Home Made Monster Beam Expander !

[steve001]

determine the focal length of the negative lens

Yes and without fancy equipment.

 

[Accutronitis]

Yes and without fancy equipment.

lol, ok that's good to know........

 

[Accutronitis]

I got some pretty cool lenses out of that Japanese TV camera zoom lens but it has several so I don't know if I will have the super powerful combination of just 2 lenses that I want, but I am going to keep looking.

Are yours scavenged or do you know the exact grinds you have, I have made about a 2.5X from a double concave and double convex, but looking at my Linos expander it seems we need some very aggressive aspheric front lenses as well as a pretty strong bi concave.

Binocular lenses will likely work but I like all my bino's, I could order some, the old K-mart focal were Japanese made and pretty good quality for the price.

I also have a spotting scope but I use it at the range, I could order an inexpensive one, a basic tube not a prism type. Galilean ?

My Linos is coated for 1064 and it is just wrong for the nubm44 corrected or not, it's a 2-8X but with the center relay lens it is made for small beams it seems and with the 1064nm AR coating I don't want to use any of the lenses.

----EDIT----

Did you keep your same primary and just add a wider longer FL exit lens? I have thought of doing that with a sanwu 3X, use the primary and replace the exit with a wider longer FL on a sliding slip over that surrounds the host body.

Hey ! maybe there is a lens that would work great as a exit lens for a BE mod ???

And only $5 bucks !!!

https://sites.google.com/site/dtrlpf/home/projector-optics-mirrors-dicros-lenses-motors

 

[VirtueViolater]

Awesome work guys, always wanted to build my own BE, even collected lenses for a while, never got around to it tho

 

[RedCowboy]

I have a dozen of those, pretty cool little set of lenses and dicros, but I am thinking I want a 2-2.5 inch wide exit lens and I suppose I should examine the FL of the sanwu as I am thinking to use the input lens and a wider longer FL exit set further away, likely I will try some trial and error.

I have probably 200 or more lenses not counting duplicates of which I have many, I'm just not moving real fast getting it done, also I have a size concept in mind and I need to build a corrected NUBM44 test bed like the one I showed you I have started so I can start testing, I've just been busy with other stuff.

Here's a 5 inch pair of bi concave and a PCX that's ridiculous, I can just imagine this on the end of my laser, maybe with a Heinz Doofensmirtz wheel on a stick to hold the end up.

-----EDIT-----

Seems like the 3X has about the perfect grind output to match its input and it's not a super long FL, it's fairly aggressive, I have tested a bunch of lenses in the size range I wanted but none are quite right, many times the beam out of the 3X input falls off the edges of the test lens, in short the 2-2.5 inch exit needed to work with the 3X input lens is going to be a shorter FL, that is bulgier in the center, a higher magnification power.

Accutronitis are your lenses both bi convex or pcx, that is does your input lens have any concave geometry on either side of it?

To use that bino output you need a low power input and a lot of length, I see you have the length, so do you have a bino style input that's convex rather than concave?

I suppose I could take the lenses out of a pair of 50mm 7X binoculars and make up for the prism with a longer tube, but using a concave input will let the expander be shorter as the beam does not need to cross over before re expanding, amazingly I think I need a higher power 2.5 inch lens than the ones I have. Actually I know I do as the 3X was designed to be short, for far field fine adjustments a longer device would work better it seems to me.

 

[RedCowboy]

I forgot about all my projector TV and projection TV lenses, did you know there were DLP TV sets, I have some of those optics too, no lasers they used the big projection bulb.

This piece is almost an expander just needs to be repackaged.

 

[Accutronitis]

I forgot about all my projector TV and projection TV lenses, did you know there were DLP TV sets, I have some of those optics too, no lasers they used the big projection bulb.

This piece is almost an expander just needs to be repackaged.

Heck ya ! I wonder what the mag is ?

 

[RedCowboy]

I don't know, but I found some 2 inch PCX lenses that work great, that's flat on one side and convex on the other, I get an open flame on my wood panel target at 6 feet which is what the 3X can do when dialed in, this by the math should hold tighter further as my lens print is bigger and the FL from the 3X primary is longer.

I unscrew the output off the 3X and use the 2 inch PCX by hand, my cam likes to auto shunt, that's why one pic looks brighter.
This is with a NUBM44 and 3 element and 3X input, if I use this with a 44/G2/6X Cyl corrected/3X input then it will be quite the nasty burner.

 

[Accutronitis]

I don't know, but I found some 2 inch PCX lenses that work great, that's flat on one side and convex on the other, I get an open flame on my wood panel target at 6 feet which is what the 3X can do when dialed in, this by the math should hold tighter further as my lens print is bigger and the FL from the 3X primary is longer.

I unscrew the output off the 3X and use the 2 inch PCX by hand, my cam likes to auto shunt, that's why one pic looks brighter.
This is with a NUBM44 and 3 element and 3X input, if I use this with a 44/G2/6X Cyl corrected/3X input then it will be quite the nasty burner.

There you go, Now your cooking ! That should really increase your range ! Maybe you can have ElectricPlasma 3D print a BE housing setup ?


That's so cool you could just screw the output lens off ! To get the output lens out of my jetlaser BE i had to destroy the housing but i got both lenses intact........

