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correcting a NDG7475

Crazlaser

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Oh lord, you are right, green.... not so bad, CDBEAM777, can't he use a 3X? I think that diode really should have a 4X, but close enough? I was still thinking NUBM44 from another active thread which needs more correction, but if CDBEAM says to use 6X, he knows, he has recently built a host with beam correction for that diode.
Are the beam specs similar to the Oclaro and Mitsu multimodes?
 



Alaskan

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Sorry, I don't know the answer to that but if you can find their beam specs and check the ratio between the fast and slow axis angles of radiation on the data sheet, you can see how similar they are.

I went looking for a comparison OptLasers.com had between using a pair of cylinder lenses he offers, or not using them, with the NDG7475 and found these two photos:



The cylinder pairs he offers are 2.5X, not enough to fully correct the difference between the two axis, but much better. Here is more about them:

Cylindrical lenses 520 nm - Opt Lasers



CDBEAM, I would like to see what the 6X does to the beam of a NDG7475 1 watt+ 520nm laser diode, if you get a chance, next time correcting one, could you take a photo similar to what OptLasers did for his 2.5X cylinder pair?
 
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CDBEAM777

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Guys....it was about 1 1/2 years ago....I think....I experimented with the Opt Laser lenses....

I could NOT get his 4X to correct the Red Oclarro 63193....as good as I could using a pair of 6X lenses.

Now...how about the Green NDG7475.....well....I just finished a NDG7475 commissioned build. I used a set of 6X....and IIRC....got about 1mRad....which is good and tight !!!

I will put a NDG7475 into a test bed I have and put a set of 6X cylindrical's in front of it.....and then give you a measurement....at about 25'

Give me a day or so. Again...IIRC....the die/emitter size on the NDG7475....is not as bad as the Oclarro 63193.......

CDBEAM :eg::eg:





Sorry, I don't know the answer to that but if you can find their beam specs and check the ratio between the fast and slow axis angles of radiation on the data sheet, you can see how similar they are.

I went looking for a comparison OptLasers.com had between using a pair of cylinder lenses he offers, or not using them, with the NDG7475 and found these two photos:



The cylinder pairs he offers are 2.5X, not enough to fully correct the difference between the two axis, but much better. Here is more about them:

Cylindrical lenses 520 nm - Opt Lasers



CDBEAM, I would like to see what the 6X does to the beam of a NDG7475 1 watt+ 520nm laser diode, if you get a chance, next time correcting one, could you take a photo similar to what OptLasers did for his 2.5X cylinder pair?
 
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Alaskan

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CDBEAM, OptLasers.com web site only shows 2.5X for 520nm, did he sell 4X at one time? Perhaps you were thinking they were 4X but are really 2.5X? I thought they were 3X myself, but see he doesn't have them listed. Maybe he did? Curious, because I have two sets of them at home waiting for a future project. Maybe I only have 2.5X.
 

CDBEAM777

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CDBEAM, OptLasers.com web site only shows 2.5X for 520nm, did he sell 4X at one time? Perhaps you were thinking they were 4X but are really 2.5X? I thought they were 3X myself, but see he doesn't have them listed. Maybe he did? Curious, because I have two sets of them at home waiting for a future project. Maybe I only have 2.5X.
ALK...All I remember is that...I was disappointed...because Opt Laser/Matuz is such a good guy to work with....and I really liked the Plano Convex and Plano Concave to be the same perimeter size...sigh...SO....at the end...I decided to stick with 6X !! Maybe the ones I tested were 3X ???? Will check my notes when I get home. CDB
 

Alaskan

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I also liked them because they are the same heights and widths, I had thought they were 3X, but after finding this on his web site maybe they were indeed 2.5X, I don't believe he discontinued larger X factor ones.
 

Light superglue

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Not sure if Optlasers cylindricals are 2.5x or 3x really, but they worked fine for me in installation combining beams of 4 diodes.
Even if this ratio is not enough to obtain square beam from NUBM44 with G-2 to infinity, they are still good to focus it to round 1cm sized spot at 5-10 meters.

And as Milos has posted before in this Optics section, by using 3 lenses (PCV-PCV--PCX) one can get any "squeeze" (I once calculated that expansion ratio up to 12x is possible) by playing with lens separations. But yes this means sacrifice 2 sets.
 

Alaskan

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Adding more lenses costs in power some due to extra loss, but with good AR coating not too much. Looking at OptLasers photo's the correction with just one pair is not too bad, I imagine at a distance without goggles the spot looks round due to flare, but maybe you were looking at it through some and it still looked good. Anyway, close enough and far better than the wide bar before correction. Although if 6X is better, I'd use those, if you can get them.
 

