Optical phenomena

thumb|The shadow of a musician cast onto a brick wall thumb|Park fence shadow is distorted by an uneven snow surface. thumb|Shadows from cumulus clouds thick enough to block sunlight A shadow is a dark area on a surface where light from a light source is blocked by an object. In contrast, shade occupies the three-dimensional volume behind an object with light in front of it. The cross-section of a shadow is a two-dimensional silhouette, or a reverse projection of the object blocking the light.

dependence of phase velocity on frequency

visual perception that differs from objective reality

right|thumb|Luminol reacting with haemoglobin is a familiar demonstration of [[chemiluminescence.]] thumb|UV-induced photoluminescence used in microbiological diagnostics.

property of an object or substance to transmit light with minimal scattering

physical phenomenon

thumb|upright=1.25|Iridescence in soap bubbles

principle of least time

light scattering by particles in a colloid

optical phenomenon

an image of a distant light source (such as a galaxy or star) which has been distorted into a ring through gravitational lensing caused by an object with an extremely large mass (such as another galaxy or a black hole)

thumb|By using two parabolic cylindric mirrors and one plane mirror, the image of the background is directed around an object, making the object itself invisible - at least from two sides.

thumb|right|220px|Saturn's moon Mimas is lit by Saturnshine on the right and sunshine at the top. thumb|right|220px|The Moon lit by [[earthshine, captured by the lunar-prospecting Clementine spacecraft in 1994. Clementine's color enhanced image reveals (from right to left) the Moon lit by earthshine, the Sun's corona rising over the Moon's dark limb, and the planets Saturn, Mars, and Mercury (the three dots at lower left).]]

thumb|300px|The gegenschein appears in this image as a bright spot on the diagonal band (running top left to lower right) above the Very Large Telescope. (The [[Andromeda Galaxy and Pleiades are prominent in the lower half of the image.)]]

global illumination; quality of surfaces that reflect light diffusely

energy transfer mechanism and microscopy technique

Photoconductivity is an optical and electrical phenomenon in which a material becomes more electrically conductive due to the absorption of electromagnetic radiation such as visible light, ultraviolet light, infrared light, or gamma radiation.

observable event that results from the interaction of light and matter

mirror-like wave reflection

thumb|right|Tiger's eye thumb|right|Tiger's eye

star-shaped concentration of light reflected or refracted from a gemstone

thumb|Rough sample of common opal thumb|Rough sample of precious opal, showing iridescence

brightening of a rough surface, when illuminated from directly behind the observer

visual effect whose source is within the eye itself

image artifact produced by scattered or flared light within a lens system

physical phenomenon of electron resonance

distinct parts of a shadow

optical phenomenon

optical property of chiral chemical compounds

optical phenomenon during a transit of Venus and Mercury

tiny bright dots moving quickly in the visual field

perception or recognition of faces in something essentially different

thumb|Adularescence in a moonstone cabochon, [[Minas Gerais, Brazil. The specimen's diameter is .]]

Optical phenomenon

thumb|250px|Light passing through a gradient-index optics|gradient-index lens is focused as in a convex lens. In self-focusing, the refractive index gradient is induced by the light itself. Self-focusing is a non-linear optical process induced by the change in refractive index of materials exposed to intense electromagnetic radiation. A medium whose refractive index increases with the electric field intensity acts as a focusing lens for an electromagnetic wave characterized by an initial transverse intensity gradient, as in a laser beam. The peak intensity of the self-focused region keeps incr

law

tendency for the eye to focus nearby in poor visibility

optical phenomenon in physics.

topic in astronomy

effect

1646 work by Athanasius Kircher

thumb|Leucophore layer composition