Lasers and optics

• Published in: Transport in Laser Microfabrication pp. 33 - 59
• Main Author: Grigoropoulos, Costas P.
• Format: Book Chapter
• Language: English
• Published: United Kingdom Cambridge University Press 30.07.2009
• Subjects: Manufacturing Engineering; Materials & Manufacturing Processes; Materials science; MECHANICAL ENGINEERING & MATERIALS; Mechanics of fluids
• ISBN: 9780521821728; 052182172X
• DOI: 10.1017/CBO9780511596674.003

Lasers for materials processingLasers (the acronym from light amplification by stimulated emission of radiation), with their unique coherent, monochromatic, and collimated beam characteristics, are used in ever-expanding fields of applications. Different applications require laser beams of different pulse duration and output power. Lasers employed for materials processing range from those with a high peak power and extremely short pulse duration to lasers with high-energy continuous-wave output.Continuous-wave – millisecond – microsecond lasersContinuous-wave (CW) and long-pulsed lasers are typically used to process materials either at a fixed spot (penetration material removal) or in a scanning mode whereby either the beam or the target is translated. Millisecond- and microsecond-duration pulses are produced by chopping the CW laser beam or by applying an external modulated control voltage. Fixed Q-switched solid-state lasers with pulse durations from tens of microseconds to several milliseconds are often used in industrial welding and drilling applications. Continuous-wave carbon dioxide lasers (wavelength λ = 10.6μm and power in the kilowatt range) are widely employed for the cutting of bulk and thick samples of ceramics such as SiN, SiC, and metal-matrix ceramics (e.g. Duley, 1983). Continuous-wave laser radiation allows definition of grooves and cuts. On the other hand, low-power CO2 lasers in the 10–150-W range are used for marking of wood, plastics, and glasses. Argon-ion lasers operating in the visible range (λ = 419–514 nm) are utilized for trimming of thick and thin resistors. In the biomedical field various CW lasers have been used.