Light amplification

The acronym LASER (Light Amplification via tire Stimulated Emission of Radiation) defines the process of amplification. For all intents and purjDoses tliis metliod was elegantly outlined by Einstein in 1917 [H] wherein he derived a treatment of the dynamic equilibrium of a material in a electromagnetic field absorbing and emitting photons. Key here is tire insight tliat, in addition to absorjDtion and spontaneous emission processes, in an excited system one can stimulate tire emission of a photon by interaction witli tire electromagnetic field. It is tliis stimulated emission process which lays tire conceptual foundation of tire laser. 

LASER, light amplification by stimulated emission of radiation... 

The word laser is an acronym derived from light amplification by the stimulated emission of radiation . If the light concerned is in the microwave region then the alternative acronym maser is often used. Although the first such device to be constructed was the ammonia maser in 1954 it is the lasers made subsequently which operate in the infrared, visible or ultraviolet regions of the spectrum which have made a greater impact. 

The term laser is an acronym constmcted from light amplification by stimulated emission of radiation. The first operating laser was produced in 1960 (1). This laser, which used a crystal of mby [12174A9-17, chromium-doped alumina, Al202 Cr, and emitted a pulsed beam of collimated red light, immediately aroused scientific interest. 

The word laser is an acronym for light amplification by the stimulated emission of radiation. Lasers of all kinds consist of several basic components an active medium, an outside energy source, and an optical cavity with carefully designed mirrors on both ends. One of the mirrors is 100 percent reflective... 

M. Berggren, A. Dodabalapur, R.E. Slusher, Z. Bao, Light amplification in organic thin films using cascade energy transfer. Nature 1997, 389, 466. 

International Union of Pure and Applied Chemistry International Union of Pure and Applied Physics Laser (Ablation) Micro Mass Spectrometry Light Amplification by Stimulated Emission of Radiation Liquid Chromatography... 

The word LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. The physical process upon which lasers depend, stimulated emission, was first elucidated by Einstein in 1917 (1). Einstein showed that in quantized systems three processes involving photons must exist absorption, spontaneous emission, and stimulated emission. These may be represented as follows ... 

Lasers are devices for producing coherent light by way of stimulated emission. (Laser is an acronym for light amplification by stimulated emission of radiation.) In order to impose stimulated emission upon the system, it is necessary to bypass the equilibrium state, characterized by the Boltzmann law (Section 9.6.2), and arrange for more atoms to be in the excited-state E than there are in the ground-state E0. This state of affairs is called a population inversion and it is a necessary precursor to laser action. In addition, it must be possible to overcome the limitation upon the relative rate of spontaneous emission to stimulated emission, given above. Ways in which this can be achieved are described below, using the ruby laser and the neodymium laser as examples. 

Figure 1.14 Light amplification resulting from stimulated emission ( represents an electronically-excited atom)...

In contrast to spontaneous emission, induced emission (also called stimulated emission) is coherent, i.e. all emitted photons have the same physical characteristics - they have the same direction, the same phase and the same polarization. These properties are characteristic of laser emission (L.A.S.E.R. = Light Amplification by Stimulated Emission of Radiation). The term induced emission comes from the fact that de-excitation is triggered by the interaction of an incident photon with an excited atom or molecule, which induces emission of photons having the same characteristics as those of the incident photon. 

Light is generated upon relaxation from the excited state to a ground state that is repulsive, e.g., Xe+Cl. This condition is extremely favorable for population inversion, i.e., the number of excited dimer molecules is greater than the number of dimer molecules in the ground state, a condition necessary for light amplification... 

Since the field of spectroscopic laser applications is so vast and the number of published papers exceedingly large, this review cannot be complete. However, the author has tried to give a reasonable survey of what has been done and to offer some ideas about what can be done in modem spectroscopy with such an interesting and stimulating invention as the laser (Light Amplification by Stimulated Emission of Radiation). 

To overcome the lasing threshold, the light amplification has to be larger than unity. For this reason, the loss from the cavity has to be small. Whereas the length of one round-trip in the largest crystals we are using is 3 p.m, it is about... 

The term LASER stands for Light Amplification by Stimulated Emission Radiation... 

Besides the direct electrical induction of electro-optical effects in liquid crystals, their activation by illumination of photoconductors could be of great technical interest. This method might well permit the electro-optical properties of nematic liquid crystals to be used on a larger scale, because photoconductor activation may eventually be applied to light amplification, optical data processing, and projection display systems, or used for recording phase-type holograms. 

Stimulated emission of photons. This process consists of electronic transitions from the excited energy level to the lower one stimulated by an external radiation of the appropriate frequency ( 2 - E fh and constitutes the basis of the laser (light amplification by stimulated emission of radiation) phenomenon. 

Considerable attention has been paid in the past few years to the study of both the absorption and emission spectra of the rare earths. This has been boosted further by the development of the new branch of physics, the Laser (light amplification through stimulated emission of radiation). The study of the optical spectra of ions yields valuable information about the energy levels of normal configurations and of excited states, and also about the nature of their environment. However, a detailed analysis of optical spectra demands a considerable knowledge of theoretical techniques. Recent advances in paramagnetic resonance techniques [479] have enabled us to understand the nature of the ground states of the rare earth ions in crystalline environments. 

Laser Diode (LD)—Light Amplification by Stimulated Emission of Radiation. An electro-optic device that produces coherent light with a narrow range of wavelengths, typically centered around 780 nm, 1320 nm, or 1550 nm. Lasers with wavelengths centered around 780 nm are commonly referred to as CD Lasers. 

Laser Laser is an acronym for Light Amplification by. Stimulated Emission of Radiation. Lasers are important in flow cytometry because, as a result of their coherent output, they are a means of illuminating cells with a compact, intense light beam that will produce fluorescence signals that are as bright as possible over a short time period. 

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