405nm beam focus to tiny dot?

[Sultanen]

Hi,

I m trying to figure out what i need to build a laser module with 405nm and a beam with a dot size of about 0,1mm at 30-40cm. What optics would i need to use? Please point me in the right direction I dont care what the beam looks like further away.

 

[Spooky]

What power and beam diameter is it?

Diameter in affects diameter out and depth of field and most importantly power density.

best wishes

Dave

 

[Sultanen]

What power and beam diameter is it?

Diameter in affects diameter out and depth of field and most importantly power density.

best wishes

Dave

I havent decided 100% on what diode i will use but i think it might be the SFAW210 that i will drive at about200-220ma.

 

[Spooky]

Ok, at 30cm (12" focal length) your going to get a pretty good DOF, a lens that will focus to 0.1mm is going to give bigish numbers on power density though,if your driving at 120mw output that's going to be a rather nasty experience for anything that gets in the way at it's focal point.

Can I ask why the need for a focal length of 30cm?

cheers

Dave

 

[Sultanen]

Thanks! Ill look into that =)

Im trying to construct a laser 3D printer, i will cure resin about 30cm away from the laser. I will have to do some calculations on what power i need, it all depends on the speed i want to be able to print in. Every "dot" is lit by the laser for a milisecond or something, the faster i can cure the 0,1mm dot the faster i will be able to print.

May i ask for a good shop for laser lenses? =) Can you give me a hint of a lens that might work? Im new to all laser things.

 

[Spooky]

I see where your going now

UV resin?

It may be a good idea to go with a short focal length, having a beam that has a big DOF may affect the layering, (I'm guessing you will be using a bath of resin and not laydown?)

Lemme have a dig through my trade catalogues in the morning for good lens suppliers, most of my stuff is IR but the work I've done in the UV spectrum used lens's from Edmund Optics
( Edmund )

Very good but expensive in long focal lengths Have a look at their plano convex defense lens's, reasonable price (40 bucks),

RMI are also very good but limited on the wavelengths they cover RMI

May also be worth looking at dental suppliers, they use a UV cured resin in tooth repairs (I have a feeling it's diode (LED) based though and not laser as such)

I'll be very interested in how you get on though, 3D printers are great fun but the material science isn't quite there yet (I have a Z-corp 650) not to mention so dam slow

One of my clients builds 3D printers (Rostock based under licence) and every month I get the joy of cutting out all the sub assemblies

best wishes

Dave

 

[Spooky]

Just been looking at the Stereolithography Form1 3d printer developed by some MIT grads, that's using a 405nm but at only 20mw, A galvanometer head does the work.

Looks very interesting and a sure fire winner, think I'm gonna go order one and see what they are like.

I wonder how long it will be before diode pumped solid states get into a power range (price range) that means they get used more for cutting and printing?

20 years ago I was using a Immatronic LS120 laser sight, £450 and a worse dot than most $2 pointers produce today.

Had a look today at lens suppliers, most of them are in the big numbers pricewise, Thorlabs may be useful for the optics though.

best wishes

Dave

 

[Sultanen]

Yea, i have seen the form1, do you have a source for it to be only 20mW? =) From what i have read its 120mW
It looks verry cool and the prints are awesome!

Ive seen Thorlabs but i have no idea of what kind of lens i need to look for, i need advice here =)

 

[Spooky]

I'll go grab the source You will need a plano convex but finding one at a sensible price for that wavelength isn't going to be easy. Edmund Optics or RMI are probably your best bet.

Back in a bit

best wishes

Dave

my bad, it's a 120mw not a 20mw

Source

 

[Sultanen]

120mW it is =)

What about those?
http://www.edmundoptics.com/optics/...aser-line-coated-plano-convex-pcx-lenses/3195

 

[Spooky]

Look good this end

The coating curve figures look good too, 0.25 reflective and narrow band pass, may well be the idea lens to go for.

best wishes

Dave

 

[Sultanen]

Look good this end

The coating curve figures look good too, 0.25 reflective and narrow band pass, may well be the idea lens to go for.

best wishes

Dave

Great! Thanks for the help, i think this will be the lens to go for, if i dont find a much cheaper one somewhere else

 

[chipdouglas]

I'm not sure how 3d printers work or how you are doing it but..

if you are laying down the resin first in your precise measured amounts, then your beam size, I think, wouldn't matter. what I think would matter the most is your blanking of the laser.

 

[Sultanen]

I'm not sure how 3d printers work or how you are doing it but..

if you are laying down the resin first in your precise measured amounts, then your beam size, I think, wouldn't matter. what I think would matter the most is your blanking of the laser.

What do you mean by blanking of the laser? I will have a bath of resin made of glass with the laser curing a layer from below so the spot size will matter im sure =)

 

[chipdouglas]

ok, is see what you mean. I was thinking of laying a nozzle with a fine tip and a laser trailing behind curing it.

blanking is turning the laser on and off via a ttl driver.

Michael.

 

[Sultanen]

Aha, okey, im using TTL to turn of the laser when moving it between "print areas" even though im not sure its nessesary, the Galvos are so fast the laser is almost invisible when they are moving with full speed =)