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New Apple and Samsung phones use infrared light to verify your identity. It’s like a loud version of the fingerprint scanner. But can the infrared rays used for face identification and iris scanner damage your eyes?

This is an honest question. People know little about infrared light and it is difficult to find information that explains the potential risks of infrared radiation in layman’s terms. Not to mention, the security disclaimer for Samsung’s Iris scanner makes infrared sound intimidating. But what is infrared light and should we be concerned about it?

What is infrared?

Infrared (IR) is a form of invisible radiation and it occupies the lower end of the electromagnetic spectrum. Like visible light, microwaves, and radio waves, IR is a form of non-ionizing radiation. It doesn’t deprive molecules of their electrons, and it doesn’t cause cancer.

It is important to know that IR radiation can come from many places. In a sense, IR can be considered a natural by-product of heat production. Your toaster emits infrared light, the sun emits infrared light, and campfires emit infrared light. Interestingly, 95% of the energy produced by fluorescent lamps is converted into IR. Even your fleshy, hideous body emits infrared light, and that’s how thermal imaging cameras in spy movies work.

electromagnetic spectrum graph.  far infrared light is close to microwaves and near infrared light is close to visible light

The IR LED built into your phone is classified as near IR (700-900nm). It spans the line between the visible light spectrum and the IR spectrum. Near infrared is very similar to visible light, it’s much harder for you to see it.

Emission of both visible and near-infrared light can heat objects depending on the intensity of the light and the time of exposure. Prolonged exposure to high-intensity IR and visible light (while looking at the sun or a bright light bulb) can cause discoloration of the photoreceptors and the development of cataracts on the lens. To lose vision with low-intensity visible or infrared light, you need to keep your eyes open within a millimeter of the light source for nearly 20 minutes. This can happen with a light bulb or an IR LED.

The main problem with near IR is simply the concentration of your exposure. With visible light, it’s easy to tell when you’re exposed to a blinding amount and your reflexes cause you to squint or look away. But your eyes are not made to see IR light, so it’s impossible to tell when you’re exposed to a dangerous amount. Do you know how you shouldn’t look at an eclipse, even if it doesn’t seem so bright? It’s kind of like.

Far infrared radiation (25 — 350 microns) is invisible and not used by your phone. Far infrared radiation overlaps microwaves in the electromagnetic spectrum, and like microwaves, far infrared radiation causes water molecules to heat up. As you can imagine, prolonged exposure to far IR can cause eye and skin burns, but we don’t need to worry about this since your phone only uses near IR.

IR scanning is very easy

Iris Scanner and Face ID are forms of biometric identification that are used to unlock a phone and to open sensitive apps (such as banking apps). Both processes are similar and easy to understand. The new Apple and Samsung phones are equipped with an IR LED that emits near IR light and an IR camera capable of capturing IR light.

With Iris Scanning, your Samsung Galaxy illuminates your eyes with an infrared LED and takes an infrared photo. Your phone then looks at the details of your eyes and compares them to previous photos. If the phone can verify who you are, then it will unlock.

iPhone X is on the table
Adrian / Shutterstock

But the iPhone X’s facial ID software doesn’t just scan your eyes; it scans your entire face. The iPhone X has an IR LED that is fixed by a dot matrix grid. When it turns on, hundreds of tiny IR dots illuminate your entire face. The phone takes an infrared photo and this photo is used to check if the 3D structure of your face matches the phone settings.

You may have noticed that the IR LED on the iPhone X is invisible, and the IR LED on the Samsung Galaxy is pretty blatant. This is because Samsung deliberately pushes its IR LED as far into the visual spectrum as possible. Believe it or not, the band of infrared light that overlaps the spectrum of visible light shows more texture and pigmentation than lower spectrum infrared light.

If you’re wondering exactly which region of the infrared spectrum Samsung and iPhone work with… well, we don’t know the exact numbers. The Samsung Galaxy and iPhone X pages don’t even mention IR LEDs. But knowing that the IR cameras on your phone need to capture a lot of detail to make the scan effective, it’s probably safe to assume that they occupy a wavelength of 870 to 950 nm — the overlap point between near-IR and visible light.

In addition, Renesas’ biometric documents classify IR LEDs in phones as «low risk» IR. By OSHA standards, low-risk infrared products are not powerful enough to heat the eyes and are not capable of causing eye damage during normal use.

There are several popular rumors about IR, and they are not true.

