Show us a picture of what you're trying to create a driver for.
In about 5 minutes, a million people are going to comment about how "green laser diodes" don't actually exist.
So - my suggestion, get a photo of what you're trying to find a driver for, up ASAP, and then maybe we'll be able to help you without creating more unnecessary confusion
ok i couldn't get any decent close ups but found some pictures that look almost identical to it.
i am not sure if it really is 800mw that is just what the casing said.
it burns stuff from about 20cm away and eats 2 aaa batteries on less than an hour.
i took it apart long ago but lost the driver and just want to use it again.
also wanted to power off lithium i have a 3.7 v 500ma battery.
Ok, so what you're actually looking at is an IR diode, that shoots through some crystals to create GREEN.
The circuit you see IS a driver. So why do you need to build one? Did the driver die?
Also - you don't have an 800mW green laser. That design of module tops out at ~200mW usually, if that (often much much less)
the pictures i got are just what mine looks like but there is no driver board.
when it still worked and the batteries got low i could see red mixed with green what does that mean.
Well, you can use almost any driver for an infrared diode because it doesn't need much voltage.
The challenge is that you probably don't have any idea what current it needs without the original driver for testing. It might need 200mA, or 1,000mA. There's no way to know without knowing what kind of diode that is.
As rhd said, green dpss lasers use a infrared diode (808nm) to "pump" a set of crystals which change the wavelength to green (532nm). When batteries are low the green is less powerful and the red from the infrared diode pump becomes more apparent. With dpss lasers the final output is aways considerably less then the IR diode input. I'm thinking your IR diode is 800mW but I'm not sure what current you'd run it at to achieve this.
I say, build a LM317 based driver with resistors and a potentiometer in a config
that lets you adjust current from 200mA to about 1000mA. Laser driver - It can be done
The IR diodes case pin is the anode, if you hold it so the case pin is at the bottom,
your cathode is the right pin.
Connect everything, put a DMM between Battery and driver to monitor current and
then slowly turn up the current, take note how much current you need to
get green light out of the crytals.
Increase current some more, until you notice the whole thing heats up alot.
Then heatsink the module and adventure further.
You get my drift....