Drill from both sides?

[antknee]

Is it possible to accurately laser drill both sides of a plate? For example I have some 200 micron thick steel, I drill from the top side right through the steel, the entry hole is 40 microns diameter and the exit hole is 20 microns diameter. I then drill from the bottom side to create a hole that is 50 microns in diameter -- but only to a depth of 50 microns. So now I have a hole that is 40 microns on the top side and 50 microns on the bottom side, but with a thinner section in between.

What sort of laser would I use to drill both sides? Does the laser apparatus have a particular name?

Thanks,

Ant.

 

[MacGyverS2000]

Fiber, for sure... you'll need to play with your pulse frequency to get a good-looking semi-blind hole.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[antknee]

So how exactly will the fiber laser drill the underside. Will the laser move, the part move, or something else? Thanks, Ant.

 

[MacGyverS2000]

Take your pick... moving the head on a fiber laser is certainly possible, but it's easier to reload the substrate flipped over. With a quality jig, registration shouldn't be an issue.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[JayMaechtlen]

wait - isn't the point to get a hole with straight sides?

If that is the point, don't you want to tailor the beam so it has a pretty flat distribution, rather than gaussian?
That, and tailor the optics so it has the right diameter with a fairly focus distance/long beam waist.
I guess you're using a YAG laser?

Jay Maechtlen

http://www.laserpubs.com/techcomm

 

[antknee]

Hi Jay,

Yes I'll be using a Nd.YAG and would prefer the taper minimised. What is the principal behind reducing the taper? For example does the focal length change? I don't understand the difference between gaussian and flat distribution.

Thanks, Ant.

 

[Timelord]

ant,

Jay is talking about the optical power distribution across the beam. A single mode beam focuses to a Gaussian distribution. A beam with sufficient modes will approach a square wave or a flat topped beam, which will cut straighter walls.

Timelord