–particle duality, Waveguide (optics), Wavelength, Waveplate, Wide-angle lens, Wundt illusion, X-ray, X-ray crystallography, Young's interference experiment, Zöllner illusion, Zenith, Zoom lens. 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"A Dynamical Theory of the Electromagnetic Field" is a paper by James Clerk Maxwell on electromagnetism, published in 1865.
In optics and lens design, the Abbe number, also known as the V-number or constringence of a transparent material, is a measure of the material's dispersion (variation of refractive index versus wavelength), with high values of V indicating low dispersion.
Absorption spectroscopy refers to spectroscopic techniques that measure the absorption of radiation, as a function of frequency or wavelength, due to its interaction with a sample.
Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image or focus on an object as its distance varies.
Acoustical engineering (also known as acoustic engineering) is the branch of engineering dealing with sound and vibration.
An acronym is a word or name formed as an abbreviation from the initial components in a phrase or a word, usually individual letters (as in NATO or laser) and sometimes syllables (as in Benelux).
Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effect of incoming wavefront distortions by deforming a mirror in order to compensate for the distortion.
An afterglow is a broad arch of whitish or pinkish sunlight in the sky that is scattered by fine particulates like dust suspended in the atmosphere.
An airborne laser (ABL) is a laser system operated from a flying platform, as in the.
In optics, the Airy disk (or Airy disc) and Airy pattern are descriptions of the best focused spot of light that a perfect lens with a circular aperture can make, limited by the diffraction of light.
Abu Yūsuf Yaʻqūb ibn ʼIsḥāq aṣ-Ṣabbāḥ al-Kindī (أبو يوسف يعقوب بن إسحاق الصبّاح الكندي; Alkindus; c. 801–873 AD) was an Arab Muslim philosopher, polymath, mathematician, physician and musician.
Albert Einstein (14 March 1879 – 18 April 1955) was a German-born theoretical physicist who developed the theory of relativity, one of the two pillars of modern physics (alongside quantum mechanics).
An Ames room is a distorted room that is used to create an optical illusion.
Ancient Egypt was a civilization of ancient Northeastern Africa, concentrated along the lower reaches of the Nile River - geographically Lower Egypt and Upper Egypt, in the place that is now occupied by the countries of Egypt and Sudan.
Ancient Greece was a civilization belonging to a period of Greek history from the Greek Dark Ages of the 13th–9th centuries BC to the end of antiquity (AD 600).
The Ancient Greek language includes the forms of Greek used in ancient Greece and the ancient world from around the 9th century BC to the 6th century AD.
Ancient Greek philosophy arose in the 6th century BC and continued throughout the Hellenistic period and the period in which Ancient Greece was part of the Roman Empire.
In historiography, ancient Rome is Roman civilization from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD, encompassing the Roman Kingdom, Roman Republic and Roman Empire until the fall of the western empire.
Angular resolution or spatial resolution describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object, thereby making it a major determinant of image resolution.
The anterior chamber (AC) is the fluid-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium.
An antireflective or anti-reflection (AR) coating is a type of optical coating applied to the surface of lenses and other optical elements to reduce reflection.
In optics, an aperture is a hole or an opening through which light travels.
Aristotle (Ἀριστοτέλης Aristotélēs,; 384–322 BC) was an ancient Greek philosopher and scientist born in the city of Stagira, Chalkidiki, in the north of Classical Greece.
Ashgate Publishing was an academic book and journal publisher based in Farnham (Surrey, United Kingdom).
Assyria, also called the Assyrian Empire, was a major Semitic speaking Mesopotamian kingdom and empire of the ancient Near East and the Levant.
Astigmatism is a type of refractive error in which the eye does not focus light evenly on the retina.
An astronomical interferometer is an array of separate telescopes, mirror segments, or radio telescope antennas that work together as a single telescope to provide higher resolution images of astronomical objects such as stars, nebulas and galaxies by means of interferometry.
Astronomical seeing is the blurring and twinkling of astronomical objects like stars due to turbulent mixing in the Earth's atmosphere, causing variations of the optical refractive index.
Astronomy (from ἀστρονομία) is a natural science that studies celestial objects and phenomena.
The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity.
Augustin-Jean Fresnel (10 May 178814 July 1827) was a French civil engineer and physicist whose research in optics led to the almost unanimous acceptance of the wave theory of light, excluding any remnant of Newton's corpuscular theory, from the late 1830s until the end of the 19th century.
Ibn Rushd (ابن رشد; full name; 1126 – 11 December 1198), often Latinized as Averroes, was an Andalusian philosopher and thinker who wrote about many subjects, including philosophy, theology, medicine, astronomy, physics, Islamic jurisprudence and law, and linguistics.
Avicenna (also Ibn Sīnā or Abu Ali Sina; ابن سینا; – June 1037) was a Persian polymath who is regarded as one of the most significant physicians, astronomers, thinkers and writers of the Islamic Golden Age.
The ångström or angstrom is a unit of length equal to (one ten-billionth of a metre) or 0.1 nanometre.
Étienne-Louis Malus (23 July 1775 – 24 February 1812) was a French officer, engineer, physicist, and mathematician.
A barcode (also bar code) is an optical, machine-readable, representation of data; the data usually describes something about the object that carries the barcode.
The beam divergence of an electromagnetic beam is an angular measure of the increase in beam diameter or radius with distance from the optical aperture or antenna aperture from which the electromagnetic beam emerges.
In biology, binocular vision is a type of vision in which an animal having two eyes is able to perceive a single three-dimensional image of its surroundings.
Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light.
Black-body radiation is the thermal electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, or emitted by a black body (an opaque and non-reflective body).
A blind spot, scotoma, is an obscurity of the visual field.
Bloodless surgery is a non-invasive surgical method developed by orthopedic surgeon, Adolf Lorenz, who was known as "the bloodless surgeon of Vienna".
In atomic physics, the Rutherford–Bohr model or Bohr model or Bohr diagram, introduced by Niels Bohr and Ernest Rutherford in 1913, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar to the structure of the Solar System, but with attraction provided by electrostatic forces rather than gravity.
The Book of Optics (Kitāb al-Manāẓir; Latin: De Aspectibus or Perspectiva; Italian: Deli Aspecti) is a seven-volume treatise on optics and other fields of study composed by the medieval Arab scholar Ibn al-Haytham, known in the West as Alhazen or Alhacen (965– c. 1040 AD).
The boundary element method (BEM) is a numerical computational method of solving linear partial differential equations which have been formulated as integral equations (i.e. in boundary integral form).
In physics, Bragg's law, or Wulff–Bragg's condition, a special case of Laue diffraction, gives the angles for coherent and incoherent scattering from a crystal lattice.
Brewster's angle (also known as the polarization angle) is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection.
Brigham Young University (BYU, sometimes referred to colloquially as The Y) is a private, non-profit research university in Provo, Utah, United States completely owned by The Church of Jesus Christ of Latter-day Saints (LDS or Mormon Church) and run under the auspices of its Church Educational System.
Brillouin scattering, named after Léon Brillouin, refers to the interaction of light and material waves within a medium.
A bubblegram (also known as laser crystal, 3D crystal engraving or vitrography) is a solid block of glass or transparent plastic that has been exposed to laser beams to generate three-dimensional designs inside.
