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G7 lens, What is it?

RedCowboy

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Yes and the emitter it's self is rectangular, so what goes into the concave cylindrical lens looks like l and the narrow side to side part is the fast expanding axis.

I just focus my horizontal line at 15 feet or infinity and then work at 15 feet to center the horizontal line, then the concave cyl expands that line from 2 inches to about 3 feet and it has to be centered and the lens tilt must align with the emitter as well as the lens rotation must be in alignment, " parallel to the emitter" as seen at a distance, then the 2nd lens the cyl convex is placed to set the least divergent beam as possible by moving fore and aft but must also be in 3 dimensional alignment. Like holding a magnifying glass under the sun it prints an image of the point source correctly when aligned on both axis.

But by working at 15 feet it's easier to get the alignment right, if attempted on a desktop your bar may look like a flag in the wind all bent and wavy when re examined at a longer distance.

The 7875 uses 2x or 3x and the 44 and 06 diodes use 6x that's not perfect but pretty good. If you want some try LSP or OPT, also I have seen some Chinese pairs on flebay but have not tested them yet.
 
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steve001

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Yes and the emitter it's self is rectangular, so what goes into the concave cylindrical lens looks like l and the narrow side to side part is the fast expanding axis.

I just focus my horizontal line at 15 feet or infinity and then work at 15 feet to center the horizontal line, then the concave cyl expands that line from 2 inches to about 3 feet and it has to be centered and the lens tilt must align with the emitter as well as the lens rotation must be in alignment, " parallel to the emitter" as seen at a distance, then the 2nd lens the cyl convex is placed to set the least divergent beam as possible by moving fore and aft but must also be in 3 dimensional alignment. Like holding a magnifying glass under the sun it prints an image of the point source correctly when aligned on both axis.

But by working at 15 feet it's easier to get the alignment right, if attempted on a desktop your bar may look like a flag in the wind all bent and wavy when re examined at a longer distance.

The 7875 uses 2x or 3x and the 44 and 06 diodes use 6x that's not perfect but pretty good. If you want some try LSP or OPT, also I have seen some Chinese pairs on flebay but have not tested them yet.
Experiment with round cylindrical lenses instead of square ones to see what it does to the beam shape.
 

RedCowboy

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This one if used after a culminating lens makes a liquid sky line from left to right, it's impressive on a foggy night.

Chris used one in a big expander set up, but I want the power in the far field, not just a dot. Correction up close 1st I think is the way to go, but show me a better way, I would love to learn a shortcut.

 

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steve001

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This one if used after a culminating lens makes a liquid sky line from left to right, it's impressive on a foggy night.

Chris used one in a big expander set up, but I want the power in the far field, not just a dot. Correction up close 1st I think is the way to go, but show me a better way, I would love to learn a shortcut.

When you have time try this experiment. Using one cylindrical lens orient it to expand the slow axis and note the spot shape. Now place the other cylindrical lens so it too expands the slow axis. Note the spot shape. Let me know the results please.
 

RedCowboy

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I get the idea that you can square up the beam that way, but it will still need to be reduced, Chris did just that with one of these lenses.

But squeezing the fast axis produces useable results now, I don't care about a perfect beam shape, just energy density at distance.

If the slow expanded would then be run through an expander or telescopic reducer then why not just use the expander to start with?

Tiny energy dense square or rectangle, either is ok with me, but an ever diverging fast axis is the problem, are you thinking the slow could cross over and surpass the fast if not squared up.

I had this discussion with an expert before and round only lenses just didn't make sense.

With portable devices starting small is a better idea, if I could get a tiny fused silica FAC on the emitter I would.

The smaller the emitter the better for long range tight beams.

p.s. I have boxes of scavenged lenses but not any scientific sets of incrementals to work through, I need to decide what to buy and not just trial and error with expensive parts.

Planters is an expert, he does the Tech Ingredients videos on youtube and builds high end light shows, he could butt heads with you on ideas.


Also what I think Chris did was to defocus his G2 "primary" and use that linos to expand the slow axis then with a large concave and aspheric made a large diameter expander.

I don't mind going that route, buy I like a fixed beam that's useful from point blank to a reasonable distance. Or doing both. But the rapidly expanding fast axis is a real issue with these MM diodes.
 
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steve001

Well-known member
Joined
Jun 3, 2007
Messages
2,466
Points
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I get the idea that you can square up the beam that way, but it will still need to be reduced, Chris did just that with one of these lenses.

But squeezing the fast axis produces useable results now, I don't care about a perfect beam shape, just energy density at distance.

If the slow expanded would then be run through an expander or telescopic reducer then why not just use the expander to start with?

Tiny energy dense square or rectangle, either is ok with me, but an ever diverging fast axis is the problem, are you thinking the slow could cross over and surpass the fast if not squared up.

I had this discussion with an expert before and round only lenses just didn't make sense.

With portable devices starting small is a better idea, if I could get a tiny fused silica FAC on the emitter I would.

The smaller the emitter the better for long range tight beams.

p.s. I have boxes of scavenged lenses but not any scientific sets of incrementals to work through, I need to decide what to buy and not just trial and error with expensive parts.

Planters is an expert, he does the Tech Ingredients videos on youtube and builds high end light shows, he could butt heads with you on ideas.


Also what I think Chris did was to defocus his G2 "primary" and use that linos to expand the slow axis then with a large concave and aspheric made a large diameter expander.

I don't mind going that route, buy I like a fixed beam that's useful from point blank to a reasonable distance. Or doing both. But the rapidly expanding fast axis is a real issue with these MM diodes.
I was only trying get the beam to an oval shape. Try both lenses to see how much they cause the fast axis not to expand. No matter how you go about it, I think you'll need a third cylindrical lens. Once you work out a solution then pass it through a beam expander focused at distance.

Square cylindrical lenses have only two orientations X,Y round ones don't, but there's no difference in how they perform.

In this vid he uses a round cylindrical lens https://www.youtube.com/watch?v=_POfjxeAEvU
 
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