what's inside the several watt laser modules?

[kecked]

is the beam stable with temperature? I mean as the temperature in the room changes does the mirror deform?

[VDX]

... depends on the mirror material - not really valid for most applications ... maybe something you have to look for in holography ...

Viktor

[planters]

I don't think this is too complicated. Several measurements would explain a lot. The near and far field beam dimensions and the far field distance for the two separate cases; with the G2 alone and with the mirror added. Even if there is no ''magic bullet" here and the divergence remains inversely proportional to the near field beam size (as with any other beam expansion technique), there could still be some advantages to a single element, reflective beam expander.

I have these general optical components and I am interested in replicating this technique. I'd like to know your results.

[VDX]

... can do some more representative/qualitative tests the next days -- I'll only have to find a box with concave laser-mirrors with different FL's from my first developments some 20+ years ago ...

Viktor

[planters]

Thanks, I'll look forward to it.

[norty303]

You are forgetting to factor in a cost for 'peace of mind' and reliability.
Compared to diodes, DPSS are a pain in the butt and fragile.
That's why we've gone for 6W 520 in the upcoming projectors.

[planters]

Building a DPSS from scratch at those power levels as opposed to a "I think I saw a brief flash of green light", experiment, is not much short of a graduate level course in optics and electronics. I know, I've done it.
It can be a lot of fun, but it is not a way to save money. If you haven't seen this video you may want to take a look at it.
https://www.youtube.com/watch?v=Pp9hliLJjg4

[blue]

You are forgetting to factor in a cost for 'peace of mind' and reliability.
Compared to diodes, DPSS are a pain in the butt and fragile.
That's why we've gone for 6W 520 in the upcoming projectors.

Well since I'm not interested in building a module for a projector, just a "non-handheld laser pointer" for lack of a better term, just for the fun of it, I don't care much about reliability.
But I have heard about the difficulty in building a DPSS laser. So I'm only thinking about red and blue builds for now. And who knows, maybe the 1W green diode price will drop a little while I'll be busy building those or a higher power one will be released.

I also watched the video by planters about building a high power DPSS modules. And I've completely forgotten what he said there... I'll need to rewatch. I only remember he said it made sence to build a DPSS yourself rather than get a chinese one only if you needed a 2W+ of power, which I'm going for, so I haven't dismissed DPSS as an option for a future green build completely.

BTW, how is 520nm compared to 532nm? Is same power noticeably dimmer for 520?

Anyway, right now I'm thinking of a 3 diode blue build. Blue is the cheapest and I actually have 0.8W blue in the single projector I own so I'll have something to compare the 9W+ beam to.

[planters]

What about knife edging few DPSS modules?

This is perfectly reasonable. There are other possibilities as well.

In order to increase the power of the green beam you can use a PBS and a wave plate (or rotate one of the DPSS heads 90 degrees) and combine two lasers. This has the advantage of increasing the brightness because the beam does not enlarge as with knife edging. However, you are limited to two lasers. Most, and possibly all, of the CN DPSS lasers are based on vanadate and are polarized. One exception is is the more powerful Laserwave modules. Here they have already combined two smaller units with a PBS within the head. The green diodes are also polarized and so you could mix a DPSS and a diode in a PBS as well.

You can knife edge DPSS heads as well as direct diodes and even mix a direct green with a DPSS. A little trick to these combinations is to include a steering mirror prior to the combining. This eases the requirements for mounting precision and makes the co-alignment more precise. Keep in mind that the more complicated the arrangement the more ways that optics can misalign.

I actually like the DPSS lasers because the power comes out of the head reasonably well focused (often this can be noticeably improved) from a mountable block with a compatible driver. I do not do mobile, professional work and so I'm not throwing projectors into the back of a van. These DPSS lasers have proved to be stable and reliable and cost effective. The choice as to which to use will change as time goes on.

[planters]

I think you get the gist of my post. I agree with your analysis. The reason to use a wave plate is that the DPSS heads are easier to mount to the base plate without fabricating a "L" shaped bracket. And if the beams are not rotationally symmetric then you might end up with a combined beam that is more like a cross "+". Wave plates don't rotate the visual appearance of the beam, just the invisible electrical field which makes PBS combining possible.