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Expansion ratio of ebay cylindrical lens set

Light superglue

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Does anyone know what it is? I mean this set:

We know expansion ratios for LSP, Optlasers and CDBeam GB cylindricals but has anyone explored this set from techhood?
 



RedCowboy

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I think I have read before that they are only 2X but I have not used this set yet.
 

likevvii

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I just received this in the mail. Can anyone else confirm what expansion ratio it is?
I dislike this because I need to space the two lens so far apart (30mm) in order to achieve a great beam profile.
If I purchase higher ratios like 3x or 6x I could space them less apart, like 10mm or less away from each other?
 

paul1598419

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I also have a set of three cyl lenses from Techhood that have an expansion ratio of 3X. About 3 cm is typical for all these lenses.
 

Light superglue

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The point was that the sellers of these sets in ebay do not specify any expansion ratio (what if f1/f2) but only so called "width reduction" =3x what means the reduction of spot width (no idea at which distance !!!) compared to spot width without cylindricals.

To know the real expansion ratio like we know it for CDBEAM`s GB cylindricals we have to mesure focal distances of both lenses.
So I would like to have real numbers and not trust to just subjective data like this "width reduction".
 

likevvii

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I messaged the seller and they responded that it is a 4x set.

superglue you are right, if we actually had numerical data, we could easily calculate.

Upon looking at pictures, it seems only the concave lens gets steeper as the magnification ratio increases. The convex lens barely changes.
Does this mean I should get a 2X set so I can get the beam to converge faster?
Or do I actually need a 6x set?

I basically want to reduce the distance needed between the set.
 

Light superglue

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Hi,
I do not get why do you want to reduce distance. It does not make sense to use those cylindricals for tightly packed multibeam like from 31T and for correction of single MM beams from NUBM44/0708 we need at least 6x or better 10-12x expansion to have a round spot at high distances.
All this was discussed here in 2016-2017 if you look back in the forum.

It is possible to make 10x expansion if you have 2 sets of 2-4x. You just put 2 plano-concave lenses back to back and in this way form a biconcave lens which has twice lower focal distance, so beam expands faster after it. Since we do not know exact f numbers from sellers, you have to experiment with distances here.
Also, if you make a biconvex lens from 2 plano-convex as well, you could get twice shorter set up with twice higher expansion ratio (by theory) if I am correct...
 

RedCowboy

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The sets you have made are a real bargain and the larger size is easy to work with, but I would like a smaller set of 2x or 3x to correct NDG7475.
I have been wanting to do a corrected 7475 build for a while now in a compact size unit, the 10x12mm optics would be about right for that.
 

CDBEAM777

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The sets you have made are a real bargain and the larger size is easy to work with, but I would like a smaller set of 2x or 3x to correct NDG7475.
I have been wanting to do a corrected 7475 build for a while now in a compact size unit, the 10x12mm optics would be about right for that.
[/QUOTE
Well...Yea....I can understand that if you have a limited area to work with....one would want the smallest C-lens footprint !!! INMSHO.....I still prefer a set of 6X for the NDG7475.

The GB lenses are larger, for sure...But...when I start what I call " The Epoxy Dance " I like the larger sets....and...It seems to me...the larger C-lenses...have a larger " Sweet Spot "....and are slightly less difficult to align....but....maybe that is just all in my head....Not Sure ??? Larger or smaller....Both sizes are demanding to get just right.

Better use One (1) hr set clear epoxy....and check and recheck and recheck and recheck....to make sure the lenses have not moved while the epoxy is setting up !!! Gravity can and will slide things around !! Trust me...I have seen it !!!.....( MMMM...Insert tasteless joke here !!! hahahah)....anyway... Later Gentlemen !! CDBeam :geek:
 

RedCowboy

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I use UV cure glue ( metal to glass formulation ) and I lock mine down while powered up and lasing, no chance of it getting moved without me knowing right then and it takes seconds to cure hard, I use a 3w UV led flashlight.
 

Light superglue

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If you remember my blaster - this could be done wth these small cylindricals from ebay and with ones from GB2 as well to obtain more than 2x-6x expansion ratio!

front lens separation adjustment.jpgBlaster 2.jpgway at evening.jpg
 

CDBEAM777

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LSG...MMMM..." A simple Blaster...Morbius " hahahahaha....

RC...YES...I should get with the 21st century....and use a good UV set adhesive !!!!! MMMM...Laser on !!! A little Dosey Doe with the Glass....a little zap with some UV photons...voilà !!! " Bob's yer Uncle " Done !!! Oh....But I would miss mixing epoxy 1:1.....Maybe not !!!

Thanx,
CDBeam
 

likevvii

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Anyone know where to get very small CYL lens 6~10mm, only the convex part but with 50mm+ FL?
I just realized the concave part is not necessary If I am not looking for an infinite beam.
 

RedCowboy

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A trick I have used it bonding the smaller lenses to little aluminum bases and then bonding the bases to my bed once aligned, that way in a tight spot where there's not a lot of finger room I could make adjustments without knocking the small lens over again and again, however I have found it's better to make a sink with an open shelf and use a slip over tube type cover that way you have room to work with any size lens.

SANY0345.JPGSANY3754.JPGSANY4669.JPG

@ LSG: I like your use of the drill body and battery pack. (y)
 




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