532nm Laser Project

marshall · Sep 28, 2006

I'd like to start a 532nm laser project myself, although I will really need the help of the forum to successfully complete I believe. I hope some of you would be willing to help here, as trying to put this together alone I am really in the dark.

I have been away from the laser scene for just a bit, and really have no clue as to what is available these days as far as diodes and their current supplier pricing - as well as crystal sets.

I would like to do something >200mw, and if I can afford to put it together, closer to 400-500mw.

The setup of the laser would be in as small of a package as possible, with external battery on a remote cord. I'm doing this to hopefully be able to build cheaper, as I won't need specialized and small parts for a pointer body, also limiting potential output.

I would like to start with the drive board, diode, and heat sink. I will then move on to crystals and optics to see what overall package size I will be working towards requiring.

With that being said, I have a few questions I hope you guys don't mind helping me with...I'll try not to ask too many at once.

For starters, I assume before buying a diode I should price everything and see what output range my wallet is really capable of achieving. I realize 9mm 1.5w Sony diodes are the most readily used today for higher outputs. What is theoretical maximum 532nm output from a diode of this size? I'm really just unsure if I should take a stab with this diode, or possibly find something in the range of >2w if possible.

My next few questions are, and I'll leave them my final for now, what specific function does the drive board have? I assume it regulates and ramps power up upon each activation of coarse to ease the diode's use. Will it be possible to attain a drive board from some other electronic device once I decide upon my diode output?

Thanks for any info which can be provided on this topic.

Corona · Sep 29, 2006

I believe Roithner Lasers (www.roithner-laser.com) has all the parts you need.

As far as output, a well-aligned, good quality crystal set (Nd:YVO4 + KTP) can achieve about 35-40% overall conversion efficiency, AFAIK

Here's another source for crystal sets and some more info:

http://www.u-oplaz.com/crystals/crystals11-4.htm

ted_park · Sep 29, 2006

marshall said:
I'd like to start a 532nm laser project myself, although I will really need the help of the forum to successfully complete I believe. I hope some of you would be willing to help here, as trying to put this together alone I am really in the dark.

I have been away from the laser scene for just a bit, and really have no clue as to what is available these days as far as diodes and their current supplier pricing - as well as crystal sets.

I would like to do something >200mw, and if I can afford to put it together, closer to 400-500mw.

The setup of the laser would be in as small of a package as possible, with external battery on a remote cord. I'm doing this to hopefully be able to build cheaper, as I won't need specialized and small parts for a pointer body, also limiting potential output.

I would like to start with the drive board, diode, and heat sink. I will then move on to crystals and optics to see what overall package size I will be working towards requiring.

With that being said, I have a few questions I hope you guys don't mind helping me with...I'll try not to ask too many at once.

For starters, I assume before buying a diode I should price everything and see what output range my wallet is really capable of achieving. I realize 9mm 1.5w Sony diodes are the most readily used today for higher outputs. What is theoretical maximum 532nm output from a diode of this size? I'm really just unsure if I should take a stab with this diode, or possibly find something in the range of >2w if possible.

My next few questions are, and I'll leave them my final for now, what specific function does the drive board have? I assume it regulates and ramps power up upon each activation of coarse to ease the diode's use. Will it be possible to attain a drive board from some other electronic device once I decide upon my diode output?

Thanks for any info which can be provided on this topic.

Check out Sam's laser FAQ - he's got some good hints if you are into this sort of thing.

My 532 nm project was much lower power, as I didn't want to go to the expense of building a higher power system.

For some of my projects I used the LDD-40 driver from Meridith Instruments.
I had used the MCA from an old laser pointer. There's a potentiometer adjustment for current. Mostly there are used for higher power 650-660nm lasers.

The driver board provides current to the diode. I've always used constant current drivers for the pump diode setups. The only places I've used automatic power control (constant power) was with 635nm and 904nm setups. The diode configuration has to support APC, and the APC driver boards that I have don't support high power devices anyway. The focusing optics were bought from optima optics, and the positioning hardware was obtained from Creative Stars. The focus lens/MCA positioning is similar to that required for a spatial filter. I aligned things using a webcam setup setup to receive IR, with a welding mask in front of the cam so I could tell whether it was properly aligned. I wore some laser goggles during the alignment, but I had things positioned so my eyes were shielded from the laser assembly itself. I never got great efficiency - 'bout 5mw out with around 200 mw of drive power, but my optics weren't coated for 808nm. I didn't use any fancy stuff like anamorphic prisms to compensate for the elliptical beam.