The café wall illusion is a geometrical-optical illusion in which the parallel straight dividing lines between staggered rows with alternating black and white "bricks" appear to be sloped.
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3).
A camera is an optical instrument for recording or capturing images, which may be stored locally, transmitted to another location, or both.
A camera lens (also known as photographic lens or photographic objective) is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing an image chemically or electronically.
A charge-coupled device (CCD) is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value.
Chemistry is the scientific discipline involved with compounds composed of atoms, i.e. elements, and molecules, i.e. combinations of atoms: their composition, structure, properties, behavior and the changes they undergo during a reaction with other compounds.
Chirality is a geometric property of some molecules and ions.
A chirp is a signal in which the frequency increases (up-chirp) or decreases (down-chirp) with time.
Christiaan Huygens (Hugenius; 14 April 1629 – 8 July 1695) was a Dutch physicist, mathematician, astronomer and inventor, who is widely regarded as one of the greatest scientists of all time and a major figure in the scientific revolution.
Christmas is an annual festival commemorating the birth of Jesus Christ,Martindale, Cyril Charles.
The Christmas season, also called the festive season, or the holiday season (mainly in the U.S. and Canada; often simply called the holidays),, is an annually recurring period recognized in many Western and Western-influenced countries that is generally considered to run from late November to early January.
Christmas Eve is the evening or entire day before Christmas Day, the festival commemorating the birth of Jesus.
Christmas traditions vary from country to country.
In optics, chromatic aberration (abbreviated CA; also called chromatic distortion and spherochromatism) is an effect resulting from dispersion in which there is a failure of a lens to focus all colors to the same convergence point.
The ciliary muscle is a ring of smooth muscleSchachar, Ronald A. (2012). "Anatomy and Physiology." (Chapter 4). in the eye's middle layer (vascular layer) that controls accommodation for viewing objects at varying distances and regulates the flow of aqueous humour into Schlemm's canal. It changes the shape of the lens within the eye, not the size of the pupil which is carried out by the sphincter pupillae muscle and dilator pupillae.
Circular dichroism (CD) is dichroism involving circularly polarized light, i.e., the differential absorption of left- and right-handed light.
In electrodynamics, circular polarization of an electromagnetic wave is a polarization state in which, at each point, the electric field of the wave has a constant magnitude but its direction rotates with time at a steady rate in a plane perpendicular to the direction of the wave.
Classical electromagnetism or classical electrodynamics is a branch of theoretical physics that studies the interactions between electric charges and currents using an extension of the classical Newtonian model.
In physics, two wave sources are perfectly coherent if they have a constant phase difference and the same frequency, and the same waveform.
Color (American English) or colour (Commonwealth English) is the characteristic of human visual perception described through color categories, with names such as red, orange, yellow, green, blue, or purple.
Color/Colour television is a television transmission technology that includes information on the color of the picture, so the video image can be displayed in color on the television set.
Compact disc (CD) is a digital optical disc data storage format that was co-developed by Philips and Sony and released in 1982.
A comparison microscope is a device used to analyze side-by-side specimens.
Compton scattering, discovered by Arthur Holly Compton, is the scattering of a photon by a charged particle, usually an electron.
Computer engineering is a discipline that integrates several fields of computer science and electronics engineering required to develop computer hardware and software.
Computer simulation is the reproduction of the behavior of a system using a computer to simulate the outcomes of a mathematical model associated with said system.
In physics, the law of conservation of energy states that the total energy of an isolated system remains constant, it is said to be ''conserved'' over time.
Constantine the African (Constantinus Africanus; died before 1098/1099, Monte Cassino) was a physician who lived in the 11th century.
A contact lens, or simply contact, is a thin lens placed directly on the surface of the eye.
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber.
A corner reflector is a retroreflector consisting of three mutually perpendicular, intersecting flat surfaces, which reflects waves back directly towards the source, but translated.
In meteorology, a corona (plural coronae) is an optical phenomenon produced by the diffraction of sunlight or moonlight (or, occasionally, bright starlight or planetlight) by individual small water droplets and sometimes tiny ice crystals of a cloud or on a foggy glass surface.
In optics, the corpuscular theory of light, arguably set forward by Descartes (1637) states that light is made up of small discrete particles called "corpuscles" (little particles) which travel in a straight line with a finite velocity and possess impetus.
A corrective lens is a lens typically worn in front of the eye to improve vision.
In statistics, dependence or association is any statistical relationship, whether causal or not, between two random variables or bivariate data.
Cosmogony is any model concerning the origin of either the cosmos or universe.
A covalent bond, also called a molecular bond, is a chemical bond that involves the sharing of electron pairs between atoms.
Crepuscular rays (more commonly known as sunbeams, sun rays, or god rays), in atmospheric optics, are rays of sunlight that appear to radiate from the point in the sky where the sun is located.
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.
Crystal optics is the branch of optics that describes the behaviour of light in anisotropic media, that is, media (such as crystals) in which light behaves differently depending on which direction the light is propagating.
A curved mirror is a mirror with a curved reflecting surface.
A cylinder (from Greek κύλινδρος – kulindros, "roller, tumbler"), has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes.
Daniel Frank Walls (13 September 1942 – 12 May 1999) FRS was a New Zealand theoretical physicist specialising in quantum optics.
Degree of polarization (DOP) is a quantity used to describe the portion of an electromagnetic wave which is polarized.
Democritus (Δημόκριτος, Dēmókritos, meaning "chosen of the people") was an Ancient Greek pre-Socratic philosopher primarily remembered today for his formulation of an atomic theory of the universe.
In optics, particularly as it relates to film and photography, the optical phenomenon known as depth of field (DOF), is the distance about the Plane of Focus (POF) where objects appear acceptably sharp in an image.
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle.
In optics, a dichroic material is either one which causes visible light to be split up into distinct beams of different wavelengths (colours) (not to be confused with dispersion), or one in which light rays having different polarizations are absorbed by different amounts.
A dielectric (or dielectric material) is an electrical insulator that can be polarized by an applied electric field.
A dielectric mirror, also known as a Bragg mirror, is a type of mirror composed of multiple thin layers of dielectric material, typically deposited on a substrate of glass or some other optical material.
--> Diffraction refers to various phenomena that occur when a wave encounters an obstacle or a slit.
In optics, a diffraction grating is an optical component with a periodic structure that splits and diffracts light into several beams travelling in different directions.
Diffraction topography (short: "topography") is an quantum beam imaging technique based on Bragg diffraction.
The resolution of an optical imaging system a microscope, telescope, or camera can be limited by factors such as imperfections in the lenses or misalignment.
Diffuse reflection is the reflection of light or other waves or particles from a surface such that a ray incident on the surface is scattered at many angles rather than at just one angle as in the case of specular reflection.
In computer science, Digital image processing is the use of computer algorithms to perform image processing on digital images.
A dioptre (British spelling) or diopter (American spelling) is a unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres.
Directional Infrared Counter Measures (DIRCM) is a system produced by Leonardo, Elbit Systems, Northrop Grumman, ITT Corporation, and BAE Systems to protect aircraft from infrared homing ("heat seeking") man-portable missiles.
