1.
United States Air Force
–
The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the seven American uniformed services. Initially part of the United States Army, the USAF was formed as a branch of the military on 18 September 1947 under the National Security Act of 1947. It is the most recent branch of the U. S. military to be formed, the U. S. Air Force is a military service organized within the Department of the Air Force, one of the three military departments of the Department of Defense. The Air Force is headed by the civilian Secretary of the Air Force, who reports to the Secretary of Defense, the U. S. Air Force provides air support for surface forces and aids in the recovery of troops in the field. As of 2015, the service more than 5,137 military aircraft,406 ICBMs and 63 military satellites. It has a $161 billion budget with 313,242 active duty personnel,141,197 civilian employees,69,200 Air Force Reserve personnel, and 105,500 Air National Guard personnel. According to the National Security Act of 1947, which created the USAF and it shall be organized, trained, and equipped primarily for prompt and sustained offensive and defensive air operations. The stated mission of the USAF today is to fly, fight, and win in air, space and we will provide compelling air, space, and cyber capabilities for use by the combatant commanders. We will excel as stewards of all Air Force resources in service to the American people, while providing precise and reliable Global Vigilance, Reach and it should be emphasized that the core functions, by themselves, are not doctrinal constructs. The purpose of Nuclear Deterrence Operations is to operate, maintain, in the event deterrence fails, the US should be able to appropriately respond with nuclear options. Dissuading others from acquiring or proliferating WMD, and the means to deliver them, moreover, different deterrence strategies are required to deter various adversaries, whether they are a nation state, or non-state/transnational actor. Nuclear strike is the ability of forces to rapidly and accurately strike targets which the enemy holds dear in a devastating manner. Should deterrence fail, the President may authorize a precise, tailored response to terminate the conflict at the lowest possible level, post-conflict, regeneration of a credible nuclear deterrent capability will deter further aggression. Finally, the Air Force regularly exercises and evaluates all aspects of operations to ensure high levels of performance. Nuclear surety ensures the safety, security and effectiveness of nuclear operations, the Air Force, in conjunction with other entities within the Departments of Defense or Energy, achieves a high standard of protection through a stringent nuclear surety program. The Air Force continues to pursue safe, secure and effective nuclear weapons consistent with operational requirements, adversaries, allies, and the American people must be highly confident of the Air Forces ability to secure nuclear weapons from accidents, theft, loss, and accidental or unauthorized use. This day-to-day commitment to precise and reliable nuclear operations is the cornerstone of the credibility of the NDO mission, positive nuclear command, control, communications, effective nuclear weapons security, and robust combat support are essential to the overall NDO function. OCA is the method of countering air and missile threats, since it attempts to defeat the enemy closer to its source
United States Air Force
–
First
F-35 Lightning II of the
33rd Fighter Wing arrives at
Eglin AFB
United States Air Force
–
Seal of the Department of the Air Force (
United States Air Force portal)
United States Air Force
–
U.S. Air Force airmen from the 720th STG jumping out of a
C-130J Hercules aircraft during water rescue training in the
Florida panhandle
United States Air Force
–
Combat Controllers participating in
Operation Enduring Freedom provide air traffic control to a
C-130 taking off from a remote airfield.
2.
Optics
–
Optics is the branch of physics which involves the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light, because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties. Most optical phenomena can be accounted for using the classical description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice, practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines, physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be accounted for in geometric optics. Historically, the model of light was developed first, followed by the wave model of light. Progress in electromagnetic theory in the 19th century led to the discovery that waves were in fact electromagnetic radiation. Some phenomena depend on the fact that light has both wave-like and particle-like properties, explanation of these effects requires quantum mechanics. When considering lights particle-like properties, the light is modelled as a collection of particles called photons, quantum optics deals with the application of quantum mechanics to optical systems. Optical science is relevant to and studied in many related disciplines including astronomy, various engineering fields, photography, practical applications of optics are found in a variety of technologies and everyday objects, including mirrors, lenses, telescopes, microscopes, lasers, and fibre optics. Optics began with the development of lenses by the ancient Egyptians and Mesopotamians, the earliest known lenses, made from polished crystal, often quartz, date from as early as 700 BC for Assyrian lenses such as the Layard/Nimrud lens. The ancient Romans and Greeks filled glass spheres with water to make lenses, the word optics comes from the ancient Greek word ὀπτική, meaning appearance, look. Greek philosophy on optics broke down into two opposing theories on how vision worked, the theory and the emission theory. The intro-mission approach saw vision as coming from objects casting off copies of themselves that were captured by the eye, plato first articulated the emission theory, the idea that visual perception is accomplished by rays emitted by the eyes. He also commented on the parity reversal of mirrors in Timaeus, some hundred years later, Euclid wrote a treatise entitled Optics where he linked vision to geometry, creating geometrical optics. Ptolemy, in his treatise Optics, held a theory of vision, the rays from the eye formed a cone, the vertex being within the eye. The rays were sensitive, and conveyed back to the observer’s intellect about the distance. He summarised much of Euclid and went on to describe a way to measure the angle of refraction, during the Middle Ages, Greek ideas about optics were resurrected and extended by writers in the Muslim world
Optics
–
Optics includes study of
dispersion of light.
Optics
–
The Nimrud lens
Optics
–
Reproduction of a page of
Ibn Sahl 's manuscript showing his knowledge of the law of refraction, now known as
Snell's law
Optics
–
Cover of the first edition of Newton's Opticks
3.
Laser
–
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term laser originated as an acronym for light amplification by stimulated emission of radiation, the first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow. A laser differs from other sources of light in that it emits light coherently, spatial coherence allows a laser to be focused to a tight spot, enabling applications such as laser cutting and lithography. Spatial coherence also allows a laser beam to stay narrow over great distances, Lasers can also have high temporal coherence, which allows them to emit light with a very narrow spectrum, i. e. they can emit a single color of light. Temporal coherence can be used to produce pulses of light as short as a femtosecond, Lasers are distinguished from other light sources by their coherence. Spatial coherence is typically expressed through the output being a narrow beam, Laser beams can be focused to very tiny spots, achieving a very high irradiance, or they can have very low divergence in order to concentrate their power at a great distance. Temporal coherence implies a polarized wave at a single frequency whose phase is correlated over a great distance along the beam. A beam produced by a thermal or other incoherent light source has an amplitude and phase that vary randomly with respect to time and position. Lasers are characterized according to their wavelength in a vacuum, most single wavelength lasers actually produce radiation in several modes having slightly differing frequencies, often not in a single polarization. Although temporal coherence implies monochromaticity, there are lasers that emit a broad spectrum of light or emit different wavelengths of light simultaneously, there are some lasers that are not single spatial mode and consequently have light beams that diverge more than is required by the diffraction limit. However, all devices are classified as lasers based on their method of producing light. Lasers are employed in applications where light of the spatial or temporal coherence could not be produced using simpler technologies. The word laser started as an acronym for light amplification by stimulated emission of radiation, in the early technical literature, especially at Bell Telephone Laboratories, the laser was called an optical maser, this term is now obsolete. A laser that produces light by itself is technically an optical rather than an optical amplifier as suggested by the acronym. It has been noted that the acronym LOSER, for light oscillation by stimulated emission of radiation. With the widespread use of the acronym as a common noun, optical amplifiers have come to be referred to as laser amplifiers. The back-formed verb to lase is frequently used in the field, meaning to produce light, especially in reference to the gain medium of a laser. Further use of the laser and maser in an extended sense, not referring to laser technology or devices, can be seen in usages such as astrophysical maser
Laser
–
United States Air Force laser experiment
Laser
–
Red (660 & 635 nm), green (532 & 520 nm) and blue-violet (445 & 405 nm) lasers
Laser
–
Laser beams in fog, reflected on a car windshield
Laser
4.