I'm selling some unneeded items associated with 532nm lasers on ebay right now - my user id on ebay is ptpark. I'll probably sell another batch of stuff in a week or so, but I'm kind of busy with other projects right now.

marshall · Sep 29, 2006

Thanks for the info guys, the suppliers link was very helpful.

Checked out your auctions too, Ted. Your optics suppliers were very helpful as well.

Alright, I'm sorry I'm soo new to this sort of thing and have to ask. I realize there is a lot of learning I will be doing along the way - but that is the fun part and I'll try not to let it hinder building the project.

Being that this is not going into a pointer body, I imagine I am more open to mounting styles of diodes. Can someone explain what a TO3 mount is? I see there are some 2w C-slot and TO3 mounting style 808's at that link, wondering if one of these may just be suitable for the project.

Are there difference in these which will permit only certain cooling heads to fit the diode? That is the next thing on the list really - mating the diode to the cooler. I imagine I will need to use TEC, or possibly a larger heat sink.

About the emitter size output of the diode, is there a certain shape/size I should avoid or look for?

Thanks again.

jkaiser3000 · Sep 29, 2006

You will probably need a TEC cooler if using a 1-2w diode. It will more effectively cool the diode. However, using this approach will prevent it from being powered by a battery pack, as these TECs can draw more than 1 amp of current.

Also, a c-mount diode will be more effective for cooling, as the diode is directly connected to the cooling medium, whereas a TO-3 mounted is connected thorugh the casing to the cooling medium (very slight difference in heat dissipation). However, c-mounts are more fragile as the diode itself is in the open, making it posible for you to touch it with your hands, and risking breaking the wires, not to mention the static too.

If what you want is 500mw of green light, you may get around with a 1w-1.5w 808nm diode, assuming 30-50% efficiency for the MCA. But, keep in mind the alignment is critical, and difficult to achieve.

Your lenses would also need to be coated for the appropriate wavelengths.

Now, to mention safety, be very careful with this project. You'll be working with very dangerous IR radiation at extreme powers, effectively a classIV device, which means not only proper eye protecion, but also skin protection. Not every goggle found on ebay will handle that amount of power, and certainly not the DeWalts and other cheapies (price wise) :grin2:

ks_physicist · Sep 30, 2006

I'm just posting to watch the thread...it's a project I wouldn't mind keeping on my list of things to do.

marshall · Sep 30, 2006

Hmm, I'd have to swing for the TO3 mount, for the sake of better element protection here I believe. Cooling should be ok, I'll just keep duty cycles low after some testing.

I've heard about correct MCA alignment being hard to achieve, I take it my best thing to fight this with is simply a good and accurate alignment assembly.

Moving right along here, can someone recommend an optics/alignment setup which I may want to use? If not that's alright, I'm sure I can figure it out.

My next main question lies in the MCA itself. How do we relate 808nm output to optimal crystal mass/size?

I don't want to overpower the MCA in so that it becomes tremendously heated. I also don't want to spend huge bucks on a crystal assembly which is indeed much too large for the output of the diode and less in output efficiency.

Is there a general formula or rule of thumb for MCA size calculation?

Also, is it correct that I need a focusing lens before the MCA and after the diode to focus on one spot of the crystal?

Appreciate the info.

jkaiser3000 · Sep 30, 2006

try these links:

casix Nd:YVO4 crystals

Casix KTP crystals

marshall · Sep 30, 2006

jkaiser3000 said:
try these links:

casix Nd:YVO4 crystals

Casix KTP crystals

I see that the largest Nd:YVO4 crystal they have is 3x3x3mm.

What is the approximate highest input from 808nm this size crystal may be suited for?

Will the crystal need to be cooled itself some way if 808nm input is around 2w?

Just trying to cover everything so that the design is built to last.

ted_park · Oct 2, 2006

Here's my cobbled together dpss laser.

In this case, I show it with parts scavenged from various laser pointers. I was using a constant current driver with a different diode until I kind of overdid it.
This is more of an exercise in alignment optics.

http://members.shaw.ca/ted.park/dpsspics/dpsspics.html

532nm Laser Project

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Corona

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