New to DIY Lasers 250mW

[Deathunter88]

This is my first post so please don't hate on it.
Anyways, I just bought 2 250mW and 2 20mW 650nm Red Laser Diodes. The 250mW only cost 8 dollars and the 20mW cost 3 dollars each. I also bought along with it 2 Aixiz kits with the driver circuit and everything. That is the good thing about living in China, despite the pollution and and traffic you can get 3 watt pre assembled lasers for aprox. 113$ I bet it would be great business illegally importing these to the US. XD
Anyway this is my first time doing DIY laser assembly so any tips anyone can give me will be great. I really don't want my diodes to die on me. I have a question; how do you calibrate the driver circuit to power the laser at 250mW, not too low or too high. As I said I really don't want to burn out the diodes.
Also I would like some tips and ideas on what to do with it. Ideas for science projects or burning stuff. For burning stuff I would like to know what 250mW can burn. Can it set a match on fire or pop a balloon? I would like to know the spectrum of burning for a 250mW Red Laser
One last thing, I wonder how much I can push the 250mW diode with it still have a decent lifespan? 300mW, 350mW, 500mW?

 

[Pman]

That's a lot of questions.
Not going to "hate" on your first post but I will say that the most important thing is safety. You NEED safety glasses and you NEED to do some serious research in this forum as the questions you are asking have been asked COUNTLESS times before.
Do you already own any working units? Safety has to come first.
According to your profile you are 13 and I applaud your curiosity but you need to fully realize that this hobby comes with a terrible price if you mess up and damage your eyes or anyone else's. I would highly encourage you to take a look at some of the accidents that have occurred to those who either weren't taking safety serious enough or accidentally managed to get hurt. We take safety extremely serious here for all our own goods.
Welcome to the forum

 

[Svenvbins]

Looks like Pman took care of the safety comments, which I'd advice to read again and again. And then look up different threads on safety and buy glasses.

As for your other questions, I can't answer them all, but I can give you some pointers, the search function on the forum & google itself could probably help you further:

* Diodes:
Electrostatic discharge! Make sure you're connected to ground to prevent any discharge from killing your diodes.
Temperature: When soldering the diodes, don't make'm too hot.

* Calibrating driver circuit:
Use a test load and a multimeter.

* Tips & ideas:
- Microscope. Have a laser point through a thin glass slide that has some cells on it. (Just do a quick cheek swab, works really nice!) Have a strong lens behind the glass slide do diverge the beam, and you should be able to project an image of the cell on the wall. Quality won't be good, but it's fun.

- Optical Tweezers.
Just some fun magic. For reasons I won't go in to (magic, physics, google it if you're interested), small particles can be suspended in mid-air in the focus of a laser beam. I remember a paper saying a 5mW beam can levitate small starch particles, which you should be able to see with the naked eye. never tried it, might be fun. Watch out for beams pointing up, don't put your eyes there!

Good luck!

 

[Deathunter88]

That's a lot of questions.
Not going to "hate" on your first post but I will say that the most important thing is safety. You NEED safety glasses and you NEED to do some serious research in this forum as the questions you are asking have been asked COUNTLESS times before.
Do you already own any working units? Safety has to come first.
According to your profile you are 13 and I applaud your curiosity but you need to fully realize that this hobby comes with a terrible price if you mess up and damage your eyes or anyone else's. I would highly encourage you to take a look at some of the accidents that have occurred to those who either weren't taking safety serious enough or accidentally managed to get hurt. We take safety extremely serious here for all our own goods.
Welcome to the forum

I will take safety very seriously, in fact my 2 pairs of Eagle Pair goggles are already on the way. One is rated for 190-470nm&610-760, with OD4+ as well as a light permeability of 40%. I was hoping to use that one against the red laser and violet/blue laser. I also ordered a pair 200-540nm, this one with OD4+ as well as 50% light permeability. I hope to use this one for the green laser. They were not cheap either, 380RMB (60 USD) each so I hope they are not fake. I also ordered a bunch of IR filters to put on my green lasers because...I live in China . Thank you for your reply to my thread.

 

[Deathunter88]

Looks like Pman took care of the safety comments, which I'd advice to read again and again. And then look up different threads on safety and buy glasses.

As for your other questions, I can't answer them all, but I can give you some pointers, the search function on the forum & google itself could probably help you further:

* Diodes:
Electrostatic discharge! Make sure you're connected to ground to prevent any discharge from killing your diodes.
Temperature: When soldering the diodes, don't make'm too hot.

* Calibrating driver circuit:
Use a test load and a multimeter.

* Tips & ideas:
- Microscope. Have a laser point through a thin glass slide that has some cells on it. (Just do a quick cheek swab, works really nice!) Have a strong lens behind the glass slide do diverge the beam, and you should be able to project an image of the cell on the wall. Quality won't be good, but it's fun.

- Optical Tweezers.
Just some fun magic. For reasons I won't go in to (magic, physics, google it if you're interested), small particles can be suspended in mid-air in the focus of a laser beam. I remember a paper saying a 5mW beam can levitate small starch particles, which you should be able to see with the naked eye. never tried it, might be fun. Watch out for beams pointing up, don't put your eyes there!

Good luck!

Hi Svenvbins!!! Thank you for you post, but I have a question about calibration. (I know this is probably answered somewhere else but I am new to using a search function and can't find any info.) I already know how to build the test load, but what is the mA to mW ratio? Because from what I understand, using a multimeter across the test load should yield a result in mA. (am I correct?) How does this correspond to mW. I would be glad to have an answer. Also, if you can find a link to a place that explains this, I will be greatly appreciate it. Thanks again for your time :yh:

 

[Svenvbins]

I'm sorry, you're completely right, I misread the mA/mW thing. There is no direct way to convert the mA to mW. The only two things you can do is
- Find someone with an LPM (LaserPowerMeter) to directly measure the outgoing power, or, easier:
- Hope you bought a common diode; in that case I'm sure you can find data tables / graphs plotting the power versus the current.

Might find a link later on, gotta go back to work now

 

[Deathunter88]

Thanks for the quick reply!!!

 

[glcon]

Are you chinese?
or a foreigner happen to live in china

 

[Deathunter88]

Are you chinese?
or a foreigner happen to live in china

I am a ABC (american born chinese) I moved to China when I was 6 and have been going to an international school ever since. I plan on attending high school in america. Hopefully Exeter