Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Calculate Laser Pulse Intensity (Optics)

  1. Oct 7, 2007 #1
    A laser pulse has a duration of 50 fs (50E-15 s) and an energy of 1 mJ. The laser is focused to an area of 50 micrometers square. What is the peak intensity and peak electric field at the focus?


    I previously tried to do this problem with normal intensity equations using

    intensity = power / area
    and
    power = joules/second

    but I got a ludicrous answer in the range of 10^20 watts/meter square. My professor told me that my answer is wrong because it is a laser PULSE, not just a laser. Any help? I'm not too sure where to go now and my Optics book doesn't seem to cover laser pulses.

    Thanks in advance - Matt
     
  2. jcsd
  3. Dec 2, 2008 #2
    Hi,

    Hope this will help

    Av Power = E/T

    Peak Power = E/t

    Intensity = Av Power/area

    where,

    E = energy of the pulse (i.e.1 mJ)
    T = 1/f (f is the freq of laser pulse)
    t = Duration of the pulse
    area = 50 micrometers square.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook