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RedCowboy

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Yea the power of the lens for its size will need to be high, like a big wide G2.

I have tried those big 100w LED lenses but it makes terrible wings.

The G2/G9/G7 has a compound shape.

We need a big wide lens with this compound shape.




I have some that are flat on the back and slightly concave on the back, also double convex, but not just slightly convex on the back, all these make wings, but my 25mm 3 element works well except it clips some, maybe a wider setup like the 3 element retuned to clip less or a big G2 grind.




 

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Alaskan

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I believe you are correct, I have a 7 inch PCX lens to do the same thing with, but it always has wings. Because so much of the beam was cut off using my two lens assembly, the wings couldn't make it through to see them.
 

RedCowboy

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100x the G2 would be 700mm wide and the FL would be 239mm.

50x the G2 would be 350mm wide "14 inches"

We need a wide lens, say 50x the G2 so rather than 7mm it would be 350mm wide or about 14 inches with a G2 shape grind.

With a FL of 119.5mm rather than 2.39, so around 5 inches out we could adjust it to focus to a point and have a big cone with all the power focused into the point, a point that would be much tighter at any given distance vs the smaller lens. 50 times tighter at any given distance.

Maybe we should go with 25X that would be 175mm wide with a FL of 60mm, that is 7 inches wide lens with a 2.4 inch rear FL.

That's if this is a linear calculation, if so then beam shaping first may be better to keep the lens width manageable and not have huge wings.


So.......if this is correct a 175mm wide G2 shape grind lens would be 1/25 of 2 inches at 5 meters, that's about 2mm wide line at 15 feet with all the power, so a 7 inch wide G2 grind would be good, and a 3.5 inch G2 grind lens would make a 4mm long line at 15 feet, still very good, but only half of what a 6X pair produces, still the adjustability would be nice and 3.5 inches wide is not too big for a line 1/12.5 of the regular G2 and twice as good as the 6X pair. But it would need to be a 3.5 inch wide lens with a G2 shape grind and if optical glass that could be expensive, maybe a less that super pure glass...I wonder about quartz or fused silica and AR coated.

I'm thinking NUBM06 with G2 and 6x pair with a 3X expander, I burn at 75 feet with the 44 so the 06 being 25% less divergent would be even better, maybe cube a pair, then if you could find a 2 inch wide expander that ran at 5x even better still.

I would like to find some larger lenses with the G2 grind, even if not AR coated.
 
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Alaskan

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Nice lenses you've been experimenting with, I don't know much about this problem or whether a larger aspherical lens with a G2 form could do the trick, but I'm eager to know if such would be the answer to reduce the wings. I did read a post on another forum regarding which lenses are best for laser diodes and they were listed like this;

#1 Aspherical

#2 Plano-Convex

#3 Bi-Convex (least desirable).

Regardless, each will collimate a laser beam to infinity but the aspherical doing the best job.

I found this on Wikipedia:

The asphere's more complex surface profile can reduce or eliminate spherical aberration and also reduce other optical aberrations such as astigmatism, compared to a simple lens. A single aspheric lens can often replace a much more complex multi-lens system. The resulting device is smaller and lighter, and sometimes cheaper than the multi-lens design.
Maybe consider this as an alternative method of reducing the wings, it worked for me with this diode:

I have another pointer with the NUBM44 diode in it, it's my Mace of Doom host with a 500mm telephoto lens assembly on it which only has one lens in it, the diameter is about 2 inches aperture. I finally found the right lens for it where I don't get wings, it's just a PCX lens too but only about 50 percent of the diameter or aperture of the lens is being used and an out of focus G2 lens is used to adjust the diameter of the spot. So, the real diameter of the beam is closer to 1 inch, but no wings and fairly low divergence at that amount of expansion. From that it appears when using a PCX lens to collimate the beam, if only half of its diameter is used, the wings disappear. From this I wonder if lenses with less curvature might be what we need, or longer focal length lenses which are far thinner might produce the same effect.

By the way, the two lens assembly I posted the video of the beam has a slightly concave lens at the input too. (Edit: I take that back, it just appeared to be slightly concave due to the way it is set inside the tube, it might actually be slightly convex).
 
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GSS

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Ok i'm going to say this, now no laughing or at least do it behind my back:whistle:
Iv'e got one of those $29.99 Walmart special telescopes. Obviously a hand magnifying glass will give you a better view of the moon, but taking about has given me use with it due to eye pieces, stand, little FS mirror etc.
I'm thinking maby iv'e seen one of you 2 have mentioned using one but that knob slide focus could come in handy as its 2 1/2 in. wide at the scope side:eek:
 
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Alaskan

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I've used a cheap telescope like that, the kind used for astronomy which don't have optics in them to turn the image back upright again (as binoculars or bird scopes do), and it worked great as a beam expander. Can be tricky in one respect though, if the raw output from your laser pointer diverges too much and wastes a lot of the light due to being wider than the collimation lens on the end, or not wide enough and then the beam doesn't expand enough.

