Myths about Laser Damage #3

200 laser shots- per test site is enough to reach „onset“ laser damage

S-on-1 testing protocol is known as the industry standard for laser damage testing of laser optics. S defines a number of laser pulses applied to one test site. There is a popular belief that with 200 laser pulses “onset” of laser damage is reached. Or in other words – laser-induced degradation of optics is stabilized after 200 laser shots.

Is that true?

In general – no.

As with everything else related to laser damage, the true answer is more complex. The so-called “onset” can indeed be reached for dielectric optics if the damage is defect-driven. Such behavior can be observed in the nanosecond regime within IR spectral region. However, for the UV spectral region or in the femtosecond laser pulse regime, the laser damage limiting processes are more complicated. There is no onset and 200 pulses are not enough. To make predictions about laser optics’ lifetime long-term, custom testing and custom analysis should be applied [1].

[1] L. Smalakys, A. Melninkaitis “Predicting lifetime of optical components with Bayesian inference”, Opt. Express, 2021 Jan 18:29(2): 903-915

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