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I'm not a physicist so I'm asking you guys.

We have been told that a device ("medical"...) uses a laser to irradiate a biological body (human, animal,...).

The laser should apparently penetrates through metal and concrete (without destroying it). Can a laser penetrate through metal, concrete, ... without destroying the material? I don't believe that. After all, laser is light and light does not penetrate through steel or concrete. Except it's super thin, so the density would not be enough.

Am I right with that?

Thanks!

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    $\begingroup$ It sounds like a scam. $\endgroup$
    – PM 2Ring
    Commented Aug 29, 2023 at 13:27
  • $\begingroup$ "We have been told" - by whom? Where is your source? $\endgroup$
    – fishinear
    Commented Aug 29, 2023 at 15:30
  • $\begingroup$ What frequency of laser light? $\endgroup$
    – hft
    Commented Aug 29, 2023 at 16:59

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An optical laser can’t. An X-ray laser might shine through thin sheets of particular metals. Afaik it is an unsolved engineering problem to create lasers that have a high enough frequency (in the short x-ray or gamma ray length, or so called neutrino lasers) to make this meaningful to your suggested application.

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    $\begingroup$ Just a minor point: There are "free-electron lasers" (en.wikipedia.org/wiki/Free-electron_laser) that can operate in the x-ray range. But they are not table top apparatuses, they are only at beam line facilities AFAIK. They would also likely burn the hell out of whatever bulk material you shoot them at. $\endgroup$
    – hft
    Commented Aug 29, 2023 at 17:01
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A maser (microwave-frequency laser) might penetrate around 5-10 centimetres of concrete. It wouldn't penetrate metal. I'm not aware of any medical applications - resolution would be too poor for scanning, and while I have heard of microwaves being used to treat hypothermia, an ordinary microwave source would work fine for that.

Laser light is no better at penetrating materials than the same intensity of ordinary incoherent light.

You might consider whether some other form of radiation beam is involved, and somebody without the necessary technical background has incorrectly described it as a 'laser' when it's actually something like a collimated x-ray in a CT scanner, or a particle beam in an 'External Beam Radiotherapy' machine. These can penetrate a variety of materials.

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