Laser Wikipedia. A laser beam used for welding. Red 6. 60 6. 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 1. 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, spatially and temporally. 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 collimation, enabling applications such as laser pointers. Lasers can also have high temporal coherence, which allows them to emit light with a very narrow spectrum, i. Temporal coherence can be used to produce pulses of light as short as a femtosecond. Among their many applications, lasers are used in optical disk drives, laser printers, and barcode scanners DNA sequencing instruments, fiber optic and free space optical communication laser surgery and skin treatments cutting and welding materials military and law enforcement devices for marking targets and measuring range and speed and laser lighting displays in entertainment. Fundamentals. Modern telescopes use laser technologies to compensate for the blurring effect of the Earths atmosphere. Buku Fisika Kelas 7 Smp there. Lasers are distinguished from other light sources by their coherence. Spatial coherence is typically expressed through the output being a narrow beam, which is diffraction limited. 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 or longitudinal coherence implies a polarized wave at a single frequency whose phase is correlated over a relatively great distance the coherence length along the beam. A beam produced by a thermal or other incoherent light source has an instantaneous amplitude and phase that vary randomly with respect to time and position, thus having a short coherence length. Lasers are characterized according to their wavelength in a vacuum. Most single wavelength lasers actually produce radiation in several modes having slightly differing frequencies wavelengths, 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 such devices are classified as lasers based on their method of producing light, i. Lasers are employed in applications where light of the required spatial or temporal coherence could not be produced using simpler technologies. Terminology. Laser beams in fog, reflected on a car windshield. The word laser started as an acronym for light amplification by stimulated emission of radiation. In modern usage, the term light includes electromagnetic radiation of any frequency, not only visible light, hence the terms infrared laser, ultraviolet laser, X ray laser, gamma ray laser, and so on. Because the microwave predecessor of the laser, the maser, was developed first, devices of this sort operating at microwave and radio frequencies are referred to as masers rather than microwave lasers or radio lasers. 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 oscillator rather than an optical amplifier as suggested by the acronym. It has been humorously noted that the acronym LOSER, for light oscillation by stimulated emission of radiation, would have been more correct. With the widespread use of the original acronym as a common noun, optical amplifiers have come to be referred to as laser amplifiers, notwithstanding the apparent redundancy in that designation. The back formed verb to lase is frequently used in the field, meaning to produce laser light,7 especially in reference to the gain medium of a laser when a laser is operating it is said to be lasing. Further use of the words laser and maser in an extended sense, not referring to laser technology or devices, can be seen in usages such as astrophysical maser and atom laser. Design. Components of a typical laser. Animation explaining stimulated emission and the laser principle. Experiments in Physics Physics 1291 General Physics I Lab Columbia University Department of Physics Fall 2012. Nuclear Physics for Medicine Nuclear physics is a coin that has two sides basic research and applications. Without basic 3 research there would be little to be. Back to Complete HeNe Laser Power Supply Schematics SubTable of Contents. Introduction to AC Line Operated Power Supply Schematics Several of the circuits described. A laser consists of a gain medium, a mechanism to energize it, and something to provide optical feedback. The gain medium is a material with properties that allow it to amplify light by way of stimulated emission. Light of a specific wavelength that passes through the gain medium is amplified increases in power. For the gain medium to amplify light, it needs to be supplied with energy in a process called pumping. The energy is typically supplied as an electric current or as light at a different wavelength. Pump light may be provided by a flash lamp or by another laser. The most common type of laser uses feedback from an optical cavitya pair of mirrors on either end of the gain medium. Light bounces back and forth between the mirrors, passing through the gain medium and being amplified each time. Typically one of the two mirrors, the output coupler, is partially transparent. Some of the light escapes through this mirror. Depending on the design of the cavity whether the mirrors are flat or curved, the light coming out of the laser may spread out or form a narrow beam. In analogy to electronic oscillators, this device is sometimes called a laser oscillator. Most practical lasers contain additional elements that affect properties of the emitted light, such as the polarization, wavelength, and shape of the beam. Laser physics. Electrons and how they interact with electromagnetic fields are important in our understanding of chemistry and physics. Stimulated emission. In the classical view, the energy of an electron orbiting an atomic nucleus is larger for orbits further from the nucleus of an atom. However, quantum mechanical effects force electrons to take on discrete positions in orbitals. Thus, electrons are found in specific energy levels of an atom, two of which are shown below When an electron absorbs energy either from light photons or heat phonons, it receives that incident quantum of energy. But transitions are only allowed in between discrete energy levels such as the two shown above. This leads to emission lines and absorption lines. When an electron is excited from a lower to a higher energy level, it will not stay that way forever. An electron in an excited state may decay to a lower energy state which is not occupied, according to a particular time constant characterizing that transition. Ableton Live 7 For Mac on this page. When such an electron decays without external influence, emitting a photon, that is called spontaneous emission. The phase associated with the photon that is emitted is random.