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by z2h-a6n
831 days ago
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4ad's comment has the right general idea. To explain in more detail: They compared pulsed light to continuous light with the same average power [1]. This means that the light intensity within the flux was much higher than the intensity of the continuous (since the pulses were short compared to the repetition rate). The proposed mechanism (and their result) depends on the square of the light intensity (because it requires simultaneous absorbtion of two photons), so the effect is scales quickly with increasing peak laser power, but (I'm guessing here) doesn't depend as strongly on average laser power. Additionally, I expect 4ad was right that sufficiently-intense continuous light would damage our eyes. My guess is basically that the timescales of two photon absorbtion and human perception are so different (i.e. two photon absorbtion is much faster), that the effects of the pulsed beam (which was repeating at 76 MHz in the experiment) can be treated basically continuous when considering human perception. [1]: https://www.pnas.org/doi/full/10.1073/pnas.1410162111 |
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