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A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term is an acronym for light amplification by stimulated emission of radiation. The first laser was built in 1960 by Theodore Maiman at Hughes Research Laboratories, based on theoretical work by Charles H. Townes and Arthur Leonard Schawlow.
An antimatter rocket is a proposed class of rockets that use antimatter as their power source. There are several designs that attempt to accomplish this goal. The advantage to this class of rocket is that a large fraction of the rest mass of a matter/antimatter mixture may be converted to energy, allowing antimatter rockets to have a far higher energy density and specific impulse than any other proposed class of rocket.
An optical disc is a flat, usually disc-shaped object that stores information in the form of physical variations on its surface that can be read with the aid of a beam of light. Optical discs can be reflective, where the light source and detector are on the same side of the disc, or transmissive, where light shines through the disc to the be detected on the other side.
Pentaerythritol tetranitrate (PETN), also known as PENT, PENTA, TEN, corpent, or penthrite, is an explosive material. It is the nitrate ester of pentaerythritol, and is structurally very similar to nitroglycerin. Penta refers to the five carbon atoms of the neopentane skeleton. PETN is a very powerful explosive material with a relative effectiveness factor of 1.66. When mixed with a plasticizer, PETN forms a plastic explosive. Along with RDX it is the main ingredient of Semtex.
Dry ice is the solid form of carbon dioxide. It is commonly used for temporary refrigeration as CO2 does not have a liquid state at normal atmospheric pressure and sublimates directly from the solid state to the gas state. It is used primarily as a cooling agent, but is also used in fog machines at theatres for dramatic effects. Its advantages include lower temperature than that of water ice and not leaving any residue (other than incidental frost from moisture in the atmosphere). It is useful for preserving frozen foods (such as ice cream) where mechanical cooling is unavailable.
A printed circuit board is a medium used in electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a laminated sandwich structure of conductive and insulating layers: each of the conductive layers is designed with an artwork pattern of traces, planes and other features etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate. Electrical components may be fixed to conductive pads on the outer layers in the shape designed to accept the component's terminals, generally by means of soldering, to both electrically connect and mechanically fasten them to it. Another manufacturing process adds vias: plated-through holes that allow interconnections between layers.
Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a poor barrier to oxygen and water vapour and has a relatively low melting point. Polystyrene is one of the most widely used plastics, the scale of its production being several million tonnes per year. Polystyrene can be naturally transparent, but can be colored with colorants. Uses include protective packaging, containers, lids, bottles, trays, tumblers, disposable cutlery, in the making of models, and as an alternative material for phonograph records.
Terahertz radiation – also known as submillimeter radiation, terahertz waves, tremendously high frequency (THF), T-rays, T-waves, T-light, T-lux or THz – consists of electromagnetic waves within the ITU-designated band of frequencies from 0.3 to 3 terahertz (THz), although the upper boundary is somewhat arbitrary and is considered by some sources as 30 THz. One terahertz is 1012 Hz or 1000 GHz. Wavelengths of radiation in the terahertz band correspondingly range from 1 mm to 0.1 mm = 100 µm. Because terahertz radiation begins at a wavelength of around 1 millimeter and proceeds into shorter wavelengths, it is sometimes known as the submillimeter band, and its radiation as submillimeter waves, especially in astronomy. This band of electromagnetic radiation lies within the transition region between microwave and far infrared, and can be regarded as either.
Many ceramic materials, both glassy and crystalline, have found use as optically transparent materials in various forms from bulk solid-state components to high surface area forms such as thin films, coatings, and fibers. Such devices have found widespread use for various applications in the electro-optical field including: optical fibers for guided lightwave transmission, optical switches, laser amplifiers and lenses, hosts for solid-state lasers and optical window materials for gas lasers, and infrared (IR) heat seeking devices for missile guidance systems and IR night vision.
An X-ray tube is a vacuum tube that converts electrical input power into X-rays. The availability of this controllable source of X-rays created the field of radiography, the imaging of partly opaque objects with penetrating radiation. In contrast to other sources of ionizing radiation, X-rays are only produced as long as the X-ray tube is energized. X-ray tubes are also used in CT scanners, airport luggage scanners, X-ray crystallography, material and structure analysis, and for industrial inspection.
Yttrium orthovanadate (YVO4) is a transparent crystal. Undoped YVO4 is also used to make efficient high-power polarizing prisms similar to Glan–Taylor prisms.
Zinc selenide (ZnSe) is a light-yellow, solid compound comprising zinc (Zn) and selenium (Se). It is an intrinsic semiconductor with a band gap of about 2.70 eV at 25 °C (77 °F). ZnSe rarely occurs in nature, and is found in the mineral that was named after Hans Stille called "stilleite."
