Picosecond laser triggering

[flyfishing]

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.

 

[eljose79]

Hi there,

I understand your frustration and the difficulty in trying to measure fluorescence/phosphorescence lifetime. It sounds like you have a good setup with a laser pumping at 532nm and a ICCD/spectrometer. However, it seems like the issue lies in the gate pulse width and triggering.

One possible solution to your problem could be to use a shorter gate pulse width and external triggering. This will allow for a faster and more precise measurement of the decay constant. Additionally, you may want to check the sensitivity settings on your spectrometer to make sure it is optimized for the shorter gate pulse width.

Another option could be to use a different type of detector, such as a photomultiplier tube (PMT), which is known for its fast response time and high sensitivity. This may help with the drop in signal when using a shorter gate pulse width.

It may also be helpful to consult with other scientists or researchers in the field who have experience with similar measurements. They may have some insights or suggestions on how to overcome this issue.

I hope these suggestions are helpful and wish you the best of luck with your REU project. Keep persevering and don't be afraid to try different approaches until you find a solution that works for you. Science is all about problem-solving and learning from challenges.