Need Advice

Hi everyone.

I'm on technological project and just find this great site looking for some info.

The target is to heat a steel sheet at atleast 200C in less than 1/2 sec. The sheet is around 0.5mm thick and 25-30mm widht and the distance between the laser and the sheet can be minimum.

I just read a few threads about the heating ability of few lasers. As I understand, the blue-ray led is most powerfull (besyde CO2...).
We have limited size for heating element so this must take in consideration.

I don't know if one emitter with a glass lens or a few of them will accomplish what I'm looking for.

I think a couple of sketch will help.

Any help will be welcomed.
Thanks in advanced.

I don't know.... Using lasers could be a very expensive setup. How reflective is the steel? The less reflective, the better. Also, if you can somehow make the steel black that would help. I would use a few ~1.5W 445 lasers. You could make a setup like your first sketch with multiple lasers. I would make them lab-style and all have the ability to be turned on and off with one switch so you don't have to try to turn all of them on in a 1/2sec. I would use a 405/445 G-1 lens focused. Remember, this will be VERY expensive and time-consuming to make. Also, I don't even know if it would work since laser light is very concentrated. It may only heat up in the small areas where the dots are.
Those are just my thoughts, but I am in no way even close to an expert or even experienced with doing this.
Hope this helps.

Whoa! you're getting ahead of yourself, sir. Let's start with some calculations before we start suggesting which lasers to use.

The specific heat of iron is 0.45.
The density is 7.874g/cm³.
Height I'm guessing from the pic is 10mm.
So volume would be .05cm*1cm*3cm=.15cm³
Weight would then be 7.874g/cm³ * .15cm³ = 1.2g

Q=mC∆T
Q=1.2 * .45 * (200-20) = 97J

In order to heat it in 1/2 second, you would need 200W ABSORBED for that time period. So assuming all the heat is absorbed by the material (and it won't), you would need a MINIMUM of a 200W laser.

Find another way. There are plenty to choose from.

I knew it! haha not really. I didn't think that would work though, I was just being optimistic. AHHH!!! It looks like physics class...