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Unrelated, but I really want to take the opportunity: How can one know what is dangerous for the eyes or not? Years ago I got an "IR illuminator" (from aliexpr

by palata 8mo ago

Unrelated, but I really want to take the opportunity: How can one know what is dangerous for the eyes or not? Years ago I got an "IR illuminator" (from aliexpress, probably) that I wanted to use with my raspberrypi NoIR camera, for fun. Say filming myself during the night to see how much I move while sleeping, or making my own wildlife camera trap. But I was scared that it could be dangerous and never used it (I tested it in an empty room, but that was it). Is there a safe way for a hobbyist to get an IR illuminator and be sure that I won't make somebody blind with it?

elictronic 8mo ago
Buy from a reputable dealer. I don’t buy batteries, lasers, or items I ingest from locations lacking any repercussions.
duskwuff 8mo ago
IR illuminators are not lasers. Their purpose is to cast light across a broad area, not to deliver it all to one point. They should not be harmful to vision.
0_____0 8mo ago
Is it just a bunch of IR LEDs? Surface mount or through-hole? What's the module power rating? What's the power supply power rating? Are there any secondary optics like lenses over the LEDs? Is there a diffuser of some kind? If it's a cluster of garden variety through-hole LEDs with domed tops (like you would see on a TV remote), they're necessarily low power on account of having poor thermal performance. Another way to tell is if nothing gets warm at all. It's pretty hard to hurt someone with an emitter that both doesn't have a focusing optic and doesn't get warm. Let me be clear - you're still responsible for verifying the safety of your stuff, and I am in no way assuring you that the device you have is benign, because I can't do that without inspecting it directly.
- palata 8mo ago
  Yeah, let's say something like this: https://www.instructables.com/DIY-IR-Infrared-Illuminator-Night-Viewing-With/ https://www.instructables.com/DIY-IR-Infrared-Illuminator-Ni... > Let me be clear - you're still responsible for verifying the safety of your stuff Obviously yeah. I was just wondering if there were known rules like "these wavelengths under this power are fine for humans and wildlife, even if they put the LEDs right in front of their eyes", and also if you have an array of such IR LEDs, how they cumulate. And curious about things like: if I don't see it, can it hurt my retina? I probably will never do it: I wouldn't want to blind a fox just because I wanted to make my own wildlife camera :).
  - 0_____0 8mo ago
    Invisible wavelengths can absolutely hurt your retina, but as wavelengths go farther beyond visible, your eye begins to not focus them properly on the retina, so the risks change. E.g. with 1550nm IR (common in telecom, sometimes in LIDAR) the risk of eye damage is to the surface of the eye rather than to the retina. Short wavelengths like UV will be absorbed by the lens at near-UV, and then eventually just be absorbed at the surface at shorter wavelengths. I think it would be a cool exercise to figure out how much optical power you would see at, idk, 5cm from your illuminator. I assume it's a shortwave IR close to visible light, so you can assume it will focus like visible light, more or less. Ideally you'd use an optical power meter but you could get a first pass by looking at the circuit and seeing how many mW pass through each LED, applying a conservatively high efficiency factor of W_optical/W_electrical, projecting that into a radiated cone for each LED and multiplying the power received on a dilated pupil sized spot at 5cm by the number of emitters. Then you have to work out what the irradiance at the retina is once the light is focused. The hazard criteria include a time factor, so you'll have to decide if you/foxes would like to stare directly into the beam for 10 seconds? Or for the entire duration of your meditation session.
    - palata 8mo ago
      Very interesting, thanks a lot! I assume CCTV surveillance cameras are usually fine because people cannot go and stare at it from very close then :-).

by palata 8mo ago

elictronic 8mo ago

Buy from a reputable dealer. I don’t buy batteries, lasers, or items I ingest from locations lacking any repercussions.

duskwuff 8mo ago

IR illuminators are not lasers. Their purpose is to cast light across a broad area, not to deliver it all to one point. They should not be harmful to vision.

0_____0 8mo ago

Is it just a bunch of IR LEDs? Surface mount or through-hole? What's the module power rating? What's the power supply power rating? Are there any secondary optics like lenses over the LEDs? Is there a diffuser of some kind? If it's a cluster of garden variety through-hole LEDs with domed tops (like you would see on a TV remote), they're necessarily low power on account of having poor thermal performance. Another way to tell is if nothing gets warm at all. It's pretty hard to hurt someone with an emitter that both doesn't have a focusing optic and doesn't get warm. Let me be clear - you're still responsible for verifying the safety of your stuff, and I am in no way assuring you that the device you have is benign, because I can't do that without inspecting it directly.

palata 8mo ago
Yeah, let's say something like this: https://www.instructables.com/DIY-IR-Infrared-Illuminator-Night-Viewing-With/ https://www.instructables.com/DIY-IR-Infrared-Illuminator-Ni... > Let me be clear - you're still responsible for verifying the safety of your stuff Obviously yeah. I was just wondering if there were known rules like "these wavelengths under this power are fine for humans and wildlife, even if they put the LEDs right in front of their eyes", and also if you have an array of such IR LEDs, how they cumulate. And curious about things like: if I don't see it, can it hurt my retina? I probably will never do it: I wouldn't want to blind a fox just because I wanted to make my own wildlife camera :).
- 0_____0 8mo ago
  Invisible wavelengths can absolutely hurt your retina, but as wavelengths go farther beyond visible, your eye begins to not focus them properly on the retina, so the risks change. E.g. with 1550nm IR (common in telecom, sometimes in LIDAR) the risk of eye damage is to the surface of the eye rather than to the retina. Short wavelengths like UV will be absorbed by the lens at near-UV, and then eventually just be absorbed at the surface at shorter wavelengths. I think it would be a cool exercise to figure out how much optical power you would see at, idk, 5cm from your illuminator. I assume it's a shortwave IR close to visible light, so you can assume it will focus like visible light, more or less. Ideally you'd use an optical power meter but you could get a first pass by looking at the circuit and seeing how many mW pass through each LED, applying a conservatively high efficiency factor of W_optical/W_electrical, projecting that into a radiated cone for each LED and multiplying the power received on a dilated pupil sized spot at 5cm by the number of emitters. Then you have to work out what the irradiance at the retina is once the light is focused. The hazard criteria include a time factor, so you'll have to decide if you/foxes would like to stare directly into the beam for 10 seconds? Or for the entire duration of your meditation session.
  - palata 8mo ago
    Very interesting, thanks a lot! I assume CCTV surveillance cameras are usually fine because people cannot go and stare at it from very close then :-).