Laser Beams Deflected Off of Nothing but Air for First Time Ever in Breakthrough Patent Pending Process - The Debrief

L4sBot@lemmy.worldmod to Technology@lemmy.world – 355 points –
Laser Beams Deflected Off of Nothing but Air for First Time Ever in Breakthrough Patent Pending Process - The Debrief
thedebrief.org

Laser Beams Deflected Off of Nothing but Air for First Time Ever in Breakthrough Patent Pending Process - The Debrief::An international team of scientists report that they have successfully used acoustics to deflect laser beams in an engineering first.

60

140 decibels. I'm sure some applications exist but it won't be a 3D TV soon.

In an ultrasonic frequency we can’t hear. But your pets and any nearby bats or rodents etc may be upset by it..

Can't hear but still cause damage?

I didn’t know the answer to this so I looked it up - yes. Over 120 Db can cause damage even if it’s ultrasonic and you can’t hear it. Apparently at 155Db the heat created by the sound wave can be dangerous as well.

Just a small note, it's written dB, small "d", big "B".

"B" is the unit symbol for bel and "d" is the symbol for the SI prefix deci, a tenth.

Trust this guy, when it comes to the small d he knows everything about it.

In that case can we use just B. MB, etc.

Oh yes, sure you can, 140 dB is 0.000014 MB. The confusing thing is just that the non-SI unit byte also uses the symbol "B" and uses the SI prefix "M" quite often.

Sometimes when I calculate optical power levels I actually use B in between. For example:

How much signal is 88 optical channels at 1.6 dBm of power each?

0 dBm = 1 mW by definition

1.6 dB = 0.16 B = log10 ( x ) --> x = 10 ^ 0.16 = 1.45

So 1.6 dBm is 1.45 * 1 mW = 1.45 mW

Then 88 channels is 88 * 1.45 mW = 127.60 mW = 127.60 * 1 mW

log10(127.60) = 2.11 B = 21.1 dB

So 127.20 mW is 21.1 dBm, just below the output specification of our amplifier, good, nothing should melt.

1 more...
1 more...

Yes. Industrial grade ultrasonic sensors are harmful to your health. They can be used, for example, to measure the water level in a tank. If you need to enter a place like that, you should physically disconnect the sensor first. You might not hear much of the noise, but you may feel it in your teeth or some other places.

1 more...
1 more...
1 more...

Light sabers?

Yelling lightsabers at that loudness. All the better imho.

Fun fact, if sound travelled through space, the sun would be as loud as a jackhammer everywhere on earth. Second fun fact, due to the fact that we evolved on earth you wouldve evolved to not be able to hear that frequency.

Luke!

WHAT?

LUKE! I AM YOUR...

WHAAAT? TURN YOUR LIGHTSABER OFF IF YOU GOT SOMETHING TO SAY

HELL NO YOU TURN OFF YOUR LIGHTSABER BOY

Holodecks soon?

considering the lab experiment with just one laser required a sound level of about 140 decibels that consume 20 gigawatts, I don't think holodecks are going to be a practical device.

Great points, but you know how things go. Proof of concept is a bloated laboratory implementation, then the tech gets smaller and more efficient over time. Next thing you know the sound is outside of human hearing range and the laser projector is fitted to a drone.

More realisticly how things go, experimental research only works in lab conditions, clickbait article suggests it's coming next year, people make giant assumptions, people lose faith in science because the promised thing doesn't arrive

Lol probably, we are definitely more on track for cyberpunk or idiocracy than star trek post scarcity socialist utopia

According to the article it's already using ultrasound.

Ultrasound at 140 dB which can still seriously damage hearing, you just don’t hear it happen.

It may be interesting to see how humidity and temperature influence the laser (or even other gases as mentioned in the article)

It was the laser that's 20 gigawatts, according to the article, which is notable because such a laser is hard to redirect.

As for the viability of holodecks... Obviously the rest of your points are still valid, but one can only hope that someday we'll figure something out, the technology being impossible/unviable right now doesn't mean it'll stay that way. And this seems to show a theoretical possibility of manipulating light mid-air in the necessary way.

1 more...
1 more...

Horseshit. Don't piss on my head and tell me it's raining.

Edit: this is more horseshit like the "room temperature superconductor" that was instantly debunked as a horseshit scheme recently.

Sound pressure waves cannot distort spacetime

Space battles would be so much cooler if every now and then the phaser gets split around the ship instead of hitting the shields.

Would also work even when shields are down.

But that needs air. There's no air in space.

Doesn't need to be air "in space", there just needs to be air somewhere between the laser weapon and whatever it is you don't want the weapon to destroy...

... although it'd probably be easier to use a mirror. Maybe one pointing directly at the person holding a laser weapon. ;-)

Corner reflector. Send it back where it came from, without knowing where they are ahead of time.

Damn... you're right.

Maybe they'll find another way now that they've found one.

A mirror? Light won't reflect off of nothing. The closest you'll get is gravitational lensing, but that requires about a galaxy's worth of mass to make any noticeable difference.

I mean, that's a 20GW laser, what about those handheld lasers? Would you still need 140db?

It would happen regardless of the power of the laser, but it would likely be undetectable at significantly lower power.

That's just an AOM

Doesn't an AOM typically have a lens?

No, it's just a crystal and a piezo. You can focus into the AOM to get lower rise times but it works without any lenses.

I think I should have said "optic" in place of "lens". The crystal is the portion that is being oscillated to divert the beam. It could be that this is exactly the same principle being used by the referenced experiment but with much higher powered acoustic equipment.

Green laser beams have been deflecting off nothing but air since we invented green lasers. That's why they are visible without adding smoke.