Laser cutting masters

[dmills]

Yep, blown out many output couplers messing with using the Q switch to do blanking on frequency doubled yags and getting the first pulse suppression not quite right.

YAG is a particular bugger for this because its upper state lifetime is just so very long (300us as I recall) so if your nominal rate is say 30kHz, you can bank a whole lot of energy stored in the rod, and then the rf cuts off and it all wants out at once!

If you used a medium with an upper state lifetime that was short compared to the PRF then it would be much less of an issue.

Several hundred kHz? with TEM-00 beam? NICE laser if the pulse energy is reasonable. Fibre laser? Hundreds of kHz is low for a mode locker but way high for a Q switch, but a QCW diode pumping a doped fibre might be in the zone, and that could be passively cavity dumped, but the switch would need to quench FAST.

How about one beam with an ultrasonic vibrating focusing element, first pulse is wide focus and cuts the outer bit, next pulse cuts the narrow bit, focus is probably better then power control for depth of cut (which is a bugger particularly close to threshold or in anything with a harmonic generator crystal, see the 'green problem' with SHG for 532nm). Of course this gives you an analogue sampled record!

Part of your AES delay issue might be that the entire UK committee just resigned! Some disagreement with head office in NY.

[misjah]

You wanna talk to somebody who makes actual stampers as I’m not sure how easy (or possible) it is to separate a nickel stamper from a stainless steel master. Using lacquers would be a shame and a bit pointless imo. You can use laser on them without catching fire. I have done many times engraving artwork.

[circitfied]

dmills.

I was reading about ultrasonic focussing today. It seems really interesting. i read this today if you google scholar search it: Vibration assisted femtosecond laser machining on metal. The taper angle looks really good.

At the moment I'm using an old Navigator ND:YAG with a 532nm head on it. Pulsed at 50KHz, with an M2 of 1.2.

The new laser with an output of 400KHz can produce 400W average power at 1064nm, so I don't think I will be struggling too much. With a pulse length of 12ps. Clocking this thing is going to be a bugger. I'm keen to start wrestling with it!

[dmills]

400W Average, 1J pulse energy, 12ps, yag? Very, very cool.

Not quite Ti/Saph, but I will take 10ps at that power level!

[circitfied]

It's a beast!

With the 355nm harmonic head I can get around 60W UV. which is pretty sweet for high speed polymer processing.

[circitfied]

Still waiting to get back in the lab. I have a new experiment set-up for modulating the laser power at audio frequencies and I can't get in to have a play.

Here's my first paper on laser cutting records: https://www.aes.org/e-lib/browse.cfm?elib=20733