• Question: what is the difference between normal light and laser light???

    Asked by lalaman to Mike, Pip, Tianfu, Tim, Tom on 27 Jun 2012.
    • Photo: Tom Lister

      Tom Lister answered on 27 Jun 2012:

      The textbook answer is that laser light can be well directed (doesn’t spread out so much), can be of one very specific colour, and can be focussed to a very small spot.

    • Photo: Philippa Bird

      Philippa Bird answered on 27 Jun 2012:

      It’s generated in a different way too, which is all kinds of complicated!

    • Photo: Tim Stephens

      Tim Stephens answered on 27 Jun 2012:

      To fully understand what the difference is, you need to understand quite a few other bits of Physics, so please forgive me if I seem to be a little bit vague. Leave a comment if you don’t think this answer satisfies your curiosity and I’ll see if I can expand on it. 🙂

      Light is made up of ‘waves’ (at least as far as this answer is concerned). In ‘normal’ light from a bulb, the waves are all emitted randomly in all directions. In a laser, the peaks and troughs of the waves are all lined up (we call this type of light “coherent light”).
      The reason that we get coherent light is because of the way that light is created within a laser, which is by creating new light ‘waves’ that are identical to the first. Coherent light has special properties, which Tom mentions, namely that you can focus it to a smaller spot and that it is of one particular colour (or wavelength).

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