In modern physics, the double-slit experiment is a demonstration that light and matter can display characteristics of both classically defined waves and particles; moreover, it displays the fundamentally probabilistic nature of quantum mechanical phenomena.
Ennackal Chandy George Sudarshan (also known as E. C. G. Sudarshan; 16 September 1931 – 14 May 2018) was an Indian theoretical physicist and a professor at the University of Texas.
The Ehrenstein illusion is an optical illusion studied by the German psychologist (1899 – 1961) in which the sides of a square placed inside a pattern of concentric circles take an apparent curved shape (Figure 1).
In physics, electromagnetic radiation (EM radiation or EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space-time, carrying electromagnetic radiant energy.
Electromagnetism is a branch of physics involving the study of the electromagnetic force, a type of physical interaction that occurs between electrically charged particles.
An electron multiplier is a vacuum-tube structure that multiplies incident charges.
An electrostatic lens is a device that assists in the transport of charged particles.
In mathematics, an ellipse is a curve in a plane surrounding two focal points such that the sum of the distances to the two focal points is constant for every point on the curve.
In electrodynamics, elliptical polarization is the polarization of electromagnetic radiation such that the tip of the electric field vector describes an ellipse in any fixed plane intersecting, and normal to, the direction of propagation.
The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted due to an atom or molecule making a transition from a high energy state to a lower energy state.
Emission theory or extramission theory (variants: extromission, extromittism) is the proposal that visual perception is accomplished by eye beams emitted by the eyes.
Engineering is the creative application of science, mathematical methods, and empirical evidence to the innovation, design, construction, operation and maintenance of structures, machines, materials, devices, systems, processes, and organizations.
Epicurus (Ἐπίκουρος, Epíkouros, "ally, comrade"; 341–270 BC) was an ancient Greek philosopher who founded a school of philosophy now called Epicureanism.
Epistemology is the branch of philosophy concerned with the theory of knowledge.
Etiology (alternatively aetiology or ætiology) is the study of causation, or origination.
Euclid (Εὐκλείδης Eukleidēs; fl. 300 BC), sometimes given the name Euclid of Alexandria to distinguish him from Euclides of Megara, was a Greek mathematician, often referred to as the "founder of geometry" or the "father of geometry".
In mathematics, physics, and engineering, a Euclidean vector (sometimes called a geometric or spatial vector, or—as here—simply a vector) is a geometric object that has magnitude (or length) and direction.
The European Optical Society (EOS), founded in 1991, is a European organisation for the development of the science of optics.
The European Photonics Industry Consortium (EPIC) is a not-for-profit association with headquarters in Brussels, Belgium.
In photography, exposure is the amount of light per unit area (the image plane illuminance times the exposure time) reaching a photographic film or electronic image sensor, as determined by shutter speed, lens aperture and scene luminance.
An eyepiece, or ocular lens, is a type of lens that is attached to a variety of optical devices such as telescopes and microscopes.
The f-number of an optical system (such as a camera lens) is the ratio of the system's focal length to the diameter of the entrance pupil.
Optical fabrication and testing spans an enormous range of manufacturing procedures and optical test configurations.
In visual perception, the far point is the point at which an object must be placed along the optical axis of the eye for its image to be focused on the retina when the eye is not accommodating.
Far-sightedness, also known as hyperopia, is a condition of the eye in which light is focused behind, instead of on, the retina.
In physics, the Faraday effect or Faraday rotation is a magneto-optical phenomenon—that is, an interaction between light and a magnetic field in a medium.
A Fata Morgana is an unusual and complex form of superior mirage that is seen in a narrow band right above the horizon.
In optics, Fermat's principle or the principle of least time, named after French mathematician Pierre de Fermat, is the principle that the path taken between two points by a ray of light is the path that can be traversed in the least time.
Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber.
Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system.
The finite element method (FEM), is a numerical method for solving problems of engineering and mathematical physics.
The focal length of an optical system is a measure of how strongly the system converges or diverges light.
In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge.
Fourier optics is the study of classical optics using Fourier transforms (FTs), in which the wave is regarded as a superposition of plane waves that are not related to any identifiable sources; instead they are the natural modes of the propagation medium itself.
The fovea centralis is a small, central pit composed of closely packed cones in the eye.
Francesco Maria Grimaldi (2 April 1618 – 28 December 1663) was an Italian Jesuit priest, mathematician and physicist who taught at the Jesuit college in Bologna.
The Fraser spiral illusion is an optical illusion that was first described by the British psychologist Sir James Fraser (1863 – 1936) in 1908.
In optics, the Fraunhofer diffraction equation is used to model the diffraction of waves when the diffraction pattern is viewed at a long distance from the diffracting object, and also when it is viewed at the focal plane of an imaging lens.
In optics, the Fraunhofer diffraction equation is used to model the diffraction of waves when the diffraction pattern is viewed at a long distance from the diffracting object, and also when it is viewed at the focal plane of an imaging lens.
In optics, the Fresnel diffraction equation for near-field diffraction is an approximation of the Kirchhoff–Fresnel diffraction that can be applied to the propagation of waves in the near field.
The Fresnel equations (or Fresnel coefficients) describe the reflection and transmission of light (or electromagnetic radiation in general) when incident on an interface between different optical media.
In optics, a Gaussian beam is a beam of monochromatic electromagnetic radiation whose transverse magnetic and electric field amplitude profiles are given by the Gaussian function; this also implies a Gaussian intensity (irradiance) profile.
Gaussian optics is a technique in geometrical optics that describes the behaviour of light rays in optical systems by using the paraxial approximation, in which only rays which make small angles with the optical axis of the system are considered.
Geometrical optics, or ray optics, describes light propagation in terms of rays.
Geometry (from the γεωμετρία; geo- "earth", -metron "measurement") is a branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space.
Glasses, also known as eyeglasses or spectacles, are devices consisting of glass or hard plastic lenses mounted in a frame that holds them in front of a person's eyes, typically using a bridge over the nose and arms which rest over the ears.
Gradient-index (GRIN) optics is the branch of optics covering optical effects produced by a gradual variation of the refractive index of a material.
The Greco-Roman world, Greco-Roman culture, or the term Greco-Roman; spelled Graeco-Roman in the United Kingdom and the Commonwealth), when used as an adjective, as understood by modern scholars and writers, refers to those geographical regions and countries that culturally (and so historically) were directly, long-term, and intimately influenced by the language, culture, government and religion of the ancient Greeks and Romans. It is also better known as the Classical Civilisation. In exact terms the area refers to the "Mediterranean world", the extensive tracts of land centered on the Mediterranean and Black Sea basins, the "swimming-pool and spa" of the Greeks and Romans, i.e. one wherein the cultural perceptions, ideas and sensitivities of these peoples were dominant. This process was aided by the universal adoption of Greek as the language of intellectual culture and commerce in the Eastern Mediterranean Sea, and of Latin as the tongue for public management and forensic advocacy, especially in the Western Mediterranean. Though the Greek and the Latin never became the native idioms of the rural peasants who composed the great majority of the empire's population, they were the languages of the urbanites and cosmopolitan elites, and the lingua franca, even if only as corrupt or multifarious dialects to those who lived within the large territories and populations outside the Macedonian settlements and the Roman colonies. All Roman citizens of note and accomplishment regardless of their ethnic extractions, spoke and wrote in Greek and/or Latin, such as the Roman jurist and Imperial chancellor Ulpian who was of Phoenician origin, the mathematician and geographer Claudius Ptolemy who was of Greco-Egyptian origin and the famous post-Constantinian thinkers John Chrysostom and Augustine who were of Syrian and Berber origins, respectively, and the historian Josephus Flavius who was of Jewish origin and spoke and wrote in Greek.