Laser construction
–
A laser is constructed from three principal parts, An energy source, A gain medium or laser medium, and Two or more mirrors that form an optical resonator. The pump source is the part that provides energy to the laser system, examples of pump sources include electrical discharges, flashlamps, arc lamps, light from another laser, chemical reactions and even explosive devices. The type of source used principally depends on the gain medium. The gain medium is the determining factor of the wavelength of operation. Gain media in different materials have linear spectra or wide spectra, gain media with wide spectra allow tuning of the laser frequency. There are hundreds if not thousands of different gain media in which laser operation has been achieved, examples of different gain media include, Liquids, such as dye lasers. These are usually organic chemical solvents, such as methanol, ethanol or ethylene glycol, to which are added chemical dyes such as coumarin, rhodamine, the exact chemical configuration of the dye molecules determines the operation wavelength of the dye laser. Gases, such as carbon dioxide, argon, krypton and mixtures such as helium–neon and these lasers are often pumped by electrical discharge. Solids, such as crystals and glasses, the solid host materials are usually doped with an impurity such as chromium, neodymium, erbium or titanium ions. Typical hosts include YAG, YLF, sapphire and various glasses, examples of solid-state laser media include Nd, YAG, Ti, sapphire, Cr, sapphire, Cr, LiSAF, Er, YLF, Nd, glass, and Er, glass. Solid-state lasers are pumped by flashlamps or light from another laser. Semiconductors, a type of solid, crystal with uniform dopant distribution or material with differing dopant levels in which the movement of electrons can cause laser action. Semiconductor lasers are typically small, and can be pumped with a simple electric current. The optical resonator, or optical cavity, in its simplest form is two parallel mirrors placed around the medium which provide feedback of the light. The mirrors are given optical coatings which determine their reflective properties, typically one will be a high reflector, and the other will be a partial reflector. The latter is called the coupler, because it allows some of the light to leave the cavity to produce the lasers output beam. Light from the medium, produced by spontaneous emission, is reflected by the back into the medium. The light may reflect from the mirrors and thus pass through the medium many hundreds of times before exiting the cavity
Laser construction
–
Schematic diagram of a typical laser, showing the three major parts
5.
Optical cavity
–
An optical cavity, resonating cavity or optical resonator is an arrangement of mirrors that forms a standing wave cavity resonator for light waves. Optical cavities are a component of lasers, surrounding the gain medium. They are also used in optical parametric oscillators and some interferometers, light confined in the cavity reflects multiple times producing standing waves for certain resonance frequencies. Different resonator types are distinguished by the lengths of the two mirrors and the distance between them. The geometry must be chosen so that the beam remains stable, resonator types are also designed to meet other criteria such as minimum beam waist or having no focal point inside the cavity. Optical cavities are designed to have a large Q factor, a beam will reflect a large number of times with little attenuation. Therefore, the line width of the beam is very small indeed compared to the frequency of the laser. In general, radiation patterns which are reproduced on every round-trip of the light through the resonator are the most stable, the basic, or fundamental transverse mode of a resonator is a Gaussian beam. The most common types of optical cavities consist of two facing plane or spherical mirrors, the simplest of these is the plane-parallel or Fabry–Pérot cavity, consisting of two opposing flat mirrors. However, this problem is reduced for very short cavities with a small mirror separation distance. Plane-parallel resonators are therefore used in microchip and microcavity lasers. In these cases, rather than using separate mirrors, an optical coating may be directly applied to the laser medium itself. The plane-parallel resonator is also the basis of the Fabry–Pérot interferometer, for a resonator with two mirrors with radii of curvature R1 and R2, there are a number of common cavity configurations. If the two curvatures are equal to half the cavity length, a concentric or spherical resonator results and this type of cavity produces a diffraction-limited beam waist in the centre of the cavity, with large beam diameters at the mirrors, filling the whole mirror aperture. Similar to this is the cavity, with one plane mirror. A common and important design is the confocal resonator, with equal curvature mirrors equal to the cavity length. This design produces the smallest possible beam diameter at the cavity mirrors for a given cavity length, a concave-convex cavity has one convex mirror with a negative radius of curvature. A transparent dielectric sphere, such as a liquid droplet, also forms an optical cavity
Optical cavity
–
A glass nanoparticle is suspended in an optical cavity
6.
Population inversion
–
It is called an inversion because in many familiar and commonly encountered physical systems, this is not possible. The concept is of importance in laser science because the production of a population inversion is a necessary step in the workings of a standard laser. To understand the concept of an inversion, it is necessary to understand some thermodynamics. To do so, it is useful to consider a simple assembly of atoms forming a laser medium. Assume there are a group of N atoms, each of which is capable of being in one of two states, either The ground state, with energy E1, or The excited state, with energy E2. The number of atoms which are in the ground state is given by N1. We may calculate the ratio of the populations of the two states at room temperature for an energy difference ΔE that corresponds to light of a frequency corresponding to visible light. In this case ΔE = E2 - E1 ≈2.07 eV, when in thermal equilibrium, then, it is seen that the lower energy state is more populated than the higher energy state, and this is the normal state of the system. In other words, an inversion can never exist for a system at thermal equilibrium. To achieve population inversion therefore requires pushing the system into a non-equilibrated state, the rate of absorption is proportional to the radiation intensity of the light, and also to the number of atoms currently in the ground state, N1. If atoms are in the state, spontaneous decay events to the ground state will occur at a rate proportional to N2. The energy difference between the two states ΔE21 is emitted from the atom as a photon of frequency ν21 as given by the relation above. The photons are emitted stochastically, and there is no fixed relationship between photons emitted from a group of excited atoms, in other words, spontaneous emission is incoherent. If an atom is already in the state, it may be perturbed by the passage of a photon that has a frequency ν21 corresponding to the energy gap ΔE of the excited state to ground state transition. In this case, the excited atom relaxes to the ground state, the original photon is not absorbed by the atom, and so the result is two photons of the same frequency. This process is known as stimulated emission, specifically, an excited atom will act like a small electric dipole which will oscillate with the external field provided. One of the consequences of this oscillation is that it encourages electrons to decay to the lowest energy state. When this happens due to the presence of the field from a photon, a photon is released in the same phase and direction as the stimulating photon
Population inversion
–
A three-level laser energy diagram.
7.
Active laser medium
–
The active laser medium is the source of optical gain within a laser. The gain results from the emission of electronic or molecular transitions to a lower energy state from a higher energy state previously populated by a pump source. g. Liquids, in the form of dye solutions as used in dye lasers, in order to fire a laser, the active gain medium must be in a nonthermal energy distribution known as a population inversion. The preparation of this requires an external energy source and is known as laser pumping. Pumping may be achieved with electrical currents or with light, generated by discharge lamps or by other lasers, more exotic gain media can be pumped by chemical reactions, nuclear fission, or with high-energy electron beams. A universal model valid for all laser types does not exist, the simplest model includes two systems of sub-levels, upper and lower. Within each sub-level system, the fast transitions ensure that equilibrium is reached quickly. The upper level is assumed to be metastable, also, gain and refractive index are assumed independent of a particular way of excitation. For good performance of the medium, the separation between sub-levels should be larger than working temperature, then, at pump frequency ω p. In the case of amplification of signals, the lasing frequency is called signal frequency. However, the term is used even in the laser oscillators. The model below seems to work well for most optically-pumped solid-state lasers, the simple medium can be characterized with effective cross-sections of absorption and emission at frequencies ω p and ω s. Have N be concentration of active centers in the solid-state lasers, have N1 be concentration of active centers in the ground state. Have N2 be concentration of excited centers, in many cases the gain medium works in a continuous-wave or quasi-continuous regime, causing the time derivatives of populations to be negligible. The steady-state solution can be written, n 2 = W u W u + W d, n 1 = W d W u + W d. The dynamic saturation intensities can be defined, I p o = ℏ ω p τ, I s o = ℏ ω s τ, the absorption at strong signal, A0 = N D σ a s + σ e s. The gain at strong pump, G0 = N D σ a p + σ e p, gain never exceeds value G0, and absorption never exceeds value A0 U. The following identities take place, U − V =1, A / A0 + G / G0 =1, the state of gain medium can be characterized with a single parameter, such as population of the upper level, gain or absorption
Active laser medium
–
Fig.1. Simplified scheme of levels a gain medium.
8.
