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Glasses
Published in Marvin J. Weber, and TECHNOLOGY, 2020
Patricia A. Morris Hotsenpiller
Tables 18.1.1 through 18.1.3 contain data regarding the fabrication and properties of crystalline waveguides produced in the dielectric oxides: LiNb03, LiTaG3, KTiPOs (KTP), KNbQ3, and Nd:Y2Al5Q12 (Nd:YAG). LiNbG3, LiTaO,, KTP, and KNbG3 are nonlinear optical materials with large second-order nonlinearities. Nd: YAG is a solid-state laser material. Table 18.1.4 summarizes the indices of refraction of the bulk crystals for comparison with the Δn and n values listed. Tables 18.1.1 through 18.1.3 contain a comprehensive summary of the data, so only a few brief comments are made here.
Machining of DTC Materials (Ceramics and Composites) by Traditional and Non-Traditional Methods
Published in Helmi Youssef, Hassan El-Hofy, Non-Traditional and Advanced Machining Technologies, 2020
Nd:YAG lasers: NG:YAG lasers are solid-state lasers that use 1–2% dopants (i.e. Neodymium (Nd3+)) dispersed in a crystalline matrix (i.e. yttrium aluminum garnet (YAG) with the chemical composition Y3Al5O12) as the gain medium. Pump sources are krypton or xenon flash lamps, or recently laser diodes. The wavelength of an Nd:YAG laser is emitted at 1.06 µm in the near-infrared spectrum. The power output of CW Nd:YAG lasers are lower by some kilowatts. But the Q-switch Nd:YAG lasers can generate short pulses with peak power in megawatts, repetition rates up to 100 kHz, and pulse durations between 15–400 ns. The average output power of a pulsed Nd:YAG laser is generally lower than 1 kW. The output laser beam (at 1.06 µm wavelength) can be coupled into an optical fiber for delivery. Therefore, it is suitable to combine with robots for more flexible processing in industries. Nd:YAG lasers have been widely used for cutting, welding, cladding, and drilling of metallic or non-metallic materials. The drawback of Nd:YAG lasers is the relatively low beam quality at high output powers (M2<6), causing a large spot size, low power density, and short focal depth. Therefore, high power Nd:YAG lasers are not suitable in precision processing and thick-section machining applications. Furthermore, maintenance is also essential to Nd:YAG lasers.
Photoacoustic Spectroscopy
Published in Grinberg Nelu, Rodriguez Sonia, Ewing’s Analytical Instrumentation Handbook, Fourth Edition, 2019
PA depth profiling can be performed either by modulated or by pulsed light sources. For experiments with modulated light sources, essentially the same choice of laser sources is available as in gas phase analysis. A typical Q-switched Nd:YAG (neodymium:yttrium aluminum garnet) laser, one of the workhorses in many laser laboratories, has an emission pulse length of few nanoseconds with a pulse repetition rate of 10 Hz to 1 kHz. Although the emission power during the pulse reaches values of 1 MW during the pulse, the average emission is only 10 mW (typical values: 10 mJ per pulse, 10 ns pulse length, 10 Hz repetition rate). The fundamental emission wavelength of Nd:YAG lasers is 1064 nm. Higher harmonics, which can be generated inside nonlinear optical crystals, are 532 nm, 366 nm and 266 nm. Again, selectivity for a chemical analysis by PA analysis depends on the selective absorption of the chosen wavelength. Thus, many experiments are carried out with a wavelength-tunable laser source. The most common systems for this purpose are Nd:YAG-pumped OPO (optical parametrical oscillator) systems. These laser sources typically emit in two adjacent wavelength ranges, which may cover from 400 nm to more than 2.5 µm; when combined with a frequency doubling device even down to about 240 nm.
Effect of Nd:YAG and Er:YAG laser tooth conditioning on the microleakage of self-adhesive resin cement
Published in Biomaterial Investigations in Dentistry, 2021
Azita Kaviani, Niloofar Khansari Nejad
Nd:YAG laser is a pulsed infrared laser that is highly absorbable in pigmented tissues. This laser can be applied to tooth hard structures to increase resistance to acid attack, remineralize primary caries, alter enamel pits and fissures to prevent caries, disinfect and debride cavities, treat dentin hypersensitivity, sterilize irradiated surfaces, and increase fluoride absorption by the enamel [18]. It might also produce a glass-like appearance on the surface due to enamel and dentin heat liquefaction and re-crystallization [19]. However, the impact of laser irradiation on the surface properties of dental tissue has not been completely elucidated as to whether such irradiation can improve the surface properties of dental tissues. Laboratory studies of microleakage are often performed with the dye penetration test in class V restorations since it is a reliable, clear, and simple procedure [20,21]. Accordingly, this study aimed to compare the microleakage of self-adhesive resin cement with Er:YAG and Nd:YAG laser tooth conditioning. The null hypothesis stated that there would be no differences in microleakage score of self-adhesive resin cement after three different surface conditioning procedures: Er:YAG laser, Nd:YAG laser, nonconditioning.
Use of lasers in minimally invasive spine surgery
Published in Expert Review of Medical Devices, 2018
Neodymium-doped yttrium-aluminum-garnet (Nd:YAG) lasers are the most widely used laser systems in a variety of medical fields. The absorption of 1064- and 1318-nm wavelengths by biological tissue is relatively low, and thus, the scattering effect is high. The penetration depth in cartilaginous tissue reaches up to 6 mm with powers 20–40 W and pulse 0.05–0.1 s. The coagulation zone can be reduced to 0.6 mm with a contact laser probe. It has been proven to be effective for ablation and coagulation of disc tissues in both experimental and clinical studies [25,26]. Nd:YAG laser has benefits of fiber-optic delivery, applicability in dry and aqueous media, and hemostatic effect. However, it is a hot laser, which generates and transmits heat through the tissues.
Study of hydrocarbons adsorbed in asphaltenes of domanic formation bitumoid
Published in Petroleum Science and Technology, 2019
Yu M. Ganeeva, E. E. Barskaya, E. S. Okhotnikova, A. H. Timirgalieva, T. N. Yusupova
The molecular weight of resins was determined on a Bruker Ultraflex III TOF/TOF mass spectrometer (GmbH, Bremen, Germany) in a linear mode. The laser is Nd:YAG, λ = 266 nm. The data were processed using the Flex Analysis 3.0 software (Bruker Daltonik GmbH, Bremen, Germany).