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By putting solar eclipse glasses directly between a remote control IR emitter and device receiver, could some unsafe glasses be detected? My guess is most fake glasses are just blocking visible light at best, while safe ones should block the IR signal as well. It would not guarantee they are 100% safe, but it might be able to detect bad ones.

I know to check for the ISO logo, cert number, and buy from a reputable vendor recommenced by the American Astronomical Society (which I have). It would still be nice to double check pairs of glasses before giving them out to friends and family.

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  • $\begingroup$ Don't forget that you need to test for pinholes as well as average transmission. That makes testing much more complicated. $\endgroup$ – MaxW Aug 14 '17 at 16:39
  • $\begingroup$ Need suggestions. I purchased a large quantity for my company's employees to use. It has the ISO label on them, but it doesn't appear that they are one of the AAS approved companies. Those from the approved companies are all sold out. I've tested them and can't see a thing inside with them. But when I look up to the sun I see an orangish ball. Does anyone have an idea of where I could take them to be tested? $\endgroup$ – user17980 Aug 14 '17 at 22:04
  • $\begingroup$ Just though of another possible at home test of glasses that might help rule out bad ones. Focus sunlight with a small magnifying glass into a glass thermometer or something. Then place a pare of the glasses in front of the magnifying glass. If the glasses correctly block the suns energy to a safe level for eye tissue, then there should hardly be any energy getting through to heat up a thermometer. $\endgroup$ – SanQC Aug 15 '17 at 0:25
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Short answer: No.

Long answer: No. You're testing at a single wavelength. The Sun emits continuously at a variety of wavelengths from deep infrared to far ultraviolet. Testing with a single kind of radiation doesn't tell you much about the filter behavior at the other wavelengths.

Buy from the online vendors that specialize in selling astronomy equipment - the ones that all astronomers buy their gear from. They tend to know the stuff they're selling. The list of vendors on the AAS page is good.

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  • $\begingroup$ That's kind of what I suspected, but I thought it might be better than just blindly trusting them with no test. I figured maybe, If you have 5 safe glasses and 5 bad ones, all the safe ones should block the IR, while some or most of the bad ones may not since they probably use cheap material that only blocks visible light. Even buying from a good vendor, isn't there a chances of defects in the filter material? With so many glasses being made, I wonder the quality control from the suppliers of the filter material with ramping production. With eyesight at risk, every check could count. $\endgroup$ – SanQC Aug 15 '17 at 0:20
  • $\begingroup$ Not being able to do some kind of test of the safety of the glasses when your eyesight deepens on it is worrisome. I don't want to use or give out possibly bad glasses. A bad pair of glasses could give you a false sense of safety to look directly at the sun. You would also not look away as fast and they would prevent your pupils from contracting due to the visible light brightness. $\endgroup$ – SanQC Aug 15 '17 at 0:23
  • $\begingroup$ @SanQC Well, your life depends on the structural integrity of the bridge you're driving over every day, and yet you're not able to personally test it in any meaningful way. Examples like this could continue ad infinitum. $\endgroup$ – Florin Andrei Aug 15 '17 at 17:34
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I was considering a similar line of thinking. However, there were a few hangups which I believe prevent yee-average-human from testing the glasses.

Many sites suggest a transmittance of 0.0032 (welding shade 12) to be the minimum to be safe (and typically recommend 13 or 14, which has even lower transmittance). That means you're only seeing 0.3% of the light get through the goggles. Your test would need to have enough sensitivity to pick up that tiny amount of IR light, and to not only receive a signal but be able to meaningfully measure its amplitude. You would also need to ensure that UV light is blocked as well... and all the other IR bands (I am not confident as to how wide-band protection one actually needs).

Even then, you'd have to deal with the issue of having built your own contraption to test a device which must protect your eyes from a permanent damage that you literally cannot see. I'd want to be quite the confident electrical engineer and systems test expert to make sure that the tests I do actually test what needs to be tested.

Note: I have a related question asking how one can track down the ISO certifications and see if your particular vendor has legitimate glasses or not. I run into the same issue: how can you trust that this device performs as indicated, because your eyesight depends on it.

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No, because among other reasons it's UV, not IR which poses the major ocular damage risk.

THere's also the fact that you can't possibly measure a 30 or 40 dB attenuation factor in the method you're proposing. Your source is very weak and your receiver is binary (it responds or it doesn't).

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