• Question: What are femtosecond laser pulses?

    Asked by Aaliyah to Ashley on 13 Nov 2015. This question was also asked by OscarRowntree, Kiran & Brandon.
    • Photo: Ashley Hughes

      Ashley Hughes answered on 13 Nov 2015:

      Hi mate,

      I guess you can compare it to a strobe light vs a normal light. So with a normal light, it is always on and with a strobe light there are flashes of light.

      My laser system is the same as the strobe light where it flashes! The femtosecond part is the amount of time the light is on for. So if it was a 1 second laser pulse you would see light for 1 second, then a gap then 1 second then a gap then 1 second. In this case it is on for 85fs (see below), and then we have a gap of 250 microseconds and then another shot!

      Why you might ask??? Well basically, this makes our machine extremely good at seeing extremely fast reactions, such as a proton leaving a compound for example and this is useful in our understanding of how a protein changes.

      femto- (symbol f) is a unit prefix in the metric system denoting a factor of 10−15 or 0.000000000000001

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