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
ASML, imec set up new high-NA optics lab for EUV...
on October 22, 2018 at 2:10 pm
Accelerated development should see next-generation tool shipped by the end of 2022. […]
Luna snaps up Micron Optics in $5M acquisition
on October 19, 2018 at 3:10 pm
Atlanta-based Micron specializes in tunable filters, swept lasers, and high-speed, long-distance optical sensing units. […]
Profits surge at Trumpf
on October 18, 2018 at 12:10 pm
Pre-tax income up more than 50% on last year as the laser firm benefits from demand for EUV lithography tools. […]
ASML positive on 2019 prospects
on October 18, 2018 at 10:10 am
Lithography giant’s stock makes gains on upbeat outlook for equipment sales next year and introduction of new higher-throughput EUV tool. […]
ELI Beamlines reports 'first' generation of...
on October 18, 2018 at 10:10 am
Successful culmination of year-long installation of the L1-ALLEGRA laser, the L1-E1 beam transport, and of the HHG beamline near Prague. […]
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.
Monitoring electromagnetic signals in the brain...
on October 22, 2018 at 4:39 pm
MIT engineers have devised a new technique to detect either electrical activity or optical signals in the brain, using a minimally invasive technique based on magnetic resonance imaging (MRI). […]
A new way to measure nearly nothing
on October 19, 2018 at 11:19 pm
Scientists have designed a vacuum gauge, based on ultracold trapped atoms, is small enough to deploy in commonly used vacuum chambers. […]
Nanodiamonds as photocatalysts
on October 18, 2018 at 4:52 pm
Diamond nanomaterials are considered hot candidates for low-cost photocatalysts. They can be activated by light and can then accelerate certain reactions between water and CO2 and produce carbon-neutral 'solar fuels'. The EU project DIACAT has now doped such diamond materials with boron and shown at BESSY II how this could significantly improve the photocatalytic properties. […]
Security vulnerabilities in terahertz data links
on October 15, 2018 at 3:35 pm
Scientists have assumed that future terahertz data links would have an inherent immunity to eavesdropping, but new research shows that's not necessarily the case. […]
Perovskites: Materials of the future in optical...
on October 15, 2018 at 2:45 pm
Researchers have shown how an inorganic perovskite can be made into a cheap and efficient photodetector that transfers both text and music. […]
Optics & Photonics News - Optics, Photonics, Physics News Phys.org provides the latest news on Optics and Photonics
Modified optical centrifuge has potential to open...
on October 19, 2018 at 1:20 pm
Using corkscrew-shaped laser pulses, scientists at DESY have devised a sophisticated optical centrifuge that can make molecules rotate rapidly about a desired molecular axis. The innovative method opens up new ways to control and study super fast spinning molecules, called superrotors. Until now, optical centrifuges can make molecules rotate about one specific axis only. The new scheme lets scientists select between two axes. Alec Owens, Andrey Yachmenev and Jochen Küpper from the […]
Bursting the clouds for better communication
on October 18, 2018 at 12:15 pm
We live in an age of long-range information transmitted either by underground optical fibre or by radio satellites. But the throughput today is so great that radio frequency is no longer enough in itself. Research is turning toward the use of lasers which, although technically complex, have several advantages, especially when it comes to security. However, this new technology, currently in the testing phase, faces a major problem: clouds. Due to their density, clouds stop the laser beams and […]
Physics: Not everything is where it seems to be
on October 16, 2018 at 10:53 am
Scientists at TU Wien, the University of Innsbruck and the ÖAW have for the first time demonstrated a wave effect that can lead to measurement errors in the optical position estimation of objects. The work now published in Nature Physics could have consequences for optical microscopy and optical astronomy, but could also play a role in position measurements using sound, radar, or gravitational waves. […]
Researchers report innovative optical tissue...
on October 15, 2018 at 12:56 pm
A UK-wide research team, led by the University of St Andrews, has developed an innovative new way to optically image through tissue, which could allow for a more detailed understanding and diagnosis of the early stages of various diseases, including cancer. […]
A novel topological insulator
on October 12, 2018 at 1:15 pm
For the first time, physicists have built a unique topological insulator in which optical and electronic excitations hybridize and flow together. They report their discovery in Nature. […]