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

Picosecond laser triggering

  1. Jul 22, 2011 #1
    Hi guys, so I'm at my wit's end. I'm trying to measure fluorescence/phosphorescence lifetime. I have a laser pumping at 532nm and it's pulsed at 25 picoseconds. I also have a ICCD/spectrometer.
    Here's the problem: Currently I'm using the spectrometer triggered internally with a gate pulse width ~100us. I can also trigger externally (with slightly less success..but still good enough) (laser is triggering the spectrometer). Now, since I'm trying to do fluorescence measurements I need to cut the gate width pulse down into the ns range (preferably in the 100s of nanoseconds). When I do this, though, my signal/spectrum drops down to nothing.

    I need to make the gate width pulse lower because I will then do a measurement that adds a few nanoseconds delay to the start of each intensity reading. Then by measuring the drop in intensity over a period of about 100ns (measured every 2ns or so) I can figure out the decay constant (aka lifetime).

    Anyone ever solve this problem before or have an idea? It's for an REU and the grad students/professor have no clue.
    Last edited: Jul 22, 2011
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?