The group velocity of a wave is the velocity with which the overall shape of the wave's amplitudes—known as the modulation or envelope of the wave—propagates through space.
Halo (from Greek ἅλως, halōs) is the name for a family of optical phenomena produced by sunlight interacting with ice crystals suspended in the atmosphere.
The Hering illusion is one of the geometrical-optical illusions and was discovered by the German physiologist Ewald Hering in 1861.
The history of quantum mechanics is a fundamental part of the history of modern physics.
Holography is the science and practice of making holograms.
The horizon or skyline is the apparent line that separates earth from sky, the line that divides all visible directions into two categories: those that intersect the Earth's surface, and those that do not.
A hot mirror is a specialized dielectric mirror, a dichroic filter, often employed to protect optical systems by reflecting infrared light back into a light source, while allowing visible light to pass.
HRL Laboratories (formerly Hughes Research Laboratories), was the research arm of Hughes Aircraft.
The Huygens–Fresnel principle (named after Dutch physicist Christiaan Huygens and French physicist Augustin-Jean Fresnel) is a method of analysis applied to problems of wave propagation both in the far-field limit and in near-field diffraction.
Hasan Ibn al-Haytham (Latinized Alhazen; full name أبو علي، الحسن بن الحسن بن الهيثم) was an Arab mathematician, astronomer, and physicist of the Islamic Golden Age.
Ibn Sahl (full name Abū Saʿd al-ʿAlāʾ ibn Sahl أبو سعد العلاء ابن سهل; c. 940–1000) was a Muslim Persian mathematician and physicist of the Islamic Golden Age, associated with the Buwayhid court of Baghdad.
An image (from imago) is an artifact that depicts visual perception, for example, a photo or a two-dimensional picture, that has a similar appearance to some subject—usually a physical object or a person, thus providing a depiction of it.
An image sensor or imaging sensor is a sensor that detects and conveys the information that constitutes an image.
Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it.
Indian philosophy refers to ancient philosophical traditions of the Indian subcontinent.
Infrared radiation (IR) is electromagnetic radiation (EMR) with longer wavelengths than those of visible light, and is therefore generally invisible to the human eye (although IR at wavelengths up to 1050 nm from specially pulsed lasers can be seen by humans under certain conditions). It is sometimes called infrared light.
In the physical sciences, an interface is the boundary between two spatial regions occupied by different matter, or by matter in different physical states.
An interference filter or dichroic filter is an optical filter that reflects one or more spectral bands or lines and transmits others, while maintaining a nearly zero coefficient of absorption for all wavelengths of interest.
Interferometry is a family of techniques in which waves, usually electromagnetic waves, are superimposed causing the phenomenon of interference in order to extract information.
The Internet is the global system of interconnected computer networks that use the Internet protocol suite (TCP/IP) to link devices worldwide.
In meteorology, an inversion is a deviation from the normal change of an atmospheric property with altitude.
Iran (ایران), also known as Persia, officially the Islamic Republic of Iran (جمهوری اسلامی ایران), is a sovereign state in Western Asia. With over 81 million inhabitants, Iran is the world's 18th-most-populous country. Comprising a land area of, it is the second-largest country in the Middle East and the 17th-largest in the world. Iran is bordered to the northwest by Armenia and the Republic of Azerbaijan, to the north by the Caspian Sea, to the northeast by Turkmenistan, to the east by Afghanistan and Pakistan, to the south by the Persian Gulf and the Gulf of Oman, and to the west by Turkey and Iraq. The country's central location in Eurasia and Western Asia, and its proximity to the Strait of Hormuz, give it geostrategic importance. Tehran is the country's capital and largest city, as well as its leading economic and cultural center. Iran is home to one of the world's oldest civilizations, beginning with the formation of the Elamite kingdoms in the fourth millennium BCE. It was first unified by the Iranian Medes in the seventh century BCE, reaching its greatest territorial size in the sixth century BCE, when Cyrus the Great founded the Achaemenid Empire, which stretched from Eastern Europe to the Indus Valley, becoming one of the largest empires in history. The Iranian realm fell to Alexander the Great in the fourth century BCE and was divided into several Hellenistic states. An Iranian rebellion culminated in the establishment of the Parthian Empire, which was succeeded in the third century CE by the Sasanian Empire, a leading world power for the next four centuries. Arab Muslims conquered the empire in the seventh century CE, displacing the indigenous faiths of Zoroastrianism and Manichaeism with Islam. Iran made major contributions to the Islamic Golden Age that followed, producing many influential figures in art and science. After two centuries, a period of various native Muslim dynasties began, which were later conquered by the Turks and the Mongols. The rise of the Safavids in the 15th century led to the reestablishment of a unified Iranian state and national identity, with the country's conversion to Shia Islam marking a turning point in Iranian and Muslim history. Under Nader Shah, Iran was one of the most powerful states in the 18th century, though by the 19th century, a series of conflicts with the Russian Empire led to significant territorial losses. Popular unrest led to the establishment of a constitutional monarchy and the country's first legislature. A 1953 coup instigated by the United Kingdom and the United States resulted in greater autocracy and growing anti-Western resentment. Subsequent unrest against foreign influence and political repression led to the 1979 Revolution and the establishment of an Islamic republic, a political system that includes elements of a parliamentary democracy vetted and supervised by a theocracy governed by an autocratic "Supreme Leader". During the 1980s, the country was engaged in a war with Iraq, which lasted for almost nine years and resulted in a high number of casualties and economic losses for both sides. According to international reports, Iran's human rights record is exceptionally poor. The regime in Iran is undemocratic, and has frequently persecuted and arrested critics of the government and its Supreme Leader. Women's rights in Iran are described as seriously inadequate, and children's rights have been severely violated, with more child offenders being executed in Iran than in any other country in the world. Since the 2000s, Iran's controversial nuclear program has raised concerns, which is part of the basis of the international sanctions against the country. The Joint Comprehensive Plan of Action, an agreement reached between Iran and the P5+1, was created on 14 July 2015, aimed to loosen the nuclear sanctions in exchange for Iran's restriction in producing enriched uranium. Iran is a founding member of the UN, ECO, NAM, OIC, and OPEC. It is a major regional and middle power, and its large reserves of fossil fuels – which include the world's largest natural gas supply and the fourth-largest proven oil reserves – exert considerable influence in international energy security and the world economy. The country's rich cultural legacy is reflected in part by its 22 UNESCO World Heritage Sites, the third-largest number in Asia and eleventh-largest in the world. Iran is a multicultural country comprising numerous ethnic and linguistic groups, the largest being Persians (61%), Azeris (16%), Kurds (10%), and Lurs (6%).
Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, astronomer, theologian, author and physicist (described in his own day as a "natural philosopher") who is widely recognised as one of the most influential scientists of all time, and a key figure in the scientific revolution.