Gaussian beam
–
This fundamental transverse gaussian mode describes the intended output of most lasers, as such a beam can be focused into the most concentrated spot. When such a beam is refocused by a lens, the transverse dependence is altered. The electric and magnetic field amplitude profiles along any such circular Gaussian beam are determined by a single parameter, at any position z relative to the waist along a beam having a specified w0, the field amplitudes and phases are thereby determined as detailed below. The equations below assume a beam with a circular cross-section at all values of z, arbitrary solutions of the paraxial Helmholtz equation can be expressed as combinations of Hermite–Gaussian modes or similarly as combinations of Laguerre–Gaussian modes. At any point along the beam z these modes include the same Gaussian factor as the fundamental Gaussian mode multiplying the additional geometrical factors for the specified mode, Gaussian beam normally implies radiation confined to the fundamental Gaussian mode. The Gaussian beam is an electromagnetic mode. The mathematical expression for the field amplitude is a solution to the paraxial Helmholtz equation. There is also an understood time dependence e i ω t multiplying such phasor quantities, since this solution relies on the paraxial approximation, it is not accurate for very strongly diverging beams. In most practical cases the form is valid. Then the waves associated magnetic field is directly proportional to the electric field. For free space, η = η0 ≈377 Ω, at a position z along the beam, the spot size parameter w is given by w = w 01 +2. Where z R = π w 02 λ is called the Rayleigh range as further discussed below. The radius of the w, at any position z along the beam, is related to the full width at half maximum at that position according to. The curvature of the wavefronts is zero at the beam waist and it is equal to 1/R where R is the radius of curvature as a function of position along the beam, given by R = z. The so-called Gouy phase of the beam at z is given by, the Gouy phase results in an increase in the apparent wavelength near the waist. The phase velocity near the waist exceeds the speed of light in the medium, the Gouy phase shift along the beam remains within the range ±π/2 and is not observable in most experiments. However it is of importance and takes on a greater range for higher-order Gaussian modes. Many laser beams have an elliptical cross-section, also common are beams with waist positions which are different for the two transverse dimensions, called astigmatic beams
Gaussian beam
–
A 5 mW green laser pointer beam profile, showing the TEM 00 profile
Gaussian beam
9.
Laser applications
–
Many scientific, military, medical and commercial laser applications have been developed since the invention of the laser in 1958. The coherency, high monochromaticity, and ability to reach extremely high powers are all properties which allow for specialized applications. Laser based lidar technology has application in geology, seismology, remote sensing, lasers have been used aboard spacecraft such as in the Cassini-Huygens mission. In astronomy, lasers have been used to create artificial laser guide stars, lasers may also be indirectly used in spectroscopy as a micro-sampling system, a technique termed Laser ablation, which is typically applied to ICP-MS apparatus resulting in the powerful LA-ICP-MS. The principles of spectroscopy are discussed by Demtröder. Most types of laser are a pure source of light. By careful design of the components, the purity of the laser light can be improved more than the purity of any other light source. This makes the laser a useful source for spectroscopy. Other spectroscopic techniques based on lasers can be used to extremely sensitive detectors of various molecules. Due to the power densities achievable by lasers, beam-induced atomic emission is possible. Heat treating with lasers allows selective surface hardening against wear with little or no distortion of the component, because this eliminates much part reworking that is currently done, the laser systems capital cost is recovered in a short time. An inert, absorbent coating for laser heat treatment has also developed that eliminates the fumes generated by conventional paint coatings during the heat-treating process with CO2 laser beams. One consideration crucial to the success of a heat treatment operation is control of the laser beam irradiance on the part surface, the optimal irradiance distribution is driven by the thermodynamics of the laser-material interaction and by the part geometry. Typically, irradiances between 500-5000 W/cm^2 satisfy the constraints and allow the rapid surface heating and minimal total heat input required. For general heat treatment, a square or rectangular beam is one of the best options. For some special applications or applications where the treatment is done on an edge or corner of the part. When the Apollo astronauts visited the moon, they planted retroreflector arrays to make possible the Lunar Laser Ranging Experiment, some laser systems, through the process of mode locking, can produce extremely brief pulses of light - as short as picoseconds or femtoseconds. Such pulses can be used to initiate and analyze chemical reactions, the short pulses can be used to probe the process of the reaction at a very high temporal resolution, allowing the detection of short-lived intermediate molecules
Laser applications
–
Laser pointers
Laser applications
–
A target designator
Laser applications
–
Laser sight used by the
Israel Defense Forces during commando training
Laser applications
–
Smith & Wesson revolver equipped with a laser sight mounted on the
trigger guard.
10.
Nonlinear optics
–
The nonlinearity is typically observed only at very high light intensities such as those provided by lasers. Above the Schwinger limit, the vacuum itself is expected to become nonlinear, in nonlinear optics, the superposition principle no longer holds. However, some effects were discovered before the development of the laser. The theoretical basis for many nonlinear processes were first described in Bloembergens monograph Nonlinear Optics, Nonlinear optics explains nonlinear response of properties such as frequency, polarization, phase or path of incident light. Third-harmonic generation, generation of light with a frequency, three photons are destroyed, creating a single photon at three times the frequency. High-harmonic generation, generation of light with much greater than the original. Sum-frequency generation, generation of light with a frequency that is the sum of two other frequencies, difference-frequency generation, generation of light with a frequency that is the difference between two other frequencies. Optical parametric amplification, amplification of an input in the presence of a higher-frequency pump wave. Optical parametric oscillation, generation of a signal and idler wave using an amplifier in a resonator. Optical parametric generation, like parametric oscillation but without a resonator, spontaneous parametric down-conversion, the amplification of the vacuum fluctuations in the low-gain regime. Optical rectification, generation of electric fields. Nonlinear light-matter interaction with electrons and plasmas. Optical Kerr effect, intensity-dependent refractive index, self-focusing, an effect due to the optical Kerr effect caused by the spatial variation in the intensity creating a spatial variation in the refractive index. Kerr-lens modelocking, the use of self-focusing as a mechanism to mode-lock laser, self-phase modulation, an effect due to the optical Kerr effect caused by the temporal variation in the intensity creating a temporal variation in the refractive index. Optical solitons, a solution for either an optical pulse or spatial mode that does not change during propagation due to a balance between dispersion and the Kerr effect. Cross-phase modulation, where one wavelength of light can affect the phase of another wavelength of light through the optical Kerr effect, four-wave mixing, can also arise from other nonlinearities. Cross-polarized wave generation, a χ effect in which a wave with polarization vector perpendicular to the one is generated. Stimulated Brillouin scattering, interaction of photons with acoustic phonons Multi-photon absorption, multiple photoionisation, near-simultaneous removal of many bound electrons by one photon
Nonlinear optics
–
Reversal of Linear Momentum and Angular Momentum in Phase Conjugating Mirror.
Nonlinear optics
Nonlinear optics
–
Dark-Red Gallium Selenide in its bulk form.
11.
