• Question: How does a laser work?

    Asked by cathalbrady to Adam on 11 Nov 2013.
    • Photo: Adam Murphy

      Adam Murphy answered on 11 Nov 2013:


      Hey, I had to go look this up to refresh my memory, and that’s going to be really useful later, so thanks! Lasers are really cool because they only emit one shade of one colour. In mine I get a very specific blue!

      You need a few things to make a laser work:
      Something that generates the colour light you want. (We used to use synthetic rubies for red light, my blue laser uses a gas mixture of Helium and Cadmium)

      You need a power source (usually electricity)

      You need a chamber for the laser to be generated. (Called an optical cavity)

      So in my laser, electricity is pumped into the gas mixture and makes some photons of light. These bounce back a forth in the optical cavity between two mirrors and when they do, they get into the gas and make exact copies of themselves, And this happens over and over again until you have loads of photons.

      One of the mirrors is usually a little transparent and lets a percentage of the light through (10% of a huge amount of photons is still a lot of light!). That all comes out the same way, in the same direction as the first photon, because they’re all copies of it.

      Lasers are cool and I hope I answered your question

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