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Feasibility of a low power etching laser setup

Tomg

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Hello,

I am not a laser expert and would like to have some advice from laser enthusiasts about the feasibility of a project involving a laser.
I want to make 30 um diameter holes in 50 nanometer thick plastic sheets at a ~0.1 m distance with a laser. Is it possible with a simple laser diode and an appropriate lense ? Is it possible at all with more sophisticated equipment ?
Additionally, I want to direct the beam over a 1 mm range at 0.1 m distance with a galvanometer mirror. I guess that I should place the lense between the diode and the mirror ? I imagine a setup consisting simply of a diode laser, a lense and an homemade galvanometer.

I kept it short, let me know if you need some more information.
Thank you for your advices
Tomg
 

KrowBar

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I'm not going to be one to say it's impossible, but I think the info you need for your best shot at this is in another thread about it that is almost suspiciously similar - here: http://laserpointerforums.com/f49/even-smaller-spot-size-using-mask-89357.html. Holes that small at 10cm might be tough. Short wavelength single mode like a blu-ray diode is the best bet. Blu-ray burners etch features on the order of 200 nm with a spot smaller than 1/2 micron, but this is done at a much closer range than 10cm. Also, if the surface over which you plan to redirect the beam is flat, then it will not be at the focal point of the beam except in a small area. You are talking about half a degree of movement, which might not seem like much, but this does add to the difficulty of the problem.

I propose throwing the following question out to the community. What is the smallest hole you have been able to burn in any material using one of your lasers? Maybe make a contest of it. Who can demonstrate the smallest hole burning capability? That might at least give us a reality check on the range of possibilities.
 

Tomg

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Thanks for your answer KrowBar.

Burning 30 um holes at 10 cm distance with additionally a small galvanometer mirror was my ideal setup. Based on your advice, I see that I have to be more flexible.

I would also be happy with for example making 60-80 um holes at a distance down to 5 mm without galvanometer. Is somebody aware of a practical configuration that could achieve these specifications ? A cheap blu ray diode with a aixiz lens mounting system would work ?

The easiest to decide would be to know what spot size I can achieve versus the working distance. I guess that using the spec sheets (parallel and perpendicular radiation angles) of the diode, knowing the characteristics of the lens and the spot size of the diode at a given distance should be what I need. From googling I learned that spot size of typical blu ray diodes at 0.15 mm working distance are around 500 nm. But there is already a lens involved here I suspect, with unknown characteristics, preventing me from doing the desired calculations ...

Any further help would be greatly appreciated
Tomg
 

Tomg

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Thanks for your replies. I asked a bit around a few companies and a member of the other forum and here I am so far:

-Optima Optics advised me the LDM 3900 or LDM 3956 kit with a 305-0066-078 lens that should produce a beam spot of size 19x41 microns at 50 mm distance (or 32x63 microns at 90mm) when tested with a Hitachi HL6312G. Their optics are suited for wavelengths from 635 to 830 nm. I would then buy a powerful enough diode, for example a ADL-63302TL 635 nm, 30 mW, sm, 50 °C, 5.6 mm from Roithner-laser, and that would be it ?
My concern might be that I want to make holes in extremely thin sheets of plastic (50 nanometers) that are rather pale, in a few milliseconds. Is a 635nm, 30 mW powerful enough for pale surfaces ? A short wavelength laser might be more efficient ?

-fiber lasers have been suggested to me. I could not find prices for them, but I think that they are much more expensive than laser diodes. Is that right ?

Thanks very much for your help
Tomg
 




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