27932[SeattleRobotics] Re: Sensing Lasers..
- Jun 3, 2006
> when i observed the output from theSounds like a laser modulation to me.
> phototransistor ... on a CRO, i found narrow and small amplitude (around
> 1.2V) spikes at the same 10 KHz frequency instead of a square wave
> with 5V amplitude.
How well did the phottransistor respond to a TV remote control?
> On the other hand the photodiode shows very little response towardsI don't understand that. When I tried it yesterday, there way a huge
> laser (unmodulated) and that too when the laser is extremely close to
> the diode.
response even if I fired the laser from the other side of the room. I wan't
using a beam-spreader. Is that the problem? Has it spread the beam too
much? Is there a lot of ambient illumination?
> The application actually requires sensing the laser from about 1 m andA TV remote control will work over a much longer distance.
> that is the reason behind using a laser instead of ir led.
Why not use one of the IR sensors that has an amp and demodulator built in?
It's only worthwhile building your own IR receiver if you're going to
produce a few thousand of them.
> how leds can be usedThey're very much cheaper but they're nowhere near as good. I've filed the
> as light sensors.. do they offer any advantage over photodiodes that
> are supposed to do the job?
"LEDs work as sensors" idea in the interesting-but-useless category.
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