Albert Einstein
–
Albert Einstein was a German-born theoretical physicist. He developed the theory of relativity, one of the two pillars of modern physics, Einsteins work is also known for its influence on the philosophy of science. Einstein is best known in popular culture for his mass–energy equivalence formula E = mc2, near the beginning of his career, Einstein thought that Newtonian mechanics was no longer enough to reconcile the laws of classical mechanics with the laws of the electromagnetic field. This led him to develop his theory of relativity during his time at the Swiss Patent Office in Bern. Briefly before, he aquired the Swiss citizenship in 1901, which he kept for his whole life and he continued to deal with problems of statistical mechanics and quantum theory, which led to his explanations of particle theory and the motion of molecules. He also investigated the properties of light which laid the foundation of the photon theory of light. In 1917, Einstein applied the theory of relativity to model the large-scale structure of the universe. He was visiting the United States when Adolf Hitler came to power in 1933 and, being Jewish, did not go back to Germany and he settled in the United States, becoming an American citizen in 1940. This eventually led to what would become the Manhattan Project, Einstein supported defending the Allied forces, but generally denounced the idea of using the newly discovered nuclear fission as a weapon. Later, with the British philosopher Bertrand Russell, Einstein signed the Russell–Einstein Manifesto, Einstein was affiliated with the Institute for Advanced Study in Princeton, New Jersey, until his death in 1955. Einstein published more than 300 scientific papers along with over 150 non-scientific works, on 5 December 2014, universities and archives announced the release of Einsteins papers, comprising more than 30,000 unique documents. Einsteins intellectual achievements and originality have made the word Einstein synonymous with genius, Albert Einstein was born in Ulm, in the Kingdom of Württemberg in the German Empire, on 14 March 1879. His parents were Hermann Einstein, a salesman and engineer, the Einsteins were non-observant Ashkenazi Jews, and Albert attended a Catholic elementary school in Munich from the age of 5 for three years. At the age of 8, he was transferred to the Luitpold Gymnasium, the loss forced the sale of the Munich factory. In search of business, the Einstein family moved to Italy, first to Milan, when the family moved to Pavia, Einstein stayed in Munich to finish his studies at the Luitpold Gymnasium. His father intended for him to electrical engineering, but Einstein clashed with authorities and resented the schools regimen. He later wrote that the spirit of learning and creative thought was lost in strict rote learning, at the end of December 1894, he travelled to Italy to join his family in Pavia, convincing the school to let him go by using a doctors note. During his time in Italy he wrote an essay with the title On the Investigation of the State of the Ether in a Magnetic Field
Albert Einstein
–
Albert Einstein in 1921
Albert Einstein
–
Einstein at the age of 3 in 1882
Albert Einstein
–
Albert Einstein in 1893 (age 14)
Albert Einstein
–
Einstein's matriculation certificate at the age of 17, showing his final grades from the Argovian cantonal school (Aargauische Kantonsschule, on a scale of 1–6, with 6 being the highest possible mark)
12.
Maser
–
A maser is a device that produces coherent electromagnetic waves through amplification by stimulated emission. The first maser was built by Charles H. Townes, James P. Gordon, Townes, Nikolay Basov and Alexander Prokhorov were awarded the 1964 Nobel Prize in Physics for theoretical work leading to the maser. Masers are used as the device in atomic clocks, and as extremely low-noise microwave amplifiers in radio telescopes. Modern masers can be designed to generate electromagnetic waves at not only microwave frequencies but also radio, for this reason Charles Townes suggested replacing microwave with the word molecular as the first word in the acronym maser. The laser works by the principle as the maser. The maser was the forerunner of the laser, inspiring theoretical work by Townes, when the coherent optical oscillator was first imagined in 1957, it was originally called the optical maser. This was ultimately changed to laser for Light Amplification by Stimulated Emission of Radiation, Gordon Gould is credited with creating this acronym in 1957. Independently, Charles Hard Townes, James P. Gordon, and H. J. Zeiger built the first ammonia maser at Columbia University in 1953. This device used stimulated emission in a stream of energized ammonia molecules to produce amplification of microwaves at a frequency of about 24.0 gigahertz. Townes later worked with Arthur L. Schawlow to describe the principle of the maser, or laser. For their research in the field of stimulated emission, Townes, the maser is based on the principle of stimulated emission proposed by Albert Einstein in 1917. When atoms have been induced into an energy state, they can amplify radiation at a frequency particular to the element or molecule used as the masing medium. By putting such a medium in a resonant cavity, feedback is created that can produce coherent radiation. This development could lead to wide range of new applications for maser technology, including communications, Masers serve as high precision frequency references. These atomic frequency standards are one of the forms of atomic clocks. They are often used as low-noise microwave amplifiers in radio telescopes, as of 2012, the most important type of maser is the hydrogen maser which is currently used as an atomic frequency standard. Together with other kinds of clocks, these help make up the International Atomic Time standard. This is the time scale coordinated by the International Bureau of Weights
Maser
–
First prototype ammonia maser and inventor
Charles H. Townes. The ammonia nozzle is at left in the box, the four brass rods at center is the
quadrupole state selector, and the resonant cavity is at right. The 24 GHz microwaves exit through the vertical
waveguide Townes is adjusting. At bottom are the vacuum pumps.
13.
Max Planck
–
Max Karl Ernst Ludwig Planck, FRS was a German theoretical physicist whose discovery of energy quanta won him the Nobel Prize in Physics in 1918. However, his name is known on a broader academic basis, through the renaming in 1948 of the German scientific institution. The MPS now includes 83 institutions representing a range of scientific directions. Planck came from a traditional, intellectual family and his paternal great-grandfather and grandfather were both theology professors in Göttingen, his father was a law professor in Kiel and Munich. Planck was born in Kiel, Holstein, to Johann Julius Wilhelm Planck and his second wife and he was baptised with the name of Karl Ernst Ludwig Marx Planck, of his given names, Marx was indicated as the primary name. However, by the age of ten he signed with the name Max and he was the 6th child in the family, though two of his siblings were from his fathers first marriage. Among his earliest memories was the marching of Prussian and Austrian troops into Kiel during the Second Schleswig War in 1864 and it was from Müller that Planck first learned the principle of conservation of energy. Planck graduated early, at age 17 and this is how Planck first came in contact with the field of physics. Planck was gifted when it came to music and he took singing lessons and played piano, organ and cello, and composed songs and operas. However, instead of music he chose to study physics, the Munich physics professor Philipp von Jolly advised Planck against going into physics, saying, in this field, almost everything is already discovered, and all that remains is to fill a few holes. Planck replied that he did not wish to discover new things, but only to understand the fundamentals of the field. Under Jollys supervision, Planck performed the experiments of his scientific career, studying the diffusion of hydrogen through heated platinum. In 1877 he went to the Friedrich Wilhelms University in Berlin for a year of study with physicists Hermann von Helmholtz and Gustav Kirchhoff and mathematician Karl Weierstrass. He wrote that Helmholtz was never quite prepared, spoke slowly, miscalculated endlessly and he soon became close friends with Helmholtz. While there he undertook a program of mostly self-study of Clausiuss writings, in October 1878 Planck passed his qualifying exams and in February 1879 defended his dissertation, Über den zweiten Hauptsatz der mechanischen Wärmetheorie. He briefly taught mathematics and physics at his school in Munich. In June 1880, he presented his thesis, Gleichgewichtszustände isotroper Körper in verschiedenen Temperaturen. With the completion of his thesis, Planck became an unpaid private lecturer in Munich
Max Planck
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Planck in 1933
Max Planck
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Max Planck's signature at ten years of age.
Max Planck
–
Plaque at the
Humboldt University of Berlin: "Max Planck, discoverer of the elementary quantum of action h, taught in this building from 1889 to 1928."
Max Planck
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Planck in 1918, the year he received the
Nobel Prize in Physics for his work on
quantum theory
14.
Einstein coefficients
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Einstein coefficients are mathematical quantities which are a measure of the probability of absorption or emission of light by an atom or molecule. The Einstein A coefficient is related to the rate of emission of light. In physics, one thinks of a line from two viewpoints. A spectrum of such photons will show an emission spike at the wavelength associated with these photons. An absorption line is formed when an atom or molecule makes a transition from a lower, E1, to a discrete energy state, E2. These absorbed photons generally come from background radiation and a spectrum will show a drop in the continuum radiation at the wavelength associated with the absorbed photons. A photon with an equal to the difference E2 - E1 between the energy levels is released or absorbed in the process. The frequency ν at which the line occurs is related to the photon energy by Bohrs frequency condition E2 - E1 = hν where h denotes Plancks constant. The emission of atomic radiation at frequency ν may be described by an emission coefficient ϵ with units of energy/time/volume/solid angle. ε dt dV dΩ is then the energy emitted by an element d V in time d t into solid angle d Ω. The absorption of atomic line radiation may be described by an absorption coefficient κ with units of 1/length, the expression κ dx gives the fraction of intensity absorbed for a light beam at frequency ν while traveling distance dx. The absorption coefficient is given by, κ ′ = h ν4 π where B12 and B21 are the Einstein coefficients for photo absorption and induced emission respectively. Like the coefficient A21, these are fixed by the intrinsic properties of the relevant atom for the two relevant energy levels. The above equations have ignored the influence of the line shape. To be accurate, the above equations need to be multiplied by the line shape. The number densities n 2 and n 1 are set by the state of the gas in which the spectral line occurs. In strict thermodynamic equilibrium, the field is said to be black-body radiation and is described by Plancks law. For example, in the atmosphere of the Sun, the strength of the radiation dominates
Einstein coefficients
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Emission lines and absorption lines compared to a continuous spectrum.