James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish scientist in the field of mathematical physics.
James Gregory FRS (November 1638 – October 1675) was a Scottish mathematician and astronomer.
Johannes Kepler (December 27, 1571 – November 15, 1630) was a German mathematician, astronomer, and astrologer.
John William Strutt, 3rd Baron Rayleigh, (12 November 1842 – 30 June 1919) was a physicist who, with William Ramsay, discovered argon, an achievement for which he earned the Nobel Prize for Physics in 1904.
In optics, polarized light can be described using the Jones calculus, discovered by R. C. Jones in 1941.
The Kapitza–Dirac effect is a quantum mechanical effect consisting of the diffraction of matter by a standing wave of light.
Kirchhoff's diffraction formula (also Fresnel–Kirchhoff diffraction formula) can be used to model the propagation of light in a wide range of configurations, either analytically or using numerical modelling.
In optics, Lambert's cosine law says that the radiant intensity or luminous intensity observed from an ideal diffusely reflecting surface or ideal diffuse radiator is directly proportional to the cosine of the angle θ between the direction of the incident light and the surface normal.
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation.
Laser capture microdissection (LCM), also called microdissection, laser microdissection (LMD), or laser-assisted microdissection (LMD or LAM), is a method for isolating specific cells of interest from microscopic regions of tissue/cells/organisms (dissection on a microscopic scale with the help of a laser).
A laser diode, (LD), injection laser diode (ILD), or diode laser is a semiconductor device similar to a light-emitting diode in which the laser beam is created at the diode's junction.
Laser hair removal is the process of hair removal by means of exposure to pulses of laser light that destroy the hair follicle.
A laser lighting display or laser light show involves the use of laser light to entertain an audience.
A laser pointer or laser pen is a small handheld device with a power source (usually a battery) and a laser diode emitting a very narrow coherent low-powered laser beam of visible light, intended to be used to highlight something of interest by illuminating it with a small bright spot of colored light.
Laser printing is an electrostatic digital printing process.
Laser surgery is a type of surgery that uses a laser (in contrast to using a scalpel) to cut tissue.
LaserDisc (abbreviated as LD) is a home video format and the first commercial optical disc storage medium, initially licensed, sold and marketed as MCA DiscoVision in the United States in 1978.
The law of superposition is an axiom that forms one of the bases of the sciences of geology, archaeology, and other fields dealing with geological stratigraphy.
The lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina.
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction.
Leonard Mandel (May 9, 1927 – February 9, 2001) was the Lee DuBridge Professor Emeritus of Physics and Optics at the University of Rochester when he died at the age of 73 at his home in Pittsford, New York.
Lidar (also called LIDAR, LiDAR, and LADAR) is a surveying method that measures distance to a target by illuminating the target with pulsed laser light and measuring the reflected pulses with a sensor.
Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum.
A light-emitting diode (LED) is a two-lead semiconductor light source.
Lighting or illumination is the deliberate use of light to achieve a practical or aesthetic effect.
Line moiré is one type of moiré pattern; a pattern that appears when superposing two transparent layers containing correlated opaque patterns.
In electrodynamics, linear polarization or plane polarization of electromagnetic radiation is a confinement of the electric field vector or magnetic field vector to a given plane along the direction of propagation.
In mathematics, a Lissajous curve, also known as Lissajous figure or Bowditch curve, is the graph of a system of parametric equations which describe complex harmonic motion.
In photography, a long-focus lens is a camera lens which has a focal length that is longer than the diagonal measure of the film or sensor that receives its image.
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction.
A lunar eclipse occurs when the Moon passes directly behind Earth and into its shadow.
Machine vision (MV) is the technology and methods used to provide imaging-based automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry.
Magnification is the process of enlarging the appearance, not physical size, of something.
A magnifying glass (called a hand lens in laboratory contexts) is a convex lens that is used to produce a magnified image of an object.
A maser (an acronym for "microwave amplification by stimulated emission of radiation") is a device that produces coherent electromagnetic waves through amplification by stimulated emission.
In the classical physics observed in everyday life, matter is any substance that has mass and takes up space by having volume.
Max Karl Ernst Ludwig Planck, FRS (23 April 1858 – 4 October 1947) was a German theoretical physicist whose discovery of energy quanta won him the Nobel Prize in Physics in 1918.
The Müller-Lyer illusion is an optical illusion consisting of a stylized arrow.
Medicine is the science and practice of the diagnosis, treatment, and prevention of disease.
Mesopotamia is a historical region in West Asia situated within the Tigris–Euphrates river system, in modern days roughly corresponding to most of Iraq, Kuwait, parts of Northern Saudi Arabia, the eastern parts of Syria, Southeastern Turkey, and regions along the Turkish–Syrian and Iran–Iraq borders.
A metamaterial (from the Greek word μετά meta, meaning "beyond") is a material engineered to have a property that is not found in nature.
Metaphysics is a branch of philosophy that explores the nature of being, existence, and reality.
The Michelson interferometer is a common configuration for optical interferometry and was invented by Albert Abraham Michelson.
A microscope (from the μικρός, mikrós, "small" and σκοπεῖν, skopeîn, "to look" or "see") is an instrument used to see objects that are too small to be seen by the naked eye.
Microwaves are a form of electromagnetic radiation with wavelengths ranging from one meter to one millimeter; with frequencies between and.
In the history of Europe, the Middle Ages (or Medieval Period) lasted from the 5th to the 15th century.
The Mie solution to Maxwell's equations (also known as the Lorenz–Mie solution, the Lorenz–Mie–Debye solution or Mie scattering) describes the scattering of an electromagnetic plane wave by a homogeneous sphere.
Mineralogy is a subject of geology specializing in the scientific study of chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts.
A mirage is a naturally occurring optical phenomenon in which light rays bend to produce a displaced image of distant objects or the sky.
A mirror is an object that reflects light in such a way that, for incident light in some range of wavelengths, the reflected light preserves many or most of the detailed physical characteristics of the original light, called specular reflection.
A mirror image (in a plane mirror) is a reflected duplication of an object that appears almost identical, but is reversed in the direction perpendicular to the mirror surface.
In mathematics, physics, and art, a moiré pattern or moiré fringes are large-scale interference patterns that can be produced when an opaque ruled pattern with transparent gaps is overlaid on another similar pattern.
A molecule is an electrically neutral group of two or more atoms held together by chemical bonds.
The Moon illusion is an optical illusion which causes the Moon to appear larger near the horizon than it does higher up in the sky.
In mathematics, a multiplicative inverse or reciprocal for a number x, denoted by 1/x or x−1, is a number which when multiplied by x yields the multiplicative identity, 1.
The terms Muslim world and Islamic world commonly refer to the unified Islamic community (Ummah), consisting of all those who adhere to the religion of Islam, or to societies where Islam is practiced.
Near-sightedness, also known as short-sightedness and myopia, is a condition of the eye where light focuses in front of, instead of on, the retina.
New Year is the time or day at which a new calendar year begins and the calendar's year count increments by one.
New Year's Day, also called simply New Year's or New Year, is observed on January 1, the first day of the year on the modern Gregorian calendar as well as the Julian calendar.