Dr_Evil

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CDBEAM, you still haven't answered the question I asked. Please let me know
 

CDBEAM777

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DR...Hahaha...I cannot remember 1 1/2 hours ago...let alone 1 1/2 years !!!

OK....I still have the Opt Cylindrical lenses....hahaha....but where ???????

I have NO idea what the beam geometry was doing as we traveled down beam.

Now...typically.....with a 6X set...the beam will enter the first lens....the Plano Concave.....and....at that point....it is a vertical line.

Between the first Plano Concave.....and the second lens....the Plano Convex.....the beam will change.....and enter exit the Plano Convex.....as a "rectangle geometry"....that is wider than it is tall.

This " rectangle geometry will then diverge( get larger )....as we travel down beam.....so at say 7M.....it will still be have a " rectangle geometry "...same ratio of height to width....just larger.

I cannot remember what the Opt 3X lenses did....but.....I will set this up again....and try various lens to lens separation distances....and see what I get.... be patient....Give me a few days.....and I will take measurements and some pics.

Alaskan....I do not think that Opt Laser ever offered 6X !!! Maybe just up to 3X ~~

Later guys !! CDBEAM
 
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CDBEAM777

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Well....Took some time from my other builds to cobble this Test Bed together !!

I have been developing many techniques for machining in Copper lately....especially achieving EXACTLY the perfect ID to accept our 12mm modules !! Nailed it !

SO...see the attached pic with 12mm NDG7475 inserted in a slab of Copper.

Now....in front of that is a set of rather large 6X optics. Of course....the 6X Cylindrical lens set can be much smaller !!

I have located the Opt C-lenses.....so....we will see !!

Note: Other commissioned works ARE being attended to concurrently !!
Not enough hours in a day !!!!! Stay tuned !! :beer:

CDBEAM
 

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Dr_Evil

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Okay, I just want to make sure I'm reading things correctly. Using the 6x cylindrical lens set, I only need those two pieces and a G2 lens? No lens goes after the 6x set? I see the Ebay listing says 35mm between the lenses that come in the set. I assume that is between the front of one and the beck of the other. Since you have a set, can you tell me how thick each piece is? I'd also like to know about how much space is needed between the front of the G2 and back of the first cylindrical lens.

Alaskan, since I can't PM or email you, can you please contact me?
 
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CDBEAM777

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Okay, I just want to make sure I'm reading things correctly. Using the 6x cylindrical lens set, I only need those two pieces and a G2 lens? No lens goes after the 6x set? I see the Ebay listing says 35mm between the lenses that come in the set. I assume that is between the front of one and the beck of the other. Since you have a set, can you tell me how thick each piece is? I'd also like to know about how much space is needed between the front of the G2 and back of the first cylindrical lens.

Alaskan, since I can't PM or email you, can you please contact me?
DE.....for my experience....the 6X Cylindrical lenses are separated by 28.89mm
between the front of the Plano Concave.....to the back of the Plano Convex lens.....for the NDG7475 LD. One MUST experiment to determine the best placement !!

And yes...just a Collimation lens....and a set of Cylindrical Lenses...THAT is it !!

How thick. are the Cylindrical lenses...IIRC...5.5 mm....BUT...this can vary from set to set !! +/- a few mm.

Oh Boy....The distance between the G2 ( collimation lens ) and the first Plano Convex optic is typically about 20mm...but is variable.

IIRC....

The closer the first lens is placed next to the Collimation lens...the more reduced the Near Field beam geometry is...but the divergence is also greater....and...

The further the first lens is placed from the Collimation lens...the larger the Near Field beam geometry becomes...but...the divergence is reduced.

You will see when you start to move the lenses around....for hour upon hour !!

In Optics...there are ALWAYS trade-offs....and power loses....and things are NEVER perfect....better....but not perfect....

Have fun " Mov'in the Glass around"

CDBEAM :eg::eg:
 

Dr_Evil

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The reason I'm wondering is because I need to come up with some final dimensions. The further apart the lenses, the more expensive the project will be. It's probably going to cost $600+ as it is.
 

CDBEAM777

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The reason I'm wondering is because I need to come up with some final dimensions. The further apart the lenses, the more expensive the project will be. It's probably going to cost $600+ as it is.
DE...I understand !....Get a set of 6X Cylindricls from AiJi....Get your LD...And experiment before you finalize your design...Then...get the machine shop to fabricate. The dimension I noted will be close...+/- 5mm...but best to lay-out the optics demands...then proceede. Good luck :san:

CDBEAM
 




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