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Treatment Devices
Published in Laurence J. Street, Introduction to Biomedical Engineering Technology, 2023
Excimer lasers use an inert gas such as argon or krypton combined with chlorine or fluorine to produce an ultraviolet laser beam. This beam can be very tightly focused and controlled, and its energy level means that tissue on which it is used vaporizes rather than burning. Excimer lasers are used to reshape the cornea of patients to correct their vision; by vaporizing specific areas, the cornea is deformed in such a way as to change the focus of the eye, reducing or eliminating the need for corrective lenses.
Thermo-Electrical Non-Traditional Machining Operations and Machine Tools
Published in Helmi Youssef, Hassan El-Hofy, Non-Traditional and Advanced Machining Technologies, 2020
Excimer lasers: Excimer lasers are a family of pulsed lasers operating in the ultraviolet (UV) region of the spectrum. Excimer is an acronym for “excited dimmer.” The beam is generated due to fast electrical discharges in a mixture of high-pressure dual gas, composed of one of the halogen gas group (F, H, Cl) and another from the rare gas group (Kr, Ar, Xe). The wavelength of the excimer laser attains a value from 157 to 351 nm, depending on the dual gas combination. Excimer lasers have low power output, so they remove the material photolithically, and have a remarkable application in machining of plastics and micromachining as previously mentioned. The main characteristics of important industrial lasers are given in Table 4.4.
Chemical vapour deposition of ultrafine particles
Published in Kwang Leong Choy, Chemical Vapour Deposition (CVD), 2019
The wavelength of the laser can range from the mid infrared to the ultraviolet region, i.e., excimer laser of different UV wavelengths such as 193 nm. The laser-ablation mechanism is illustrated in Figure 2.8. The material absorbs the laser light and forms the melt, which propagates into the remaining solid. The melt then absorbs the laser energy and evaporates. The vaporisation continues to form the plume which absorbs the laser, leading to the formation of a plasma. The plume will expand away from the interaction volume, the target would cool and become solid after cessation of laser pulse [20].
A critical review of copper electroless deposition on glass substrates for microsystems packaging applications
Published in Surface Engineering, 2022
Excimer lasers are suitable for machining high-accuracy microstructures on the glass substrate [221–223]. Microstructures of 1–100 µm can be machined on the glass substrate using excimer lasers. Excimer laser systems may concentrate their beams on smaller areas, resulting in stronger intensities and a thinner heat-affected zone. Excimer lasers remove material from the workpiece by ablation. It can be either photo-thermal [224], photochemical [225,226], or combined [227,228]. The material removal by the photo-thermal process is due to the melting and vaporization; however, direct chemical bond decomposition results in material removal during the photochemical process. The energy of a krypton fluoride excimer laser [229] having an emission wavelength of 248 nm is roughly 5 eV. This energy is adequate to break chemical bonds resulting in a sudden increase in pressure and ejecting material into vapour and particles [230]. Pulse durations are short for the excimer laser. As a result of the rapid exchange with the substance, thermal damage to the adjoining material is reduced using an excimer laser. Therefore, micro-patterns are machined by laser machining on the glass surface to improve the copper layer and glass substrate adhesion.
Laser processing of glass fiber reinforced composite material: a review
Published in Australian Journal of Mechanical Engineering, 2019
Vineeta Bhaskar, Dhiraj Kumar, K. K. Singh
A fibre laser is a laser whose active gain medium is an optical fibre doped with rare earth elements, such as Erbium, Neodymium and Ytterbium. Fibre lasers, mostly incorporated in the material processing applications, such as marking, engraving, cutting. Excimer lasers are pulsed gas lasers using a mixture of rare gas and halogen gas as the active medium. The excimer lasers operate primarily in the UV region in the mixture of rare gases (argon, krypton or xenon) with halide molecules (chlorine or fluorine). The lasers typically produce short pulses of peak power 10–20 MW with a repetition rate of up to 1000 pulses per second.
Use of lasers in minimally invasive spine surgery
Published in Expert Review of Medical Devices, 2018
Excimer laser is a pulsed gas laser that emits light with wavelengths between 157 and 351 nm. The most commonly used wavelength is 308 nm, emitted by XeCL excimer laser. As the ablation effect proceeds very rapidly, there are virtually no thermal side effects. Hence, excimer laser is mainly used in ophthalmology and angiology [21–23]. However, it has some critical disadvantages such as carcinogenic and mutagenic potential, high costs, and low radiation power, which makes the ablation process time-consuming. Therefore, it has been rarely used in spine surgery.