A laser weapon is a directed-energy weapon based on lasers. After decades of R&D, as of January 2020 directed-energy weapons including lasers are still at the experimental stage and it remains to be seen if or when they will be deployed as practical, high-performance military weapons. Atmospheric thermal blooming has been a major problem, still mostly unsolved, and worsened if fog, smoke, dust, rain, snow, smog, foam, or purposely dispersed obscurant chemicals are present. Essentially, a laser generates a beam of light which needs clear air, or a vacuum, to work without thermal blooming.
Inertial Fusion Energy is a proposed approach to building a nuclear fusion power plant based on performing inertial confinement fusion at industrial scale. This approach to fusion power is still in a research phase. ICF first developed shortly after the development of the laser in 1960, but was a classified US research program during its earliest years. In 1972, John Nuckolls wrote a paper predicting that compressing a target could create conditions where fusion reactions are chained together, a process known as fusion ignition or a burning plasma. On August 8, 2021, the NIF at Livermore National Laboratory became the first ICF facility in the world to demonstrate this. This breakthrough drove the US Department of Energy to create an Inertial Fusion Energy program in 2022 with a budget of 3 million dollars in its first year.
Sputter deposition is a physical vapor deposition (PVD) method of thin film deposition by the phenomenon of sputtering. This involves ejecting material from a "target" that is a source onto a "substrate" such as a silicon wafer. Resputtering is re-emission of the deposited material during the deposition process by ion or atom bombardment. Sputtered atoms ejected from the target have a wide energy distribution, typically up to tens of eV. The sputtered ions can ballistically fly from the target in straight lines and impact energetically on the substrates or vacuum chamber. Alternatively, at higher gas pressures, the ions collide with the gas atoms that act as a moderator and move diffusively, reaching the substrates or vacuum chamber wall and condensing after undergoing a random walk. The entire range from high-energy ballistic impact to low-energy thermalized motion is accessible by changing the background gas pressure. The sputtering gas is often an inert gas such as argon. For efficient momentum transfer, the atomic weight of the sputtering gas should be close to the atomic weight of the target, so for sputtering light elements neon is preferable, while for heavy elements krypton or xenon are used. Reactive gases can also be used to sputter compounds. The compound can be formed on the target surface, in-flight or on the substrate depending on the process parameters. The availability of many parameters that control sputter deposition make it a complex process, but also allow experts a large degree of control over the growth and microstructure of the film.
Tantalum hafnium carbide is a refractory chemical compound with a general formula TaxHfy-xCy, which can be considered as a solid solution of tantalum carbide and hafnium carbide. It was originally thought to have the highest melting of any known substance but new research has proven this assumption to be incorrect.
In the U.S. military, reactive materials (RM) are a new class of materials currently being investigated by the Office of Naval Research and others as a means to increase the lethality of direct-hit or fragmentation warheads. Reactive materials are similar to insensitive high explosives, but are usually thermite-like pyrotechnic compositions of two or more nonexplosive solid materials, which stay inert and do not react with each other until subjected to a sufficiently strong mechanical, electrical or laser stimulus, after which they undergo fast burning or explosion with release of high amount of chemical energy in addition to their kinetic energy. Fragments or projectiles made of such materials have therefore greater damaging effect than inert ones, with expected lethality increase up to 500%.
A quantum well laser is a laser diode in which the active region of the device is so narrow that quantum confinement occurs. Laser diodes are formed in compound semiconductor materials that are able to emit light efficiently. The wavelength of the light emitted by a quantum well laser is determined by the width of the active region rather than just the bandgap of the materials from which it is constructed. This means that much shorter wavelengths can be obtained from quantum well lasers than from conventional laser diodes using a particular semiconductor material. The efficiency of a quantum well laser is also greater than a conventional laser diode due to the stepwise form of its density of states function.
An X-ray laser is a device that uses stimulated emission to generate or amplify electromagnetic radiation in the near X-ray or extreme ultraviolet region of the spectrum, that is, usually on the order of several tens of nanometers (nm) wavelength.
Aerogels are a class of synthetic porous ultralight material derived from a gel, in which the liquid component for the gel has been replaced with a gas, without significant collapse of the gel structure. The result is a solid with extremely low density and extremely low thermal conductivity. Aerogels can be made from a variety of chemical compounds. Silica aerogels feel like fragile expanded polystyrene to the touch, while some polymer-based aerogels feel like rigid foams.
