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# Re: What's the minimum mA needed to be a burner?

#### Kloan

##### New member
Re: Re: What's the minimum mA needed to be a burne

weird.. i thought delete would just get rid of the whole thread...

anyway, i figured it out... 80-100mW = burn yes no prob

#### Lol

##### New member
Re: Re: What's the minimum mA needed to be a burne

Wow, what a weird bug...
It looks like I was the topic creator, while Kloan is it.

Haha!

#### benmcntsh

##### New member
Re: Re: What's the minimum mA needed to be a burne

I tried to do this calculation and it turns out to be non-trivial!

For example, take paper:

Mass is about 100 grams per square meter
Heat Capacity is about 1.4 Joules per gram per Kelvin
Autoignition temperature is about 500 degrees Kelvin
Absorption of 405 nm light is maybe 10% for white paper

So if you turned on a laser for one second and were able to focus it to a spot that is about 2 mm in diameter, you would need an output power of about 1.5 Watts. But that's to spontaneously ignite the paper in one second... so just to char it would only maybe take 100 or 200 mW. Who knows if that's all right but it's not bad for midnight.

#### Tech_Junkie

##### Banned
Re: What's the minimum mA needed to be a burne

benmcntsh said:
I tried to do this calculation and it turns out to be non-trivial!

For example, take paper:

Mass is about 100 grams per square meter
Heat Capacity is about 1.4 Joules per gram per Kelvin
Autoignition temperature is about 500 degrees Kelvin
Absorption of 405 nm light is maybe 10% for white paper

So if you turned on a laser for one second and were able to focus it to a spot that is about 2 mm in diameter, you would need an output power of about 1.5 Watts.  But that's to spontaneously ignite the paper in one second... so just to char it would only maybe take 100 or 200 mW.  Who knows if that's all right but it's not bad for midnight.

Lol said:
Wow, what a weird bug...
It looks like I was the topic creator, while Kloan is it.

Haha!
If someone replies to the first post you cant delete the whole thread anymore.

100mW min for decent burning.