This might work for you too: When using a pointer with a threaded lens such as a G2 or 3 element, just defocus the pointers lens the amount needed so 80% of the lens on the end (the objective lens) is filled with light and move that focus knob in and out so the laser pointer attached to it is moved to and fro to find infinity focus, worked for me. Oh, I didn't use the eye piece at all, took it out and put my laser pointer into the tube where it was.
 
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badboybilly

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Today I was messing around with some telescope eyepieces and by expanding the raw output of my NUBM44 using these 2 lenses I was able to get a really small dot at 8 metres, it looked awesome, no line whatsoever, I had the first lens about 10mm from my diode and the second about 20mm from the first, I tried many different spacing but the best was the way I show in the pics, the hard part is now arranging them in a tube at the wright distances, I haven't yet tested the power loss but I'm thinking it's substantial with the second doublet lens, but it looks awesome a 20mm expanded beam ending in a dot not a line, I also had a 10mm eyepiece but that didn't work out to good!

Yeah I was right nearly 2.5w loss that is crazy but a very nice beam.
 

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GSS

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bbb, yes looks good. The big lens on my cheapie scope is basicly just thick glass with very very little maginification. Who has tried the knob turned slide focus to do just that as the eye piece side is small enough to fit a medium size laser and its exit would fit a 2 1/2in. lens?

bbb, really 2.5W but still very cool like you said!
 
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Alaskan

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I've done that with this telescope:



Eye piece from the telescope was removed to allow me to insert a small 8 dollar laser I found on ebay. Also, I took the lens out of the laser and the beam happened to expand enough to completely fill the lens on the end of the telescope without over filling its diameter, sliding the focus adjustment in and out by turning the knob I could focus to infinity. Cheap beam expander since I bought this at a 2nd hand store for five dollars, ifI remember correctly, ten at the most. It is just a cheap plastic kids telescope but worked fine. It doesn't have a 2.5 inch diameter hole to put a larger diameter laser pointer into with, but was just right for this cheapie.

I did buy a 2 inch diameter helical focus adjuster meant for use with a telescope and put a PCX lens on the end of it, then fastened the focuser to a large pointer and it worked great too. The trick is finding a PCX lens which has a focal length that will fall within the adjustment range of the focuser. The beam from the pointer must expand to approximately 50-80 percent the diameter of the lens on the end for this to be worthwhile, I was able to accomplish that by leaving the G2 lens in the pointer, but de-focusing it enough that it produced a large spot on the PCX lens. This is a poor mans expander, but worked well for me using a 1 watt 520nm green laser diode.



In these following two photo's you can see I put a larger diameter lens on the end, I just thought it looked better. I only used black electrical tape to fasten everything together.




Link to the same model helical focuser on ebay: http://www.ebay.com/itm/2-Ultrawide...-f-telescope-guider-Photography-/181570237172
 
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GSS

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Yes thats what i'm trying to get at. I can't post pics to show but were your focus slide goes directly into the a little bit wider scope itself, mine just expands at that enterance point to 2 1/2 in. with a 1 in. lip that slides onto a aluminum tube that make up the length of the telescope. So if I were to find the right lens it will be right there in front of the inserted laser.
 
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Alaskan

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If your telescope already has a lens on the end of the tube which was made for it, you might be able to get this to work by simply defocusing your laser pointers lens.
 

GSS

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If your telescope already has a lens on the end of the tube which was made for it, you might be able to get this to work by simply defocusing your laser pointers lens.
The only lenses it came with was the big 2 1/2 in. at the far end but its just about flat with barely any magnification and its 2 different eye pieces where each one has 2 lenses inside but are just little magnifing glasses so I can't see them working as an expanding lens just probably a tighter dot.
I see BillyB's eye piece lens that looks like a colominator type?
 
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Alaskan

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The lens on the end doesn't need to be a high magnification, as long as it has enough curve so that the beam from your laser diode can be fully collimated. The less curve, the longer the focal length, that's all. I don't know anything about eye piece lenses, zero, sorry.
 

GSS

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The lens on the end doesn't need to be a high magnification, as long as it has enough curve so that the beam from your laser diode can be fully collimated. The less curve, the longer the focal length, that's all. I don't know anything about eye piece lenses, zero, sorry.
I'm going to try a bit more to take it out without breaking the plastic as it seems to have a little glue in to see just how much of a curve it has or hasn't. It seems to just make my 40 in. TV look like a 42 in. As a matter of fact I think it did help produce a kinda tight spot when I focused out my 1W 445 to a big splash. I tried a bunch of other lenses so i'm not sure if that was the one. Thx Alaskan:)
 

Alaskan

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In this case, they way I see things, it is how much the beam itself expands which creates the magnification, not the lens itself, all the lens does is collimate the light into a parallel output.
 

CDBEAM777

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Wow...Just stumbled upon this thread !! Nice work all on taming that optically rotten, yet very powerful 044E beam !!!

Thanx for sharing !!!

CDBEAM=======>
 




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