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Can you take a laser beam of high intensity and refract it in a way to convert it to a safe level? White light traveling through a prism refracts into the individual wavelengths, could something similar be achieved with a high powered laser?

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Perhaps you're looking for a beam expander? It takes a collimated beam and expands or reduces its size.

I make no claim as to whether it reduces the intensity to a "safe" level, but it certainly reduces intensity.

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  • $\begingroup$ Is it possible to have a high enough energy level to melt the glass or will it always pass through? $\endgroup$ – user3304179 Nov 6 '14 at 5:15
  • $\begingroup$ You'll likely have to know the specific properties of your laser and the glass. $\endgroup$ – BMS Nov 6 '14 at 5:16
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    $\begingroup$ Yes you can lower to a "safe" level: you just expand it so that the eye's fully expanded pupil cannot gather more than the maximum permissible exposure (MPE) defined by the laser safety standards. This is the meaning of the "M" subclasses: e.g. class 1M is intrinsically safe as long as you don't use optical instruments to view the beam. The beam itself might be very powerful, but wide enough to achieve low intensity. If you viewed it with a beam shrinker, you would get back to where you began and thus your eye could gather a dangerous dose of light. $\endgroup$ – WetSavannaAnimal Nov 6 '14 at 12:02
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No because laser light is almost monochromatic, that is, it has only a single wavelength (that is for an ideal laser, in actual lasers some wavelengths around the main one are also included), but for the practical purposes you are mentioning, you can consider it purely monochromatic.

Updated answer from questions on comments:

1)how would you reduce the intensity of a laser already fired in mid-air? you can put on the path some material that disperses light, this is different than refraction. Dispersion can happen to monochromatic waves. Intuitively, is like the wave crashes and bounces off in several directions.

2) What makes lasers not dangerous after they hit solid objects? Wouldn't they just reflect off in different directions? If it was reflected by a perfect mirror (without absorption or dispersion, the intensity would stay the same. But most objects are not mirrors, they are rather rough surfaces in which different parts point to different directions (at the microscopical level). This will cause a dispersion of the beam with the corresponding decrease in power per unit area. Plus most materials also absorb part of the light.

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  • $\begingroup$ How would you go about reducing the intensity of a laser? $\endgroup$ – user3304179 Nov 6 '14 at 4:56
  • $\begingroup$ Do you mean using a less powerful laser, or if the refraction will reduce the power? In any case, the answer in both case is the same, because the laser is quasi monochromatic, a prism will not split the light into different wavelengths, so unless the is absorption, the laser light will not spread by refraction and will keep the same intensity $\endgroup$ – Wolphram jonny Nov 6 '14 at 5:03
  • $\begingroup$ I mean, how would you reduce the intensity of a laser already fired in mid-air? What makes lasers not dangerous after they hit solid objects? Wouldn't they just reflect off in different directions? $\endgroup$ – user3304179 Nov 6 '14 at 5:05

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