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Topic: Infrared wavelength (Read 1 time) previous topic - next topic

Jek90

Apr 10, 2013, 12:39 am Last Edit: Apr 16, 2013, 12:05 am by panosip Reason: 1
Hello.
In order to detect both a 940nm and 850nm wavelength signals, I need to use an 940nm and 850nm receivers?

I need, the 940nm wavelength, to be detected only by one receiver (with no scattering - ir beam) and the 850nm only by the other one. Is this possible?

p.s: I'm thinking of buying an Wrobot Digital 38KHz receiver/transmitter. Does anyone knows its wavelength?

Thanks in advance

Grumpy_Mike

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I need, the 940nm wavelength, to be detected only by one receiver (with no scattering - ir beam) and the 850nm only by the other one. Is this possible?

No.

A 850nm sensor and a 940nm will both respond to either wavelength emitter, it is just that the sensitivity will be less.

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I'm thinking of buying an Wrobot Digital 38KHz receiver/transmitter. Does anyone knows it's wavelength?

I don't know but find out what IR receiver chip it uses and look up the data sheet, it will tell you the wavelength.

Jek90

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A 850nm sensor and a 940nm will both respond to either wavelength emitter, it is just that the sensitivity will be less.


Thanks for your reply.

What about with a 300nm and 940nm instead?

Grumpy_Mike

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What about with a 300nm and 940nm instead?

Well 300nm is up in the ultra violet region. Can you get 300nm detectors?
You would have to look at the sensitivity curve in the data sheet but in general a high energy photon will always induce current in a low energy photon detector without filtering.

adrian_h

#4
Apr 11, 2013, 02:19 am Last Edit: Apr 11, 2013, 02:26 am by adrian_h Reason: 1
Practically speaking, the farther off the wavelength is off from the tuned receiver, the less it will respond.  This is how the eye works with just being able to see only 3 colours, red, green and blue.  All three receivers have some overlap (the red receiver overlaps green, but red doesn't overlap blue that much).  However, because of the different amount they respond to any wavelength, the brain can approximate what the wavelength is and attach a colour to that received radiation.  See http://ed.ted.com/lessons/how-we-see-color-colm-kelleher.

What is it you are attempting to do?  Does it have to be outside of the visible spectrum?  Maybe you can stay within the same wavelength and use something like ALOHA protocol http://en.wikipedia.org/wiki/ALOHAnet.  A close variant is used for Ethernet communication and all communication that uses a shared medium/band.

Or maybe you can try for different colour sensors?
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