When you use Google «IR iris scanner» you will find that many people ask if infrared light can damage your eyes. And this is a fair question. Most people don’t know anything about IR, and Samsung’s dreaded Iris Scanner rejection warns that epileptics, children, and people who experience blackouts should avoid using the Iris scanner. (Interestingly, Apple’s facial disclaimer statement makes no such warnings.)

Your Google results will also show you a lot of misinformation posted by Reddit users and bloggers. News and tech sites mindlessly internalize this nonsense, which makes it hard to find accurate information about the IR scanner in your phone. Accurate scientific information suggests that IR is safe or dangerous, doesn’t matter. Blatant disinformation is bad for everyone, so we’ll take a little time to quell some rumors.

Let’s get out of the way. IR does not cause cancer. IR is a form of non-ionizing radiation, which means it cannot strip molecules of its electrons and cannot cause cancer. X-rays, gamma rays, and high-frequency ultraviolet light (stronger than black light) are forms of ionizing radiation and can cause cancer. Anyone who tries to tell you that radio waves, microwaves or infrared light causes cancer has no idea what they are talking about.

scientist in gloves and holding a rabbit
Elena Yakobchuk

Another big misconception is that the infrared LED in your phone is a laser. This is not true. Lasers have a narrow wavelength of light and they travel in one direction. The lights on your phone occupy a wide wavelength. They are also diffused by lenses and filters because they need to be able to illuminate your entire face.

Finally, a scientific paper on the effects of infrared radiation on the eyes of rabbits is floating around and it scares a lot of people. Essentially, rabbits were exposed to infrared light and developed lens damage and cataracts. But if you take a minute to read this article, it will become clear that you cannot apply these results to the use of IR scanners in phones.

First of all, the scientists in this study used large lamps to expose the eyes of the rabbits to light, and they performed these exposures for 5-10 minutes at a time. The infrared light in a Samsung or Apple phone is smaller than that of an ant and only lights up for 10 seconds at a time. In addition, the IR illumination used in phones uses only the near-IR frequency. The lamps used on the rabbits emitted light from ultraviolet frequency, visible light frequency, near-IR frequency, mid-IR frequency, and far-IR frequency. As you probably know, ultraviolet light is strong enough to cause sunburn, while far infrared light is similar to a microwave oven and causes water molecules to heat up.

So, are there any health issues?

So we’ve cleared the air of some bullshit, but Samsung’s intimidating caveat doesn’t go away. While consumer infrared devices have been on the market for a long time and there are strict regulations for IR LEDs, this is the first time we have had a product that regularly emits infrared light into people’s eyes. How can we be sure that the technology is safe?

Less than 10 seconds of near-IR visual exposure is classified as low risk according to Renesas and Smartvisionlights. For the infrared LED in your phone to immediately damage your eye, you must keep it 1mm away from your eye for 17 minutes. This cannot be done with Galaxy or iPhone X as both products limit infrared exposure to 10 seconds and they will not emit infrared light if the device is 20cm away from your head.

These documents also mention that «abnormally photosensitive people» are at greater risk of eye damage due to near-IR light. It’s interesting to note that the exposure limits set for IR LEDs don’t take into account «abnormally light sensitive people», so it’s possible that the IR LED in your phone could damage your eyes if your eyes are abnormally light sensitive. Of course, if you are unusually photosensitive, then you probably already know about it. Going outside on a sunny day would be a nightmare.

As Samsung’s health warning states, people with epilepsy or other light-inducing conditions should not use the IR LED. This warning exists to help people avoid fainting or having a seizure; it has nothing to do with vision loss. Unless you have a medical condition caused by light, you don’t need to worry about it.

We also need to take into account some new research that suggests that occasional, low-risk exposure to infrared light is actually good for the eyes. These exposures are not long enough or intense enough to raise your eye’s temperature, and they can stimulate cells to heal damaged tissue. Some scientists are experimenting with IR LEDs as an eye treatment and these LEDs are about the same intensity as the IR LEDs in your phone.

Based on what we know right now, we can be sure that the Iris scanner and Face ID won’t hurt your eyes. But nothing is certain. Even though current scientific research shows that low-risk IR products are harmless, no one has tested the effects of daily exposure over, say, 30 years.

If you are concerned that the infrared light from your phone is harmful to your eyes, then you can turn it off as well. However, there is a very good chance that everything is fine.

Sources: INCIRP, NCBI, COGAIN, Dovepress, Renesas, Smartvisionlights.

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