Help focusing my 50mw laser pointer into a burning laser

OP if it's not burning when focused, it's not gonna burn.
Enjoy the colour, it is really one of the more beautiful things I have personally seen.

Zeebit said:

Did you miss the part when you said something about a million watts?

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I'm quoting the article. That millions of watts equivalent is over one square centimeter with a diffraction limited spot size if that much power is distributed evenly over one square centimeter. One can calculate the energy density over one square millimeter or fractions thereof which would be more the sufficient to cause burning with 5 mw. An everyday example of the phenomenon is burning with a magnifying glass.

steve001 said:

An everyday example of the phenomenon is burning with a magnifying glass.

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I'm fairly sure that a magnifying glass on a sunny day focuses a lot more than 5mw. No hard facts or figures to back this up, just personal experience when I was younger (folded up some paper, tried to burn it, didn't realise it punctured all the way through the first few layers and set the bottom on fire until I tried to pick it up. Yeah I wasn't a clever child).

CheeseHasLeafs said:

I'm fairly sure that a magnifying glass on a sunny day focuses a lot more than 5mw. No hard facts or figures to back this up, just personal experience when I was younger (folded up some paper, tried to burn it, didn't realise it punctured all the way through the first few layers and set the bottom on fire until I tried to pick it up. Yeah I wasn't a clever child).

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Of course it does. That is an example for what happens when concentrating energy into a small area

steve001 said:

What matters is power density.

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thats correct .
power density is most important when it comes to burning .

and yes , you can focus 5mw beam to a small area , so the power density will be thousands of watts / area .
the problem is , the optics thats needed to do so , will be more expensive then ready made burning laser .

when you hold a magnifying glass or focusing laser , there is a limit to how tiny spot you can focus it .normally , you cant focus it to a very tiny spot .

same with binoculars , you cant get one with 10000x zoom right?

If you use a magnifying glass it helps focus the light better