15.
Absorption (electromagnetic radiation)
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In physics, absorption of electromagnetic radiation is the way in which the energy of a photon is taken up by matter, typically the electrons of an atom. Thus, the energy is transformed into internal energy of the absorber. The reduction in intensity of a wave propagating through a medium by absorption of a part of its photons is often called attenuation. The mass attenuation coefficient, also called mass extinction coefficient, which is the absorption coefficient divided by density, the absorption cross section and scattering cross-section are closely related to the absorption and attenuation coefficients, respectively. Extinction in astronomy is equivalent to the attenuation coefficient, absorbance and optical depth are two related measures All these quantities measure, at least to some extent, how well a medium absorbs radiation. However, practitioners of different fields and techniques tend to use different quantities drawn from the list above. The absorbance of an object quantifies how much of the incident light is absorbed by it and this may be related to other properties of the object through the Beer–Lambert law. A few examples of absorption are ultraviolet–visible spectroscopy, infrared spectroscopy, understanding and measuring the absorption of electromagnetic radiation has a variety of applications. Here are a few examples, In meteorology and climatology, global and local temperatures depend in part on the absorption of radiation by gases and land. In medicine, X-rays are absorbed to different extents by different tissues, for example, see computation of radiowave attenuation in the atmosphere used in satellite link design. In chemistry and materials science, because different materials and molecules will absorb radiation to different extents at different frequencies, in optics, sunglasses, colored filters, dyes, and other such materials are designed specifically with respect to which visible wavelengths they absorb, and in what proportions. In physics, the D-region of Earths ionosphere is known to significantly absorb radio signals that fall within the electromagnetic spectrum. Optical Propagation in Linear Media, Atmospheric Gases and Particles, Solid-State Components, physics Archive - Ask a scientist
Absorption (electromagnetic radiation)
16.
Spontaneous emission
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Spontaneous emission is the process in which a quantum mechanical system transitions from an excited energy state to a lower energy state and emits a quantum in the form of a photon. Spontaneous emission is responsible for most of the light we see all around us. If atoms are excited by means other than heating, the spontaneous emission is called luminescence. And there are different forms of luminescence depending on how excited atoms are produced, if the excitation is effected by the absorption of radiation the spontaneous emission is called fluorescence. Sometimes molecules have a level and continue to fluoresce long after the exciting radiation is turned off. Figurines that glow in the dark are phosphorescent, lasers start via spontaneous emission, then during continuous operation work by stimulated emission. Spontaneous emission cannot be explained by classical theory and is fundamentally a quantum process. Contemporary physicists, when asked to give an explanation for spontaneous emission. In 1963 the Jaynes-Cummings model was developed describing the system of an atom interacting with a quantized field mode within an optical cavity. It gave the nonintuitive prediction that the rate of spontaneous emission could be controlled depending on the conditions of the surrounding vacuum field. These experiments gave rise to cavity quantum electrodynamics, the study of effects of mirrors and cavities on radiative corrections. If a light source is in a state with energy E2, it may spontaneously decay to a lower lying level with energy E1. The photon will have angular frequency ω and an energy ℏ ω, E2 − E1 = ℏ ω, note, ℏ ω = h ν, where h is the Planck constant and ν is the linear frequency. The phase of the photon in spontaneous emission is random as is the direction in which the photon propagates and this is not true for stimulated emission. In the rate-equation A21 is a proportionality constant for this transition in this particular light source. The constant is referred to as the Einstein A coefficient, and has units s −1, the number of excited states N thus decays exponentially with time, similar to radioactive decay. After one lifetime, the number of excited states decays to 36. 8% of its original value, the radiative decay rate Γ r a d is inversely proportional to the lifetime τ21, A21 = Γ21 =1 τ21. Spontaneous transitions were not explainable within the framework of the Schroedinger equation, in which the energy levels were quantized
Spontaneous emission
–
Contents
17.
Stimulated emission
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Stimulated emission is the process by which an incoming photon of a specific frequency can interact with an excited atomic electron, causing it to drop to a lower energy level. This is in contrast to spontaneous emission, which occurs at random intervals without regard to the ambient electromagnetic field. The process is identical in form to atomic absorption in which the energy of a photon causes an identical but opposite atomic transition. In normal media at thermal equilibrium, absorption exceeds stimulated emission because there are electrons in the lower energy states than in the higher energy states. However, when an inversion is present, the rate of stimulated emission exceeds that of absorption. Such a gain medium, along with a resonator, is at the heart of a laser or maser. Lacking a feedback mechanism, laser amplifiers and superluminescent sources also function on the basis of stimulated emission, electrons and their interactions with electromagnetic fields are important in our understanding of chemistry and physics. In the classical view, the energy of an electron orbiting a nucleus is larger for orbits further from the nucleus of an atom. However, quantum mechanical effects force electrons to take on positions in orbitals. Thus, electrons are found in energy levels of an atom, two of which are shown below, When an electron absorbs energy either from light or heat. But transitions are allowed between discrete energy levels such as the two shown above. This leads to lines and absorption lines. When an electron is excited from a lower to an energy level. An electron in a state may decay to a lower energy state which is not occupied. When such an electron decays without external influence, emitting a photon, the phase and direction associated with the photon that is emitted is random. This is the mechanism of fluorescence and thermal emission, an external electromagnetic field at a frequency associated with a transition can affect the quantum mechanical state of the atom without being absorbed. In response to the electric field at this frequency, the probability of the electrons entering this transition state is greatly increased. Thus, the rate of transitions between two states is increased beyond that of spontaneous emission
Stimulated emission
–
Contents
18.
Rudolf W. Ladenburg
–
Rudolf Walter Ladenburg was a German atomic physicist. He emigrated from Germany as early as 1932 and became a Brackett Research Professor at Princeton University, when the wave of German emigration began in 1933, he was the principal coordinator for job placement of exiled physicist in the United States. Ladenburg was the son of the Jewish chemist Albert Ladenburg, ordinarius professor of chemistry at the University of Kiel and he was a non-practicing Jew and an atheist. From 1900 to 1906, Ladenburg studied at the Ruprecht-Karls-Universität Heidelberg, the Universität Breslau, and he received his doctorate under Wilhelm Röntgen at Munich. After completion of his Habilitation, Ladenburg became a Privatdozent at Breslau, Ladenburg went to the United States as early as 1930, where he became a Brackett Research Professor at the Palmer Physics Laboratory, Princeton University. When the emigration wave from Germany began in April 1933, Ladenburg was the coordinator for the employment of exiled physicists in the United States. He retired from Princeton in 1950, Rudolf Ladenburg and Stanislaw Loria Nature, Anomalous Dispersion of Luminous Hydrogen Volume 79, 7-7 Rudolf Ladenburg Die quantentheoretische Bedeutung der Zahl der Dispersionelektronen, Z. Phys. English translation, The quantum-theoretical number of electrons in B. L. van der Waerden Sources of Quantum Mechanics pp.139 –157. Annalen der Physik, Volume 383, Issue 23, pp. 659-679 Hans Kopfermann, anomale Dispersion in angeregtem Neon Einfluß von Strom und Druck, Bildung und Vernichtung angeregter Atome, Zeitschrift für Physik Volume 48, Numbers 1-2, pp. 26-50. Institutional affiliation, Kaiser-Wilhelm Institut für physikalische Chemie und Elektrochemie, Berlin-Dahlem, institutional affiliation, Kaiser-Wilhelm Institut für physikalische Chemie und Elektrochemie, Berlin-Dahlem. Rudolf Ladenburg Dispersion in Electrically Excited Gases Rev. Mod, the author was cited as being at Princeton University
Rudolf W. Ladenburg
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Rudolf Ladenburg, 1937
19.
