Calculating Nd:YAG Laser pulse energy

[bakelas83]

I have a question, I used pulsed Nd:YAG laser to weld a steel part but I didn’t measure the pulse energy during the experiment. I was wondering if there is a way to calculate it somehow?
I have laser pulse duration, frequency (repetition rate), and laser (mean) power.
Thanks

 

[Redbelly98]

Welcome to Physics Forums

The pulse energy is (mean) power x pulse period, or equivalently

(mean power) / (rep. rate)​

This makes sense if you think about the units, and the fact that power is energy-per-second:
\frac{( \text{energy/second)}}{ \text{(pulses/second)}} = \text{(energy/pulse)}

 

[bakelas83]

Yes. You are right. But doesn’t the pulse duration have an effect on the pulse power?
I mean does the pulse power change directly with change in pulse duration or not?
Thanks

 

[Redbelly98]

Yes, it affects the pulse power. But it does not affect the pulse energy, which was your original question.

Pulse power = (pulse energy) / (pulse duration)​

 

[bakelas83]

Thanks. I have one other question. The laser machine I was working with had an adjustment option for I (electric current in terms of mA) instead of laser power. How can I find laser power with this information?

 

[Redbelly98]

There is no way to calculate laser power just from knowing the current. Different lasers have different efficiencies for converting the electrical energy into laser beam energy.

You would have to measure the laser power at the current setting you used. Or, measure the laser power at several different currents and make a graph (should be a straight line, if this YAG laser emits in the infrared), from which you can get the laser power at any current.