Laser Audio Transmission (Need Help)

[lousyanson]

Hey Senior,

I got a Laser Pointer, and i would like to transmit the audio signal either in AM or ASK, but i would like to know that, is that any recommend photodiode or phototransistor can be used compatible instead of solar cell?
And any reference i can study for Laser Audio Transmission in free space?
my laser pointer wavelength is 650nm

Thanks

 

[photonaholic]

How do you plan to modulate the pointer?

 

[Cyparagon]

Didn't kipkay illustrate something like this?

 

[photonaholic]

Didn't kipkay illustrate something like this?

Yes, it was 2 coffee cans and some string.

 

[bobhaha]

Yep here it is... I think a solar cell would be the easiest/cheapest option.

 

[LSRFAQ]

K3PGP - Experimenters Corner - Home

His site has a lot of far out stuff on it, some that I really think is pushing the BS limit...

I don't agree with the guy's attitude towards laser safety in airspace.. But hey.. He's got what your looking for..

And any form of pointer modulation is AM when it boils down to it. Changing the diode current does change the wavelength a bit, but its not "FM" that is easily demodulated.

For example that eyeball EME is impossible, even with a 60 watt laserscope. The NASA rangefinding lasers get about 3-5 photons back from the Apollo retroreflectors on the moon and they have 10 to 20 inch telescopes..

For the receiver, look here:

http://www.electrooptical.net/www/frontends/frontends.pdf


Steve

 

[lousyanson]

How do you plan to modulate the pointer?

I planed to modulate my signal in DIGITAL rather than ANALOG. so i used to get some source online, but most of the modulation in AM.. anyway to develop and transmit in DIGITAL signal thru Laser?
and if i modulate it in DIGITAL signal, is that any specific type of Laser Diode i need to use?

 

[lousyanson]

Yep here it is... I think a solar cell would be the easiest/cheapest option.

hey dude, thanks for the video. I cant get any audio transformer in MALAYSIA. SO instead of using the transformer, is that other amplifier by using the transistor work?
However, I still looking for any solution to transmit the signal in DIGITAL badly.. any recommend on this type of transmission?

 

[Things]

The transformer works because it's output is proportional to it's input, so the audio sounds as good as it's gonna get. Maybe consider ordering an audio transformer online ...

 

[HIMNL9]

Digital modulation is extremely easy (in fact, TTL modulation is digital )

You just need a fast switching transistor, and maybe a logic port for drive it (also just an inverter, just for have an input that already is at logic livils and impedances, and a clear output signal for the transistor)

 

[lousyanson]

Digital modulation is extremely easy (in fact, TTL modulation is digital )

You just need a fast switching transistor, and maybe a logic port for drive it (also just an inverter, just for have an input that already is at logic livils and impedances, and a clear output signal for the transistor)

Yea, i know TTL modulation is in digital signal.. but i still not understand how the way i need to convert in transmitter and demodulate the signal in receiver. ur fast switching transistor is used to receiving the signal?