Looking for a replcement diode for a 50mW green laser module

[brainiac]

Greetings!

After successfully coupling an audio signal onto my green laser pointer, I decided I want more (particularly more range), so I got a broken spirograph from my friend and it turned out the laser was still intact. Unfortunately, that was to change as my circuit seemed to have inadequate current limiting and the diode burned out. After the initial overwhelming feeling of disappointment, I decided to look for a replacement, but being a complete novice to lasers I soon found myself wondering what it is that I actually need. At first, I was looking for "green" laser diodes, but when reading up about lasers, I was reminded that green lasers tend to use DPSS, so now I am unsure about what to buy.
Side note, apologies if I'm posting this in the wrong board, I'm also new to using a forum

Without further ado, here is what I know about the module:

• At first I was sure it's a "standard" 532nm laser, but the great variety of green hues I found in here made me unsure even about that. Regardless, the color seemed very familiar, so I hope there is a common green hue and that's what I have.
• The case of the spirograph mentioned an output power of approximately 50mW
• The heatsink / optics seems very sturdy, the attached picture shows the block with the diode (6mm base)
• In operation with the original driver, it pulled 400mA, but the trim pot could be adjusted to increase the current to 600.

Obviously, if the case had a part number on it, I could just google that, but with the actual component broken, I have to resort to some forensics to determine them. A quick browse on a famous online auctioning platform revealed that sizeable 808nm diodes are dirt cheap, but with the price of visible light ones, I feel like there is a catch to this, so I wanted to consult with experts before spending any money.

I hope this information is useful at all. Thank you for your time and help!

brainiac

 

[ultimatekaiser]

808 diodes are common and cheap, and come in all flavors. sadly I have bad news for you.

DPSS is complex and replacing a diode in something unlabeled is a matter of luck. you'd just need one of the same diameter and just reorient the polarization of the diode to the crystal orientation. but the power you'll get will vary heavily on the quality of the diode. you can buy 808 diodes from lots of places, but say you had a 100mW pump diode....you can have one for probably as little as a few dollars, or you can buy a super nice one that is over a hundred. there's a lot of variables, mostly in the stability and heat-wavelength shift department. Your run-of-the-mill diode may or may not give you the power it once had. (more likely) or it may give you more (not likely at all) variant on about 10 factors I can think of off the top of my head....and more. where did you get this laser module from?

Edit: btw, most lasers dislike being pulsed, so usually if you want to modulate it, find one with a good circuit meant for that, and modulate it with a controlled specified voltage, (usually 5VDC is common)

 

[brainiac]

Well, the appropraite casing and orientation sounds like a day's worth of screwing in, running and estimating the output power. I mean it's not plug and play, but I'm more than willing to spend some time optimizing the setup.
Unfortunately I cannot tell you anything meaningful about the module itself. I got the siprograph from a friend, who bought it a long time ago and I doubt there will be any specific datasheets anywhere. I will figure out the manufacturer and model tomorrow, as right now it's 3 in the morning and going to the workshop would wake up the entire family.
As for diodes, I found several with a nominal power of 300mW and more for under $10, which again compared to visible light ones is so cheap I'm actually very suspicious about the quality. In fact I have a 500mW one for $6.88 here, nevermind the centuries of shipping time, Hong Kong tends to be reliable for me. I'm not planning to run that at full power in any case, both for the diode and all of the optics. I just feel like a more powerful laser could withstand a little "overdrive" (compared to the old one), in case my circuitry fails me yet again.
Actually, side note, green lasers require a certain minimum power beforethey start emitting green light - am I right in assuming that that's because the frequency doubler crystal needs a minimum radiation density to operate or does that happen in the pump diode?

Also, my approach to modulating the beam involves driving it at a constant limited current and then "leeching" off some of the current with a transistor. As far as I see, the diode never exceeds its nominal power that way.. Then again, that's a pretty obvious way to do it, so is there something about changing the current in general that damages them?