Laser garnet-type

Management of adverse effects Teeth discolored from exposure to tetracycline in a 32-year-old Japanese man have been successfully bleached using a KTP laser, a type of neodymium-doped yttrium aluminium garnet (Nd YAG) laser [151 ]. 

Garnet activated by trivalent Cr is a promising system for tunable laser appUcations and those systems have been well studied. Cr + replaces Ap" in octahedral sites with a weak crystal field. The transition involved in laser action is T2- A2, a vibrationally broadened band. At room temperature it has a maximum in the 715-825 nm range with a decay time in the 100-250 ps range depending on AE between the E and T2 levels. When the AE is maximal, narrow fines also appear from the E level. At low temperatures, when thermal activation of the T2 level is difficult, J -lines luminescence becomes dominant with the main fine at 687 nm (Monteil at al. 1988). We studied pyrope artificially activated by Cr and also found the two emission types described above (Fig. 5.26). 

Laser Desorption Ionization. A pulsed laser beam can be used to ionize samples for mass spectrometry. Because this method of ionization is pulsed, it must be used with either a time of flight or a Fourier transform mass spectrometer (Section 1.4.5). Two types of lasers have found widespread use A COz laser, which emits radiation in the far infrared region, and a frequency-quadrupled neodymium/yttriumaluminum-garnet (Nd/YAG) laser, which emits radiation in the UV region at 266 nm. Without matrix assistance, the method is limited to low molecular weight molecules (<2 kDa). 

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. 

In a solid state laser, the active species is distributed throughout a solid, usually crystalline, material, although glass can also be used as a host. The lasers are robust and frequently tunable, though heat dissipation can sometimes be an issue. Certain types of solid state crystals, for example neodymium-doped yttrium aluminum garnet (Nd YAG), can be pumped by diode lasers instead of by other lasers or by flashlamps, which is often the case for other materials. Such diode-pumped, solid state systems are reliable, economical, compact, and easy to operate—in fact, many commercial systems are turnkey, needing only to be plugged in and turned on to operate. 

The technique of laser heating in a DAC is based on three main features optical transparency of diamond anvils the samples can be heated via the optical absorption of intense laser radiation, and the temperature can be determined from the thermal radiation spectrum of the heated sample using the Planck formula [10]. Laser radiation for heating of a sample in a DAC was first implemented by Ming and Bassett [11], who used a pulsed ruby laser, and a continuous-wave Nd-YAG (yttrium-aluminum-garnet) laser to heat samples in a DAC above 3300 K, and up to 2300 K, respectively. Today two types of continuous wave infrared (IR) lasers are extensively used in laser heating experiments Solid state lasers (Nd-doped YAG, or YLF (yttrium-lithium-fluorite) crystals with the most intense line at... 

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). 

Sasaki, K., Kinoshita, T., and Karasawa, N., Second harmonic generation of 2-methyl-4-nitroaniline by a neodymiumiyttrium aluminum garnet laser with a tapered slab-type optical waveguide, Appl. Phys. Lett., 45, 333, 1984. 

One type of laser used in the treatment of vascular skin lesions is a neodymium-doped yttrium aluminum garnet or Nd YAG laser. The wavelength commonly used in these treatments is 532 mn. 

A similar procedure was made recently by Honma et al. [237]. The authors used glasses in the system BaO —Ti02—Ge02-Si02, which are suitable for fresnoite-type crystallisation. The applied heat source was a cw-YAG (yttrium-aluminum-garnet) laser. 

Laser is an acronym for light amplification by simulated emission of radiation. In SERS, as well as in other types of Raman scattering experiments, a continuous-wave (CW) gaseous ion laser is normally used, e.g., an argon-or krypton-ion laser. It is also possible to use a pulsed laser, such as a neodymium, Nd ", in yttrium-aluminum garnet (YAG) laser however, a much... 

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