looking to build first ir laser

ok i wanna make an ir laser that can burn things, maybe around 100-200mW, i dont know what diode to get, what current to run it at, and the pin assignment

Heruursciences has been selling grab bags of high-powered IR diodes (9mm or cmount) in the group buy section for some time.. that's the cheapest source. Typically they are 1W and up. The pin assignment varies, but with many of the 9mm diodes there are only two pins so it's not hard to figure out. You'll need to use a digital camera to "see" the IR along with IR goggles (A MUST!!!!!!!). You can drive most of them with a LM317 driver, but some of the higher-powered ones will require more. A Flexmod from DrLava works great.. IR diodes in 5.6mm and 9mm packages are usually case-positive, so if the diode has two pins, the one connected to the case is positive. With c-mounts, the block is positve and the lead is negative.

Get as many 808nm diodes as you can (ask heru, he will most likely oblige) so that you have the possibility of pumping crystals and experimenting with green DPSS lasers.

i keep hearing c-mount, what is that?

You will not have much luck burning with <400mW of IR (due to the beam shape and long wavelength). 400mW and up will make a great burner.
Also... what elektrofreak said^^^

C-mount is a package type for laser diodes. They are generally used for powers from 500mW and up to 7W. Do some reading to get an idea of what you are dealing with.
Good luck!

well for just a general invisible laser has anyone tried a phr-803t sled's ir diode? what current do you run it at, and what pins are what?

The PHR diode is no good, but if you have an IR diode from a high-speed cd-burner you could use that. The 780nm CD burning diodes from the LPC-815 or GGW sled can do ~200mW @ 250mA. They do OK as burners even though they're not too powerful since they're single-mode diodes. This means you can focus the spot down very small with just an aixiz module and lens. This won't end up being a super-burner or anything, but it will smoke a few things..

For a super-burner, start with a grab bag like suggested or look at IR laser diodes on ebay. Go for 500mW and up. You should be able to find some nice inexpensive diodes since IR tens to be fairly cheap. With high-powered stuff, you need slightly more complicated optics usually consisting of a cylinder lens and a convex collimating lens.