These are organized by a classification scheme developed exclusively for Cosma. More…
light : electromagnetic radiation of any wavelength that travels in a vacuum with a speed of 299,792,458 meters (about 186,000 miles) per second; specifically : such radiation that is visible to the human eye. — Webster
Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is the visible spectrum that is visible to the human eye and is responsible for the sense of sight. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), or 4.00 × 10−7 to 7.00 × 10−7 m, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). This wavelength means a frequency range of roughly 430–750 terahertz (THz).
The main source of light on Earth is the Sun. Sunlight provides the energy that green plants use to create sugars mostly in the form of starches, which release energy into the living things that digest them. This process of photosynthesis provides virtually all the energy used by living things. Historically, another important source of light for humans has been fire, from ancient campfires to modern kerosene lamps. With the development of electric lights and power systems, electric lighting has effectively replaced firelight. Some species of animals generate their own light, a process called bioluminescence. For example, fireflies use light to locate mates, and vampire squids use it to hide themselves from prey.
The primary properties of visible light are intensity, propagation direction, frequency or wavelength spectrum, and polarization, while its speed in a vacuum, 299,792,458 metres per second, is one of the fundamental constants of nature. Visible light, as with all types of electromagnetic radiation (EMR), is experimentally found to always move at this speed in a vacuum.
In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays, microwaves and radio waves are also light. Like all types of electromagnetic radiation, visible light propagates as waves. However, the energy imparted by the waves is absorbed at single locations the way particles are absorbed. The absorbed energy of the EM waves is called a photon, and represents the quanta of light. When a wave of light is transformed and absorbed as a photon, the energy of the wave instantly collapses to a single location, and this location is where the photon “arrives.” This is what is called the wave function collapse. This dual wave-like and particle-like nature of light is known as the wave–particle duality. The study of light, known as optics, is an important research area in modern physics. — Wikipedia
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. Optics usually describes the behavior of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties.
Most optical phenomena can be accounted for using the classical electromagnetic description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces. Physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be accounted for in geometric optics. Historically, the ray-based model of light was developed first, followed by the wave model of light. Progress in electromagnetic theory in the 19th century led to the discovery that light waves were in fact electromagnetic radiation.
Some phenomena depend on the fact that light has both wave-like and particle-like properties. Explanation of these effects requires quantum mechanics. When considering light’s particle-like properties, the light is modeled as a collection of particles called “photons”. Quantum optics deals with the application of quantum mechanics to optical systems.
Optical science is relevant to and studied in many related disciplines including astronomy, various engineering fields, photography, and medicine (particularly ophthalmology and optometry). Practical applications of optics are found in a variety of technologies and everyday objects, including mirrors, lenses, telescopes, microscopes, lasers, and fiber optics. — Wikipedia
Optics.org News latest News from Optics.org
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Optics News -- ScienceDaily Optics. Can light go backwards? Researchers push the limits of our understanding of light. Also see amazing new applications of light energy. Full-text, images, free.
- Crystal structures in super slow motionon January 22, 2021 at 8:44 pm
Laser beams are used to change the properties of materials in an extremely precise way. However, the underlying processes generally take place at such unimaginably fast speeds and at such a small scale that they have so far eluded direct observation. Researchers have now managed to film, for the first time, the laser transformation of a crystal structure with nanometer resolution and in slow motion in an electron microscope.
- Bringing atoms to a standstill: Miniaturizing...on January 21, 2021 at 9:31 pm
Scientists have miniaturized the optical components required to cool atoms down to a few thousandths of a degree above absolute zero, the first step in employing them on microchips to drive a new generation of super-accurate atomic clocks, enable navigation without GPS, and simulate quantum systems.
- Innovations through hair-thin optical fiberson January 21, 2021 at 6:19 pm
Scientists have built hair-thin optical fiber filters in a very simple way. They are not only extremely compact and stable, but also color-tunable. This means they can be used in quantum technology and as sensors for temperature or for detecting atmospheric gases.
- Lasers create miniature robots from bubbleson January 21, 2021 at 6:19 pm
Robots are widely used to build cars, paint airplanes and sew clothing in factories, but the assembly of microscopic components, such as those for biomedical applications, has not yet been automated. Lasers could be the solution. Now, researchers have used lasers to create miniature robots from bubbles that lift, drop and manipulate small pieces into interconnected structures.
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Researchers are paving the way towards the production of green hydrogen.
Optics & Photonics News - Optics, Photonics, Physics News The latest news on Optics and Photonics
- Researchers propose new method for accurate...on January 22, 2021 at 1:18 pm
Recently, researchers from the Shanghai Institute of Optics and Fine Mechanics (SIOM) of the Chinese Academy of Sciences (CAS) have proposed a novel measurement method of the electro-optic (EO) coefficient based on the χ(2) nonlinear optical technology to measure the linear EO coefficients of KH2PO4 (KDP) and K(H1−xDx)2PO4 (DKDP) precisely. Relevant results were published in Optics Express on Jan. 18, 2021.
- Record-breaking laser link could provide test of...on January 22, 2021 at 1:18 pm
Scientists from the International Centre for Radio Astronomy Research (ICRAR) and the University of Western Australia (UWA) have set a world record for the most stable transmission of a laser signal through the atmosphere.
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Microscopy is the workhorse of contemporary life science research, enabling morphological and chemical inspection of living tissue with ever-increasing spatial and temporal resolution. Even though modern microscopes are genuine marvels of engineering, minute deviations from ideal imaging conditions will still lead to optical aberrations that rapidly degrade imaging quality. A mismatch between the refractive indices of the sample and its immersion medium, deviations in the thickness of sample […]
- Two-photon polymerization of PEGda hydrogel...on January 21, 2021 at 8:02 pm
The fabrication of shape-memory hydrogel scaffolds not only requires biocompatibility, micrometer resolution, high mechanical strength, but also requires a low polymerisation threshold in high-water content environment to incorporate microstructures with biological tissues. Towards this goal, scientists from China and Australia developed a new hydrogel formula that full fills this goal and demonstrated water-responsive structures with a shape-memory effect at a micrometer scale. This work is of […]
- Innovations through hair-thin optical fiberson January 21, 2021 at 4:17 pm
Scientists at the University of Bonn have built hair-thin optical fiber filters in a very simple way. They are not only extremely compact and stable, but also color-tunable. This means they can be used in quantum technology and as sensors for temperature or for detecting atmospheric gases. The results have been published in the journal Optics Express.