Willis E. Lamb
–
Willis Eugene Lamb Jr. was an American physicist who won the Nobel Prize in Physics in 1955 for his discoveries concerning the fine structure of the hydrogen spectrum. The Nobel Committee that year awarded half the prize to Lamb and the half to Polykarp Kusch. Lamb was able to determine precisely a surprising shift in electron energies in a hydrogen atom, Lamb was a professor at the University of Arizona College of Optical Sciences. Lamb was born in Los Angeles, California, United States, first admitted in 1930, he received a Bachelor of Science in Chemistry from the University of California, Berkeley in 1934. For theoretical work on scattering of neutrons by a crystal, guided by J. Robert Oppenheimer, because of limited computational methods available at the time, this research narrowly missed revealing the Mössbauer Effect,19 years before its recognition by Mössbauer. He worked on theory, laser physics, and verifying quantum mechanics. Lamb was the Wykeham Professor of Physics at the University of Oxford from 1956 to 1962, and also taught at Yale, Columbia, Stanford and he was elected a Fellow of the American Academy of Arts and Sciences in 1963. Lamb is remembered as a rare theorist turned experimentalist by D. Kaiser, in addition to his crucial and famous contribution to quantum electrodynamics via the Lamb shift, in the latter part of his career he paid increasing attention to the field of quantum measurements. In one of his writings Lamb stated that most people who use quantum mechanics have little need to know much about the interpretation of the subject, Lamb was also openly critical of many of the interpretational trends on quantum mechanics. In 1939 Lamb married his first wife, Ursula Schaefer, a German student, after her death in 1996 he married physicist Bruria Kaufman in 1996, whom he later divorced. In 2008 he married Elsie Wattson, Lamb died on May 15,2008, at the age of 94, due to complications of a gallstone disorder. Biography and Bibliographic Resources, from the Office of Scientific and Technical Information Obituary, hans Bethe talking about Willis Lamb Willis E Lamb Award for Laser Science and Quantum Optics. Nobel lecture Collection of articles and group photograph, Obituary, Willis E. Lamb Jr.94, Nobel Prize-Winning Physicist National Academy of Sciences Biographical Memoir
Willis E. Lamb
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Willis Lamb
20.
Alfred Kastler
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Alfred Kastler was a French physicist, and Nobel Prize laureate. Kastler was born in Guebwiller and later attended the Lycée Bartholdi in Colmar, Alsace, after his studies, in 1926 he began teaching physics at the Lycée of Mulhouse, and then taught at the University of Bordeaux, where he was a university professor until 1941. Georges Bruhat asked him to back to the École Normale Supérieure. Collaborating with Jean Brossel, he researched quantum mechanics, the interaction between light and atoms, and spectroscopy, Kastler, working on combination of optical resonance and magnetic resonance, developed the technique of optical pumping. Those works led to the completion of the theory of lasers and masers and he won the Nobel Prize in Physics in 1966 for the discovery and development of optical methods for studying Hertzian resonances in atoms. He was president of the board of the Institut doptique théorique et appliquée, in 1971 he published Europe, ma patrie, Deutsche Lieder eines französischen Europäers. In 1978 he became member of the Royal Netherlands Academy of Arts. In 1979, Kastler was awarded the Wilhelm Exner Medal, professor Kastler spent most of his research career at the Ecole Normale Supérieure in Paris where he started after the war with his student, Jean Brossel a small research group on spectroscopy. Over the forty years that followed, this group has trained many of young physicists and had a significant impact on the development of the science of physics in France. Professor Kastler died on 7 January 1984, in Bandol, France, optical Methods for Studying Hertzian Resonances. Applications of polarimetry to infra-red and micro-wave spectroscopy, Alfred Kastler biography at Timeline of Nobel Winners Alfred Kastler at the Mathematics Genealogy Project
Alfred Kastler
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Alfred Kastler
Alfred Kastler
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Kastler ca. 1967
21.
Optical pumping
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Optical pumping is a process in which light is used to raise electrons from a lower energy level in an atom or molecule to a higher one. It is commonly used in construction, to pump the active laser medium so as to achieve population inversion. The technique was developed by 1966 Nobel Prize winner Alfred Kastler in the early 1950s, Optical pumping is also used to cyclically pump electrons bound within an atom or molecule to a well-defined quantum state. The frequency and polarization of the laser determines which m F sublevel the atom is oriented in. Laser pumping Optical cavity Rabi cycle Atomic coherence
Optical pumping
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Optical pumping of a laser rod (bottom) with an
arc lamp (top). Red: hot. Blue: cold. Green: light. Non-green arrows: water flow. Solid colors: metal. Light colors:
fused quartz. Refs: [1], [2], [3]
22.
Nikolay Basov
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Nikolay Gennadiyevich Basov was a Soviet physicist and educator. Basov was born in the town Usman, now in Lipetsk Oblast in 1922 and 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, Basov graduated from Moscow Engineering Physics Institute in 1950. Basov was the Director of the LPI in 1973–1988 and he was elected as corresponding member of the USSR Academy of Sciences in 1962 and Full Member of the Academy in 1966. In 1967, he was elected a Member of the Presidium of the Academy and he was Honorary President and Member of the International Academy of Science, Munich. He was the head of the laboratory of quantum radiophysics at the LPI until his death in 2001, basovs contributions to the development of the laser and maser, which won him the Nobel Prize in 1964, led to new missile defense initiatives seeking to employ them. He entered politics in 1951 and became a member of parliament in 1974, following U. S. President Ronald Reagans speech on SDI in 1983, Basov signed a letter along with other Soviet scientists condemning the initiative, which was published in the New York Times. In 1985 he declared the Soviet Union was capable of matching SDI proposals made by the U. S. N. G. Basov, K. A. Brueckner, S. W. Haan, C. Inertial Confinement Fusion,1992, Research Trends in Physics Series published by the American Institute of Physics Press, V. Stefan and N. G. Basov. Semiconductor Science and Technology, Volume 1, V. Stefan and N. G. Basov. Semiconductor Science and Technology, Volume 2, Quantum Dots and Quantum Wells, lenin Prize Nobel Prize in Physics Hero of Socialist Labour — twice Gold Medal of the Czechoslovak Academy of Sciences A. Oral History interview transcript with Nikolay Basov 14 September 1984, American Institute of Physics, Niels Bohr Library and Archives
Nikolay Basov
–
Nicolay Gennadiyevich Basov
23.
Alexander Prokhorov
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As a child he attended Butchers Creek School. In 1923, after the October Revolution, the returned to Russia. In 1934, Prokhorov entered the Saint Petersburg State University to study physics and he graduated with honors in 1939 and moved to Moscow to work at the Lebedev Physical Institute, in the oscillations laboratory headed by academician N. D. Papaleksi. His research there was devoted to propagation of waves in the ionosphere. At the onset of World War II in the Soviet Union, in June 1941, during World War II, Prokhorov fought in the infantry, was wounded twice in battles, and was awarded three medals, including the Medal For Courage in 1946. In 1947, Prokhorov started working on coherent radiation emitted by electrons orbiting in a particle accelerator called a synchrotron. He demonstrated that the emission is mostly concentrated in the spectral range. His results became the basis of his habilitation on Coherent Radiation of Electrons in the Synchrotron Accelerator, by 1950, Prokhorov was assistant chief of the oscillation laboratory. Around that time, he formed a group of scientists to work on radiospectroscopy of molecular rotations and vibrations. The group focused on a class of molecules which have three moments of inertia. The research was conducted both on experiment and theory, in 1954, Prokhorov became head of the laboratory. Together with Nikolay Basov he developed theoretical grounds for creation of a molecular oscillator and they also proposed a method for the production of population inversion using inhomogeneous electric and magnetic fields. Their results were first presented at a conference in 1952. He focused on relaxation times of ions of the group elements in a lattice of aluminium oxide. In 1957, while studying ruby, a variation of aluminium oxide. As a new type of resonator, he proposed, in 1958, an open type cavity design. In 1963, together with A. S. Selivanenko, he suggested a laser using two-quantum transitions, for his pioneering work on lasers and masers, in 1964, he received the Nobel Prize in Physics shared with Nikolay Basov and Charles Hard Townes. In 1959, Prokhorov became a professor at Moscow State University – the most prestigious university in the Soviet Union, in 1960, he became a member of the Russian Academy of Sciences and elected Academician in 1966
Alexander Prokhorov
–
Alexander Prokhorov
24.
