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Home Made Monster Beam Expander !

Accutronitis

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Right now it's just a prototype to see how well the two lenses work together but judging from my "across the room test" it's going to work VERY good because from across the room the spot is like the head of a pin !!!

So far, So GREAT !












 



RedCowboy

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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.





 

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Accutronitis

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Did you keep your same primary and just add a wider longer FL exit lens?
Yes that's exactly what i did ! I'm using the strong bi concave from my other home made BE and a wider longer FL exit lens, With the longer FL the beam is expanded to fill the exit lens at around 85%.......

All my lens are scavenged, I don't know the grinds of any of them, The exit lens i'm using in the monster is from a set of binoculars and it is AR coated...

The dot from across the room is so tiny and super intense that when shooting the bottom of a dead keyboard that besides the flame jetting out there are somehow sparks flying out as well !
 
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RedCowboy

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I was thinking I could use a G2 and 6X Cyl corrected beam through a 3X BE input but replace the output with this: NEW Projector Replacement Part Condenser Lens Photographic 78-8704-4753-5 | eBay

The sleeve I put it in could fit over my 2.5 inch heat sink body and simply slide to focus.

I will make the body screws bugle head and counter sink them instead of these round heads.








--------EDIT--------

I wonder how crap these lenses are? and ruby coated, hmm ?

http://www.ebay.com/itm/30x-MAGINFICATION-x-50mm-LENS-DIAMETER-RUBY-COATED-LENS-BINOCULAR-30x50-BC-3048B-/371214073093?hash=item566e153d05:g:qTYAAOSw0vBUjJtA

These say they are Glass lens: http://www.ebay.com/itm/BARSKA-10-30x50-Zoom-Gladiator-Binocular-New-/311337897370?hash=item487d2f4d9a:g:EBwAAOSwNSxVLJDh
 

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steve001

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Right now it's just a prototype to see how well the two lenses work together but judging from my "across the room test" it's going to work VERY good because from across the room the spot is like the head of a pin !!!

So far, So GREAT !












Since the spot a few feet away is tiny then you have the expander focused. Is that correct? What are the focal lengths of the lenses?
 

Accutronitis

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Since the spot a few feet away is tiny then you have the expander focused. Is that correct? What are the focal lengths of the lenses?
I don't know the focal lengths of the lenses, I focus it by sliding the large black section fore and aft, I made this BE through trial and error using scavenged lenses from a hand full of sources...



This is one of two lenses i got out of a set of binocular's, i'm using the other one as the exit lens in the BE.....








 
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steve001

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I don't know the focal lengths of the lenses, I focus it by sliding the large black section fore and aft, I made this BE through trial and error using scavenged lenses from a hand full of sources...



This is one of two lenses i got out of a set of binocular's, i'm using the other one as the exit lens in the BE.....








When you have time measure the focal length of both lenses.
 

RedCowboy

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Do you mean the distance from the lens to it's tightest point?

This will allow us to calculate how wide the spot will be over a distance.

If it's 10 feet across the room and the dot is a pin head wide at it's tightest focus, then at 20 feet it's going to be 2 pin heads wide and so on.

Rather than sensor/film insert wall/ceiling fan.



Here's something to think about, hell I have some of those lenses, that bubble shaped one I just ordered would work with the raw diode output.

 
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steve001

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Do you mean the distance from the lens to it's tightest point?

This will allow us to calculate how wide the spot will be over a distance.

If it's 10 feet across the room and the dot is a pin head wide at it's tightest focus, then at 20 feet it's going to be 2 pin heads wide and so on.

Rather than sensor/film insert wall/ceiling fan.

Yes, but there's only one focal length for any lens
Knowing the focal lengths allows one to know the expanders power.
 

RedCowboy

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Right, the distance from an emitter at which it reproduces an equal size image of the emitter, is that correct?
 

steve001

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Right, the distance from an emitter at which it reproduces an equal size image of the emitter, is that correct?
No. In this case the beam will be collimated for lowest divergence when a given positive focal length lens is place at its focal length from the emitter. You can then measure the separation to get the focal length.
Another is to place a lens in the path of a laser beam an measure the point where the beam converges to the smallest diameter.
 
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Accutronitis

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Another is to place a lens in the path of a laser beam an measure the point where the beam converges to the smallest diameter.
Using this way I'd say the FL of the exit lens is about 180mm ?
 
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steve001

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Using this way I'd say the FL of the exit lens is about 180mm ?
Good. Now determine the focal length of the negative lens if unknown. If known then what is the expansion power of this beam expander?
 
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