New Video

[steve-o]

Yes this was partially in response to your post:

Something that has occurred to me is whether the enthusiasm for the construction of more powerful and higher quality laser projectors has largely disappeared. Has the availability of inexpensive projectors from China made the construction of a projector anachronistic?

On another (personal) note, I find myself not getting as excited as I used to be about drilling, tapping and mounting lasers, dichros and scanners anymore. I hope that I have not lost the bug. Maybe just taking a breather (and to let the wallet cool off too) .. heh ..

[planters]

I HAVE lost THAT bug. That is why my projects have largely turned away from simple projectors. Aside from the multiplexing technique, I'm working on a pulsed laser (I give a short view at the end of the video) that could be used for display, but is laid out to allow it to be used for targeting. The large optical deck will allow me to experiment with different cavity designs to maximize power and minimize divergence. Also, there is room for galvo driven, slow and huge mirrors as well as a camera. We'll start with manual targeting and we're looking at auto tracking, auto targeting software. The problem (as I see it) with the current military systems is that although they are more powerful, they are all IR and that just doesn't look that neat.

[steve-o]

Sounds like you have some interesting projects lined up Eric. I saw that last part of your vid of the pulsed laser. Can't wait to see that monster fired-up. I also like slow scanners with huge mirrors! Allows for big fat beam at the ap and very very low divergence (as you know)
I'd like to start working on a visible energy beam device with cutting power at 300 ft or so .. I don't have a clue where to begin with that one heh

[planters]

For energy delivery divergence is important. There are some exciting cavity designs that fool the bulk medium into seeing the cavity as exceptionally long and this reduces divergence without sacrificing power. The mirrors can be big because the requirements for tracking are so much slower than for scanning. I'm thinking of mirrors with a minor axis of 50mm. The large optics also help increase the damage threshold of the optics when dealing with pulsed lasers. Another advantage of large optics is the ability to set a strongly converging focus, so that once the target is hit (or missed) the energy quickly diverges.

If you were going to go this route as well then the decision is lots of CW power (like a bunch of 9mm 445 lasers) or less, but pulsed, power. The problem with CW is you have to remain on target for some minimum time and the tracking software might not be able to hold a precise spot even if we're talking tens of milliseconds. And if it is auto tracking how does it know what is long enough, but not too long?

Let's say your target is a uniquely colored helium balloon. The camera has to have a wide enough FOV to "see" it, then the software has to detect it and then decide to fire. This is all pretty neat and can be implemented in levels from the laser on up.

[steve-o]

Slightly off topic, but back on topic ..sort of.. would one be likely to combine a 520nm di diode laser with a 532 dpss using this prism setup that you displayed in your video? Of course the cooling of the diodes would not be relevant in this case ..

[swamidog]

Slightly off topic, but back on topic ..sort of.. would one be likely to combine a 520nm di diode laser with a 532 dpss using this prism setup that you displayed in your video? Of course the cooling of the diodes would not be relevant in this case ..

modulation timing would be an issue, and it would be simpler to use a pbs cube.

[planters]

It would work. That is why I brought up the possibility of 445nm/462nm combining. You can use a PBS cube AND wavelength combining to double the power, twice. The relatively large spacing from 520nm to 532nm and from 445nm to 462nm would make the prisms easier than when combing the more closely varying red wavelengths and the spacing between the prisms could be smaller.

The timing issue has always stumped me. If the goal is to have all the lasers start and stop with the precision of the all diode systems and many of us use the Stanwax color correction boards to reduce the delays in the DPSS lasers then the addition of a diode green should not make that a problem. Use the fourth channel and feed it with the same modulation input as the DPSS, but output it to the 520 diode. This way you can adjust both green channels independently. The result should be no worse than the old DPSS plus diode systems and probably better with the diode cleaning up the starts and tails.

[steve-o]

I can foresee a 405/445/462/520/532/610/638/660 sometime in the future .. but having 8 lines like this causes a problem iirc .. I just can't remember what it is .. probably alignment .. :/

[swamidog]

It would work. That is why I brought up the possibility of 445nm/462nm combining. You can use a PBS cube AND wavelength combining to double the power, twice. The relatively large spacing from 520nm to 532nm and from 445nm to 462nm would make the prisms easier than when combing the more closely varying red wavelengths and the spacing between the prisms could be smaller.

The timing issue has always stumped me. If the goal is to have all the lasers start and stop with the precision of the all diode systems and many of us use the Stanwax color correction boards to reduce the delays in the DPSS lasers then the addition of a diode green should not make that a problem. Use the fourth channel and feed it with the same modulation input as the DPSS, but output it to the 520 diode. This way you can adjust both green channels independently. The result should be no worse than the old DPSS plus diode systems and probably better with the diode cleaning up the starts and tails.

yes. i have one of the old dz boards (before he sold the rights to stanwax) in my dpss/diode projector and it makes a huge difference. i'm a little spoiled with my all single mode projector, but then it's only ~300mW.

[planters]

You do not need 405 and 610 doesn't exist (as far as I know). I think there will be a richer color palate when broader sources like the built up reds and the combo greens and combo blues are used, even if there are still only 3 channels. I may be wrong.