Laser beam makes sound...

[dsli_jon]

..i've noticed the same phenomenon:..

..boy, did that thread go casey-jones!..

@ Mark.. 'scanner echo'?

..I mean, I'm probably bats for suggesting this, as I know the 'correct' way to transmit sound over light waves is mod / demod, etc, but.. what about the 'tin-can / string' phenomenon? Any-way possible for the scanner-resonances to be being 'mimicked', or even 'piggy-backing' almost like a 'carried-echo'?

Questions: a) Does your pj have a glass-window? If not, hmm.. b) What happens to the 'sound' if you change the scan-rate (same pattern, just slower / faster..) Anything? What about a static 'dot' (might wanna turn the power-pots-down, tho.. That might argue more in favor of it having something to do with being-scanned (?) c) What about a different color? Or, is it only with full-power / 'white'? What about lower power? (I mean, if it 'sounds the same' with just 445 or even white at 'lower-power', that would seem to move away from 'thermal' causals..) (?)

..d) Can you replicate this with any other surfaces, (dark or light; smooth / rough; paper, plastic, etc..) or only on this fabric? Other fabrics? Would be interesting to compare 'subjective observations' between swami's curtains and this jack't... both: Cotton? Polyester? Umm.. Rayon?

..I've heard this with Q-Sw'd KTP-scans before (even if not 'focused-down' / burning-stuff..) but that's easily explainable / understandable.. but a (relatively low) amount of CW...
Most-curious..

j

[swamidog]

the sound i heard was definitely a result of the light hitting my curtains. i could change the sound by moving and bunching the curtains. the sound was not present when the laser was hitting the wall. only when it scanned onto the curtains. the sound changed very obviously with different patterns being scanned.

my curtains are cheap cotton panels from JC Penny.

my projector was doing about 3W and scanning from 40' away.

..boy, did that thread go casey-jones!..

@ Mark.. 'scanner echo'?

..I mean, I'm probably bats for suggesting this, as I know the 'correct' way to transmit sound over light waves is mod / demod, etc, but.. what about the 'tin-can / string' phenomenon? Any-way possible for the scanner-resonances to be being 'mimicked', or even 'piggy-backing' almost like a 'carried-echo'?

Questions: a) Does your pj have a glass-window? If not, hmm.. b) What happens to the 'sound' if you change the scan-rate (same pattern, just slower / faster..) Anything? What about a 'dot' (might wanna turn the power-pots-down, tho.. What about a different color? Or, is it only with 'white'? c) Can you replicate this with any other surfaces, (dark or light..) or only on this fabric? Other fabrics? Would be interesting to compare 'subjective observations' between swami's curtains and this jack't... both Cotton? Polyester? Rayon?

..I've heard this with Q-Sw'd KTP-scans before (even if not 'focused-down' / burning-stuff..) but that's easily explainable / understandable.. but a (relatively low) amount of CW...

Most-curious..
j

[dsli_jon]

...the sound changed very obviously with different patterns being scanned...

Most-interesting.. What about a 'single dot' projected (probably-best 'lowerish-power'.. - and... move the curtains thru-it.. any 'noise'? Also, same-questions / test-proposals, as above - Lower power: Sound? ..Other colors: Sound? Different material: Sound? ..Umm, 'sounds' like you gents have a cool homework project on your hands..

..Show and Tell at 09:30...


j

[daction]

I too have heard it. It was when it was touching my tee shirt ( not a cotton one).

[mccarrot]

I have also witnessed this many times when projecting a 2w rgb at black curtains from 10 meters.

Its a very strange experiance the first time, but now take it as normal behaviour.

I will do some tests next time to se if the scanrate influence the frequency.

[kecked]

http://www.youtube.com/watch?v=a2SnYa2aJNo