I use a thorlabs Photodetector (DET10A) to measure a 1064nm pulse width(about 10 ns according to the manufacture). However, just as shown in figure 1, the width is about 500us and the rise part is multi-pulse, see figure 2. I use a 1064nm filter before the detector and carefully avoid the incident light of flashing lamp, so what are the possible reasons? The oscilloscope is DSOX2012A (100MHz,1Gs/s)
If You wont to measure your pulse duration with resolution time 1ns oscilloscope should have transmission band as f=1/1ns =1000MHz; the same demand to time constant of load resistence multiplied input (parasite) capacity = RC must be less than pulse duration about one order of value; at last the same condition of application for photodiods. Use speed highfrequency avalanche diodes. For approximate eveluation of pulse duration all recommendations of from above SG members are good.
Hi
It is hard to tell just by looking at the oscilloscope, but I would pay attention to the load resistance you use to convert your current signal to a voltage to be seen on the oscilloscope. A 50 ohm load would be best... furthermore there could be parasite resistances and capacitances on your electronics. Finally, seeing that your oscilloscope works at 2Gsa/s, i guess that you could resolve your laser pulse width, but not without problems.
Giovanni
You can use any high speed photodiode connected to an oscilloscope. The rise time of the photodiode have to be less than the pulse width that you want to measure.
Both points from the above are correct: combine a high-speed photodetector with a correct load resitance and a high-bandwidth oscilloscope.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Optics