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Does increasing the intensity of the incident light increase the proportion of the light that is scattered?

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  • $\begingroup$ Do you mean: does increasing the intensity of the incident light change the percentage of the light that is scattered? $\endgroup$ Jan 16, 2016 at 11:50
  • $\begingroup$ @JohnRennie: Yes. $\endgroup$
    – kunal18
    Jan 16, 2016 at 12:09

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In most situations we are familiar with when it comes to light in everyday life, the interaction with light and matter is linear with respect to the electromagnetic field. This means that if you have a material that scatters 50% of a beam of light, then a 2mW beam will scatter 1mW or a 100mW will scatter 50mW etc… In these normal everyday situations, increasing the intensity of the incident light does not increase the proportion of the light that is scattered.

However, if the intensity of the light is great enough (such as at the focus of an ultra-short pulsed laser beam), then the light will no longer interact with matter in a linear way. This situation is known as nonlinear optics. In this situation the light is intense enough that the material itself temporarily changes, and this change causes the light to interact differently with the material. In these situations, the scattering does depend on the intensity of the light. This effect is used all the time in fields such as microscopy and spectroscopy. For instance, nonlinear processes are used to greatly increase (by many orders of magnitude) the amount of Raman scattering in a process known as Coherent anti-Stokes Raman spectroscopy or "CARS".

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Think of a mirror and you shine a bright light in it after enough photons are increased hitting and scattering off the surface it is also getting hotter. There is a range where metal stops reflecting and begins absorbing the photons more generating heat and glows. The colder the atom the better the scatter.

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    $\begingroup$ What about the light coming from the Sun that gets scattered thru the sky? $\endgroup$ Jan 16, 2016 at 14:37
  • $\begingroup$ Think of all molecules has a level of transparency. What light isn't absorbed by the ground and air gets reflected back into space. If the sun gets to hot the atmosphere would ignite and burn off. $\endgroup$
    – Muze
    Jan 16, 2016 at 19:55
  • $\begingroup$ physics.stackexchange.com/questions/9523/… $\endgroup$
    – Muze
    Jan 16, 2016 at 19:58
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    $\begingroup$ The question is whether the proportion of the scattered light increases when the intensity of incoming light increases. In other words whether a higher % of incoming light gets scattered if the intensity of incoming light increase. I don't see how your answer deals with answering the question neither in the general case nor in case of Sun-sky. $\endgroup$ Jan 16, 2016 at 20:38
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    $\begingroup$ Hey @Jen, Nice job thinking carefully about this issue. The down votes you'be gotten are a bit unfair (to compensate I up-voted your answer). You are absolutely correct, if you have enough light or energy, the thing scattering the light will change, and when it changes the properties (such as how it scatters) will also change. This can happen in a permanent way (such as an object heating up and melting), but it can also happen temporarily (even almost instantaneously so). E.g. see my answer to see how something called "nonlinear optics" can temporarily change the material (& the scattering). $\endgroup$ Jan 17, 2016 at 2:04

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