The sound of laser beams..

[tonyt]

So,

I was just using one of my 2.5W+ 445's and i was about 3 meters away from the host and i put my ear next to the beam and it has a sound!!! I never knew they made a sound?? It is like the sound you hear when lasing something.. Like a high pitched humm..
Very cool.

 

[norbyx]

I don't hear any sound out of my laser. Just one makes a sound but obviously has to be the driver.

 

[Cyparagon]

You're hearing the switching noise from the driver. It won't be coming from the beam itself.

Another interesting phenomenon happens with high(ish) power flashlights and PWM. You can hear the pwm faintly if you point the beam at your ear, but it is louder if you put a black piece of cloth or paper in front of your ear. The black absorbs the light, heats up slightly on the "on-phase," and cools slightly on the "off-phase." This expansion and contraction of the thermal cycling material produces sound. Try it.

 

[tonyt]

Even 3 meters from the actual laser?? That is what it sounds like.. But i didn't expect it so far away from the actual unit??

 

[Blord]

Maybe you have sensitive ears and hear the high pitch very good.

 

[tonyt]

Maybe you have sensitive ears and hear the high pitch very good.

LoL i doubt it.. My ears are useless! Years of loud music has destroyed my hearing!

 

[Sigurthr]

It is the driver you are hearing. Unless your laser is not CW and operating in a PWM mode you won't get any thermal induced sound (like what Cyparagon was describing) at all. A CW beam's carrier oscillations are a few terahertz too high in frequency for your to hear =P . If your CW driver had enough ripple to AM modulate the beam you could get thermally induced sound, but it would be a pretty piss poor driver then.

 

[lasersbee]

So,

I was just using one of my 2.5W+ 445's and i was about 3 meters away from the host and i put my ear next to the beam and it has a sound!!! I never knew they made a sound?? It is like the sound you hear when lasing something.. Like a high pitched humm..
Very cool.

I think what you are hearing is the sizzle of your
ear in the 2.5W Laser's beam.....:crackup::crackup::crackup:


Jerry

 

[Things]

High frequency sound can be weird like that. You could have your ear right next to the source and not hear a thing, yet move around the room a bit and you'll hear it fine.

 

[Antharak]

I've noticed a very high pitch sound when I run the beam from my 2.75W 445nm across a wood box. Like a high speed band saw. Only when moving, wood cells popping?