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Pico green laser module on eBay...anyone tried this?

H

honeyx

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But you are speaking about a lappie, right? In this case the benefit in using optics is obvious. The temperature of the diode has less influence to the temperature of the cristals due to a larger distance, so the temperature of the cristals can be better controlled resulting in a more stable output. You also don´t have to care that much how much current is drawn compared to a handheld.

So for using them in a lappie these cristals seems to be a good choice but not for handheld lasers.
 





rocket689

rocket689

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I have been wanting to build my own 532 for a while.
This may just be the ticket. I eagerly await RHD's results. :pop:
Good find. :cool:
 
qumefox

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Um. How you pump the gain medium affects efficiency a lot. And just sticking a lens between an IR diode and the crystals probably isn't going to gain much because you really have to you the RIGHT lenses, properly AR coated, and with the correct focal lengths to pump a shallow cone in the gain medium.

You'll probably find that pretty much ALL high power DPSS lasers with a nice gaussian output uses this.

You might can get 'more power' by just flooding the whole gain medium with IR, but you also get the awful modes and mode hopping that goes along with that.
 
rhd

rhd

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honeyx said:
But you are speaking about a lappie, right? In this case the benefit in using optics is obvious. The temperature of the diode has less influence to the temperature of the cristals due to a larger distance, so the temperature of the cristals can be better controlled resulting in a more stable output. You also don´t have to care that much how much current is drawn compared to a handheld.

So for using them in a lappie these cristals seems to be a good choice but not for handheld lasers.
Click to expand...

Nope, I'm using it in a handheld, with CNI stock optics (pre and post crystal), diode, and TEC.

In the 589, it went:
Diode - Optics - Crystal - Crystal (On TEC) - Optics -> 589 OUTPUT

Essentially I'm going to retain the optics, move the pico module onto the existing TEC, put it where the first set of post-optic crystals were, and attempt to regulate the pico module at 30 degrees with the TEC. It's not going to be active regulation of the TEC as it was in the 589, but rather I'll trial and error to get a roughly stable current/voltage through the TEC for 30 degrees when the system is active, and then solidify that as the final TEC current/voltage before closing up the build.
 
qumefox

qumefox

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What are you going to use for OC optics rhd? I can already tell you the 589 OC won't work. because it's.. well.. coated for 589. Not 532.

Well, actually it may 'sort of' work, depending on how broadband their coatings are, but you won't get nearly the efficiency an actual 532nm coated optic would provide.
 
benmwv

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qumefox said:
What are you going to use for OC optics rhd? I can already tell you the 589 OC won't work. because it's.. well.. coated for 589. Not 532.

Well, actually it may 'sort of' work, depending on how broadband their coatings are, but you won't get nearly the efficiency an actual 532nm coated optic would provide.
Click to expand...

I believe the OC is built into that "pico green laser module".

Probably in the form of a coating on the back.
 
qumefox

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benmwv said:
I believe the OC is built into that "pico green laser module".

Probably in the form of a coating on the back.
Click to expand...

Nope. The back is HR coated. The front is just AR coated for 532nm. You'll still need an output coupler to form the cavity for the 532nm.
 
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Meatball

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The optics after the second crystal might not have to be coated as an OC should be. A lot of these crystal sets use an OC coating on the backside of the doubler.. this actually actually helps the typical "green module" from DX or ebay or wherever to retain its relatively low price.

The OC optics should be there already as this crystal set already spits out 532.. so I would imagine that collimation optics used a typical green module or even a yellow laser should be good enough to effectively provide a tight beam without unexpected losses.

The cheaper the AR coating... the greater the odds of it being relatively broad-banded.
 
qumefox

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I'm just going by the coatings list in the auction. They don't list an OC coating on the front face. Only an AR coating for 532nm.

Regardless. I guess RHD will find out soon enough either way.
 
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H

honeyx

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qumefox said:
Um. How you pump the gain medium affects efficiency a lot. And just sticking a lens between an IR diode and the crystals probably isn't going to gain much because you really have to you the RIGHT lenses, properly AR coated, and with the correct focal lengths to pump a shallow cone in the gain medium.
Click to expand...

Agree on that with you.

But am not sure about this:

qumefox said:
You'll probably find that pretty much ALL high power DPSS lasers with a nice gaussian output uses this.

You might can get 'more power' by just flooding the whole gain medium with IR, but you also get the awful modes and mode hopping that goes along with that.
Click to expand...

As far I know also the poweful handhelds with a separate diode and cristals are having that awful modedrifting. They also must use optics in between if the diode and the cristals are separated. Therefore I more belive it´s more temperature related because there the temperature is not stabilized by a TEC.

benmwv said:
I believe the OC is built into that "pico green laser module".

Probably in the form of a coating on the back.
Click to expand...

I think so too. See the description:

Facet Coating: Input: HT@808nm, HR@1064nm&532nm

Output: HR@1064nm,AR@&532nm
 
qumefox

qumefox

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There are big differences between OC coatings and AR coatings though. OC coatings will be reflective (but not as much as HR coatings) while AR coatings are transmissive.

Whether this set needs an OC or not depends on if they really meant OC, or AR.. If it's really only an AR coating, it will need a front OC mirror. If it was a mistake and they really meant OC, it won't.

But just going how it's currently typed, these will need an external OC mirror.
 
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H

honeyx

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I know but IIRC the very first generation of DPSS lasers had no coatings on the output but on the external OC mirrows and lenses. All the new cristal sets are already sets and coated with mirrows.
 
rhd

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Meatball said:
The OC optics should be there already as this crystal set already spits out 532.. so I would imagine that collimation optics used a typical green module or even a yellow laser should be good enough to effectively provide a tight beam without unexpected losses.
Click to expand...

That's what I was thinking (hoping). It sounds like this module is *at least intended* to be a dirt simple 808 in / 532 out enclosed system. Jury is out on whether that ends up the case, but it certainly seems like that is the intention.
 
benmwv

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^^ That is how I'm thinking it is. In their diagrams and descriptions they never mention needing an OC.

If it ends up not needing one, this will be great for making high power 532's. Seems like it will be fairly simple to take one of those non-working 10mw 473 units on ebay and modify it to use these crystals.
 
Meatball

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^^Heh, you're right. Those things already include a pump diode which is already apparently at 808nm... many times buying "808" could really mean "802-815"
 
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