Page 61 - Blog Posts v1

A19 - More about laser power - average versus peak!! With videos...
Following my post yesterday re laser power, I thought I'd explain further using the medium of video...
https://youtube.com/shorts/V8ZTKC-ncbo?feature=share
The above shows a Q-switched Nd:YAG laser outputting pulses of energy 0.3 Joules in 10 nanosecond pulsewidths. These equate to a peak power of 30 million Watts in each pulse (30 MW).
However, the 'peak' power relates to the individual pulsewidths for each pulse. The 'average' power relates to the total time over which these pulses are delivered. So, if we fire these pulses at 10 Hz (10 shots every second), then the total energy delivered in one second is 10 times 0.3 Joules. The average power is simply the total energy divided by the total time - 3 Joules / 1 second, which is only 3 Watts.
We can see a big difference between firing these pulses at photo paper and at the tangerine skin. That's simply because the photo paper absorbs much more of the laser energy than the tangerine does.
This example shows the massive difference between average and peak powers - they are NOT equivalent.
In the video above, we can see that the laser pulses have very little effect on the tangerine skin, even though the peak power in each pulse is huge.
https://youtube.com/shorts/cqea57yzH-4?feature=share
Mike’s Blog Posts 61