Can sound be focused like a laser?

[GreenAce92]

I am asking with regard to LIDAR, apparently there may be regulations that prohibited onboard lasers on aircraft although I'm not sure how Facebook's internet drones get passed that. At any rate, I would think sound "dissipates" rather quikcly or becomes large. If to be used for LIDAR application eg. 3D mapping of surrounding, also this question applies to IR. Is the focused part aside from uniform waves, through optics of strictly uniform waves?

 

[BradtheRad]

Bats use their audio 'sonar', to detect large and small objects.

Humans can use ultrasonic range-finding instruments.

These uses are not exactly the same as focused sound waves. Sound disperses more readily than light. Nevertheless to generate a coherent wavefront is easier with sound, than with light.

A single pressure wave through the air might be called a soundwave. It can exert a surprising amount of force. Search for 'sonic cannon' on Youtube, to see videos where a large tube sends a blast of air several yards, and knocks over bulky targets.

It is not too different from a smoke ring travelling a distance at high speed, while retaining its shape.

Porpoises have been filmed creating similar air bubble rings underwater. Then they swim through them! Incredible but true.

 

[Warpspeed]

There was once an amazing demonstration at a local science museum, where at each end of a very long public gallery was set up a large parabolic reflector, each possibly about three meters in diameter. They looked like, and probably were old recycled microwave dishes.

The two dishes were pointed straight at each other, and a platform with steps leading up was arranged at each end so you could place your head right at the focal point.
It was possible (right at the focal point) to conduct a two way conversation with the person at the other end at a whisper, as if the person were right next to you.

The distance was such that you could hardly see the other person, and if you moved even slightly away from the focal point it did not work.

So yes, sound can be very powerfully focussed and reinforced.

 

[Audioguru]

Museums, art galleries and foreign language translation in large conference rooms focus an ultrasonic beam and a sound modulated ultrasonic beam at an object or at a person and the beams interfere with each other, become de-modulated and voices seem to come from the object or person. It is easy for a very high audio or ultrasonic sound to be focussed.

 

[andre_luis]

The same concept is also applied to the microphone wrapped in parabolic dishes that are able to hear weak audible sources from far away, and with the advantage of being less subjected to the surrounding noise.

 

[Warpspeed]

Just the thing...

 

[GreenAce92]

----- the session live value for this site is so short.

Well you see, it would be used as a substitute for the laser component of LIDAR for drone navigation as apparently it is illegal to have an airborn laser despite how useful it is at mapping for navigation. So if sound can be used instead, in a range that is not audible/disturb humans/animals or property for that matter, then that could replace LIDAR and be very useful. Probably require a phased/pulsed (a BS substitute with no scientific backing) array design that does not need the dish.

I once thought of using ultrasound as a loudspeaker for regular sound on phones. A concentric multi-sound speaker design that would amplify regular sound using ultrasound wow that pointless and redundant.

Thank you for the responses.

When I think about it further I don't think that it would work just because of how "pure" a laser beam is compared to a sound wave. I mean a beam could be just as easily deflected but it is less (diameter?) to be dispersed and a laser is more likley to return a useful ping to determine the range of an object.

 

[jiripolivka]

Sound can be focused like light but not like in lasers. There are commercial devices that can focus high-power sound over a distance like 1000 ft or more, used as deterrents against pirates and demonstrators.

 

[Audioguru]

The toy drones at the park are navigated by using GPS, not LIDAR, not ultrasound and not infrared. They go exactly where they were programmed to go to and return and land on exactly the same spot they took off from.

 

[GreenAce92]

The toy drones at the park are navigated by using GPS, not LIDAR, not ultrasound and not infrared. They go exactly where they were programmed to go to and return and land on exactly the same spot they took off from.

I did not say that.

I watched this video here and I was amazed how it was able to fly through an inside parking lot with tons of obstacles around autonomously. I figured that if all drones had this capability, they would be better in flying and less accidents. Especially if they were to navigate near the ground like the Amazon drones that would land in the back or front yard of people's houses.

Since I found out that mapping via LIDAR or laser based, is not legal, maybe with permission, I was looking for an alternative substitute to generate 3D mapping... I have heard of bluetooth being used but not sure.

 

[Warpspeed]

I suppose a navigation system like that could be made completely visual.

If stationary, stereoscopic vision may enable distances to be judged, but if moving, the constantly changing relative perspective of objects may be all that you need ?

 

[GreenAce92]

That's been done as well

 

[larry_walker]

Hi,

I think it would be useful to take a look at the AcuSpaDe product.
https://www.ultrasonic-audio.com/products/acouspade.html

Cheers.