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Q-switching, also known as giant pulse formation, is a technique by which a laser can be made to produce a pulsed output beam. Q-switched lasers such as Nd:YAG lasers are ideal for various types of surface modification applications including paint stripping, decontamination, and surface sterilization. Lasers using this mode provide high energy, high peak power pulses at high repetition rates. Q-Switched lasers are also an important part of the medical community. Q-switching logic incorporates short and long pulses, aka micro-burst, great for laser surgery such as tattoo removal, pigmented lesions, and vascular and hair removal applications. Q-switched diode-pumped green lasers are the work horse of the medical industry allowing for innovative techniques to emerge. With state of the art procedures comes increased recovery times.
Lasers using rapid, high pulsed Q-Switched technology are ported to many wavelengths and lasing configurations such as Nd-YAG, Q-switched Alexandrite, and Q-Switch Ruby lasers to name a few. More than a decade ago, Q-Switched Alexandrite laser was introduced operating at a wavelength of 755nm. These lasers have become highly proficient tools for the skin care professionals and dermatologist. Q-switched lasers can also be used for measurement purposes such as range finding by measuring the time it takes for the pulse to get to some target and the reflected light to get back to the sender.
In a conventional Q-switched laser, the resonator quality (Q) is spoiled, usually by blocking one of the mirrors with a modulator (the Q-switch). With nowhere to go, energy builds up in the population inversion until the modulator switches to its transmissive mode. Then a few spontaneous photons quickly stimulate the laser to emit all the stored energy in a giant, Q-switched pulse. The duration of this pulse is dependent on many parameters, including the resonator’s length and output coupling, the repetition rate, and the pump power. |
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