Charles H. Townes
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Charles Hard Townes was an American physicist and inventor of the maser and laser. He shared the Nobel Prize in Physics during 1964 with Nikolay Basov, Charles was also a major advisor to the United States Government, meeting every US President from Harry Truman to William Clinton. Townes was religious and believed that science and religion are converging to provide an understanding of the nature. Townes was born in Greenville, South Carolina, the son of Henry Keith Townes, an attorney and he earned his B. S. in Physics and B. A. in Modern Languages at Furman University, where he graduated during 1935. During World War II he worked on radar bombing systems at Bell Labs, Townes was appointed Professor during 1950 at Columbia University. He served as Executive Director of the Columbia Radiation Laboratory from 1950 to 1952 and he was Chairman of the Physics Department from 1952 to 1955. During 1951 he conceived a new way to intense, precise beams of coherent radiation for which he invented the acronym maser. When the same principle was applied to higher frequencies the term laser was used, during 1953, Townes, James P. Gordon, and H. J. Zeiger built the first ammonia maser at Columbia University. This device used stimulated emission in a stream of energized ammonia molecules to produce amplification of microwaves at a frequency of about 24.0 gigahertz, between 1961 and 1967 Townes served as both Provost and Professor of Physics at the Massachusetts Institute of Technology. Between 1966 and 1970, he was chairman of the NASA Science Advisory Committee for the Apollo lunar landing program, for his creation of the maser, Townes along with Nikolay Basov and Alexander Prokhorov received the 1964 Nobel Prize in Physics. During 2002–3, Townes served as a Karl Schwarzschild Lecturer in Germany and this information is drawn from the authoritative oral history on Charles Townes done by the Bancroft Library at UC Berkeley and underwritten by the Sloan Foundation. Refer to other aspects of his life too, when Charles failed to be promoted to President of MIT during 1967 he accepted an offer from Clark Kerr to join UC Berkeley and begin an astrophysical program. Charles soon began searching for molecules in space, at the time most astronomers thought molecules could not exist in space because UV rays would destroy them. Townes eventually discovered ammonia and water in dust clouds that shielded them from damaging rays by essentially doing microwave spectroscopy on the sky and this created the topic of molecular/millimeter astronomy which continues to find many complex molecules, some the precursors to life. The Galactic Center had long puzzled astronomers, and thick dust obscured its view, Charles worked together with John Lacy, Neal Evans, Reinhard Genzel and Mike Werner. When the team studied Sagittarius A which is at the galactic center, in such a small space this indicated a supermassive black hole, one of the first black holes observed in our universe. Charles most recent technological creation has been the Infrared Spatial Interferometer with Walt Fitelson, Ed Wishnow, the project combines three mobile infrared detectors aligned by lasers that study the same star. If each telescope is 10 meters from the other, it creates an impression of a 30 meters lens
Charles H. Townes
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Townes in 2007
Charles H. Townes
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Charles Hard Townes
Charles H. Townes
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Townes (right) receiving the 2006
Vannevar Bush Award
25.
James P. Gordon
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James Power Gordon was an American physicist known for his work in the fields of optics and quantum electronics. His contributions include the design, analysis and construction of the first maser in 1954 as a student at Columbia University under the supervision of C. H. A. Haus in 1986. James P. Gordon was a member of the National Academy of Engineering, J. P. Gordon was born in Brooklyn, New York, on March 20,1928, and was raised in Forest Hills, Queens and Scarsdale, New York. His father, Robert S. Gordon was a lawyer and worked as VP and General Counsel for National Dairy, Gordon attended Scarsdale High School and Phillips Exeter Academy. In 1949 he received a degree from the Massachusetts Institute of Technology. He received his Masters and PhD degrees in physics in 1951 and 1955, in the framework of his doctoral research he designed, built and demonstrated the successful operation of the first maser together with H. Zeiger and with his doctoral advisor Prof. Charles H. Townes. The invention of the won the Nobel Prize in Physics. Townes shared in 1964 with the Russian scientists N. Bassov, starting in 1955 and until his retirement in 1996, James P. In 1962-1963 he spent one year as a visiting Professor at the University of California, in 1960 he married Susanna Bland Waldner, a former Bell-Labs computer programmer. The couple had three children, James Jr. Susanna, and Sara, a resident of Rumson, New Jersey, he died aged 85 on June 21,2013, at a hospital in New York City due to cancer. In addition to his career, Gordon played platform tennis, having won the U. S. National Championship for men’s doubles in 1959. Gordon’s brother, Robert S. Gordon Jr. set up a Cholera Clinic in East Pakistan, the Gordon Lecture in Epidemiology is a yearly award in his honor, granted by the National Institutes of Health. During his doctoral training period with C. H, Townes at Columbia University, Gordon worked on the design, analysis and construction of the maser. This work produced the first prototype of what evolved into the laser. Gordon’s later contribution to lasers included the analysis of the confocal and he joined with G. Boyd, to introduce the concept of Hermite-Gaussian modes into resonator study, influencing all subsequent research conducted on laser resonators. Martinez in 1994, a mechanism for generating tunable negative dispersion using pairs of prisms was proposed and this invention was instrumental in achieving ultra-short laser pulses, critical in many applications using laser technology. In 1962, Gordon studied the implications of quantum mechanics on Shannon’s information capacity and he pointed out the main effects of quantization and conjectured the quantum equivalent of Shannon’s formula for the information capacity of a channel. Gordon’s conjecture, later proven by Alexander Holevo and known as Holevos theorem, in his work with W. H. Louisell published in 1966, Gordon addressed the problem of measurement in quantum physics, focusing in particular on the simultaneous measurement of noncommuting observables
James P. Gordon
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James P. Gordon (1928–2013)
James P. Gordon
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Picture of James P. Gordon with Charles H. Townes behind maser components, at the exhibit in National Museum of American History, Washington, DC, USA.
26.
Nobel Prize in Physics
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The Nobel Prize in Physics is a yearly award given by the Royal Swedish Academy of Sciences for those who conferred the most outstanding contributions for mankind in the field of physics. The first Nobel Prize in Physics was awarded to German/Dutch physicist Wilhelm Röntgen in recognition of the services he has rendered by the discovery of the remarkable rays. This award is administered by the Nobel Foundation and widely regarded as the most prestigious award that a scientist can receive in physics and it is presented in Stockholm at an annual ceremony on December 10, the anniversary of Nobels death. Through 2016, a total of 203 individuals have been awarded the prize, only two women have won the Nobel Prize in Physics, Marie Curie in 1903, and Maria Goeppert Mayer in 1963. Though Nobel wrote several wills during his lifetime, the last one was written a year before he died and was signed at the Swedish-Norwegian Club in Paris on 27 November 1895. Nobel bequeathed 94% of his assets,31 million Swedish kronor, to establish. Due to the level of surrounding the will, it was not until April 26,1897 that it was approved by the Storting. The executors of his will were Ragnar Sohlman and Rudolf Lilljequist, the members of the Norwegian Nobel Committee who were to award the Peace Prize were appointed shortly after the will was approved. The prize-awarding organisations followed, the Karolinska Institutet on June 7, the Swedish Academy on June 9, the Nobel Foundation then reached an agreement on guidelines for how the Nobel Prize should be awarded. In 1900, the Nobel Foundations newly created statutes were promulgated by King Oscar II, according to Nobels will, The Royal Swedish Academy of sciences were to award the Prize in Physics. A maximum of three Nobel laureates and two different works may be selected for the Nobel Prize in Physics, compared with other Nobel Prizes, the nomination and selection process for the prize in Physics is long and rigorous. This is a key reason why it has grown in importance over the years to become the most important prize in Physics, the Nobel laureates are selected by the Nobel Committee for Physics, a Nobel Committee that consists of five members elected by The Royal Swedish Academy of Sciences. In the first stage begins in September, around 3,000 people – selected university professors, Nobel Laureates in Physics and Chemistry. The completed nomination forms arrive at the Nobel Committee no later than 31 January of the following year and these nominees are scrutinized and discussed by experts who narrow it to approximately fifteen names. The committee submits a report with recommendations on the candidates into the Academy. The Academy then makes the selection of the Laureates in Physics through a majority vote. The names of the nominees are never announced, and neither are they told that they have been considered for the prize. Nomination records are sealed for fifty years, while posthumous nominations are not permitted, awards can be made if the individual died in the months between the decision of the prize committee and the ceremony in December
Nobel Prize in Physics
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Wilhelm Röntgen (1845–1923), the first recipient of the Nobel Prize in Physics.
