• Question: Can a laser be any spectrum of light?

    Asked by yourmum to Meeks, Pete, Stephen, Steve, Tom on 22 Jun 2010 in Categories: .
    • Photo: Stephen Curry

      Stephen Curry answered on 17 Jun 2010:

      Almost but not quite. The electromagnetic spectrum spans from very short wavelength gamma rays to X-rays, ultraviolet, visible light, infra-red, microwaves and radio waves (which have the longest waves).

      The first laser was a micro-wave device and therefore was called a maser. Lasers have now been made with all wavelengths down to X-rays. In Germany they are currently building an X-ray Free Electron Laser (X-FEL) which will produce extraordinarily intense beams of X-rays (but don’t worry – the facility is shrouded in thick concrete). According to their web-site they will be able to “map the atomic details of viruses, decipher the molecular composition of cells, take three-dimensional images of the nanoworld, film chemical reactions and study the processes in the interior of planets.”.

      Not a bad to do list.

      I’ve not heard of gamma ray or radiowave lasers but perhaps one of the others knows?

    • Photo: Steve Roser

      Steve Roser answered on 17 Jun 2010:

      Yes and no….The lasing effect comes from electrons falling down a very well defined energy ladder, so as they fall down they give out a very well defined energy, or colour of light. So they are a basically a single colour – but you can make materials that have different energy gaps aand therefore give all different colours, including infra red and microwave, so you can get a good coverage of the spectra….

    • Photo: Tom Hartley

      Tom Hartley answered on 17 Jun 2010:

      I am going to leave this one to the physicists, but I think you can get lasers where you can control the wavelength. If true, I would like some, because I would do some experiments on colour vision (something which I could easily become obsessed with).

    • Photo: Pete Edwards

      Pete Edwards answered on 18 Jun 2010:

      I think that we can build lasers to produce most colours of visible light plus infra red and ultra violet wavelengths too, so the quick answer is yes any colour of visible light is possible.
      As Stephen has already explained, we can also make lasers to produce X-ray light and microwave lasers are also produced.

    • Photo: Marieke Navin

      Marieke Navin answered on 22 Jun 2010:

      The L in laser stands for light, and this usually refers to the visible
      spectrum (the colours you can see from red to violet). But, you can make
      lasers in other parts of the spectrum too, for example Infra-Red lasers, as
      used by welding robots in car manufacturing. Alternatively, a maser emits
      microwaves.

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