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Maser
A maser is a device that produces coherent electromagnetic waves ( microwaves), through amplification by stimulated emission. The term is an acronym for microwave amplification by stimulated emission of radiation. Nikolay Basov, Alexander Prokhorov and Joseph Weber introduced the concept of the maser in 1952, and Charles H. Townes, James P. Gordon, and Herbert J. Zeiger built the first maser at Columbia University in 1953. Townes, Basov and Prokhorov won the 1964 Nobel Prize in Physics for theoretical work leading to the maser. Masers are used as timekeeping devices in atomic clocks, and as extremely low-noise microwave amplifiers in radio telescopes and deep-space spacecraft communication ground-stations. Modern masers can be designed to generate electromagnetic waves at microwave frequencies and radio and infrared frequencies. For this reason, Townes suggested replacing "microwave" with "molecular" as the first word in the acronym "maser". The ''laser'' works by the sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Clock
An atomic clock is a clock that measures time by monitoring the resonant frequency of atoms. It is based on atoms having different energy levels. Electron states in an atom are associated with different energy levels, and in transitions between such states they interact with a very specific frequency of electromagnetic radiation. This phenomenon serves as the basis for the International System of Units' (SI) definition of a second: The second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the caesium frequency, \Delta \nu_\text, the unperturbed ground-state hyperfine transition frequency of the caesium-133 atom, to be when expressed in the unit Hz, which is equal to s−1. This definition is the basis for the system of International Atomic Time (TAI), which is maintained by an ensemble of atomic clocks around the world. The system of Coordinated Universal Time, Coordinated Universal Time (UTC) that is the basis of civil time implements ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as 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 and the optical amplifier patented by Gordon Gould. A laser differs from other sources of light in that it emits light that is coherence (physics), ''coherent''. Spatial coherence allows a laser to be focused to a tight spot, enabling uses such as optical communication, laser cutting, and Photolithography#Light sources, lithography. It also allows a laser beam to stay narrow over great distances (collimated light, collimation), used in laser pointers, lidar, and free-space optical communication. Lasers can also have high temporal coherence, which permits them to emit light ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Maser
A hydrogen maser, also known as hydrogen frequency standard, is a specific type of maser that uses the intrinsic properties of the hydrogen atom to serve as a precision frequency reference. Overview Both the proton and electron of a hydrogen atom have spins. The atom has a higher energy if both spins are aligned, and a lower energy if they are opposed. The amount of energy needed to reverse the spin of the electron is equivalent to a photon at the frequency of , which corresponds to the 21 cm line in the hydrogen spectrum. Hydrogen masers are very complex devices and sell for as much as . There are two types to be distinguished: active and passive. In both types, a small storage bottle of molecular hydrogen, , leaks a controlled amount of gas into a discharge bulb. The molecules are dissociated in the discharge bulb into individual hydrogen atoms by an electric arc. This atomic hydrogen passes through a collimator then a magnetic state selector and into a storage bulb. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microwave
Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300 MHz and 300 GHz, broadly construed. A more common definition in radio-frequency engineering is the range between 1 and 100 GHz (wavelengths between 30 cm and 3 mm), or between 1 and 3000 GHz (30 cm and 0.1 mm). In all cases, microwaves include the entire super high frequency, super high frequency (SHF) band (3 to 30 GHz, or 10 to 1 cm) at minimum. The boundaries between far infrared, terahertz radiation, microwaves, and ultra-high-frequency (UHF) are fairly arbitrary and differ between different fields of study. The prefix ' in ''microwave'' indicates that microwaves are small (having shorter wavelengths), compared to the radio waves used in prior radio technology. Frequencies in the micr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gordon Gould
Richard Gordon Gould (July 17, 1920 – September 16, 2005) was an American physicist who is sometimes credited with the invention of the laser and the optical amplifier. (Credit for the invention of the laser is disputed, since Charles Townes and Arthur Schawlow were the first to publish the theory and Theodore Maiman was the first to build a working laser). Gould is best known for his thirty-year fight with the United States Patent and Trademark Office to obtain patents for the laser and related technologies. He also fought with laser manufacturers in court battles to enforce the patents he subsequently did obtain. Early life and education Gould was born in New York City in 1920, the son of Helen Vaughn (nee Rue) and Kenneth Gould. He was the oldest of three sons. His father was the founding editor of Scholastic Magazine Publications in New York City. His mother encouraged his interest in inventors such as Thomas Edison and gave him a toy Erector set at an early age. He gre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theodore Maiman
