Combining multiple pen lasers 4mW to burn paper is this possible

[Guest]

Greetings, All

Is it possible to combine multiple pen lasers angled down at one point (around 4mw) to burn paper?

What wattage is needed for a laser to burn paper?

TIA

 

[tlbs]

Red LASER pens produce photons at one narrow frequency (~620 nm red
light). That particular frequency is well reflected and not well
absorbed by plain paper, so you would need alot of them to burn paper.
If the paper has a reflectance to visible light of 95%, only 5% of the
photons are absorbed. I would estimate you could probably do it with a
few hundred of them.

On the other hand, if you had say, a 4 mW, 1 micron LASER pen
(infared), you would only need about 5 to 10 of those (and it's cool to
watch paper fry, paint peel and char on the wall, etc, etc.).

 

[Terran Melconian]

Red LASER pens produce photons at one narrow frequency (~620 nm red
light). That particular frequency is well reflected and not well
absorbed by plain paper, so you would need alot of them to burn paper.

Perhaps he could just get black paper, or draw a dot on it with a
marking pen.

It sounds like this is a one-off project for fun, so solutions like that
may be perfectly acceptable.