Do IR sensors sense polycarb?

Can’t test our sensor yet and having trouble getting an answer to this from search. Thank you.

If memory serves, the most common infrared LED emitters have peak wavelengths of 850 or 940 nm. In this graph stolen from Wikipedia the transmittance of polycarbonate is about 90% at those wavelengths. From this somewhat sketchy mix of evidence it seems that if IR sensors can detect polycarbonate, they won’t do it very well.

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They absolutely will, and it will be absolutely insanity to try and get it to be consistent. If you get head-on to a very glossy finish it can work, or if there’s schmoo on the PC surface it can trip, or…

We wound up with a ton of difficult-to-reproduce false-positives last year when using IR sensors to help pickup and handoff game pieces in and around the HP station where there is a lot of PC on the field.

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Do you want it to detect the polycarb or have the IR sensor detect something on the other side of it? In either case I probably wouldn’t trust the polycarb, and add something opaque to stop the IR beam, or cut a hole so it can’t disrupt the beam.

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Sounds like the answer is IR sensors will only detect polycarb if you don’t want it to.

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It also is dependent on how the polycarb was made/extruded. They can vary somewhat and though they look clear to the naked eye, they refract light both visible and invisible in weird ways

We put black gaffers tape on the polycarbonate to “see it”. Low tech, but effective.

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Too bad OP wasn’t specific about their use case. Even your answer has multiple possibilities. Black tape will almost always trip a beam break sensor but a distance sensor including proximity switches could read “infinite” even at close distances as IR is completely absorbed by some blacks.

Don’t laugh… but in industry (manufacturing) we’ve been known to do the same trick.

Clear plastics and optical sensors often don’t play well together. Especially once it’s gotten scratched/worn a bit. To the point of $3000+ laser scanners (industrial safety devices) being stumped by a mere polycarb fence panel (machinery guarding) that’s just a little too reflective (we had to hang some weld guarding cloth to kill the reflections). Not exactly elegant, but cheap and effective.

I agree, a little bit of gaffers tape or some other polycarb-friendly substance/material is a decent solution for using an optical sensor to detect polycarb. The more opaque and matte, the better.

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