Theodore Harold Maiman (July 11, 1927 – May 5, 2007) was an American engineer and physicist who is widely credited with the invention of the laser.Johnson, John Jr. (May 11, 2008). "Theodore H. Maiman, at age 32; scientist created the first LASER". ''Los Angeles Times'' Maiman's laser led to the subsequent development of many other types of lasers. The laser was successfully fired on May 16, 1960. In a July 7, 1960, press conference in Manhattan, Maiman and his employer, Hughes Aircraft Company, announced the laser to the world. Maiman was granted a patent for his invention,Maiman, Theodore H. (1961) "Ruby laser systems " and he received many awards and honors for his work. His experiences in developing the first laser and subsequent related events are recounted in his book, ''The Laser Odyssey'', later being republished in 2018 under a new title, ''The Laser Inventor: Memoirs of Theodore H. Maiman''. Early and student life Maiman was born in Los Angeles to a Jewish family. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nikolay Basov
Nikolay Gennadiyevich Basov (; 14 December 1922 – 1 July 2001) was a Russian Soviet physicist and educator. For his fundamental work in the field of quantum electronics that led to the development of laser and maser, Basov shared the 1964 Nobel Prize in Physics with Alexander Prokhorov and Charles Hard Townes. Early life Basov was born in the town of Usman, now in Lipetsk Oblast in 1922. He finished school in 1941 in Voronezh, and was later called for military service at Kuibyshev Military Medical Academy. In 1943 he left the academy and served in the Red Army participating in the Second World War with the 1st Ukrainian Front. Professional career Basov graduated from Moscow Engineering Physics Institute (MEPhI) in 1950. He then held a professorship at MEPhI and also worked in the Lebedev Physical Institute (LPI), where he defended a dissertation for the ''Candidate of Sciences'' degree (equivalent to PhD) in 1953 and a dissertation for the ''Doctor of Sciences'' degree in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexander Prokhorov
Alexander Mikhailovich Prokhorov (born Alexander Michael Prochoroff, ; 11 July 1916 – 8 January 2002) was an Australian-born Russian physicist and researcher on lasers and masers, in the former Soviet Union. He shared the Nobel Prize in Physics in 1964 with Charles Hard Townes and Nikolay Basov. Early life Alexander Michael Prochoroff was born on 11 July 1916 at Russell Road, Peeramon, Queensland, Australia (now 322 Gadaloff Road, Butchers Creek, situated about 30 km from Atherton), to Mikhail Ivanovich Prokhorov and Maria Ivanovna (née Mikhailova), Russian revolutionaries who had emigrated from Russia to escape repression by the tsarist regime. As a child he attended Butchers Creek State School.Tablelander (newspaper) 19 July 2016 'Prokharov centenary' The family returned to Russia in 1923, after the October Revolution and the Russian Civil War. In 1934, Prokhorov entered the Saint Petersburg State University to study physics. He was a member of the Komsomol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthur Leonard Schawlow
Arthur Leonard Schawlow (May 5, 1921 – April 28, 1999) was an American physicist who, along with Charles Townes, developed the theoretical basis for laser science. His central insight was the use of two mirrors as the resonant cavity to take maser action from microwaves to visible wavelengths. He shared the 1981 Nobel Prize in Physics with Nicolaas Bloembergen and Kai Siegbahn for his work using lasers to determine atomic energy levels with great precision. Biography Schawlow was born in Mount Vernon, New York. His mother, Helen (Mason), was from Canada, and his father, Arthur Schawlow, was a Jewish immigrant from Riga (then in the Russian Empire, now in Latvia). Schawlow was raised in his mother's Protestant religion. When Arthur was three years old, they moved to Toronto, Ontario, Canada. At the age of 16, he completed high school at Vaughan Road Academy (then Vaughan Collegiate Institute), and received a scholarship in science at the University of Toronto (Victoria Colle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph Weber
Joseph Weber (May 17, 1919 – September 30, 2000) was an American physicist. He gave the earliest public lecture on the principles behind the laser and the maser and developed the first gravitational wave detectors, known as Weber bars. Early life Joseph Weber was born in Paterson, New Jersey, on 17 May 1919, the last of four children born to Yiddish-speaking Jewish immigrant parents. His name was "Yonah" until he entered grammar school. He had no birth certificate, and his father had taken the last name of "Weber" to match an available passport in order to emigrate to the US. Thus, Joe Weber had little proof of either his family or his given name, which gave him some trouble in obtaining a passport at the height of the red scare. Early education Weber attended Paterson public schools (and the Paterson Talmud Torah), graduating at sixteen from the "Mechanic Arts Course" of Paterson Eastside High School in June 1935. He began his undergraduate education at Cooper Union, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stimulated Emission
Stimulated emission is the process by which an incoming photon of a specific frequency can interact with an excited atomic electron (or other excited molecular state), causing it to drop to a lower energy level. The liberated energy transfers to the electromagnetic field, creating a new photon with a frequency, polarization, and direction of travel that are all identical to the photons of the incident wave. This is in contrast to spontaneous emission, which occurs at a characteristic rate for each of the atoms/oscillators in the upper energy state regardless of the external electromagnetic field. According to the American Physical Society, the first person to correctly predict the phenomenon of stimulated emission was Albert Einstein in a series of papers starting in 1916, culminating in what is now called the Einstein B Coefficient. Einstein's work became the theoretical foundation of the maser and the laser. The process is identical in form to atomic absorption in which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
