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OPT Lasers Cylindric lenses - NUBM44 beam correction tests

Milos

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As I promised, am starting a new thread on this subject because i'll have a lot of stuff to post and don't want to pollute other threads.

I now have mostly OPT Lasers lenses, but will try others if I get them to compare.
I gotta say that guys at OPT Lasers have been super friendly and happy to help with this kind of projects we do here. They do lens design and current 12mmx 12mm square cylindric lenses are the most available and project friendly that I could find.

I plan on doing testing until the optimum squeeze ratio is established using a simple and fairly affordable cylindric lens system for extremely wide NUBM44 diode after a G2 lens.

I will also need your input for some of the measurements and comparison.

Goal: Obviously - is the tightest beam with most power transmission. Best beam profile, and simplest way to do it.

Prize: quickest way for everyone to do it either built into their laser, or add on adapter to already existing laser.

If we can get this sucker FINALLY under "tight" control, we can get any diode in the future.

 
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Milos

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First I'll start with diode output after G2 lens.

This image is taken at 10m at about 450mW

The main line is 110cm long. However if you look closely on the left edge, you'll see it isn't so solid.




Now here is at 15 meters and the line is now 17cm long. You can see that the left edge has a portion where there is a lot less power and it is now a lot more pronounced.



The "main" line or the full power portion of the line is about 13.5cm long.



These are rough measurements and I'm mainly posting to analyze beam projection and take a closer look at what we will be squeezing.
Keeping this in mind will help us understand shapes of the squeezed beam post cylindric lenses and specially resulting artifacts.

Let me know guys if you want me to measure this line any other way, or at different distance if that helps you.




..
 
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Milos

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Here is the setup with two 3x lenses back to back producing theoretically an 9x squeeze of the final projected line (beam). This is what i originally bought from OPT Lasers.

The distance between anamorphic lens pair and the final plano-convex lens is about 2.5mm. I am still playing with this distance as any adjustment of +/- 0.25mm makes a visible difference in the final width of the line. But Lets call it roughly 2.5mm.

Mateusz from OPT lasers was super helpful in getting me the lenses quickly, and even giving me a generous discount on the third anamorphic 2x lens i received later on. Thanks man !!!

The square shape and size of the lenses make it for an easy mounting inside cylinders such as parts we use for building lasers. I did not find any other cylindric lenses yet that are more practical for our use.





 
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Milos

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All this can be easily inserted into the correct size assembly tube you can machine to just fit the square lenses. They can't move but can only rotate for beam orientation matching to diode position.

I'm using double sided scotch tape stuck to the steal machinist ruler to keep them in position. Its easily moved back and forth for fine adjustment and optimum distance finding.

The silver cylinder fits very snugly into the Stingray front, and can be rotated. The first cylindric lens is touching the ring of the G2 lens.







Ultimately I will make it nicer with tighter machining tolerances once i reach the decision on the final optical assembly.
It will probably look something like this:

 
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Light superglue

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Hi Milos,

Can Mateusz from OPT lasers sell a 3-lens set containing 2 PCV lenses of his 3x set? In another thread I have posted a calculation how to make 6-12x expansion using these.

I have tried to find him on LPF but I don't know his PM.
 

Milos

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You mean just build a three lens set with two 3x PCV like set on my photo?

He has not done that yet. I actually emailed him today, so I'll let you know.
 

Bionic-Badger

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If you have an outer heatsink for 12mm modules you can try flipping the diode around so that it extends out the back of your module (instead of towards the lens threading). Then use a second module with the lens, and you can position it as close as needed to the diode that is sticking out.
 

Bionic-Badger

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Yeah, from what I remember, some of those Chinese G-type lenses (e.g. from O-like) are already flush with the very end of the lens holder. For the two modules, what I was thinking was that the second holder would allow the extended can to reach somewhat into the lens barrel itself, offsetting that inset.
 

Light superglue

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Hi Milos,

Yes, I meant the 3 lens set like on you photo.

Any reply from tomorrow systems?
 

Milos

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Hi Milos,

Yes, I meant the 3 lens set like on you photo.

Any reply from tomorrow systems?
I have been way too busy lately and not much time for lasers. Thanks for keeping the thread alive.

Yes, Mateusz replied the same evening.

He did design these 3x and 2x cylindrical lenses for their specific project and later decided to make more and sell. They can cut them and modify them in form as per their need or for small batches, but generally not for large orders.
He also said that OPT Lasers make many customized things for their customers which are not on website. All depends on price and quantity.

Also, and I quote "Producing 1 sample piece of cylindrical lens cost around 300-400 USD it is tooling cost. So this is for example flat price, then you can add around 50usd/pair each additional. So it is quite expensive for small quantities.

This is of coarse if we came up with ideal single cylindrical lens that makes the most out of the particular diode. It, combined with a simple, small mount would be a great option for many laser hobbyists, don't you think?

For now my goal is to find the closest possible answer with the stuff I got.

btw, my mount I showed in the 3D drawing above is finished. Anodizing came out very nice. I will show you very soon.

I will be ordering another 2x from OPT Lasers looks like as I have to try 12x.

I learned a bunch about 18x combination on Friday, but ... will see.
 
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Light superglue

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Me too, I have time to play with lasers mostly only on weekends.

Yes, having a single cheap cylindrical concave-convex lens would be great - you could do a construction of 8 to attach directly to a 8LD bank. But if it was easy to produce, then someone would already have done it, do not you think? Maybe the light path inside of glass would be too long, so 2 lens sets we see today are more common.

I want to do a 3 lens variable expander because today we have access to NUBM44, but in a year or two maybe other LDs with different beam shape can be available, so variable can be adjused in the future to something else.

Question: when you talk about 12x and 18x expansion with a set on your picture, how can you do this with last lens 12mm wide, if the beam out of G-2 is already not less than 1mm wide? If the expanded beam is wider than the last plano-convex lens, will you not lose a part of the power?
 

Milos

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Its not 9x, 18x expander. Its squeeze. We are reducing the width of the generated line, right?

The exit beam of the 9x squeeze lens assembly is 4mm. I will post photos of my new setup very soon. Hopefully tonight. I took a nice shot of the exit beam diameter as well where you will see it is just about one third of the width of the lens.

P.S. I also have idea for variable squeeze assembly for different diodes but it will have to wait. :)
 

Milos

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Here is my new 9x setup. I found that putting the two 3x lenses back to back ( flat sides up agains each other) creates much cleaner line. Day and night comparing to putting them one in front of the other facing same direction like i posted in photos earlier. So much cleaner for measuring. Specially when projected at longer distances like 30-100ft.

I highly recommend this layout.!!

you can also see double stick scotch tape in the center which holds lens temporarily. I will cement the corners to the steal when all is done.


 

Milos

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Here is my newly anodized machine work. It will fit the Stingray 3 in front perfectly and contain the best set of lenses i can find.



 
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Milos

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Here is the output beam of the 9x squeeze achieved with the two 3x lenses both facing forward ( like my original setup from the last page) The OPT Lasers square lens's sides are 12mm and the beam width measures pretty much exactly 4mm.

I will take same photo again with the latest setup. I expect to see even cleaner rectangle at the output lens.



 
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