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Exploring the Science of Light! (Optical Society of America)

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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

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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 (Eric Weisstein’s World of Physics, Wolfram Research)
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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

Encyclopædia Britannica




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Scientists & Discovery, Light (Museum Victoria Australia)

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How Light Works (HowStuffWorks)

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Optics Timeline (Optical Society of America)
A History of Light and Lighting (Bill Williams)

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Quotations Page Bartlett’s

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The Museum of Optics (University of Arizona)

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WorldCat, Library of Congress, UPenn Online Books, Open Library

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OER Commons: Open Educational Resources

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Careers in Optics and Photonics (Optical Society of America)

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International Society for Optics and Phontonics (SPIE)
Optical Society of America

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International Society for Optics and Phontonics (SPIE)
Nature of Light (Science Daily)
Optics and Photonics News (Phys.org), Optics (Science 2.0), NPR Archives

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We Are One Step Closer to a Lightsaber (Darren Orf, Popular Mechanics
Scientists Catch Up With Jedi in Understanding Light (Richard Adhikari, TechNewsWorld)

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OEDILF: The Omnificent English Dictionary In Limerick Form

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Optics.org News latest News from Optics.org


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.

  • 'Whispering gallery' effect controls electron...
    on June 5, 2020 at 2:53 pm

    When you speak softly in one of the galleries of St Paul's cathedral, the sound runs around the dome and visitors anywhere on its circumference can hear it. This striking phenomenon has been termed the 'whispering gallery' effect, and one variant is where a wave travels nearly perfectly around a structure. Researchers have now harnessed the effect to control the beam of an electron microscope by light.

  • Discovery unlocks 'hot' electrons for more...
    on June 4, 2020 at 7:20 pm

    Highly energetic, "hot" electrons have the potential to help solar panels more efficiently harvest light energy. But up until now, scientists haven't been able to measure the energies of those electrons, limiting their use. Researchers have now demonstrated how a technique using a scanning tunneling microscope integrated with lasers and other optical components reveals the energy distribution of hot electrons.

  • Butterfly-inspired nanotech makes natural-looking...
    on June 4, 2020 at 7:20 pm

    The new technology creates digital displays that are lit by surrounding light and are more natural looking than current display technologies that rely on energy-intensive bright lights hidden behind screens.

  • Showtime for photosynthesis
    on June 4, 2020 at 3:16 pm

    Using a unique combination of nanoscale imaging and chemical analysis, researchers have revealed a key step in the molecular mechanism behind the water splitting reaction of photosynthesis, a finding that could help inform the design of renewable energy technology.

  • Fluorescence bioimaging: Near-infrared...
    on June 4, 2020 at 3:16 pm

    Scientists can monitor biomolecular processes in live tissue by noninvasive optical methods, such as fluorescence imaging. However, the fluorescent dyes used for that purpose are often rather unstable, and photobleaching, lack of specificity, and poor pharmacokinetics are recurrent issues. Scientists have now developed a molecular shield that stabilizes near-infrared fluorescent dyes and enhances their functionality.


Optics & Photonics News - Optics, Photonics, Physics News Phys.org provides the latest news on Optics and Photonics

  • New discovery advances optical microscopy
    on June 5, 2020 at 9:38 pm

    New Illinois ECE research is advancing the field of optical microscopy, giving the field a critical new tool to solve challenging problems across many fields of science and engineering including semiconductor wafer inspection, nanoparticle sensing, material characterization, biosensing, virus counting, and microfluidic monitoring.

  • Physicists create quantum-inspired optical sensor
    on June 5, 2020 at 3:09 pm

    Researchers from the Moscow Institute of Physics and Technology, joined by a colleague from Argonne National Laboratory, U.S., have implemented an advanced quantum algorithm for measuring physical quantities using simple optical tools. Published in Scientific Reports, their study takes us a step closer to affordable linear optics-based sensors with high performance characteristics. Such tools are sought after in diverse research fields, from astronomy to biology.

  • 'Whispering gallery' effect controls electron...
    on June 5, 2020 at 3:07 pm

    When you speak softly in one of the galleries of St Paul's cathedral, the sound runs so easily around the dome that visitors anywhere on its circumference can hear it. This striking phenomenon has been termed the 'whispering gallery' effect, and variants of it appear in many scenarios where a wave can travel nearly perfectly around a structure. Researchers from the University of Göttingen have now harnessed the effect to control the beam of an electron microscope by light. The results were […]

  • Researchers experimentally prove flat mirror...
    on June 5, 2020 at 1:10 pm

    For the first time, researchers of Tomsk Polytechnic University jointly with teams from Taiwan and Spain have experimentally confirmed the flat focusing mirror effect, which they previously predicted. Physical properties of the effect and simplicity of its reproduction make it promising for application in microelectronics, photonics, and on-chip systems, where a single microcircuit functions as an entire device. The study results are presented in Scientific Reports.

  • New microscopy method provides unprecedented look...
    on June 4, 2020 at 2:00 pm

    Neurodegenerative diseases such as Alzheimer's and Parkinson's are often accompanied by amyloid proteins in the brain that have become clumped or misfolded. A newly developed technique that measures the orientation of single molecules is enabling optical microscopy to be used, for the first time, to reveal nanoscale details about the structures of these problematic proteins.