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Doubt: what power to light a match?

Leodahsan

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well, lets say I have a red match 5 meters (17ft) away, and no atmospherical fog/smoke/rain or so.
with red, what the power needed to light it?
and with green/blue/violet?
200mW violet will do it?

Thanks in advance.
 

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200mw would be a huge over kill

50mw of 405 can easily do if it is properly focused to a point with a lens and then held still.
Heck someone even got it lit with a 27mw.
 

Ash

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You could do it with 100mW of red, but you would spend lots of time focusing it, and you would need to sharpie the red match head (black) so it would even light with a red laser. A 200mW red would be much easier.
You would need at least 30mW of bluray (also hard to get to a pin-point at 17feet)
You would need at least 50mW of green.
 

daguin

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It doesn't take as much power as you would think. The problems are with focus and movement. Most greens are not "focused." Plus, you would have to have the laser held by some sort of secure mount. Even the movement caused by your heartbeat could cause the "spot" to move around too much

Here is 35mW of well focused, violet (bluray) lighting a red match.



Peace,
dave
 

snoutke

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I don't think that the laser color (wavelength) matters.

The burning ability of a laser depends on several factors:
Laser Output Power: Higher power laser beams burn things more easily and faster.
Laser Beam Width: A thinner laser beam always burn things better than a wider laser beam.
Object Color: Dark colored objects normally absorb more light energy so they are easier to burn than light colored objects that sometimes do not absorb light energy.
Immobile: A moving laser beam does not give the object enough time to absorb light energy. The laser beam dot needs to keep still on the object for several seconds to make it burn.

I personaly managed to burn a match 14ft away (4.25 meters) with a 1W 447nm Spartan just holding in my hand, no focus and no tripod.
 

Ash

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I don't think that the laser color (wavelength) matters.
We have established that lasers with a smaller wavelength burn better as the energy-density is greater at the focal point. The rest of your points are valid, however.
As Daguin's video (above) shows: a focused 37mW bluray can light a match.
Personally, I have not been able to light a match with 37mW (or even 50mW) of red because there is less energy per square µm (micrometer) [or nm, nanometer].
37mW at 405nm = 0.091mW/nm
37mW at 660nm = 0.056mW/nm
You would need around 60mW of red to have the same energy-density as 37mW of bluray.
60mW at 660nm = ~0.091mW/nm
 
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Indeed it does matter since 50mw of red couldn't smoke a match marked black while the 50-60mw from my of 405nm lit it.
 

Leodahsan

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@Daguin
I've noticed my heartbeat moving my laser's aiming, didn't know it was normal on a human being haha :) thanks

@snoutke
laser beam width is called energy density (W/cm)
object color need to matche with different wavelength lasers, and makes no difference for infrared (I think.) for 1000+nm

@Ash
I've read somewhere that lower wavelengths (~400nm) have lower power than higher wavelengths (~600nm) and that makes the difference in burning

BUT I've read somewhere else that the energy-density is balanced by the lower quantity of photons emitted by the gain medium.
because of this, 20mW of bluray is 20mW of heat on a complete black target, and 20mW of green is 20mW of heat on a complete black target, and 20mW of red is 20mW of heat on a complete black target (despite atmospherical interefences, etc).
^I may be wrong, but for me, this make sense :)

---

thanks all answers people, I just lighted a match using a 10mW NewWish pen from DinoDirect (yes.. DD shipped) and glass lenses from o-like.
 
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extremeodd

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One thing to note is the "lower" wavelenths of 405 are actually higher on the electromagnetic spectrum
 

Leodahsan

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yes, we call they "lower" wavelengths because they have a lower wavelength (shorter).
 

AUTO XX

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One trick I have found useful:
Hold the laser against the side of your head (not pointing AT your head... Pointing where you are looking)
The muscles in your neck hold your head very stable and the mass of your head isn't as prone to shaking as your hands are.
I always thought it looked kind of goofy beam viewing when the laser is shaking all over the place, putting it against your head also lets you hold a spot on your target better.

*Careful you don't hit your glasses/goggles, your finger, etc. you are very close to your eye and a mistake could turn out pretty bad*
 

Leodahsan

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something like Alien VS PREDATOR???
:confused: I'm scared


j/k, it works haha
I think some pointers would be hard to do this, but it works
someone should try with a CO2
 

AUTO XX

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The predators had a pansy little (triple) red, I want to see a superpredator with a 2W 445nm targeting laser :na:
 

Leodahsan

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oh yeah, right
haha, it would not be needed any weps anymore
just aim for the eye and poof! blind target :beer:

lol, fail reply :(
 
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I have strike anywhere matches with a green head, and I could not get them to light with a 650nm at 100mw. I set them up at 2' and had no success, but with the laser at 200mw they light right up. I did have trouble with the focus trying to get all of the spot on the head. I'll try My PHR later it's set at 110ma it should light them just fine.
 




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