This is huge, it means that laser cutters will be even cheaper than they are now, and that much more ubiquitous. Laser cutters are already making their way into small scale shops and hackerspaces, this'll just hasten that. But it also has a ton of applications elsewhere. Likely it will lower the cost and increase access to the minimum set of machine tools necessary to sustain a developed economy, which has implications for the entirety of the developing world as well as further afield in things like Mars colonization.

Additionally, it makes things such as low-footprint or modular factories, configurable/programmable or wholly automated factories, and self-replicating factories more of a possibility in the near future.

Yeah, that might happen, in 20 years when the patents expire. Before that, this will be much higher cost than tube lasers which anyone can make and repair.

What would be the point of a business inventing a laser that is cheaper and more efficient than current lasers if they weren't going to be cheaper to own than other lasers?

Reduced weight, reduced power consumption (power infrastructure is expensive to set up even where power is cheap), reduced size, better reliability (diode lasers have no loss of gas pressure issues), better power density. All reasons to go for this setup even if it's much more expensive than gas lasers.

> in 20 years when the patents expire.

or when you can order them on ebay from china in a couple of years.

This seems to be the way it goes.

Looks like multi-core asynchronous with load balancer wins even in the laser world.

Cool, but I wouldn't call it a single diode LASER since it is forming an incoherent beam from several diodes. Now if you could get a single, coherent beam at several kW, that would be really cool.

So now we only need better batteries, and we'll soon be able to cut and weld metal with our phone?? :D

Wouldn't about 12kg of laptop batteries provide 4kW?( wikipedia: ~250-~340 W/kg ) Put them in a backpack.

My limited experience with lasers is the heatsink problem is significant, so worry about dissipating a couple KW of heat in your hand or backpack, not carrying around a mere couple KWh of energy.

I imagine it would sound and feel much like holding an industrial heat gun for awhile. This might be a problem.

Hmm, now I'm imagining something like Reason (http://en.wikipedia.org/wiki/Snow_Crash#Reason). A backpack sized battery, but needs a water-submersed heatsink.

right; 40% efficiency means 40% comes out as light; the other 60% comes out as heat.

One of these would provide 4 kW, too (although I don't know for how long), and is only 5.8 kg:

http://www.ev-power.eu/Winston-40Ah-200Ah/WB-LYP160AHA-LiFeY...

Well, Osborne 1 was 10.7 kgs and it was considered a laptop, so there is that.

My dad had one when I was a kid. They were called luggables, and weren't meant to be put on laps....

What if you had really strong legs? You're right, of course.

Even if we had the batteries, where would you put the kilowatts of waste heat that would be generated by it's use?

That would be like storing your super battery inside a toaster that it's powering. Yikes.

The individual laser blades aren't small and all the assorted cooling apparatus is pretty sizable. Some video of it in action: http://www.photonics.com/VideoGallery.aspx?DGID=4c2495b26887...

I wonder what these kinds of huge gains in laser technology might mean for fusion and beamed energy rocket propulsion?

Not much for now, I don't think. They haven't improved on the intensity or accuracy of lasers in general, just the efficiency and cost-effectiveness of them. Large scale experimental projects like you mentioned don't generally care about efficiency as much as intensity and accuracy. When fusion becomes mainstream it might matter.

This seems a quite dangerous toy to me... a portable laser strong enough to cut through metal.

Blu-ray lasers are already dangerous to humans and quite portable.

It's 1m3, larger than your average plasma torch.

Not sure how 4000 Watts is toylike. (yet)