how to make pencil thin beams

[kecked]

So I was playing around with beam expanders and spatial filters and found a neat all be it power eating trick to take even the m140 blue make 1mm beams at 30 feet.

I put a 2x beam expander on each diode so I can adjust the focus of each diode. I then run all this through a second 2x extracted from the red section of an arctos projector. You could just use separate lens. I have the diodes combining backwards so the combine beam shoots to the back of the projector. This then makes two turns to shoot it back toward the front. The idea is to lengthen the beam path before the scanners. This lets the expanded beam to start coming back together before the scanners. If you don't do that the beams will not it on 3mm scanners. The image on the screen is pencil thin and bright. A nice side effect is that alignment is more forgiving on the wall. The spatial filter cuts all the crap from the beam. When you then have a pencil thin beam the image is extra sharp and there are no colored edges. It looks ion good.

Down side is you loose about 40% of your power but the reward is worth it. If you use the high power 3w blue, 1w green, and some combine 500mw reds this might be all the beam shaping you need for graphics. For beams I suspect the beam will fall apart in the far field. Still you could get 3-4W all diode doing this. Too bad the reds are not as good as the blues or this would be the end game.

Thanks Planters for pointing me down this path. Credit where credit is do. PS: Spatial filter is before the last telescope (guess it could be the last telescope)

[Galvonaut]

Sounds interesting - do you have photos of the set-up and the beams?

Michelrietveld had a nice combined single mode set-up at Dutchlem and it would be interesting to compare beam specs.

Keith

[badger1666]

yep we like pictures
i would like to know what kvant is doing to get their new dual wavelength blues to such a tight and low diverging beam

[dzodzo]

rip the module open and you shall see or?

[andy_con]

yep we like pictures
i would like to know what kvant is doing to get their new dual wavelength blues to such a tight and low diverging beam

really was that a joke?!

[kecked]

I'll take some photos tonight and post. basically I add 2x telescopes from meshtel.com for like $20usd each and then I have a last telescope that is from an arctos projector. This will soon be replaced by a spatial filter telescope combo. If this works out then one spatial filter will work on the whole beam train. As I said I sacrifice lots of power but the result is stellar. Tell me what you most want to see and I'll photograph it. for example I'll photo the beams on the wall uncorrected but scanned, the beams with the telescopes on them, and then the beams with the telescopes and the final arctos expander. I think you might be able to 3x instead of 2x telescopes direct on the diodes and eliminate the last telescope. Thing is that will need to be a spatial filter with the same optics anyways. It's just a matter of the ratio of the lens in the spatial filter if they expand or not. Last and most important is you need to have enough length of path so the beam will fit scanners after all the expansion. For now I just let it spill over. 50% of my loss is right there. Once I get longer paths that should be fixed. I have achromats coming for the filter.
Please though tell me what you want to see. If I can make this all canned I'll put the design up here so anyone can laser cut the plastic and insert the lens for the filter. You have to get your own blades though. Not getting sued cuz you cut yourself.

[kecked]

update: What works: The telescopes on the individual diodes works very well to HELP make smaller beams.
What could work better. There is no way inside my small projector to get enough path lengths after the last master telescope/filter to make it fit on 3mm scanners. You would need 1 cm mirrors to make it fit. Granted if you live with the spill the beam is really pencil lead thin and looks good but you are losing way to much power
What I could not make work is the spatial filter on all the diodes together. I just can't make all the focus points line up for this one. I suggest on one each diode and just make a single telescope for each one in the 3-5x range. I just don't have the skills to make the lens mounts and all that. It would be nice to see a bit of kit developed by someone. There you have it.

Beam sizes. uncorrected the blue is about 4-6mm at 15 feet. With a 2x telescope it's 2-4mm with the additional telescope it's 1mm
uncorrected the red is about 2-3mm at 15 feet I don't use a 2x on this diode with the additional telescope it's 1mm
uncorrected the green is about 4-5mm at 15 feet after the 2x telescope its 2-4mm with the additional telescope it's 1mm!

I decided not to take picture because I'm embarrassed for the mess my projector is at the moment. I've taken it apart an rewired soo many times playing it looks like a bomb hit it.

[planters]

Kecked,

Take a look at this thread I started.

http://www.photonlexicon.com/forums/...or-A-New-Video

I was afraid that your three color spatial filter would be difficult to align even if the achromats made the focal lengths similar. The problem for me at this point is the flexmounts and the scanners. If we establish the standard of discussing divergence in urad then these components have to improve or we're just going to see multicolored ribbons in the far field and no blended colors. If you remember some time back when Lasertack posted laser beam power distribution "hills", you could see that about 70% of the energy was in a radius only 1/2 as large as the full spot. Spatial filtering allows you to take advantage of this central core.

[kecked]

Ok there you have it. some pictures of my messy projector. those lines are about 1mm thick projected from 15 feet and the full graphic is about 36" wide.
All my electronics but drivers is below. Now that's just power supplies and flexmods. This is straight from Beyond. That yellow is not that bad.

[swamidog]

that sliding rail mount for the mm1's is really slick.

Ok there you have it. some pictures of my messy projector. those lines are about 1mm thick projected from 15 feet and the full graphic is about 36" wide.
All my electronics but drivers is below. Now that's just power supplies and flexmods. This is straight from Beyond. That yellow is not that bad.