Nobel Prize in Physics
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The Nobel Prize in Physics
Nobel Prize in Physics
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Three Nobel Laureates in Physics. Front row from left:
Albert A. Michelson (1907),
Albert Einstein (1921) and
Robert A. Millikan (1923).
27.
Ruby laser
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A ruby laser is a solid-state laser that uses a synthetic ruby crystal as its gain medium. The first working laser was a laser made by Theodore H. Ted Maiman at Hughes Research Laboratories on May 16,1960. Ruby lasers produce pulses of coherent visible light at a wavelength of 694.3 nm, typical ruby laser pulse lengths are on the order of a millisecond. A ruby laser most often consists of a rod that must be pumped with very high energy, usually from a flashtube. The rod is placed between two mirrors, forming an optical cavity, which oscillate the light produced by the rubys fluorescence. Ruby is one of the few solid state lasers that produce light in the range of the spectrum, lasing at 694.3 nanometers, in a deep red color. The ruby laser is a three level solid state laser, the active laser medium is a synthetic ruby rod that is energized through optical pumping, typically by a xenon flashtube. Ruby has very broad and powerful absorption bands in the spectrum, at 400 and 550 nm. This allows for high energy pumping, since the pulse duration can be much longer than with other materials. While ruby has a very wide absorption profile, its efficiency is much lower than other mediums. The finely polished ends of the rod were silvered, one end completely, the rod, with its reflective ends, then acts as a Fabry–Pérot etalon. Modern lasers often use rods with antireflection coatings, or with the ends cut and this eliminates the reflections from the ends of the rod. External dielectric mirrors then are used to form the optical cavity, curved mirrors are typically used to relax the alignment tolerances and to form a stable resonator, often compensating for thermal lensing of the rod. Ruby also absorbs some of the light at its lasing wavelength, to overcome this absorption, the entire length of the rod needs to be pumped, leaving no shaded areas near the mountings. The active part of the ruby is the dopant, which consists of chromium ions suspended in a sapphire crystal. The dopant often comprises around 0. 05% of the crystal, depending on the concentration of the dopant, synthetic ruby usually comes in either pink or red. One of the first applications for the laser was in rangefinding. By 1964, ruby lasers with rotating prism q-switches became the standard for military rangefinders, until the introduction of more efficient Nd, ruby lasers were used mainly in research
Ruby laser
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Diagram of the first ruby laser.
Ruby laser
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A ruby laser rod. Inset: The view through the rod is crystal clear
Ruby laser
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Maiman's original ruby laser
Ruby laser
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Components of original ruby laser
28.
Hughes Research Laboratories
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HRL Laboratories, was the research arm of Hughes Aircraft. It is a research center, established in 1960, in Malibu. Currently owned by General Motors Corporation and Boeing, the facility is housed in two large, white multi-story buildings overlooking the Pacific Ocean. In the 1940s, Howard Hughes created a R&D facility in Culver City, California, by 1960, it moved to Malibu, General Motors purchased Hughes Aircraft in 1985. GM sold the Hughes aerospace and defense operations to Raytheon in 1997, GM sold the Hughes satellite operations to Boeing in 2000, and the co-owners became Boeing, GM, and Raytheon. In 2007, Raytheon decided to sell its stake, though it still maintains research, for more details, please see Hughes Aircraft. HRL receives funding from its LLC partners, US defense contracts, HRL focuses on advanced developments in microelectronics, information & systems sciences, materials, sensors, and photonics, their workspace spans from basic research to product delivery. It has particularly emphasized capabilities in high performance integrated circuits, high power lasers, antennas, networking, despite downsizing during the aerospace industrys contraction of the 1990s, HRL still continued to be the largest employer in Malibu. The first working model of the laser was created at Hughes Research Laboratories in 1960 by Theodore Maiman, HRL began research on atomic clocks in 1959. In the late 1970s they produced experimental maser oscillators for NRL, HRL began research on ion propulsion in 1960. This research led to the Hughes developed xenon ion propulsion system, XIPS was used as the primary propulsion system on NASAs Deep Space 1. It is an option for primary stationkeeping on the Hughes/Boeing 601HP. HRL claims to have developed the liquid crystal watch in 1975, HRL SyNAPSE neuromorphic chip is first chip to learn like the brain by altering synapses. Developed world’s largest most biologically accurate, integrated model of 9 brain systems underlying emergent sensemaking. First hybrid satellite-wireless ad hoc network First stabilized outdoor augmented reality system, HRL developed the metallic microlattice, the lightest material, in 2011 Cognitive Technology Threat Warning System Official website
Hughes Research Laboratories
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HRL Laboratories, LLC
Hughes Research Laboratories
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Divisions and subsidiaries
29.
Charles Hard Townes
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Charles Hard Townes was an American physicist and inventor of the maser and laser. He shared the Nobel Prize in Physics during 1964 with Nikolay Basov, Charles was also a major advisor to the United States Government, meeting every US President from Harry Truman to William Clinton. Townes was religious and believed that science and religion are converging to provide an understanding of the nature. Townes was born in Greenville, South Carolina, the son of Henry Keith Townes, an attorney and he earned his B. S. in Physics and B. A. in Modern Languages at Furman University, where he graduated during 1935. During World War II he worked on radar bombing systems at Bell Labs, Townes was appointed Professor during 1950 at Columbia University. He served as Executive Director of the Columbia Radiation Laboratory from 1950 to 1952 and he was Chairman of the Physics Department from 1952 to 1955. During 1951 he conceived a new way to intense, precise beams of coherent radiation for which he invented the acronym maser. When the same principle was applied to higher frequencies the term laser was used, during 1953, Townes, James P. Gordon, and H. J. Zeiger built the first ammonia maser at Columbia University. This device used stimulated emission in a stream of energized ammonia molecules to produce amplification of microwaves at a frequency of about 24.0 gigahertz, between 1961 and 1967 Townes served as both Provost and Professor of Physics at the Massachusetts Institute of Technology. Between 1966 and 1970, he was chairman of the NASA Science Advisory Committee for the Apollo lunar landing program, for his creation of the maser, Townes along with Nikolay Basov and Alexander Prokhorov received the 1964 Nobel Prize in Physics. During 2002–3, Townes served as a Karl Schwarzschild Lecturer in Germany and this information is drawn from the authoritative oral history on Charles Townes done by the Bancroft Library at UC Berkeley and underwritten by the Sloan Foundation. Refer to other aspects of his life too, when Charles failed to be promoted to President of MIT during 1967 he accepted an offer from Clark Kerr to join UC Berkeley and begin an astrophysical program. Charles soon began searching for molecules in space, at the time most astronomers thought molecules could not exist in space because UV rays would destroy them. Townes eventually discovered ammonia and water in dust clouds that shielded them from damaging rays by essentially doing microwave spectroscopy on the sky and this created the topic of molecular/millimeter astronomy which continues to find many complex molecules, some the precursors to life. The Galactic Center had long puzzled astronomers, and thick dust obscured its view, Charles worked together with John Lacy, Neal Evans, Reinhard Genzel and Mike Werner. When the team studied Sagittarius A which is at the galactic center, in such a small space this indicated a supermassive black hole, one of the first black holes observed in our universe. Charles most recent technological creation has been the Infrared Spatial Interferometer with Walt Fitelson, Ed Wishnow, the project combines three mobile infrared detectors aligned by lasers that study the same star. If each telescope is 10 meters from the other, it creates an impression of a 30 meters lens
Charles Hard Townes
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Townes in 2007
Charles Hard Townes
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Charles Hard Townes
Charles Hard Townes
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Townes (right) receiving the 2006
Vannevar Bush Award
