How to focus a laser?

[tiansili]

Hello everyone,
I'm starting a science project and the problem is how would a laser beam react to different surfaces such as aluminium sheets or plastic bags. I have 200mw 532nm green laser and I've read somewhere that I need to focus and compress the beam to get to burn things and make a big enough effect.
Please help everyone,
Thank you
P.S.: Please don't call me a newbie, you all have been in this stage before...

 

[Blord]

Is your laser focusable ? If yes then turn the knob on the front for the focus.
If it is a fix focus use a magnify glass to turn the dot into a pinpoint.
200mW should smoke any plastic but I think you don't have a real 200mW green.
The shops are advertising it as 200mW green but they are much lower in output.

 

[tiansili]

The shops are advertising it as 200mW green but they are much lower in output.

If so, can you recommend some sites with powerful enough lasers to experiment on that are not very expensive?
Anyways, thanks for the reply

 

[InfinitusEquitas]

Laserglow, optotronics, jetlasers, laserbtb, lazerer, o-like.

 

[tiansili]

http://www.o-like.com/index.php?mai...ducts_id=100&zenid=navh1u5ge02qekohhmajrqav62
Will this be a good choice for my requirements?

 

[Blord]

First if burning is your major concern get a 445nm diode laser. Nothing beats the high power of these lasers, except for the CO lasers.

Second burning is dangerous. A safety goggle is a MUST. The intense burning spot can harm your eyes.

 

[InfinitusEquitas]

You would be better off joining the current skylasers group buy, but yeah, that would work too.

Get goggles..

 

[Rainbow]

I'd either join a group buy or buy a laser off one of the people in Buy, Sale, and Trade that build them. You can get a 1W 445nm for around $100 on there and that will have no problem burning.

Get a set of safety glasses too so you're not blinding yourself.

 

[Bionic-Badger]

We can call you a newbie precisely because we've been at that stage before. Anyway, before you buy any lasers that you're going to try and burn surfaces with, get some goggles so you can see what you're doing and won't blind yourself. Almost any higher powered laser will work, and yes, I'd go with those other brands, not whatever O-like might have.