Infrared emitter into SK68 - I call it the IR68

Here’s a quick mod I made this week. It is not nearly as impressive as the TV-B-Gone IR system, but it works for what I need. I needed some night time baby monitoring functionality so I took an old webcam I had and took out the IR filter behind the lens. The colors of it are all washed out and purplish now, but I didn’t need color detail anyway. I then needed an IR source, so I got a cheapy single 1 W IR emitter and a dead SK68 clone. Sorry for the crappy pics.

The higher power IR emitters have multiple chip dies. Anyway, this works fine for my close up lighting needs. I ended up dropping the resistor out since it made it too dim.

Here it is working as it looks to my cell phone camera with its filter. I power straight of an AA NiMH cell direct drive. At their fully charged voltage it might run a bit hot ( I was seeing up to 1.5 amps at the tail), but at the 1.2 working voltage the output is just right for my use, and since it’s a diode, I can leave it on all night and it won’t over discharge my cells. To the eye, there is a faint red glow when looking at it. The the IR-stripped webcam, it’s a bright purple, which is what all lights look like to it.

This isn’t actually for illuminating a baby is it?

It is. I also have my sunwayman D40a ceiling bouncing on moon mode on in the room to function as a nightlight, but that alone was way too dim to get anything to register on the webcam.

Arrays of lower power IR leds should be used when family can accidentally cast their gaze toward the leds.

A single source of high power IR can do harm to your eyes that you won’t notice. With visible leds constricting pupils provide automatic protection and discomfort will make them shield their eyes.

Interesting, I haven’t found any data suggesting that IR radiation is dangerous unless very focused like a laser. It’s not very bright anyway, the arrays on security cameras off 12V are dumping out way more IR than this, much less all the IR that comes to earth the via the sun, which I assume you know with a name like helios :).

If your seeing a dim red glow its 850nm.

Security camera arrays of individually high power IR leds can be hazardous as well but there just isn’t any regulation. Though the wavelength choice and typical locations usually reduce the hazard enough anyway. Most will be 980nm matched with cameras that are particularly sensitive to wavelengths that high. They are often mounted high & back from the area of interest to provide a field of view.

Pupils constrict outdoors in daylight and more so if the actual sun is in your field of view. Low light indoors pupils are wide open.
Doesn’t need to be coherent laser light to be hazardous. Consider that you have a couple millimeters square source with its focus narrowed by an aspheric lens.

95% transmission for 850nm vs ~40% for 980nm.

I have heard this some times here but a serious link who explains why ir light is dangerous and what it will make would be nice….

My opinion, ir light has lot less power than maybe uv radiation from the sun and I am not so afraid of the sun(a bit maybe :wink: ) also the sun sends tons of ir light…
Also I am not sure how it will behave in the eye as the eye doesn’t see it and so it doesn’t gets focused…
That are just my guesses I have always, but I would like to learn…

Interesting. I don’t think there is any definitive studies out there that I have seen. As for this light, I feel it is fine. Based on your graph, it would be the same as having a 1 W led around which is fine. Also, your chart suggests there is some occular focus and eyeresponse into that range. Who knew? Oh and the aspheric is on flood mode, so as to cover more area.

Well the problem here is there isnt enough data for hard safety limits, and its something we cant see, so have a hell of a time documenting. There are minimum safe distances for IR cameras and motion sensors, and they arent really a problem because nobody tends to sit and stare at them. For medical eye tracking IR lights there are even lower safety limits. It would be very hard to ever say “my visual loss is due to IR exposure” even if it ever happened, because well…how could you know? Its just not possible, nobody wears an IR sensor at eye level to track it. Visual loss is hard to detect anyways, we all have blind spots, and slowly detaching retnas can obscure HUGE areas of vision before the person actually notices. Also, light in shorter wavelengths also causes damage to the outer layers of the eye, or whats known as a cataract…could IR have a hand in this too? I don’t think its ever been studied, and again, people will go on for years before noticing the damage, and when its removed, I’m sure you’ve heard how different and easier to see an older person says the world looks afterwards.

