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Generating an infrared plane

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sederberg

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I am trying to find a way to generate an infrared plane that is parallel to a table-top and a few millimeters above the table top. When an object crosses the plane I want to be able to sense where in the plane this occurred. I have been looking at some infrared diodes and transistors, but I haven't been able to find anything specific enough for my application. Does anyone know of a way that I could make this possible, or would I have to have some custom optics built?

Thanks
 
P

Paul Obrien

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Some touch screens for kiosks work in exactly this fashion so that might be a starting point.
 

dknguyen

Well-Known Member
Most Helpful Member
What do you need? This company makes some very narrow focused IR LEDs that work up to a couple meters (if I remember right).
http://www.clairex.com/

Products->IREDs->Point Source Emitters->CLE331 or CLE333 which are 1~5 degrees beam widths. The narrower of the two is only 0.35mW though. The slightly wider one is 2mW.

They probably also have suitable narrow view receivers as well.
 
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sederberg

New Member
Products->IREDs->Point Source Emitters->CLE331 or CLE333 which are 1~5 degrees beam widths. The narrower of the two is only 0.35mW though. The slightly wider one is 2mW.
This is a good idea. The way i was thinking of earlier was more of an "analog" solution I guess, where I would be generating a single plane. The way you've suggested is more "digital" and would probably be easier to implement and would be more reliable. It might be a pain to do somehting like an entire keyboard or something like a board game using this principle though since it could mean using quite a few of these
 

hjames

New Member
Incidentally, it's probably a good idea if you limit the field-of-view of the IR sensors as well. Either use a lens, or better yet if the emitters are sufficiently bright, just have an aperture a good distance in front of the sensor. If you have a 1-2 mm hole a cm or two in front of the sensor, lined up with the emitter, you'll have a really well defined sensing 'beam'.

If you want an 'analog' solution, you might be able to find a linear PSD(position sensitive diode - it's a large photodiode with multiple taps, google it) and adapt a scanner optics assembly. The digital version is to just *use* the scanner, complete with CCD sensor and use a pair of them as the sensors.

James
 

sederberg

New Member
you might be able to find a linear PSD(position sensitive diode - it's a large photodiode with multiple taps, google it)
Do you know of any specific manufacturers. I did a search on it and found lots of academic papers describing projects that used them and a couple manufacturers, but they were all fairly big - around 60mm x 60mm. Do you know if they come in a smaller package than that?
 
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