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How to achieve 0.01mm laser spot size?

rajhlinux

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Take your calipers if you want to make SURE that its sub 0.05mm just look hard into it, may be difficult to get proper readings and make sure they have a good vernier scale Lol. Focus it down and try different lenses. Get a G2 lens from dtr. It has a short focal length that will get you the smallest spot possible. and Remarking on your point, If its not rocket science you already know how to do, You asking us is just wasting your precious time if it inst hard to do *right princess*? Also check your diode, If its 5.6mm in dia its the sharp diode, If its 3.8mm you got the good single mode BDR. If its not the BDR swap it out for one, gonna get you the smallest spot easily reaching 0.01mm since you know it is used in a blu ray writer so by default the spot has to be a lot smaller than that to write the data.

Well finally I found some valid information.

So from what I understand with your concept, I need to obtain "G2 lens" (I have seen them advertised at random times when purchasing laser modules) from "dtr". If you do not mind, can you please elaborate what "dtr" means?

The reason why I say it's not rocket science is because of basic math: 0.1mm - 0.01mm is 0.09mm. Therefore achieving a better focal point by a difference of 0.09mm is not rocket science, I hope you get my focal point (pun indented... ;) )

So the laser diodes has to be "BDR" (whatever that means, I'm assuming it is a Sony laser diode part number after googling "BDR laser" lol...).
So after googling, when you say "BDR", I need to get the authentic Sony's "BDR-209" laser diodes?
From what I understand with your concept, the "BDR" laser diode is used for Blu-Ray drives.
Blu ray discs needs smaller than 0.01mm 405nm laser focal point so that the "BDR" laser can properly write/burn digital bits to the Blu-Ray disc.

So a Sony "BDR-209" laser diode along with a good "G2 lens" from "dtr" will solve majority of my problems... thank you kind sir.
(Wouldn't it be more accurate and scientifically valid if I used a CCD/CMOS sensor using the Gaussian method to accurately adjust the beam focal point? It's not like I need an expensive camera, many university papers discuss about this. I'm sure any webcam can be used with a laser filter to not burn the camera's sensor)
 



rajhlinux

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I hope this helps

Ahhh, now I see what "dtr" means...

Just for sake of curiosity, who run's that website and business?
I'm not gunna get burned when purchasing stuff at that website like a burned laser diode...

Reliable, honest people selling laser stuff?
 

Alien Laser

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I get everything from DTR Best seller you can find i bin purchasing from DTR since 2012/2013
 

Anthony P

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The rays of an expanded beam are more parallel allowing for sharper focus.
 

Unown (WILD)

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Welcome back Mr. C., I was only guessing it was you. Glad to see you have settled down a lot and no one is attacking you for your past behavior anymore. I was prompted to respond, since I was the one who banned that guy. What you did was a back handed slap at me, was you who stepped out of line with that.. I kept my mouth shut since you came back, until that remark. Let's walk away from any further of this.
You're mistaken. I didn't even know you were the one who banned him. Sorry for the confusion
 

Jimmymcjimthejim

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Shorter focal length lenses have a smaller beam waist. This is why cd/dvd/blu-ray drives use short focal length lenses. Visually, these lenses have a lot of curvature. However, the tradeoff is that the shorter focal length lenses will have shorter depth of focus. Achieving the small spot size probably isn't too difficult using quality glass optics, but getting the focus right on your engraving surface will be very challenging. As a rough calculation, your beam will only be 0.01mm diameter for 0.02mm deep. This is why cd/dvd/blu-ray lenses are electromagnetically actuated for depth focus, likely controlled in a feedback loop. I'm not familiar with the engraving system so I am not sure if it has this level of precision or control. I would look into how cd/dvd/blu-ray drives work for inspiration on how to control the focus accurately. I believe some drives have ccd sensors that pick up the reflection and process it in a feedback loop. If your surface is extremely flat and machine is well-built, then feedback may not be necessary, and you can manually focus the laser before each cut. Hope that helps!
 

rajhlinux

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The rays of an expanded beam are more parallel allowing for sharper focus.

So you think it's better to have the Sony BDR laser to be expanded before or after the G2 lens?
 

rajhlinux

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I think it would be better to use a laser with a shorter wavelength such as 300-355nm, the G2 lens will cause the laser beam to be much shorter focal point than using a 405nm laser. But not sure how much of a difference it would make...
 

Alaskan

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Yep, you are correct, but go ahead and price out a UV laser and all of the special parts needed for wavelengths shorter than 405 nm. So far, you appear to be wanting to spend just a few hundred dollars, maybe you can get lucky and find something used which is being sold uber cheap but 355 nm? OMG $$... Right now true UV wavelengths at more than a few mw are $$$. Used gas UV lasers are relatively inexpensive on ebay but not much power.
 
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rajhlinux

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Yep, you are correct, go ahead and price out a UV laser and all of the special parts needed for wavelengths shorter than 405 nm. So far, you appear to be wanting to spend just a few hundred dollars, maybe you can get lucky and find something used which is being sold uber cheap but 355 nm? OMG... Right now true UV wavelengths at more than a few mw are $$$. Used gas UV lasers are relatively inexpensive on ebay but not much power.

I remember from every other year to year always wanting to buy UV-A (315-400 nm), UV-B (280-315 nm) or UV-C (100-280 nm) lasers, but there's no such technology available in the market as of now.

Where did you see a gas UV laser shorter than 405nm? I just went on eBay and couldn't find any legitimate UV laser that has a wavelength shorter than 405nm.

I wonder how did the "Next Scan" company mentioned above got their lasers to be down to 355nm, I could do a patent search and possibly find more details about it... wonder if they buy the 355nm laser modules from a special laser manufacturer or they deigned everything and built it in-house.

Also I don't need more than 100mJ of laser energy at it's focal point.
 
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rajhlinux

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Wow, this is a solid state module for around $100, not bad...

But it can only outputs about 10mJ of energy... Which could be "doable" for exposing the photoresist, but will require for me to scan the surface for much longer, for this reason I'm not sure if this will have the effect of "over exposing" and have a negative impact overall of the resolution...

Edit: Never mind... that "price" was a click bait... $100 is only for deposit money, the final price will be in the thousands...

I'll just stick with 405nm much more "wallet" friendly...
 
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Alaskan

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To find the gas UV lasers on ebay, search "337 nm laser" and "nitrogen laser" separately.

 




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