Difference OPSL and DPSS

[kecked]

I've been buying 808 modules off of ebay for a few years off and on, have a few good ones now, up to 50 watts which were used in a Coherent 532 nm laser as well as some c-mount 808 nm diodes, so I'm happy to see this

Attachment 58897
Shooting IR into the night sky in Alaska.

Photo of the collimated output of one of the FAP 808 nm multiple fiber output modules using a 2 VDC Cyclon battery as the DC supply. I did this only once, not a good idea to be playing with IR outside. I made sure no one was around and didn't point at anything more than the top of a tree. Just 3 minutes, then put it away. Of course, the camera had the IR filter removed to be able to pick it up.

where you are at you might get something nasty sent your way thinking someone was painting you.

[VDX]

... yes! - even if the 808nm-beam is (mostly) invisible for the human eye (I can see a dim "red" if enough energy density), digital cameras or web-cams will see it perfect (as seen in your image), so could provoke some nasty questions or more

I've done some of my tests with 975nm-beams in the backyard only, so none involved

How is your diode module in the image "organized"? -- have some diodes with 19 single emitters "bundled" into a 0,7mm fiber-output (similar to your image) ... or "pregrouped" in 5x7 into a quadrate, what's pretty good visible in the "far field" or widened beams ...

Viktor

[danielbriggs]

Rattle, rattle, I'm waking the dead, this is an old thread.

Too bad that link to Laser Focus World no longer works, I've been googling trying to find how an OPSL works, I mean, in regard to the pump wavelength. It occurred to me my 577 nm OPSL probably isn't being pumped by 1154 nm, as I was told by the seller, or more likely I just misunderstood him and he was talking about the wavelength into the LBO crystal. I mean why use OPSL if you can just double the wavelength of 1154 to produce 577?

Edit: Of course, when I post this I soon after find the new link: https://www.laserfocusworld.com/lase...mplaser-market

Although after reading, I still don't understand what wavelength the IR pump is at in the 577 nm OPSL.

Hi!
I got Adam's message to come and have a look.
You're mostly correct; the output 577nm is frequency doubled from 1154nm. This IR wavelength will of course vary from whatever the output wavelength. I think it's possible to do in OPSL:
460nm, 480nm, 488nm, 514nm, 532nm, 561nm, 577nm, 590nm, 607nm and 639nm
There are other IR and UV ones too. (Frequency tripled, and undoubled ones 1154nm, 1064nm, 920nm etc.)

607nm and 639nm are exceptions from "normal" OPSL's in that they are actually blue output OPSL's pumping another cavity bolted onto the end, Pr:YLF, to convert the blue light to 607nm (orange) or 639nm (red). That's what's in the little bolt on "nozzle" on the end of it.

So for 577nm you'd actually be going: 808nm -> 1154nm -> 577nm
And for 639nm you'd be going: 808nm -> 920nm -> 460nm -> 639nm

The corresponding undoubled IR orginal wavelengths are created from the specific design of the OPS chip. They are essentially designed to have a variety of deposited layers to create a useable IR laser for a specific wavelength. This range is about 700-1200nm. If you want 1154nm? You design an OPS chip for that. You want 920nm? You design a chip for that etc. Then stick in a frequency doubler to get your visible wavelength.
So you can pretty much pick any wavelength it's worth throwing R&D money at to warrant the costs. That's why most of the OPSL's you can buy happen to be at useful wavelenths for processes, or identical to power hungry argons they would be replacing etc.
However: you're absolutely stuck to the wavelength you have for the OPS chip you've got; there's no tunability on the ouptut wavelength.

There is a birefringent and LBO you can tune, but this will not alter the output wavelength.

ALL OPSL's are 808nm pump; but the spot size and geometry is important for proper beam profiles.
If you have one there, you should get some light out around 12-16A on the diode. Most high power Taipans will output their nameplate rating when ideally tuned and healthy around the 30-36A. Do not exceed 40A. This is the absolute max for the diodes.

There's a lot more to it, and I've omitted many many details, but hopefully the above is what you need to know?

I think I have some 577nm OPS chips in my collection if your one is dead. They are literally hen's teeth though
If it's a pump diode that is dead... that is not the usual failure mode unless it has many 1000's of hours on the clock or a badly set driver.

All the best,
Dan

[Laser57]

where you are at you might get something nasty sent your way thinking someone was painting you.

well, I pointed into the sky very briefly making sure no aircraft, not that it would cause a problem unless pointing at a law enforcement craft which could detect it. It was in the middle of nowhere Alaska.

[Laser57]

... yes! - even if the 808nm-beam is (mostly) invisible for the human eye (I can see a dim "red" if enough energy density), digital cameras or web-cams will see it perfect (as seen in your image), so could provoke some nasty questions or more

I've done some of my tests with 975nm-beams in the backyard only, so none involved

How is your diode module in the image "organized"? -- have some diodes with 19 single emitters "bundled" into a 0,7mm fiber-output (similar to your image) ... or "pregrouped" in 5x7 into a quadrate, what's pretty good visible in the "far field" or widened beams ...

Viktor

Yes, I can see the beam visually too, but only if pointed at something close, I see nothing pointed into the sky by eye. My camera had the IR filter removed, so the beam would be visible, with the filter in place, my camera wasn't sensitive enough to see the beam at all. Now, night vision cameras would pick it up for sure, since they don't block IR. The beams were 19 single emitters bundled together, I wanted to see what the beam from all of them would look like into the night sky, that's why I took the photo. The mRad was close to 16, as best I could tell measuring the spot size inside my apartment at a given distance, that's wide, and why at distance, there isn't enough power to cause anyone a problem. Although close up it can, that is why I made sure no one was about where I was doing the photo and only for a few seconds up high into the sky.

[Laser57]

Hi!
I think I have some 577nm OPS chips in my collection if your one is dead. They are literally hen's teeth though
If it's a pump diode that is dead... that is not the usual failure mode unless it has many 1000's of hours on the clock or a badly set driver.

All the best,
Dan

Dan, thank you so much for helping me understand, with your response I have a basic understanding of how they work now. I don't know if it is the OPS chip or not in my 577 units, I hope not, as you are telling me, they are far and few between, if ever, to find one. If you were to sell one, I'd be interested just to have it as a worst case repair. I don't know when I will get to troubleshooting my 5 watt 577 nm unit, it might be awhile.

Are the OPS chips all the same power output capability if pumped hard enough by a laser diode, or vary between the different power output rated heads? I'm more active on a less active forum, if you want to contact me there, we would be happy to have one more member, even if a single post. Right now there are only three of us who are active over there. Here's a thread I started on this same subject: Coherent Genesis Taipan 577 nm Optically Pumped Semiconductor Laser (OPSL) - Lasers - Laser Discourse

Chris

Guys, forgive me for three posts one after the other, but I wanted to answer the responses separately, I didn't know they were waiting for me to see until today.

[VDX]

... if you're searching more infos about laser-diodes and "internas" - here I've uploaded images of some of my diodes (and other relevant infos):

https://reprap.org/wiki/Laser_Cutter_Notes


Have much more, but don't update this wiki regularly (could be, lost interest) ...

Viktor