How much refection back do you get from that PCX flat surface ? And have you tried it curved surface first ?

 

[RedCowboy]

It's out of a projector TV I think so it's likely VIS coated, answer is not much.

Here's a bigger aspheric, about 3 inches wide, from a projection TV optic, the outer lenses are acrylic but the center is a strong aspheric, I will have to try both on a 6X corrected beam.

Uncoated optics only lose 5% max IIRC

 

[Accutronitis]

It's out of a projector TV I think so it's likely VIS coated, answer is not much.

Here's a bigger aspheric, about 3 inches wide, from a projection TV optic, the outer lenses are acrylic but the center is a strong aspheric, I will have to try both on a 6X corrected beam.

Uncoated optics only lose 5% max IIRC

By the time you get done you could end up doubling or even tripling your range with a home brew BE !

For a second there i thought i was going to go by you with the smallest dot with the most power at the farthest range, But i can see that's not going to happen ! lol :banghead:

 

[RedCowboy]

I have a bunch of these lenses, I can send you some, no money needed.
I will probably get EP to 3D print some holders for me.
Did you say you used the 10X input lens?

 

[Accutronitis]

I have a bunch of these lenses, I can send you some, no money needed.
I will probably get EP to 3D print some holders for me.
Did you say you used the 10X input lens?

I'm going to grab some late dinner. bbiab

No, So far i've only used the output lens because the input lens from the JL BE is too small for the 6X cyl corrected beam......

But i'm will to bet the input i'm using now is at least as concave as the JL input lens ?

The JL input lens is a PCX lens (flat on one side) and the one i'm using right now is a double concave lens...

 

[RedCowboy]

I went down to my basement and the 3.25 inch aspheric works great with the sanwu 3X primary following a 3 element, the trick is alignment, just like holding a magnifying glass between the sun and the ground you have to be aligned, so as long as I have my laser firing straight then using a sliding lens holder will work, the spot is tighter and smokes the wood at 15 feet like mad, with the 6X corrected beam its just spitting a flame kernel like the wood had a natural gas leak on fire.

Correcting the aggressive axis 1st is still the way to go and I may still find a more fine tuned lens setup, but just the 3X BE after 6X correction makes a big difference, I still want a lot more power, but it's going to need to be focused as well.

I wonder how well the aspheric might work with the raw output? We would not have the 3 element losses if it fits the lens. Maybe a G2 lens but only focused to a wide beam slightly less divergent than raw output to custom tune the beam width to the larger lens.

More testing is needed, but so far the smoke and flames look good.

 

[Accutronitis]

I went down to my basement and the 3.25 inch aspheric works great with the sanwu 3X primary following a 3 element, the trick is alignment, just like holding a magnifying glass between the sun and the ground you have to be aligned, so as long as I have my laser firing straight then using a sliding lens holder will work, the spot is tighter and smokes the wood at 15 feet like mad, with the 6X corrected beam its just spitting a flame kernel like the wood had a natural gas leak on fire.

Correcting the aggressive axis 1st is still the way to go and I may still find a more fine tuned lens setup, but just the 3X BE after 6X correction makes a big difference, I still want a lot more power, but it's going to need to be focused as well.

I wonder how well the aspheric might work with the raw output? We would not have the 3 element losses if it fits the lens. Maybe a G2 lens but only focused to a wide beam slightly less divergent than raw output to custom tune the beam width to the larger lens.

More testing is needed, but so far the smoke and flames look good.

That's the same as i experienced ! Your right the trick is alignment for sure, The temp housing i made on the quick wasn't very good at the alignment so the farther away i checked the dot the more messed up it was but even so it still burned hot but i know once the alignment is much more precise the dot will straighten up and all the power will be in it ! Like i said before the flame was jetting out and somehow the dot was so intense there was tiny sparks flying out as well ! Even with my eagle laser safety glasses the dot was super bright, So bright i had to squint almost like i needed additional eye protection on top my eagle laser safety glasses and that was from across the room !

But the temp housing proved to me the lens combo that i was trying is a very good one and all that is needed is a housing that maintains much better lens alignment and i'll have a great beam expander for focused high power at long distance !

 

[RedCowboy]

Yep, I know that feeling, the orange spot is painful bright.

I just found a nice 40mm Plano concave and a pair of 100mm PCX lenses, or they could be bi convex, they look like long FL lenses except the Plano-concave, it's pretty aggressive.

Best part is the 100mm's are in a telescoping aluminum housing, I bet I could make use of that, dam it would be big....really needs a 40w single emitter to make it right as I will have 20 pounds of batteries as well.

I also have a 6 inch PCX in a flat mount, it needs 2 of the 8 diode NUBM06 blocks or really maybe an array or NDB7875's like came out of that unit in a round pattern.

A bunch of real lasers that make proper beams, like about 100 x BDR-209's arranged in a round pattern, that could be fun.

-----EDIT-----

If you put your laser module and driver into a 12mm hole centered in a length of round bar stock, then make a lens holder that slides around that round bar stock it should stay centered, but I do like having a run out adjustment.

Still there's a limit to what 7 watts can do, I'm really ready for more power so I can do my wood burning art at natural hand speeds.