Rumors are swirling that the Samsung Galaxy Note 4 could have a retina or iris scanner built-in, allowing the user to unlock the phone just by looking at it. This sounds like something out of a science fiction movie, but as we've learned with the fingerprint scanner implementation in the iPhone 5S and Galaxy S5, these kinds of personalized locking mechanisms aren't always perfect.

So how is eye-scanning technology used right now, and when can we realistically expect it to be implemented in mobile devices? When it does arrive, will it be as secure and reliable as we need it to be? Let's find out.

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Retina Scanners Vs. Iris Scanners

First off, we need to differentiate between retina and iris scanners, as the terms are often used interchangeably, but are in fact very different processes.

Retina Scanner: How It Works

A retina scanner shoots an invisible infrared light into your eyeball and measures how much light is reflected back off your retina. Your retina is a thin layer of cells in the back of your eye that is made up of a complex network of blood vessels unique to only you. Since blood vessels reflect less light than the rest of the retina, the pattern of reflection in your eye from this infrared light is completely unique.

retina

Pros And Cons Of Retina Scanning

Unfortunately, while your retina is generally unchanged for your entire life, certain diseases like diabetes, glaucoma, and other eye-related disorders can affect the structure of the retina. This means that if you rely on a device unlocking from a perfect image of your retina, and your retina changes due to a disease, you would be locked out of your device.

Retina scanning also involves a user getting very close to a device (within inches) and having a beam of infrared light shot into their eye. This makes it rather invasive and annoying to perform on a regular basis.

However, while it has many drawbacks as a use for smartphone unlocking, its medical applications are huge. While only certain diseases actually change the blood vessel structure of the retina enough to make it unidentifiable, many other diseases, including AIDS and malaria, can be detected by retina scanners. If a retina scanner was built-in to your phone, a weekly or monthly scan could keep you up-to-date on any diseases you may have caught and allow you to see a doctor before other symptoms arise.

Iris Scanner: How It Works

An iris scanner works much like a regular camera, except that after taking a picture (or short video) of your eye, it runs some serious calculations to measure the exact patterns in your iris. Your iris is the colorful part of your eye surrounding the black dot in the center called the pupil. Your "eye color" is really the color of your iris.

If you take a look closely in the mirror, you can see that your iris isn't one solid color, but rather a complex structure of cells that is huge, magnificent, and best of all, entirely unique. The scanner can identify the unique patterns of the iris by shooting near-infrared light into the eyeball and determining the intricate structures of the iris from the light that returns.

iris

Pros And Cons Of Iris Scanning

Iris scanning, for the most part, is considered the better of the two methods. It can be done from a greater distance, in some cases up to meters away from an individual, and is therefore less intrusive. It's also less prone to changes due to disease, because a person's iris generally stays the same for their entire life, except in cases of extreme injury to the eye. The iris, as a protected, unchanging, yet completely unique feature of the human body, is often seen as the best chance we have of ever perfectly identifying people.

Of course, because it works by taking a picture or short video of the iris, it is theoretically possible that an iris scanner could be fooled by a high quality image or a convincing reproduction of an eyeball. Some iris scanners, though, incorporate checks to ensure that the eyeball belongs to a live person. These kinds of checks can vary, and are still in production in many cases, but they range from shooting a burst of light to dilate the pupils, to judging the subtle facial movements around the eye over the course of a couple seconds. Many of these live checks offer less convenience, though, since a burst of bright light to the eye isn't very fun, and recording a short video to judge facial movements takes too much time.

Because iris scanners are in many ways superior to retina scanners, it's probably safe to assume that if scanners ever do make it into smartphones, they will be iris scanners.

Is It Secure?

