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Video Projector Zoom/Focus Assembly as Beam Expander

aaronnoraa

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Just wanted to share my experience and some pics of a large Epson LCD video projector's zoom/focus assembly working as an excellent beam expander. An added benefit is that you do not need a collimating lens in front of the diode with this setup, the diode's output goes directly in to the assembly. The lenses are wideband AR coated and there was hardly any reflection at all from the input lest back to the diode. Output was pretty spectacular, these pictures are with an M462 and a PL520 as sources. I'm sort of itching to try this with an NUBM44..
 

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RedCowboy

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Very Nice +++

This is what I want to see more of, repurposing what's at hand, I love to see people make something out of spare parts work, it's a cost effective way to obtain otherwise expensive special made parts and the desired results.

You may want to try a NUBM06 with it's GBall intact, I have been using them with the sanwu 3X BE and as long as the initial focus is anywhere from half a square to a line it produces a useful beam that does work.

If that setup has enough range of adjustment you could use a cylindrical pair or a prism pair although I prefer the cylindrical pair to correct that aggressive axis of a NUBM44, you will need a G2 primary but they are efficient so that's good and you can adjust to fit your units range.

I wonder about knife edging 3 or 4 NUBM44's with G2's, not focused to infinity but just reduced to a level 1 divergence such as the 462 puts out.

Many options can be tested, have fun and do post more pics. :gj:
 
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steve001

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A couple more..
Ok, interesting photos. The whole point and purpose of a beam expander is to create a smaller spot in the *"far field". In other words, showing photos of the beam in your bedroom does not demonstrate what a beam expander can do. You've got to find some distant object to do that type of demonstration. It would be interesting to include beam divergence measurements.

*Far field means a distance passed the Rayleigh Length.
 
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RedCowboy

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I thought about that too and that's the range that could be compensated for by changing the input beams focus, it's worth a try, you may get wings but as it's a multi lens projector output zoomer you have a good chance.
 

aaronnoraa

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I'll try to give a divergence measurement if I can get a long enough distance to me meaningful. I live near an airport so next time I remember when I'm heading out somewhere more accommodating I'll bring it along. I figured just the idea might be useful to people and if someone had one available that they might give it a shot themselves. I can say that it definitely is reducing divergence as a beam expander should, the M462 does not expand a measurable amount in 25 feet when it very clearly expands as a bare beam.. though yes, I'm interested to see what it does at a few hundred feet myself.
 
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paul1598419

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Yes, I too, would like to see what his can do in the far field. You might have to go somewhere there is less population, but the airport shouldn't be a problem as you will be using this along the horizontal axis.
 

aaronnoraa

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I also wanted to mention that the reason that the beam appears to expand as depicted in picture 2 is that the beam is at in incline, getting nearer to the camera after reflection off the mirror.. the beam was not actually getting wider to any degree that was visible to the eye in such a short distance.
 

paul1598419

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I caught that. It wasn't a problem I was thinking of at all. Just would like to see what the BE can do in the far field.
 

Ricker

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Too awesome!! Keep up the good work, + rep!
 
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RedCowboy

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Yes, I too, would like to see what his can do in the far field. You might have to go somewhere there is less population, but the airport shouldn't be a problem as you will be using this along the horizontal axis.
AIRPORT ?
Lasers and airports don't go together at all, I stick to my yard and the trees 180 degrees from the airport, a controller in an airport tower doesn't need to see any beams or intermittent flashes even coming his way so if you do point to a tree line make sure it's not even in the direction of any airports just to be safe.
 

paul1598419

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Since he is in Seattle, I assumed he was talking about the Boeing airport, which is not Seatac. I think he knows how to keep laser light from going near an airport just as I do. The warning was unnecessary and just overkill.
 

RedCowboy

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It's not just us " EXPERT " who read these post, no the majority of those here are visitors and I want everyone to understand it's a good idea to know where your airports are and to avoid any helicopters being dispatched to investigate flashes, just watch youtube videos of lasers many miles away and see how noticeable they can be at a great distance in the night sky.

I don't know the average height of an airport tower, but from the 20th floor of a downtown building I can see stone mountain and ribbons of highways for a long way.

These guys are looking across water 9 KM apart, but being elevated in a tower/building has the same effect.

 
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paul1598419

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Yes, they can be quite visible at night, but usually only when pointed directly at someone or something. Your YouTube video shows that very well. If not pointed upwards or at anyone, it is difficult to see a laser even in darkness. Even low flying aircraft can't see lasers that aren't pointed at them. The problem you are describing only happens when someone is intentionally trying to disrupt aircraft. To use a laser with a BE at night to try to get an idea of it's divergence after expansion should cause no real problems if one is aware of his surroundings.
 
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RedCowboy

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Since he is in Seattle, I assumed he was talking about the Boeing airport, which is not Seatac. I think he knows how to keep laser light from going near an airport just as I do. The warning was unnecessary and just overkill.
When giving advise about something that can land a person in prison it's best not to assume.

He said he lives near an airport.

Here are his exact words : I live near an airport so next time I remember when I'm heading out somewhere more accommodating I'll bring it along.

Just admit you gave bad advise and learn something, you can blame the Russians when you're alone, but don't give someone bad advise that could cause them serious trouble on an unfounded assumption.

There are municipal and private airports.
 
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paul1598419

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You are quoting me in my response to your post, not his. I don't regret anything I said to aaronnorra. I only regret having to deal with you and your assumptions about me. It is getting to the point where I no longer feel like responding to you at all.
 




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