• Question: How do you measure the intensity of a laser?

    Asked by 22nebula21 to Philip, Ceri on 22 Jun 2011.
    • Photo: Ceri Brenner

      Ceri Brenner answered on 22 Jun 2011:

      the intensity is given by the equation:
      I = energy in joules/(area of laser spot on target x time duration of laser pulse)

      we measure the energy by doing some test shots, and firing the laser (in low power) onto a calorimeter (energy diagnostic) and calibrating this energy with an electrical signal that we take from the laser on every shot

      we know the laser spot size because we can image the spot illuminating the target (again in low power mode) using a lens and camera

      and we know the laser pulse time duration because the laser guys have a diagnostic that measures the length (in time) of the laser pulse

      put this all together and we’ve got our estimate of the laser intensity