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Animal Reflectors
Animal reflectors or mirrors are important to the survival of many kinds of animal, and, in some cases, have been mimicked by engineers developing photonic crystals. Examples are the scales of silvery fish, and the tapetum lucidum that causes the eyeshine of dogs and cats using the sclera. All these reflectors work by interference of light in multilayer structures with dimensions less than a wavelength, so can be classed as photonic crystals. Other animal photonic crystals have evolved to reflect narrow spectra, producing animal coloration. Functions of animal reflectors Camouflage The scales of silvery fish, by reflecting light from the flank make detection by a predator difficult because the reflected light is similar to the incident light in the absence of the prey (Fig. 1). Focusing light The eyes of some bivalve mollusks, such as the scallop (Pecten) use a concave mirror, the argentea, at the back of the eye, to create an image on the retina. The deep-sea ostracod Gigantocypri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photonic Crystals
A photonic crystal is an optical nanostructure in which the refractive index changes periodically. This affects the propagation of light in the same way that the structure of natural crystals gives rise to X-ray diffraction and that the atomic lattices (crystal structure) of semiconductors affect their conductivity of electrons. Photonic crystals occur in nature in the form of structural coloration and animal reflectors, and, as artificially produced, promise to be useful in a range of applications. Photonic crystals can be fabricated for one, two, or three dimensions. One-dimensional photonic crystals can be made of thin film layers deposited on each other. Two-dimensional ones can be made by photolithography, or by drilling holes in a suitable substrate. Fabrication methods for three-dimensional ones include drilling under different angles, stacking multiple 2-D layers on top of each other, direct laser writing, or, for example, instigating self-assembly of spheres in a m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tapetum Lucidum
The ''tapetum lucidum'' ( ; ; ) is a layer of tissue in the eye of many vertebrates and some other animals. Lying immediately behind the retina, it is a retroreflector. It reflects visible light back through the retina, increasing the light available to the photoreceptors (although slightly blurring the image). The tapetum lucidum contributes to the superior night vision of some animals. Many of these animals are nocturnal, especially carnivores, while others are deep sea animals. Similar adaptations occur in some species of spiders. Haplorhine primates, including humans, are diurnal and lack a ''tapetum lucidum''. Function and mechanism Presence of a ''tapetum lucidum'' enables animals to see in dimmer light than would otherwise be possible. The ''tapetum lucidum'', which is iridescent, reflects light roughly on the interference principles of thin-film optics, as seen in other iridescent tissues. However, the ''tapetum lucidum'' cells are leucophores, not iridophores. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eyeshine
The ''tapetum lucidum'' ( ; ; ) is a layer of tissue in the eye of many vertebrates and some other animals. Lying immediately behind the retina, it is a retroreflector. It reflects visible light back through the retina, increasing the light available to the photoreceptors (although slightly blurring the image). The tapetum lucidum contributes to the superior night vision of some animals. Many of these animals are nocturnal, especially carnivores, while others are deep sea animals. Similar adaptations occur in some species of spiders. Haplorhine primates, including humans, are diurnal and lack a ''tapetum lucidum''. Function and mechanism Presence of a ''tapetum lucidum'' enables animals to see in dimmer light than would otherwise be possible. The ''tapetum lucidum'', which is iridescent, reflects light roughly on the interference principles of thin-film optics, as seen in other iridescent tissues. However, the ''tapetum lucidum'' cells are leucophores, not iridophores ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Coloration
Animal coloration is the general appearance of an animal resulting from the reflection or emission of light from its surfaces. Some animals are brightly coloured, while others are hard to see. In some species, such as the peafowl, the male has strong patterns, conspicuous colours and is iridescent, while the female is far less visible. There are several separate reasons why animals have evolved colours. Camouflage enables an animal to remain hidden from view. Animals use colour to advertise services such as cleaning to animals of other species; to signal their sexual status to other members of the same species; and in mimicry, taking advantage of the warning coloration of another species. Some animals use flashes of colour to divert attacks by startling predators. Zebras may possibly use motion dazzle, confusing a predator's attack by moving a bold pattern rapidly. Some animals are coloured for physical protection, with pigments in the skin to protect against sunburn, while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
