• Question: How come lasers can cut through things?

    Asked by michaelplease to Mike, Pip, Tianfu, Tim, Tom on 23 Jun 2012. This question was also asked by waldock.
    • Photo: Tim Stephens

      Tim Stephens answered on 23 Jun 2012:

      A laser beam is a beam of energy. If you focus the beam into an intense enough spot, it contains enough energy to melt, burn or vaporise the material that it hits. Different materials are affected in different ways by different lasers.
      Once you have a laser that can break down the material in a spot, you move the spot over the material (or the material under the spot) which lets you make a cut. As it happens, some of my colleagues use lasers to cut small holes in lots of different types of materials with a process called laser micromachining. There are some pictures and information on the website http://www.oxfordlasers.com/micromachining.

    • Photo: Tom Lister

      Tom Lister answered on 25 Jun 2012:

      We cut through skin sometimes, when people let us. The laser we use heats up water just below the surface, turning it to steam. The steam takes up much more space than the water and so explodes out of the skin, taking a load of other stuff with it and leaving a hole. Doing this again and again cuts through the skin.

      People use the same lasers to cut through metal, although there is no water in metal. I believe the laser melts the metal which is blown away by a jet of air.

    • Photo: Philippa Bird

      Philippa Bird answered on 25 Jun 2012:

      What they said.

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