In the Gregorian calendar, New Year's Eve (also known as Old Year's Day or Saint Sylvester's Day in many countries), the last day of the year, is on 31 December which is the seventh day of Christmastide.
Newton's rings is a phenomenon in which an interference pattern is created by the reflection of light between two surfaces—a spherical surface and an adjacent touching flat surface.
Niels Henrik David Bohr (7 October 1885 – 18 November 1962) was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922.
Night vision is the ability to see in low-light conditions.
The Nimrud lens, also called Layard lens, is a 3000-year-old piece of rock crystal, which was unearthed in 1850 by Austen Henry Layard at the Assyrian palace of Nimrud, in modern-day Iraq.
Nonimaging optics (also called anidolic optics)Roland Winston et al., Nonimaging Optics, Academic Press, 2004 R. John Koshel (Editor), Illumination Engineering: Design with Nonimaging Optics, Wiley, 2013 is the branch of optics concerned with the optimal transfer of light radiation between a source and a target.
Nonlinear optics (NLO) is the branch of optics that describes the behavior of light in nonlinear media, that is, media in which the dielectric polarization P responds nonlinearly to the electric field E of the light.
In geometry, a normal is an object such as a line or vector that is perpendicular to a given object.
In photography and cinematography, a normal lens is a lens that reproduces a field of view that appears "natural" to a human observer.
The Novaya Zemlya effect is a polar mirage caused by high refraction of sunlight between atmospheric thermoclines.
The symbol # is most commonly known as the number sign, hash, or pound sign.
In optical engineering, the objective is the optical element that gathers light from the object being observed and focuses the light rays to produce a real image.
Ophthalmology is a branch of medicine and surgery (both methods are used) that deals with the anatomy, physiology and diseases of the eyeball and orbit.
The optic nerve, also known as cranial nerve II, is a paired nerve that transmits visual information from the retina to the brain.
Aberration in optics refers to a defect in a lens such that light is not focused to a point, but is spread out over some region of space, and hence an image formed by a lens with aberration is blurred or distorted, with the nature of the distortion depending on the type of aberration.
Optical communication, also known as optical telecommunication, is communication at a distance using light to carry information.
Optical or photonic computing uses photons produced by lasers or diodes for computation.
Optical engineering is the field of study that focuses on applications of optics.
An optical fiber or optical fibre is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair.
An optical instrument either processes light waves to enhance an image for viewing, or analyzes light waves (or photons) to determine one of a number of characteristic properties.
Optical lens design is the process of designing a lens to meet a set of performance requirements and constraints, including cost and manufacturing limitations.
The optical microscope, often referred to as the light microscope, is a type of microscope that uses visible light and a system of lenses to magnify images of small subjects.
Optical physics is a subfield of atomic, molecular, and optical physics.
Optical resolution describes the ability of an imaging system to resolve detail in the object that is being imaged.
Optical rotation or optical activity (sometimes referred to as rotary polarization) is the rotation of the plane of polarization of linearly polarized light as it travels through certain materials.
Optical storage is the storage of data on an optically readable medium.
An optical telescope is a telescope that gathers and focuses light, mainly from the visible part of the electromagnetic spectrum, to create a magnified image for direct view, or to make a photograph, or to collect data through electronic image sensors.
Optical tweezers (originally called "single-beam gradient force trap") are scientific instruments that use a highly focused laser beam to provide an attractive or repulsive force (typically on the order of piconewtons), depending on the relative refractive index between particle and surrounding medium, to physically hold and move microscopic objects similar to tweezers.
An optical vortex (also known as a photonic quantum vortex, screw dislocation or phase singularity) is a zero of an optical field; a point of zero intensity.
An optician, or dispensing optician, is a technical practitioner who designs, fits and dispenses corrective lenses for the correction of a person's vision.
Opticks: or, A Treatise of the Reflexions, Refractions, Inflexions and Colours of Light is a book by English natural philosopher Isaac Newton that was published in English in 1704.
Ptolemy's Optics (2nd century) is a (partially lost) work on geometrical optics, dealing with reflection, refraction, and colour.
Optoelectronics is the study and application of electronic devices and systems that source, detect and control light, usually considered a sub-field of photonics.
Optometry is a health care profession which involves examining the eyes and applicable visual systems for defects or abnormalities as well as the medical diagnosis and management of eye disease.
The Orbison illusion (or Orbison's illusion) is an optical illusion first described by American psychologist William Orbison (1912–1952) in 1939.
A parabolic (or paraboloid or paraboloidal) reflector (or dish or mirror) is a reflective surface used to collect or project energy such as light, sound, or radio waves.
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines.
In geometric optics, the paraxial approximation is a small-angle approximation used in Gaussian optics and ray tracing of light through an optical system (such as a lens).
In quantum mechanics, a parity transformation (also called parity inversion) is the flip in the sign of one spatial coordinate.
Paul Adrien Maurice Dirac (8 August 1902 – 20 October 1984) was an English theoretical physicist who is regarded as one of the most significant physicists of the 20th century.
Perception (from the Latin perceptio) is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information, or the environment.
Peripheral vision is a part of vision that occurs only on the side gaze.
A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position.
Perspective (from perspicere "to see through") in the graphic arts is an approximate representation, generally on a flat surface (such as paper), of an image as it is seen by the eye.
Phase is the position of a point in time (an instant) on a waveform cycle.
The phase velocity of a wave is the rate at which the phase of the wave propagates in space.
Photosensors or photodetectors are sensors of light or other electromagnetic energy.
Photoelasticity describes changes in the optical properties of a material under mechanical deformation.
The photoelectric effect is the emission of electrons or other free carriers when light shines on a material.
Photographic film is a strip or sheet of transparent plastic film base coated on one side with a gelatin emulsion containing microscopically small light-sensitive silver halide crystals.
Photographic plates preceded photographic film as a capture medium in photography.
Photography is the science, art, application and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film.
Photomultiplier tubes (photomultipliers or PMTs for short), members of the class of vacuum tubes, and more specifically vacuum phototubes, are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum.
The photon is a type of elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force (even when static via virtual particles).
A photonic integrated circuit (PIC) or integrated optical circuit is a device that integrates multiple (at least two) photonic functions and as such is similar to an electronic integrated circuit.
Photonics is the physical science of light (photon) generation, detection, and manipulation through emission, transmission, modulation, signal processing, switching, amplification, and detection/sensing.
Photopic vision is the vision of the eye under well-lit conditions (luminance level 10 to 108 cd/m2).
A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction.
In physics, physical optics, or wave optics, is the branch of optics that studies interference, diffraction, polarization, and other phenomena for which the ray approximation of geometric optics is not valid.
