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Comment by vmarsy | Hacker News Reader

Not to be alarmist, but how do we know this IR blasting won't be damaging to the eyes, a 3 seconds google search leads to a 2011 study[1] which concludes:

> The protein of eye lens is very sensitive to IR radiation which is hazardous and may lead to cataract.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3116568/

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In short because an optical engineer at apple checked that the emission was at a safe level, and if it wasn't they'd be shafted by lawsuits. Assuming it's a laser, it'll be a Class 1. The emitter is short range, so the power doesn't need to be as high (though interesting to see how well it works outdoors).

> Workers in hot environments, exposed to IR, developed lenticular opacities due to IR irradiance in the order of 80–400 mW/cm2 on a daily basis for 10–15 years

That is really high. The original Kinect has an output power (at the emitter) of around 60mW. The expanded beam is safe to look at beyond a centimeter or two (I think less, actually) due to energy conservation.

On top of that you're only being exposed for a second or two to grab the depth image, not 5 minutes.

The Kinect has a number of hardware interlocks as well, and will shut the laser down (without firmware intervention, because firmware might not be working) based on some hard-wired detections. The unexpanded raw laser in the Kinect, prior to hitting the hologram, wouldn't be great to look at.

Sure, in my post I assume it's going through the diffractive optical element (DOE). A 60mW, 940nm laser is absolutely not class 1!

The amount probably is low enough not to be an issue. If it needs to be somewhat high, they could use the output of the face detection from the visible light image capture not to blast anything at the eyes themselves.

I highly doubt the iPhone will be able to compete with the flux density of sunlight, at any wavelength, which we generally regard as safe.

(1400 watts / m^2) * 0.2 [ground albedo] * 0.5 [proportion in infrared] = 14 mW / cm^2 of infrared radiation looking at the ground on a sunny day.

(14 mW / cm^2) * 1 square foot [approx size of a face] = 13 watts

I'm going to guess there isn't a 13 watt infrared laser in the iPhone, or we'll be seeing some great hacks where people take the lens out and start setting things on fire from hundreds of feet away.

What difference does it make whether they know or not? AFAIK TSA knows of at least 3 independent studies done by different Universities of harmful radiation from backscatter machines; yet it didn't stop them from using those and making pat downs more invasive so even less people opt out.

Unless some technology is capable of killing more than few percent of population, government is the last to worry about statistics.

link to these studies?

backscatter machines are considered complete safe, from what I understand. they use radio waves (not ionizing radiation) the same as phones/microwaves, and the waves don't even penetrate skin (or else they wouldn't be very effective, would they)?

you have nothing to worry about, medically, from them. I guarantee you're being bombarded right this moment with a similar amount of energy in a similar portion of the spectrum from Wifi, phone calls, bluetooth, FM/AM radio, GPS radio, etc.

I think GP is referring to these:

https://en.wikipedia.org/wiki/Backscatter_X-ray

whereas you're thinking of these:

https://en.wikipedia.org/wiki/Millimeter_wave_scanner.

They are compating technoogies; the former employ ionizing radiation, the latter do not. I don't really know which ones are employed on US airports right now, but backscatter X-rays were employed at some point, which generated a bit of media shitstorm few years back.

Ah, yes, my mistake. I was aware the TSA used X-ray machines at some point, but I thought those were phased out long ago. I absolutely would refuse to get into one of those.

The linked article used 200 mW/cm^2 for 5 to 10 minutes. This is orders of magnitude more light exposure than an iPhone would create - it wouldn't even be able to from its battery capacity. The light emitted by the iPhone would be closer in power to what a normal TV remote emits.

Exposure of a few seconds is one thing but when they demo'd SnapChat, it sure looked like they might be using a depth map to plaster a texture on to your face for as long as you're in the app.

The iris scanner on my S8 carried a warning not to let young children use it.

That was enough to put it off for myself for long term use after trying it a a couple of weeks, until I can find something that explains the risks - or rather, lack thereof - very definitely. I've attempted to search but have come up short each time.

The S8 iris scanner was super quick, very impressed by it.

I will not say it is safe for you to use or not. But the reason for that and many of the "don't let children near it" is better be safe and make it user error than take an useless risk. In particular, I'm sure there are very little if any studies on the effects of that tech on children, for obvious reasons.

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