• Question: how do you make a lazer ?

    Asked by chewyoda007 to Stuart on 18 Jun 2013. This question was also asked by amina2001, epic3000.
    • Photo: Stuart Archer

      Stuart Archer answered on 18 Jun 2013:

      That’s a difficult question to answer – lasers are very complicated pieces of kit and I only really understand the very basics of how they work. Maybe someone else in the zone has some more detailed knowledge?

      To understand how a laser works, you need to know a little bit about what atoms are made out of. On a basic level, an atom is composed of a central ‘nucleus’ surrounded by a number of ‘electrons’ in a cloud. These electrons sit in specific ‘orbits’ or ‘energy levels’ around the nucleus (imagine them a little like the planets orbiting the Sun – it’s not as simple as that but it’s a good place to start!).

      Now, if you give these electrons energy, they can jump (or ‘transition’) into a higher orbit called an ‘excited state’ (think what you feel like when you eat a lot of sugar!). Electrons (much like chemists..) are basically lazy, and they don’t like having a lot of energy, they want to be in the lowest energy orbit possible, called the ‘ground state’. We call this process ‘relaxation’.

      However, all of the energy the electron has needs to go somewhere before it can relax. One thing that can happen is that this energy can be converted into light, a process we call ’emission’. The light flies away from the atom, leaving a nice relaxed electron in the same condition it was before we chucked a load of energy at it. The colour of the light is directly related to the amount of energy the electron had before it relaxed – higher energy gives of blue light, lower energy gives off red light.

      This is actually how most things that give off light work, such as a bulb or the screen on your phone. Lasers work in basically the same way, however they give off very strong light of a very specific colour. This is because we give the atoms in a laser a very specific amount of energy, so that the electrons are all excited into the same orbit. This means that each of them lose the same amount of energy and therefore emit the same colour light. The light is then focused using lenses and mirrors so it comes out in a straight beam.

      I hope that makes some sense – if you’ve any follow up questions feel free to ask them 🙂

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