Yttrium aluminium garnet lasers

NBTC NC ND Nd YAG ndc NDR NEST NEXAFS Nanobiotechnology Center (Cornell University) nanocrystal nanodiamond neodymium-doped yttrium aluminium garnet (laser) 2,6-naphthalenedicarboxylate 2-nitro-jV-methyl-4-diazonium-formaldehyde resin New and Emerging Science and Technology near-edge x-ray absorption fine structure (spectroscopy)... 

Figure 1 depicts a commercial instrument. The sample is mounted inside the vacuum chamber of the MS. The DI is commonly performed by 266 nm UV pulses from a frequency-quadrupled Nd YAG (neodymium yttrium- aluminium- garnet) laser. This instrument allows repositioning of the sample and the optics for analysis in transmission or in reflection. In the former case, the laser hits the lower surface of the sample while the upper surface faces the MS. This suits thin films or particles of about 1 [im on a polymer film. Reflection means that the beam impinges on the sample side facing the MS. The surface of bulk samples can thus be characterized. Micropositioners allow one to move the spot of interest on... 

Laser action can be induced in Nd ions embedded in a suitable solid matrix. Several matrices, including some special glasses, are suitable but one of the most frequently used is yttrium aluminium garnet (Y3AI5O12), which is referred to as YAG. 

Lasers produce spatially narrow and very intense beams of radiation, and lately have become very important sources for use in the UV/VIS and IR regions of the spectrum. Dye lasers (with a fluorescent organic dye as the active substance) can be tuned over a wavelength range of, for instance, 20-50 nm. Typical solid-state lasers are the ruby laser (0.05% Cr/Al203 694.3 nm) and the Nd YAG laser (Nd3+ in an yttrium aluminium garnet host 1.06 pm). 

Solid-state lasers, such as the ruby laser, neodymium doped yttrium aluminium garnet (Nd-YAG) laser and the titanium doped sapphire laser. 

Figure 8.16 illustrates the energy levels of Nd in yttrium aluminium garnet (Y3AI5O12), which are involved in the laser action of this crystal (known as the neodymium YAG laser). Describe the processes that occur when the laser is working. 

A 30-year-old man, a cocaine sniffer, who had used cocaine more than five times a month for 4 years, complained of shortness of breath and acute chest pain. He had episodic cough and bloody sputum. A chest X-ray showed an 80% pneumothorax on the left side. On thoracoscopy the entire lung visceral pleura seemed to be covered by fibrinous exudate. After yttrium aluminium garnet (YAG) laser pleurodesis surgery, which abrades the pleura, he made a full recovery within 4 days. 

Laser Ablation [7]. The modern method for quantitative solid analyses is carried out using a laser ablation technique (Figure 2.16). The laser, usually in the form of Nd YAG (Neodymium - Doped Yttrium Aluminium Garnet), is focused on to the surface of a sample which, by continuous pulsing, leads to vaporisation at that point and the vapour is transported directly to the plasma with argon for detection and quantification. Detection limits are... 

Laser ablation can be carried out on any material without special sample preparation. The laser beam can be directed onto a defined spot of the sample or moved to different parts to analyse over a defined area. It can be moved in an XYZ plane using a stepper motor and driven in translational motions on which the cell is mounted and with more expensive models can be turned for analysis in other parts of the sample. Lasers can operate in UV, visible, and IR regions of the spectrum and a recent development in laser technology uses neodymium yttrium aluminium garnet (Nd YAG) which gives high repetition rate at a comparatively low power. This method of analysis is suited to bulk analysis of solid materials and the amount of volatility varies from sample to sample. The size of the laser spot can vary from 10 to 250 pm and little or no sample preparation is required. Errors are greatly reduced because of the simple sample preparation, and the fact that no solvents are required reduces interferences. 

Ceramics in aluminate systems are usually formed from cubic crystal systems and this includes spinel and garnet. Rare earth aluminate garnets include the phase YAG (yttrium aluminium garnet), which is an important laser host when doped with Nd(III) and more recently Yb(III). Associated applications include applications as scintillators and phosphors. 

Laser based on neodymium-doped yttrium-aluminium garnet. The emission wavelength is 1,064 nm, the power can be up to several tens of W. Mode-synchronisation delivers picosecond pulses at a repetition rate of 50 to 100 MHz. 

UV light with a wavelength of 254 nm can be generated with a mercury vapom lamp and the appropriate filters. U V radiation with a wavelength of 350 nm is obtained with an yttrium-aluminium-garnet (YAG) laser. Optional is as well the irradiation with a KrF laser (248 nm), or a nitrogen laser (337 nm). 

The solid phase lends itself to the preparation of lanthanide arrays. Indeed, lanthanide doped yttrium aluminium garnets are weU known as laser materials, while doped materials containing more than one kind of lanthanide have proved very effective at upconversion of energy - the sequential absorption of two photons giving rise to anti-Stokes emission [9]. In such systems, excited state absorption by the intermediate state gives rise to formation of a high energy... 

For all their usefulness, gas lasers are very inefficient lasers, with normally much less than 0.1 per cent conversion of electrical energy into laser light. A very widely used solid-state laser material is Nd YAG (and various similar doping/host material combinations). The abbreviation Nd YAG stands for neodymium atoms (Nd) being implanted in an yttrium aluminium garnet crystal host (Y3AI5O12). These implants, in the form of triply ionized neodymium Nd, form the actual active laser medium. 

Nd YAG Solid-state Nd ions embedded in yttrium aluminium garnet (Y3AI5O12) Flash lamp, laser diode Fundamental X = 1064 nm Harmonic generation 533 nm (2nd), 355 nm (3rd), 266 nm (4th) 10 ns for Q-switched 2-50 W, continuous MW-GW, Q-switched... 

Many different laser types have been developed for the treatment of different materials. The higher the absorption rate of the laser radiation, the faster the material can be heated. While some highly reflective materials (e.g. aluminium and copper) absorb short wavelengths best (e.g. Nd YAG/Neodynium Yttrium Aluminium Garnet or diode lasers), less reflective materials (e.g. iron and steel) can best be treated with lasers operating at longer wavelengths (e.g. CO2 lasers) (see Fig. 6.11). 

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