Laser coherent beam

The scattered radiation V3 is to high wavenumber of Vj (i.e. on the anti-Stokes side) and is coherent, unlike spontaneous Raman scattering hence the name CARS. As a consequence of the coherence of the scattering and the very high conversion efficiency to V3, the CARS radiation forms a collimated, laser-like beam. 

The iavention of the laser ia 1958 prompted the beginning of the story of optical fiber communications. This device was capable of produciag a high iatensity, coherent beam of light which could be modulated at a high rate (see Lasers). StiU, no transmission medium of suitable clarity was available. 

ESO VLT/Max Planck CW Dye Laser. The MPI is developing a CW dye laser for deployment on one ESO 8-m VLT telescope in 2004 (Eig. 13). The oscillator is a Coherent 899 ring dye laser, with a 2-5 W output, pumped by a 10 W, Coherent Verdi frequency-doubled Nd YAG laser. The beam is amphfied in a four-pass amphfier with 4 high velocity dye jets pumped with 4 10 W Verdi lasers. The system utihzes Rhodamine 6G in ethylene glycol however, because of the high pump power, the dye degrades quickly, and must... 

Enhancement of x2 will lead to improvement (in terms of efficiency per interaction volume) in the following applications up-conversion in the visible or near U.V. of powerful I.R. laser radiation, frequency modulation of a laser carrier beam, optical parametric oscillation and amplification for solid state infrared tunable coherent devices. 

Amplification by Stimulated Emission of Radiation . (Similar devices producing coherent beams of microwave radiation are known as masers) A typical arrangement for a pulsed ruby laser is depicted in Figure 8.5. 

Phosphors are solids which absorb energy and re-emit it as light. As in the lasers we have just described, the emitter is usually an impurity ion in a host lattice. However, for the uses to which phosphors are put it is not necessary to produce intense, coherent beams of light, and the emitting process is spontaneous instead of induced. Phosphors have many applications, for example, the colours of your television picture are produced by phosphors that are bombarded with electrons from a beam (cathode rays) or from a transistor (flat screen LCD displays). In terms of tonnage produced, one of the most important applications is the fluorescent light tube. 

Lasers are highly coherent beams allowing reflection through the reaction cell very many times. This increases the path length and hence the sensitivity. 

The arrangement employed for the VPC experiment is described in Reference 4. A cw argon-ion laser at 488 nm was used in a standard DFWM geometry. The s-polarized output beam was first split by a beam-splitter to provide the pump and the probe beams. The transmitted beam from the beam-splitter was then divided into the two s-polarized pump beams each with a power of approximately 0.35 mW. The reflected beam from the beamsplitter was used as the probe beam, whose intensity was about 7% of the total intensity in both pump beams. The forward pump beam and the probe, which constituted writing beams, were overlapped at the sample. Their optical path length difference was much smaller than the laser coherence length, so that they were coherent at the sample. The backward pump beam was... 

An ultraviolet fluorescence excitation beam was generated with an intracavity frequency doubled argon ion laser (Coherent, FRED) providing a tunable wavelength range of 229 - 264 nm. The excitation beam was focused onto the sample with a 10 cm lens to give a spot size of 60-70 pm. For fluorescence experiments, front-face illumination geometry was used. The... 

With the advent of laser technology, and the resulting intense and coherent beams, our ability to study the interaction of crystals with light has been greatly expanded. Just as an electric field can modify the optical properties of a material, so can an intense laser beam. The electric field of the light waves is comparable in magnitude to the electric field that binds electrons in atoms and molecules. 

The nonlinear coherent anti-Stokes Raman scattering ° (CARS) technique gives similar information to that obtainable in spontaneous Raman scattering. In general three high-power laser pulses of frequency to, to, and cuj and polarization e, e,., and are sent into the sample (frequently to, s cu, and = e,). A coherent beam at is radiated with an... 

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