170306 Denton Mirror(65a)
Seventeen or 17 may refer to: *17 (number), the natural number following 16 and preceding 18 * one of the years 17 BC, AD 17, 1917, 2017 Literature Magazines * ''Seventeen'' (American magazine), an American magazine * ''Seventeen'' (Japanese magazine), a Japanese magazine Novels * ''Seventeen'' (Tarkington novel), a 1916 novel by Booth Tarkington *''Seventeen'' (''Sebuntiin''), a 1961 novel by Kenzaburō Ōe * ''Seventeen'' (Serafin novel), a 2004 novel by Shan Serafin Stage and screen Film * ''Seventeen'' (1916 film), an American silent comedy film *''Number Seventeen'', a 1932 film directed by Alfred Hitchcock * ''Seventeen'' (1940 film), an American comedy film *''Eric Soya's '17''' (Danish: ''Sytten''), a 1965 Danish comedy film * ''Seventeen'' (1985 film), a documentary film * ''17 Again'' (film), a 2009 film whose working title was ''17'' * ''Seventeen'' (2019 film), a Spanish drama film Television * ''Seventeen'' (TV drama), a 1994 UK dramatic short starring Christien ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Reflectors Fig 2
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a bilaterally symmetric body plan. The Bilateria include the protostomes, containing animals such as nematodes, arthropods, flatworms, annelids and molluscs, and the deuterostomes, containing the echinoderms and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dielectric Mirror
A dielectric mirror, also known as a Bragg mirror, is a type of mirror composed of multiple thin layers of dielectric material, typically deposited on a substrate of glass or some other optical material. By careful choice of the type and thickness of the dielectric layers, one can design an optical coating with specified reflectivity at different wavelengths of light. Dielectric mirrors are also used to produce ultra-high reflectivity mirrors: values of 99.999% or better over a narrow range of wavelengths can be produced using special techniques. Alternatively, they can be made to reflect a broad spectrum of light, such as the entire visible range or the spectrum of the Ti-sapphire laser. Mirrors of this type are very common in optics experiments, due to improved techniques that allow inexpensive manufacture of high-quality mirrors. Examples of their applications include laser cavity end mirrors, hot and cold mirrors, thin-film beamsplitters, high damage threshold mirrors, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carnivora
Carnivora is a Clade, monophyletic order of Placentalia, placental mammals consisting of the most recent common ancestor of all felidae, cat-like and canidae, dog-like animals, and all descendants of that ancestor. Members of this group are formally referred to as carnivorans, and have evolved to specialize in eating flesh. The order is the fifth largest order of mammals, comprising at least 279 species. Carnivorans live on every major landmass and in a variety of habitats, ranging from the cold polar regions to the hyper-arid region of the Sahara Desert to the open seas. They come in a very large array of different body plans in contrasting shapes and sizes. Carnivora can be divided into two subclades: the cat-like Feliformia and the dog-like Caniformia, which are differentiated based on the structure of their ear bones and cranial features. The feliforms include families such as the felidae, cats, the hyenas, the mongooses and the viverridae, civets. The majority of felifor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bragg's Law
In physics and chemistry , Bragg's law, Wulff–Bragg's condition or Laue–Bragg interference, a special case of Laue diffraction, gives the angles for coherent scattering of waves from a crystal lattice. It encompasses the superposition of wave fronts scattered by lattice planes, leading to a strict relation between wavelength and scattering angle, or else to the wavevector transfer with respect to the crystal lattice. Such law had initially been formulated for X-rays upon crystals. However, It applies to all sorts of quantum beams, including neutron and electron waves at atomic distances, as well as visible light at artificial periodic microscale lattices. History Bragg diffraction (also referred to as the Bragg formulation of X-ray diffraction) was first proposed by Lawrence Bragg and his father, William Henry Bragg, in 1913 in response to their discovery that crystalline solids produced surprising patterns of reflected X-rays (in contrast to that of, say, a liquid). They ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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