Physics (from knowledge of nature, from φύσις phýsis "nature") is the natural science that studies matterAt the start of The Feynman Lectures on Physics, Richard Feynman offers the atomic hypothesis as the single most prolific scientific concept: "If, in some cataclysm, all scientific knowledge were to be destroyed one sentence what statement would contain the most information in the fewest words? I believe it is that all things are made up of atoms – little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another..." and its motion and behavior through space and time and that studies the related entities of energy and force."Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular succession of events." Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves."Physics is one of the most fundamental of the sciences. Scientists of all disciplines use the ideas of physics, including chemists who study the structure of molecules, paleontologists who try to reconstruct how dinosaurs walked, and climatologists who study how human activities affect the atmosphere and oceans. Physics is also the foundation of all engineering and technology. No engineer could design a flat-screen TV, an interplanetary spacecraft, or even a better mousetrap without first understanding the basic laws of physics. (...) You will come to see physics as a towering achievement of the human intellect in its quest to understand our world and ourselves."Physics is an experimental science. Physicists observe the phenomena of nature and try to find patterns that relate these phenomena.""Physics is the study of your world and the world and universe around you." Physics is one of the oldest academic disciplines and, through its inclusion of astronomy, perhaps the oldest. Over the last two millennia, physics, chemistry, biology, and certain branches of mathematics were a part of natural philosophy, but during the scientific revolution in the 17th century, these natural sciences emerged as unique research endeavors in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms studied by other sciences and suggest new avenues of research in academic disciplines such as mathematics and philosophy. Advances in physics often enable advances in new technologies. For example, advances in the understanding of electromagnetism and nuclear physics led directly to the development of new products that have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.
A pinhole camera is a simple camera without a lens but with a tiny aperture, a pinhole – effectively a light-proof box with a small hole in one side.
A plane mirror is a mirror with a flat (planar) reflective surface.
Plato (Πλάτων Plátōn, in Classical Attic; 428/427 or 424/423 – 348/347 BC) was a philosopher in Classical Greece and the founder of the Academy in Athens, the first institution of higher learning in the Western world.
Pleochroism (from Greek πλέων, pléōn, "more" and χρῶμα, khrôma, "color") is an optical phenomenon in which a substance has different colors when observed at different angles, especially with polarized light.
The Poggendorff illusion is a geometrical-optical illusion that involves the misperception of the position of one segment of a transverse line that has been interrupted by the contour of an intervening structure.
Polarimetry is the measurement and interpretation of the polarization of transverse waves, most notably electromagnetic waves, such as radio or light waves.
A polarization rotator is an optical device that rotates the polarization axis of a linearly polarized light beam by an angle of choice.
A polarizer or polariser is an optical filter that lets light waves of a specific polarization pass through while blocking light waves of other polarizations.
The Ponzo illusion is a geometrical-optical illusion that was first demonstrated by the Italian psychologist Mario Ponzo (1882–1960) in 1911.
Presbyopia is a condition associated with the aging of the eye that results in progressively worsening ability to focus clearly on close objects.
In optics, a prism is a transparent optical element with flat, polished surfaces that refract light.
The propagation constant of a sinusoidal electromagnetic wave is a measure of the change undergone by the amplitude and phase of the wave as it propagates in a given direction.
Claudius Ptolemy (Κλαύδιος Πτολεμαῖος, Klaúdios Ptolemaîos; Claudius Ptolemaeus) was a Greco-Roman mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology.
The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina.
The term quantum efficiency (QE) may apply to incident photon to converted electron (IPCE) ratio, of a photosensitive device or it may refer to the TMR effect of a Magnetic Tunnel Junction.
In particle physics, quantum electrodynamics (QED) is the relativistic quantum field theory of electrodynamics.
In theoretical physics, quantum field theory (QFT) is the theoretical framework for constructing quantum mechanical models of subatomic particles in particle physics and quasiparticles in condensed matter physics.
Quantum mechanics (QM; also known as quantum physics, quantum theory, the wave mechanical model, or matrix mechanics), including quantum field theory, is a fundamental theory in physics which describes nature at the smallest scales of energy levels of atoms and subatomic particles.
Quantum optics (QO) is a field of research that uses semi-classical and quantum-mechanical physics to investigate phenomena involving light and its interactions with matter at submicroscopic levels.
Quartz is a mineral composed of silicon and oxygen atoms in a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2.
Radio frequency (RF) refers to oscillatory change in voltage or current in a circuit, waveguide or transmission line in the range extending from around twenty thousand times per second to around three hundred billion times per second, roughly between the upper limit of audio and the lower limit of infrared.
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light.
Radiometry is a set of techniques for measuring electromagnetic radiation, including visible light.
A rainbow is a meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky.
Raman scattering or the Raman effect is the inelastic scattering of a photon by molecules which are excited to higher vibrational or rotational energy levels.
Rasmus Bartholin (Latinized: Erasmus Bartholinus; 13 August 1625 – 4 November 1698) was a Danish scientist, physician and grammarian.
In optics a ray is an idealized model of light, obtained by choosing a line that is perpendicular to the wavefronts of the actual light, and that points in the direction of energy flow.
In physics, ray tracing is a method for calculating the path of waves or particles through a system with regions of varying propagation velocity, absorption characteristics, and reflecting surfaces.
Rayleigh scattering (pronounced), named after the British physicist Lord Rayleigh (John William Strutt), is the (dominantly) elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation.
In optics, a real image is an image which is located in the plane of convergence for the light rays that originate from a given object.
A rear-view mirror (or rearview mirror) is a mirror in automobiles and other vehicles, designed to allow the driver to see rearward through the vehicle's rear window (rear windshield).
In photography reciprocity is the inverse relationship between the intensity and duration of light that determines the reaction of light-sensitive material.
Reference.com is an online encyclopedia, thesaurus, and dictionary.
A reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image.
A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens as its objective to form an image (also referred to a dioptric telescope).
Refraction is the change in direction of wave propagation due to a change in its transmission medium.
In optics, the refractive index or index of refraction of a material is a dimensionless number that describes how light propagates through that medium.
René Descartes (Latinized: Renatus Cartesius; adjectival form: "Cartesian"; 31 March 1596 – 11 February 1650) was a French philosopher, mathematician, and scientist.
The retina is the innermost, light-sensitive "coat", or layer, of shell tissue of the eye of most vertebrates and some molluscs.
A retroreflector (sometimes called a retroflector or cataphote) is a device or surface that reflects light back to its source with a minimum of scattering.
Robert Grosseteste (Robertus Grosseteste; – 9 October 1253) was an English statesman, scholastic philosopher, theologian, scientist and Bishop of Lincoln.
Robert Hooke FRS (– 3 March 1703) was an English natural philosopher, architect and polymath.
Roger Bacon (Rogerus or Rogerius Baconus, Baconis, also Rogerus), also known by the scholastic accolade Doctor, was an English philosopher and Franciscan friar who placed considerable emphasis on the study of nature through empiricism.
Roy Jay Glauber (born September 1, 1925) is an American theoretical physicist.
The Sander illusion or Sander's parallelogram is an optical illusion described by the German psychologist Friedrich Sander (1889–1971) in 1926.
A scalar or scalar quantity in physics is a physical quantity that can be described by a single element of a number field such as a real number, often accompanied by units of measurement.
Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more paths due to localized non-uniformities in the medium through which they pass.
The science of photography refers to the use of science, such as chemistry and physics, in all aspects of photography.
Scotopic vision is the vision of the eye under low-light levels.
A sense is a physiological capacity of organisms that provides data for perception.
Sensitometry is the scientific study of light-sensitive materials, especially photographic film.
Shot noise or Poisson noise is a type of electronic noise which can be modeled by a Poisson process.
In physics, a sign convention is a choice of the physical significance of signs (plus or minus) for a set of quantities, in a case where the choice of sign is arbitrary.
