Typical continuous-wave (CW) laser damage, which is based on average power, differs considerably from its ultra-short-pulse counterpart, which is based on maximum field. Despite this fundamental difference, it has recently been found that CW breakdown in the presence of surface particle contamination (i.e. dirt) has some of the dependences of ultra-short pulse breakdown, such as bandgap dependences, albeit based on very different physical mechanisms. Further studies have shown that particles in air are also a danger to surfaces in high average power applications, with laser breakdown potentially occurring at power levels well below that of both clean optics and optics with fixed surface particles.
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