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ArcticMyst Security by Avery
what optics need for focusing to 10um spot ?
- Thread starter dlkn
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There's no way in hell you'll get a 10µm dot at half a meter. What's this for?
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In a CD drive, the focal point is VERY close to the lens. You can't get near that tiny if the point is half a meter away. I'll ask again, what is this for?
In the Newport Gaussian Beam Tutorial you get all formulas to calculate your optics:
2 w0 = (4 lambda/PI) (F/D)
DOF = (8 lambda/PI) (F/D)^2
So lets check for your numbers: F = 0.5m, lambda = 650nm, 2w0 = 10µm -> you need a collimated beam of D = 2cm diameter, which is possible with a beam expander (or two lenses, one to expand the beam, one to collimate at the larger diameter).
Unfortunately, with this diameter your resulting DOF will be only about 1mm.
Like Cyparagon, I'm interested in your application. Why do you need exactly these values? Do you have tolerances?
Good luck with your project:beer:
2 w0 = (4 lambda/PI) (F/D)
DOF = (8 lambda/PI) (F/D)^2
So lets check for your numbers: F = 0.5m, lambda = 650nm, 2w0 = 10µm -> you need a collimated beam of D = 2cm diameter, which is possible with a beam expander (or two lenses, one to expand the beam, one to collimate at the larger diameter).
Unfortunately, with this diameter your resulting DOF will be only about 1mm.
Like Cyparagon, I'm interested in your application. Why do you need exactly these values? Do you have tolerances?
Good luck with your project:beer:
Bluefan
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This is assuming you have a gaussian beam and the optics have no abberations.
Thats right, these formulas base on perfect optics and gaussian beams. But it gives you a VERY good feeling what is possble. In most cases gaussian beams describe laser beams very well.
Bluefan
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It definately gives an idea of how it works, but for most lasers the M^2 value is significantly larger than 1.
Bluefan
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Using the gaussian beam propagation you can determine the focus needed to have a 10um waist. donprado posted the needed equations, but the complete newport acticle is a good read.
This depends on the laser used, your application seems to need a UV laser. You happen to have a UV laser? It's an ambitious project, micrometer precision, large cylindical lenses.
This depends on the laser used, your application seems to need a UV laser. You happen to have a UV laser? It's an ambitious project, micrometer precision, large cylindical lenses.
Bluefan
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When I saw this printer I thought of your project. Those are probably BK7 lenses (I think the most common optical glass), good down to 350nm. A tripled yag would work. I'm still curious what laser you want to use.
Most laser printers aren't made for a 10um focus, that would be roughly 2500 DPI. But laser printer optics would definately be a good option, and a shorter wavelength means a smaller spot size, so it may work out just fine.
Most laser printers aren't made for a 10um focus, that would be roughly 2500 DPI. But laser printer optics would definately be a good option, and a shorter wavelength means a smaller spot size, so it may work out just fine.
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Your findings may vary.
I took apart an old applewriter laser printer, similar era equipment as what was posted in that link. Odd lenses were made of plastic. In fact, from memory, I believe everything was plastic except the raster scanner and the final output mirror, both FS mirrors (one polished metal, one metalized glass)
I took apart an old applewriter laser printer, similar era equipment as what was posted in that link. Odd lenses were made of plastic. In fact, from memory, I believe everything was plastic except the raster scanner and the final output mirror, both FS mirrors (one polished metal, one metalized glass)
The best printer laser head i can find on ebay is a 1200dpi, working with a 780nm laser so with a 405nm it would be twice better ?? I plan to use a 500-600mW laser out of a 12X Blu-Ray disk Writer. I'll post pictures when I receive the laser scanner.
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Bluefan
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If the lens system isn't precise enough for 10um spot size the shorter wavelength won't improve the spot size, but I don't know if laser printer are limited by their lens system or by something different. Measuring the spotsize would be necessary.
I have no experienced in making PCB's, is 405nm good enough for the photoresist? Usually some UV lights are used. 405nm won't be attenuated much by plastic lenses, so that would be a problem less.
I have no experienced in making PCB's, is 405nm good enough for the photoresist? Usually some UV lights are used. 405nm won't be attenuated much by plastic lenses, so that would be a problem less.
