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Question about aixiz modules

alessnilsen

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Hi! After using much the lens/housing from DVD-RW to make my lasers, I decided to start in the aixiz modules world.

To start, I got 5 of those modules and got a LPC-815 to play with it.

I pressfitted (that word is right?) the LD in the place, screwed the lens on it and powered it on, but I got a problem with the lens/focus ring (not sure if a problem or a characteristic):

When the focus ring is at the start, the beam is unfocused.
If I rotate the focus ring, I can collimate the light, and ...
If I rotate the focus ring a bit more, I get the focus to burn things.

So, the question is, is normal that when the focus ring is at the start (totally screwed in the module) the beam becomes unfocused?


(When the module is in this position and I power it up, the beam is unfocused)


(I destroyed one of the lenses trying to correct this)
 



Pi R Squared

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Yes that is normal but it depends on the type of lens, the position the lens needs to be in to be focused will be a little different with a 3 element, G2, or acrylic.

Alan
 

hakzaw1

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Hi! After using much the lens/housing from DVD-RW to make my lasers, I decided to start in the aixiz modules world.

To start, I got 5 of those modules and got a LPC-815 to play with it.

I pressfitted (that word is right?) the LD in the place, screwed the lens on it and powered it on, but I got a problem with the lens/focus ring (not sure if a problem or a characteristic):

When the focus ring is at the start, the beam is unfocused.
If I rotate the focus ring, I can collimate the light, and ...
If I rotate the focus ring a bit more, I get the focus to burn things.

So, the question is, is normal that when the focus ring is at the start (totally screwed in the module) the beam becomes unfocused?


(When the module is in this position and I power it up, the beam is unfocused)


(I destroyed one of the lenses trying to correct this)


If you are asking is it normal for there to be a gap between the focus ring and the copper module when focused to your liking --YES--



With 'trail and error' you may be able to position the lens where you wont see very much gap - try FIRST just screwing in the lens to the rest- then turn on the laser to see what size dot you have- move the lens to the size and distance you desire .

-THEN trying NOT to turn the lens any more screw the focus ring onto the lens.

IF you dont somehow affix the lens to one of these two parts you may have continuing problems with the focus-- at times the lens will not be able to focus -to far in or too far out.


.....sometimes we need to adjust how far into the focus ring we have put the lens-- (which I hope is the red laser lens made of glass) this needs to be done in a way that the best focus is obtainlable - that is --is possible to place the lens in such a way that you won't get a tight dot-- too far in or out.

that way you can adjust the focus for a smallest dot both close to the laser and , when desired also at a longer distance. -

I like to secure the lens once i have found the best place with some teflon tape or a tiny dot of glue- HOWEVER use very little of either-(and NEVER use superglue) any stray bits of teflon tape can be the a cause for damage- This happens more often when a lot of focusing needs to be done- If you can set the focus to one place and not need to re-focus its less possible that any Teflon will get onto the diode or lens. I use the smallest bit of Teflon as possible... and keep lookout for any stray bits.

I will assume you are doing the rest correctly-- but I do wonder how you damaged a lens??

also 'pressfitted' is correct as well as just 'pressed'-

that can be tricky without a proper pressing tool as those cans are very easy to dent or worse and sometimes they are not pressed far enough into the diode module as well as too far .. there are tutorials on this and much more
--try the search.
hope this helps
:D
hak




-



These diagrams are ~6 years old but still apply to the most common diodes we use 5.6 mm.

Sorry that these are not exactly on-topic but how they are pressed affects the focus a little..

The diagram by ROG1188 shows better how far the can needs to be pressed into the module. BUT I think he does NOT show the diode completely pressed--I THINK that small grey colored area is where it should be when correctly presses-- so almost enough as-is but a tad more makes for a tighter fit


also some use a very tiny amount of thremal pasted between the can and the holder-It makes a slightly better transfer of heat--- BUT take care that like the teflon tape you dont get ANY on the lens or diode window.
 

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alessnilsen

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Hi, thanks for the answers!

In my case of the LPC-815, I wasn't able to adjust the lens in a way that at the start it will be focused, I used a sandpaper to cut a bit of the lens barrel in order to get the proper adjustment, and I was able to do this, but some of the dust from the plastic and the sandpaper came into the lens, I think compressed air must clean it.
Looking better, I will be able to get the proper focus if I have adjusted it in the pressfit process instead of pressing it all the way.

I used the tape trick for a 405nm diode and it worked, but I used insulation tape instead of glue or teflon tape.

Slowly I'll learning how to use it! :yh:
Next will be a 780nm LD.

----------------------------

No way to do this with a LPC-815 without tweaking the lens! :(

----------------------------

I was able to get the focus ring at the start and the beam focused, this took me some hours but I done it carefully. I crop part of the screw of the plastic frame of the lens, in a manner that the lens enters more in the focus ring.
 
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hakzaw1

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Okay

there are two approaches to this-- you can screw the lens first into the module then add the focus ring OR you can screw the lens into the focus ring THEN into the laser-- with trial and error you will find the best way-- BUT unless you affix one of both of these you may need to 'fiddle' with it often to get a good focus-- I dont understand why you had to alter the lens-- could you have it backwards??-- can you tell if the lens housing is plastic(very black) or metal (dark but not black) & some like the AixiZ 'G"' are brass($8))?? AFAIK all the AixiZ stock acrylic lenses come in a plastic housing and all the rest are in metal housing either full thread or (405) half threaded.

can you post some pics??
 

alessnilsen

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HI! :yh: Is a bit hard for me to give a good explanation, but let's try!

I dont understand why you had to alter the lens-- could you have it backwards??

No! I tried to use it backwards and I got a terrible spherical aberration, in a way that it can't focus to a little dot.

I installed first the lens in the focus ring, and then, in the module, but at this point the beam was out of focus, to get it in focus the lens must go up a bit, but it is already all screwed in the focus ring, screwing it deep in the focus ring will let the lens go up a bit, and focus the light correctly.
I observed that there's a little space that the lens screw takes inside the focus ring that limit's its position, I removed the four firsts lines of the lens screw and tested to see if it made some change in the focus, and it did! The effect is that I was able to screw the lens "a bit more" in the focus ring, making the lens a bit more far from the LD too, when I found the best focus I glued the focus ring and the lens in place, so I can't disassemble it now.

can you tell if the lens housing is plastic(very black) or metal (dark but not black) & some like the AixiZ 'G"' are brass($8))?? AFAIK all the AixiZ stock acrylic lenses come in a plastic housing and all the rest are in metal housing either full thread or (405) half threaded.

The lens that comes with my modules looks like this (plastic lens, 200nm-1100nm):


And the module is like this:


:thanks:
 




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