Page 57 - Blog Posts v1

A18 - Diode Lasers - Average Power vs Peak Power
Someone asked me recently “Should I buy a 5000 Watt diode laser or a 3500 Watt laser?” I was a bit puzzled...
I‘ve noticed a few laser companies promoting their systems om the basis of the “power”. With quotes like “the most powerful laser on the planet” and similar nonsense, they are trying to ‘hoodwink’ potential buyers into buying their devices.
They are, of course, playing on people’s ignorance. Most people don’t really understand what “power” is. Or how it relates to lasers and skin treatments.
So, here’s the lowdown.
A bit of physics...
Firstly, any cheap Q-switched laser is hugely more ‘powerful’ than any diode laser! Picosecond lasers are even more powerful. So, what does it actually mean?
Basic physics tells us that ‘power’ is simply how quickly or slowly energy is delivered. So, the shorter the time some energy is delivered, the higher the power. If you fire 10 Joules of energy at the skin in 1 millisecond, then the peak power of that pulse is simply 10/0.001 which is 10,000 Watts. (Note that 1 ms = 0.001 seconds).
If you deliver exactly the same energy over 2 ms, then the peak power becomes 10/0.002 = 5000 Watts.
Did you spot the word “peak”?
This is very important when discussing power. And this is where some laser suppliers are
trying to pull the wool over your eyes...
The ‘peak’ power is the maximum possible power that might be generated in a laser pulse. It is a specific measurement – maximum energy divided by the pulsewidth. And this becomes a bit trickier when you need to define precisely how you measure the pulsewidth!!
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