Now the biggest concern many of you are going to have with this is your security and your privacy. If iris scanners do make their way into smartphones in the future, you can bet that there will be a huge hubbub over security and privacy concerns -- just as there was when Apple announced their iPhone's fingerprint scanner.

iris-scanner-unlock

And many of the questions remain the same. Users were worried that if Apple stored fingerprints in their databases, then organizations like the NSA could gain access to that and therefore have your fingerprint without your permission. Iris scanners pose the same problem: once your iris is scanned and that information is stored somewhere, it is possible that it could be stolen or snooped on by nefarious groups.

nsa-watching-iris-scanning

On the other hand, many people wondered if a severed finger could be used to unlock an iPhone, and that's an even scarier prospect when you're talking about iris scanning -- nobody wants to have their eyeball gouged out after having their phone stolen. This concern boils down to how these scanners are implemented and whether or not smartphone manufacturers implement live person checks with their scanners. But since live checks often come at the cost of convenience, it's unlikely we'll see a perfect foolproof eye scanner hitting the market anytime soon.

In the mean time, passwords are still going to be one of the most secure and reliable forms of locking, although they aren't the most convenient.

Current Implementations

Many government and corporate organizations use iris scanning as a secure means of restricting access to certain areas, and hundreds of airports around the world have implemented iris scanners as a form of identification even more secure than passports for easier travel. These kinds of scanners are large, expensive, and not at all suited for mobile. Below, you can see a picture of the scanners used in a Frankfurt airport in 2005.

iris-scanner-frankfurt

Other times, mobile scanners, about the size of a big camera, can be used to quickly identify many people at once. In 2002, when Afghan refugees to Pakistan were being repatriated into their country, iris scanners were used to ensure that nobody was receiving multiple cash grants or more than their fair allowance of other assistance items. US Marines also used similar handheld iris scanners to identify members of the Baghdad City Council back in 2007, shown below.

iris-scanner-marine-baghdadi-city-council

In other cases, large multi-person iris scanners have been deployed as a security measure. In Leon, Mexico, scanners can identify up to 50 people per minute, even while they're walking, and can help identify those who want to use an ATM, a hospital, or even ride a bus. That may seem a little futuristic and dystopic to some, but it was actually put into place four years ago in 2010. Privacy concerns aside, the technology behind that is amazing.

So far, consumer scanners are limited, although EyeLock is looking to change that. Their myris scanner plugs into your computer via USB and can replace all of your passwords. This isn't quite at the level of being integrated into a smartphone, but it's certainly getting there.

Can It Fit Inside A Smartphone?

Anthony Antolino, the Chief Marketing and Business Development Officer at EyeLock, expects to see iris scanners coming to computers and mobile devices in 2015. He says that while the technology has been around for a while, it is now finally becoming fast enough and easy enough to be used by the everyday consumer.

mobile-iris-scanner

Modern scanners can work in an instant, even if users are walking or wearing glasses or contacts. The biggest problem might be fitting a high quality camera and a near-infrared light into a smartphone. Current front-facing shooters, like the 2MP cameras on most high-end Android phones and the 1.2MP camera on the iPhone 5S, simply aren't high enough quality to view the iris well enough.

Additionally, smartphone manufacturers will need to find a way to squeeze in the near-infrared light and have it all operate fast enough that it isn't noticeable for users or a significant drain on the phone's resources.

galaxy-note-3-front-camera

Whether or not this comes as soon as the Galaxy Note 4 or iPhone 6 is yet to be seen, but it will almost certainly be coming at some point within the next few years.

Would You Use An Iris Scanner?

Iris scanning clearly has its strengths and weaknesses, but what it really comes down to is if people will use it in their mobile devices.

Would you use an iris scanner if it was built into your next smartphone? Is the convenience and security good enough to warrant it, or are you worried about the privacy aspect of having your iris scanned? Let us know in the comments.

Image Credit: browsing her smart phone Via Shutterstock, Iris scanner to unlock phone, Scan for security or identification, Video surveillance and privacy issues concept illustration, Eye macro, and Human eye anatomy from Shutterstock, Flickr/John Karakatsanis, Wikipedia/USMC Sergeant identifies Baghdaddi city council member with iris scanner.