Another more theoretical issue, babies brains have fast growing neuronal connections, and it has been established that even the concept of “color” is learned to match different wavelengths as we grow, and not all can see all of the spectrum…plus the fact that we do see some constriction/reaction to “invisible IR” even though we cant see it…so we do have SOME sensitivity to it…maybe it is possible to encourage growth in extremely plastic neurons in a growing baby, even if not damaged by the emissions, biology adapts. Is it possible you can increase proliferation of these cells? Or cause a sensitivity? Or cause a reaction the child cant “deal” with in the brain as we arent wired to respond to this stimulus and he would have an overabundance of it?

That last paragraph is just ideas/theoretical abstractions, but if we get back to what we do know: can you tell if you fried some of your retna if its not massive? Can you tell if you caused a mild corneal reaction just like UV light causing a beginning cataract? Can a baby?….and could he even tell you if he could? Do you think you could tell the baby just dont look into the light and stare at random objects like babies do… Could you be certain to never focus the light accidentally (bumping, pulling with a blanket, leaning on it, etc.) on him even if you knew for a fact low setting wasnt an issue? Could he develop migraine sensitivities now or later in life due to over exposure to intense IR light like people who develop these sensitivities to visible light? I think really the answers to all of these are we dont really know what the limits are or any of these answers, and no way would I risk my child to experiment. Just try to stare at a visible light of the same model for a second and then extrapolate a baby sitting wide eyed and staring at the funny object getting the same light…

Here’s some guidelines for a IR camera if you are still intending to experiment on him, I’d at least make certain to keep distance much greater than they advise:

Oh well.
I tried.

Its a transmission chart. Response (visibility of wavelengths) is not on the chart.

Thanks for all the input and info!
I was mainly inspired by the products out there that already do this like these:

Thanks for the document B42. I will have to do some calculations. My current distance is about 1 meters. Also, the baby is asleep the whole time it is in use, so the eyes should be closed. If it’s awake, you go get the baby. I just use the setup to distinguish an “i am uncomfortable and just rolling” cry vs a “come and get me now” cry.

“Just try to stare at a visible light of the same model for a second and then extrapolate a baby sitting wide eyed and staring at the funny object getting the same light…”
To clarify, I just used the host. The rating on this is 0.5 or 1 W, much less than what the Cree is delivering in the regular SK68.

Yes I’d at least make certain you are further away than the “danger zones” with equivalent or lower energy from the emitter. But really all the same questions are still there, less and less likely to be an issue the lower the emission becomes, but…I dont think anyone knows for sure, and if it did cause any change it would be very very difficult to ever know. Maybe a “guestimate guide” could be made of a visible emitter with the same power, and if you have any issues sleeping or staring at it for a few seconds, then dont do it, a baby is much more sensitive. Just an idea if you are going to do it.

I just found this document:

Citing IEC62471, the max irradiance should be 100W/m^2, which they use to convert to intensity with the square of distance.

Here’s a sensitivity chart for photopic (color) vision in the infrared. Everything up to 830 nm is based on the CIE luminosity function. Everything above that is from a variety of studies that all arrived at the same result: sensitivity just keeps on dropping off at a steady rate, except for eye opacity, which in the near infrared is equal to 22 mm of pure water for the adult human eye. For example, there’s an absorption band in the high 900s, another one starting at 1200 but too high up to be relevant.

All other factors being equal, infrared is less damaging than visible light, which is less damaging than ultraviolet. The problem is that you can’t see how bright it is. For example, at 1200 nm you would need to shine a 30 - 40 mW laser in your eye to just barely see the light, even though that could cause eye injury. At 1150 you would need 3-4mW which is still above safety limits.

Or another way of looking at it, whatever the output is of you emitted, just put a visible-light emitter there of the same power and see what it looks like. If it doesn’t look dangerously bright, you’re probably OK.

I'm no expert and I don't know what levels and length (I believe it is years) of exposure are dangerous, but I have read in several places that prolonged exposure to infrared light can cause gradual, irreversible blindness. The above post sounds reasonable as sunlight and other mixed sources make you squint due to the visible wavelengths. IR does travel through tissues though. I just wouldn't gamble with exposing anyone other then myself to such a potential risk though.

Thanks for the input guys. I have heard of high intensity heat/IR (like blacksmithing and glass blowing) leading to increased cataracts. In this situation though, I am not overly concerned because of a couple reasons. Compared to a regular LED flashlight on my filter removed camera, it is lower than my 15 lumen T10 mode. Also, I haven’t heard much negative news with so many commercial products out there that use IR for night vision yet. Eyes are closed and I don’t think there is much potential for damage to skin or whatnot.