Neodymium:yttrium aluminum garnet laser

Several of the early problems associated with Raman have been overcome. Fluorescence emission from the sample was a problem when visible light sources were used. Now, NIR sources such as the NdrYAG (neodymium yttrium aluminum garnet) laser diminish fluorescence and provide variable power levels for measurement optimization. The major difficulty with Raman is the lack of experienced interpretive spectroscopists and detailed texts. Even NIR seems commonplace when compared with the number of Raman applications. Only time will solve these latter problems as more applications occur and more are published. 

Matthewson K, Coleridge-Smith P, O Sullivan JP, et al (1987) Biological effects of intrahepatic neodymium yttrium-aluminum-garnet laser photocoagulation in rats. Gastroenterology 93 550-557... 

Neodymium-doped yttrium aluminum garnet laser (NldiYAG)... 

Figure 8.7. Delayed fluorescence and diffuse reflectance transient absorption spectroscopy on scattering substrates. Example terthicnyl on silica gel excited with = 354 nm (neodymium/yttrium-aluminum-garnet) (Nd/YAG) laser pulse of 10 nsec, 20 mj), recorded with a gated diode array spectrometer.

Before the invention of lasers in 1960 (Maiman), radiation emitted by the mercury arc, especially at 435.8 and 404.7 nm, has been u.sed for exciting Raman spectra (Brandmiiller and Moser, 1962). Today, most types of lasers ( continuous wave (cw) and pulsed, gas, solid state, semiconductor, etc.), with emission lines from the UV to the NIR region, are used as radiation sources for the excitation of Raman spectra. Especially argon ion lasers with lines at 488 and 515 nm are presently employed. NIR Raman spectra are excited mainly with a neodymium doped yttrium-aluminum garnet laser (Nd YAG), emitting at 1064 nm. 

The principle of SFG and the components of an SFG spectrometer based on neodymium yttrium-aluminum-garnet (Nd YAG), titanium sapphire (Ti Sa), or free-electron lasers are described, and the reader is referred to these articles for details (46,116,119,122-124,126,127,137-145). Here, we restrict the discussion to those aspects that are important to understanding the advantages and limitations of the method. 

When the calcium plaque is thick, it can be removed by scraping with a scalpel or by performing a superficial keratectomy. Other reported methods include the use of a diamond burr, neodymium-yttrium aluminum garnet (Nd YAG) laser, lamellar keratoplasty, and PTK. A recent treatment option described the combined use of superficial lamellar keratectomy, NaEDTA chelation, and amni-otic membrane transplantation. In this procedure the calcific lesions were treated with NaEDTA and a blunt superficial lamellar keratectomy was performed. Once a smooth ocular surface was achieved, an amniotic membrane was transplanted to replace the excised epithelium and stroma. The procedure resulted in the... 

Neodymium and its compounds have a number of important uses. One is in a kind of laser known as a neodymium yttrium aluminum garnet (Nd YAG) laser. A laser is a device for producing very bright and focused light of a single color. The Nd YAG laser is used for treating bronchial cancer and certain eye disorders. The bronchi are air tubes that lead into the lungs. 

Laser ablation This method is used as a microchemical sampling procedure for locaHzed determinations. A pulsed neodymium-yttrium aluminum garnet (Nd-YAG) laser is used to ablate material from solid samples. Repetitive laser pulses and sample translation can be used to improve the precision and accuracy of the analysis. Refractory materials and geological samples can be analyzed for trace and major elements. Powdered samples can be pelleted under high pressure for bulk analysis. 

Neodymium-doped yttrium aluminum garnet lasers have found extensive applications as range finders and have also become standard laboratory equipment for research in photochemistry and related fields. 

For the SHG measurements we used the frequency-doubled output of a Q-switched neodymium-doped yttrium aluminum garnet laser at 532 nm with a 7-nsec pulse width as the pump beam. 

Neodymium-doped yttrium-aluminum garnet is among the most commonly applied laser material and has broad application (neodymium-YAG). 

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