Wouldn’t it be cool if you could cut the grass with lasers? Everyone knows that lasers are basically magic, and if you strap a diode laser or two to a lawn mower, it should slice through those pesky blades of grass with zero effort. Cue [Allen Pan]’s video on doing exactly this, demonstrating in the process that we do in fact live in a physics-based universe, and lasers are not magical light sabers that will just slice and dice without effort.
The first attempt to attach two diode lasers in a spinning configuration like the cutting blades on a traditional lawn mower led to the obvious focusing issues (fixed by removing the focusing lenses) and short contact time. Effectively, while these diode lasers can cut blades of grass, you need to give them some time to do the work. Naturally, this meant adding more lasers in a stationary grid, like creating a Resident Evil-style cutting grid, only for grass instead of intruders.
Does this work? Sort of. Especially thick grass has a lot of moisture in it, which the lasers have to boil off before they can do the cutting. As [Allen] and co-conspirator found out, this also risks igniting a lawn fire in especially thick grass. The best attempt to cut the lawn with lasers appears to have been made two years ago by [rctestflight], who used a stationary, 40 watt diode laser sweeping across an area. When placed on a (slowly) moving platform this could cut the lawn in a matter of days, whereas low-tech rapidly spinning blades would need at least a couple of minutes.
Obviously the answer is to toss out those weak diode lasers and get started with kW-level chemical lasers. We’re definitely looking forward to seeing those attempts, and the safety methods required to not turn it into a laser safety PSA.
Just crazy.
Like fishing with explosives.
It kind of works.
Grenade simulators… Fun times… :D
you know like digging for worms with electricity.
two rodds in the ground and wall power.
The just plain climb just out of the ground, no digging.
Did that with an old telephone hand crank generator I got given age 10, almost 40 years ago
I thought it took an old telephone magneto to do this anywhere not needing mains power. Like down by the crick. I’ve still got the copper rods my middle school teacher gave me and somewhere one of those crank ups. Approx 90v AC! Oddly, those copper rods allow me to “dowse” and get repeated results.
No they don’t. Dowsing is nonsense.
Sounds like the name of a forest fire “The lawnmower laser fire”
Fishing with explosives somehow makes far more sense
What about cutting the grass with explosives?
Now you’re cookin
Cooking on explosives? (Vietnam vets cooked on C4, according to several articles I read)
I think Mythbusters did a quick aside on cooking with C4.
Quite safe, most explosives these days can be burnt safely. They need a shock to make them go boom, that’s what the detonator does. The detonators are far more dangerous than the explosives, heaps more pages in the instruction manuals saying “Don’t do this!”
In German its called “Rasen sprengen”
The efficiency of a standard continuous laser beam is well below that of a pop laser. I recall early studies of weaponizing lasers finding that a pop laser allows the plasma state of the material to dissipate whereas before with a continuous laser, the plasma would interfere with the beam’s focus.
As with the older video, this is kina fun, but what I want is a turret (perhaps concealed in a baroque fountain in the shape of Neptune & Thetis) that mows the whole lawn AND trims the topiary from a single point. That’s the sort of thing that could properly menace some 70s sci-fi characters centuries after its abandonment in the Great Catastrophe.
If lasers are too difficult I’m also prepared to accept a neutral particle beam / metal nanoparticle railgun / etc.
That would have to be one flat lawn :)
I’ve thought about a stationary rotating laser, but if any distance was feasible, it would take some seriously careful ground sculpting to get good results…
… And a power supply that might dim the whole neighborhood :)
Why don’t they use a lightsaber, just like Obi-Wan ?
New plan.
Get a bunch of brushless motors and embed them in your lawn like pop up sprinklers.
Attach a 2m braided cable with a weight on the end to each motor spindle.
Then you can cut/string trim your lawn all at once, with no safety hazards like a laser.
Squirrels, possum, cats, they’ll all leave.
Together or in pieces, their choice.
HAD discussed this in the recent podcast…… Having an unterminated high power laser is not just dangerous; it’s stupid. Sure the operators are protected, but random pets, innocent wildlife, curious passer bys, etc. are not.
I wonder what the ecological effects are of blinding all the bugs in your lawn
I fully agree. This is highly irresponsible and IMHO should be condemned not praised.
Yes, lasers are hecking cool. A laser mower is a crazy stupid idea that you definitely should try to build. BUT, running it outside like that is just a danger and highly illegal.
You can clearly see that they are next to the open road on the cover photo. Anyone passing by will look in their direction (wtf is that blue glow?) and is at high risk of eye damage.
Wait, they didn’t put beam dumps on it? Haven’t watched the vid, I assumed they had some sort of termination under the chassis. Yikes.
I would’ve loved to see a version of this attached on a fixed point and do one clean sweep.
Bonus points for doing it wearing open toed sandals, could be extended to simultaneously trim your toenails.
This needs to be a pulsed fiber laser on a galvo set up to spin. Or even better, motion tracking to zap the individual blades of grass
I said I wanted fricking lawn mowers with fricking laser beams attached to their blades!
Yeah; I once tried to get an idea on exactly how powerful a laser would have to be to slice off your arm, they way they do in the movies. I modeled the “arm” as a slice of water, 1cm thick by about 15cm diameter, and figured you’d have to pump in at least enough energy to vaporize that water in a 0.1s or so.
That turned out to be an awful lot of Watts (delivered beam watts.) Then I factored in the plug-to-emission efficiency of a typical laser. Amusing, I guess.
The really annoying bit is the steam coming off the arm absorbs most of the laser power.
Would it be better if you had a rail around the perimeter of the garden and have the laser slowly move round the edge? Theoretically it should get 360° cut and the metal on the other side wouldn’t get hot enough to melt as it’s constantly moving
How to set your garden on fire in a draught.
Wonder if instead of fully cutting it could boil the moisture in the grass blade at a horizontal line. Perhaps by “combing” through the grass, similar to a barber combing hair in advance of clippers.
If the grass woul die along that scorch line, perhaps the top would wither away and just fall into yard bed. Supposedly, this kind of scorching is how I am supposed to use a propane weed killer- saving fuel by only killing, not fully incinerating.
Running over the yard often, like a robotic lawn mower does, perhaps the “combing” would be effective.
If all that would check out, wonder if energy savings would be significant enough to make it a go, perhaps for special niches at least. (In fact, I’m thinking a laser-edger…)