Signal processing concerns the analysis, synthesis, and modification of signals, which are broadly defined as functions conveying "information about the behavior or attributes of some phenomenon", such as sound, images, and biological measurements.
The sky (or celestial dome) is everything that lies above the surface of the Earth, including the atmosphere and outer space.
Snell's law (also known as Snell–Descartes law and the law of refraction) is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through a boundary between two different isotropic media, such as water, glass, or air.
A solar cell, or photovoltaic cell, is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon.
A solar eclipse (as seen from the planet Earth) is a type of eclipse that occurs when the Moon passes between the Sun and Earth, and when the Moon fully or partially blocks ("occults") the Sun.
Specular reflection, also known as regular reflection, is the mirror-like reflection of waves, such as light, from a surface.
The speed of light in vacuum, commonly denoted, is a universal physical constant important in many areas of physics.
Spherical aberration is an optical effect observed in an optical device (lens, mirror, etc.) that occurs due to the increased refraction of light rays when they strike a lens or a reflection of light rays when they strike a mirror near its edge, in comparison with those that strike close to the centre.
SPIE is an international not-for-profit professional society for optics and photonics technology, founded in 1955.
Statistical mechanics is one of the pillars of modern physics.
Stereoscopy (also called stereoscopics, or stereo imaging) is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision.
Stimulated emission is the process by which an incoming photon of a specific frequency can interact with an excited atomic electron (or other excited molecular state), causing it to drop to a lower energy level.
The Stokes parameters are a set of values that describe the polarization state of electromagnetic radiation.
In continuum mechanics, stress is a physical quantity that expresses the internal forces that neighboring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material.
A sun dog (or sundog) or mock sun, formally called a parhelion (plural parhelia) in meteorology, is an atmospheric optical phenomenon that consists of a bright spot to the left or right of the Sun.
In photography, the sunny 16 rule (also known as the sunny rule) is a method of estimating correct daylight exposures without a light meter.
Sunrise or sun up is the instant at which the upper edge of the Sun appears over the horizon in the morning.
Sunset or sundown is the daily disappearance of the Sun below the horizon as a result of Earth's rotation.
In physics and systems theory, the superposition principle, also known as superposition property, states that, for all linear systems, the net response caused by two or more stimuli is the sum of the responses that would have been caused by each stimulus individually.
Telephony is the field of technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties.
In photography and cinematography, a telephoto lens is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length.
The Optical Society (originally established as The Optical Society of America, OSA) is a scientific society dedicated to advancing the study of light—optics and photonics—in theory and application, by means of publishing, organizing conferences and exhibitions, partnership with industry, and education.
Theodore Harold "Ted" Maiman (July 11, 1927 – May 5, 2007) was an American engineer and physicist who was widely, but not universally, credited with the invention of the laser (Others attribute the invention to Gordon Gould).
Theology is the critical study of the nature of the divine.
In optics, a thin lens is a lens with a thickness (distance along the optical axis between the two surfaces of the lens) that is negligible compared to the radii of curvature of the lens surfaces.
Thin-film optics is the branch of optics that deals with very thin structured layers of different materials.
Thomas Young FRS (13 June 1773 – 10 May 1829) was a British polymath and physician.
Thomson scattering is the elastic scattering of electromagnetic radiation by a free charged particle, as described by classical electromagnetism.
Timaeus (Timaios) is one of Plato's dialogues, mostly in the form of a long monologue given by the title character Timaeus of Locri, written c. 360 BC.
Total internal reflection is the phenomenon which occurs when a propagated wave strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface.
The transmission-line matrix (TLM) method is a space and time discretising method for computation of electromagnetic fields.
In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without being scattered.
A transverse wave is a moving wave that consists of oscillations occurring perpendicular (right angled) to the direction of energy transfer (or the propagation of the wave).
Twinkling, or scintillation, is a generic term for variations in apparent brightness or position of a distant luminous object viewed through a medium.
The Tyndall effect, also known as Willis–Tyndall scattering, is light scattering by particles in a colloids or in a very fine suspension.
Ultraviolet (UV) is electromagnetic radiation with a wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays.
Unconscious inference (German: unbewusster Schluss), also referred to as unconscious conclusion, is a term of perceptual psychology coined in 1867 by the German physicist and polymath Hermann von Helmholtz to describe an involuntary, pre-rational and reflex-like mechanism which is part of the formation of visual impressions.
Vacuum is space devoid of matter.
A vanishing point is a point on the image plane of a perspective drawing where the two-dimensional perspective projections (or drawings) of mutually parallel lines in three-dimensional space appear to converge.
In optics, a virtual image is an image formed when the outgoing rays from a point on an object always diverge.
In physics, a virtual particle is a transient fluctuation that exhibits some of the characteristics of an ordinary particle, but whose existence is limited by the uncertainty principle.
Visual perception is the ability to interpret the surrounding environment using light in the visible spectrum reflected by the objects in the environment.
The visual system is the part of the central nervous system which gives organisms the ability to process visual detail, as well as enabling the formation of several non-image photo response functions.
Witelo (also Erazmus Ciołek Witelo; Witelon; Vitellio; Vitello; Vitello Thuringopolonis; Vitulon; Erazm Ciołek); born ca.
The vitreous body is the clear gel that fills the space between the lens and the retina of the eyeball of humans and other vertebrates.
In physics, a wave is a disturbance that transfers energy through matter or space, with little or no associated mass transport.
In physics, interference is a phenomenon in which two waves superpose to form a resultant wave of greater, lower, or the same amplitude.
Wave propagation is any of the ways in which waves travel.
Wave–particle duality is the concept in quantum mechanics that every particle or quantic entity may be partly described in terms not only of particles, but also of waves.
An optical waveguide is a physical structure that guides electromagnetic waves in the optical spectrum.
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
A waveplate or retarder is an optical device that alters the polarization state of a light wave travelling through it.
In photography and cinematography, a wide-angle lens refers to a lens whose focal length is substantially smaller than the focal length of a normal lens for a given film plane.
The Wundt illusion is an optical illusion that was first described by the German psychologist Wilhelm Wundt in the 19th century.
X-rays make up X-radiation, a form of electromagnetic radiation.
X-ray crystallography is a technique used for determining the atomic and molecular structure of a crystal, in which the crystalline atoms cause a beam of incident X-rays to diffract into many specific directions.
Young's interference experiment, also called Young's double-slit interferometer, was the original version of the modern double-slit experiment, performed at the beginning of the nineteenth century by Thomas Young.
The Zöllner illusion is an optical illusion named after its discoverer, German astrophysicist Johann Karl Friedrich Zöllner.
The zenith is an imaginary point directly "above" a particular location, on the imaginary celestial sphere.
A zoom lens is a mechanical assembly of lens elements for which the focal length (and thus angle of view) can be varied, as opposed to a fixed focal length (FFL) lens (see prime lens).
2018 has been designated as the third International Year of the Reef by the International Coral Reef Initiative.
2019 (MMXIX) will be a common year starting on Tuesday of the Gregorian calendar, the 2019th year of the Common Era (CE) and Anno Domini (AD) designations, the 19th year of the 3rd millennium, the 19th year of the 21st century, and the 10th and last year of the 2010s decade.