* Asterism ( gemmology ), an optical phenomenon in gemstones

Alexander's band, an optical phenomenon, is named after him.

Any slight deformation in the antique telescopic lenses would lead to a dramatic decrease in optical performance, a phenomenon that is not observed.

The gain medium is excited by the pump source to produce a population inversion, and it is in the gain medium that spontaneous and stimulated emission of photons takes place, leading to the phenomenon of optical gain, or amplification.

In 1898, Lowry noted the change in optical rotation on nitro-d-camphor with time and invented the term mutarotational to describe this phenomenon.

One of the earliest of these was Al-Kindi ( c. 801 – 73 ) who wrote on the merits of Aristotelian and Euclidean ideas of optics, favouring the emission theory since it could better quantify optical phenomenon.

In 1871, optical redshift was confirmed when the phenomenon was observed in Fraunhofer lines using solar rotation, about 0. 1 Å in the red.

A rare optical phenomenon may occur shortly after sunset or before sunrise, known as a green flash.

Pure enantiomers also exhibit the phenomenon of optical activity and can be separated only with the use of a chiral agent.

Total internal reflection is an optical phenomenon that happens when a ray of light strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface.

Use of the term " false dawn " in this context should not be confused with false sunrise, which is a different, unrelated optical phenomenon.

In 1874, Jacobus Henricus van't Hoff and Joseph Achille Le Bel independently proposed that the phenomenon of optical activity could be explained by assuming that the chemical bonds between carbon atoms and their neighbors are directed towards the corners of a regular tetrahedron.

The shot noise of a coherent optical beam ( having no other noise sources ) is a fundamental physical phenomenon, reflecting quantum fluctuations in the electromagnetic field ( due to the so-called zero-point energy.

When the speckle pattern changes in time, due to changes in the illuminated surface, the phenomenon is known as dynamic speckle, and it can be used to measure activity, as in ( for example ) an optical computer mouse.

* Fata Morgana ( mirage ), an optical phenomenon

An optical phenomenon is any observable event that results from the interaction of light and matter.

A mirage is an example of an optical phenomenon.

Sun Halo ( optical phenomenon ) | halo at 41st parallel south | latitude 41 degrees south

Reggio has commonly used popular nicknames: The " city of Bronzes ", for the Riace bronzes which are testimonials of its Greek origins ; the " city of bergamot ", which is exclusively cultivated in the region ; and the " city of Fatamorgana ", an optical phenomenon visible in Italy only from the Reggio seaside.

The name camera obscura, Latin for " dark room ", derives from this early implementation of the optical phenomenon.

* 120 ° parhelion, relatively rare halo, an optical phenomenon occasionally appearing along with very bright sun dogs

* Infralateral arc, a rare halo, an optical phenomenon appearing similar to a rainbow under a white parhelic circle

* Lower tangent arc, rarely observable halo, an optical phenomenon appearing under and tangent to a 22 ° halo centred around the sun

* Parry arc, a rare halo, an optical phenomenon which occasionally appears over a 22 ° halo together with an upper tangent arc

* Supralateral arc, a rare halo, an optical phenomenon often confused with the indeed infrequently appearing 46 ° halo

In classical physics, the diffraction phenomenon is described as the apparent bending of waves around small obstacles and the spreading out of waves past small openings.

Italian scientist Francesco Maria Grimaldi coined the word " diffraction " and was the first to record accurate observations of the phenomenon in 1665.

The speckle pattern which is observed when laser light falls on an optically rough surface is also a diffraction phenomenon.

The speckle pattern which is seen when using a laser pointer is another diffraction phenomenon.

* 1665 — Francesco Maria Grimaldi highlights the phenomenon of diffraction

In his autobiography given to the Nobel Prize Committee, he recalled, " The first stirrings of interest in science that I remember occurred during a moment of boredom at religious school, when, looking out of the window at twilight through a hand curled to simulate a telescope, I noticed something peculiar about the light ; it was the phenomenon of diffraction.

Colored rings close to the moon are a corona, a diffraction phenomenon produced by very small water droplets or ice crystals in clouds.

In the early 19th century, Brougham, a follower of Newton, launched vicious anonymous attacks in the Edinburgh Review against Thomas Young's research that proved light was a wave phenomenon that exhibited interference and diffraction, attacks that slowed acceptance of the truth for a decade until François Arago and Augustin-Jean Fresnel championed Young's work.

In connection with lithography of electronic components, this phenomenon is known as the diffraction limit and is the reason why light of progressively higher frequency ( smaller wavelength ) is required for etching progressively finer features in integrated circuits.

Since the basic physical phenomenon is based on diffraction, the periodicity of the photonic crystal structure has to be of the same length-scale as half the wavelength of the EM waves i. e. ~ 200 nm ( blue ) to 350 nm ( red ) for photonic crystals operating in the visible part of the spectrum-the repeating regions of high and low dielectric constants have to be of this dimension.

A monochromator can use either the phenomenon of optical dispersion in a prism, or that of diffraction using a diffraction grating, to spatially separate the colors of light.

When radio waves travel into this zone, which commences about 80 kilometers above the earth, they experience diffraction in a manner similar to the visible light phenomenon described above.

A useful branch of acoustics dealing with the design of noise barriers examines this acoustical diffraction phenomenon in quantitative detail to calculate the optimum height and placement of a soundwall or berm adjacent to a highway.

The zone plate's focusing ability is an extension of the Arago spot phenomenon caused by diffraction from an opaque disc.

Since light propagates as waves, the patterns it produces on the film are subject to the wave phenomenon known as diffraction, which limits the image resolution to features on the order of several times the wavelength of light.

From the sequence of colors with the red on the outside one can conclude that the phenomenon is caused by diffraction because halos always have their red part on their inside.

* Talbot effect, a near-field diffraction phenomenon

Two twelfth grade students from La Ronge, Northern Saskatchewan, won science fair gold medals for investigating and eventually duplicating the phenomenon, which they determined to be caused by the diffraction of distant vehicle lights.