Iris vs. Retina

I have already introduced you to retinal scanning in my previous post The King of Biometrics.  However retinal scanning has a younger more lighthearted brother: the iris scan.  

To most people scanning of the eye is all the same and people constantly mix up the terms iris and retina scans (even the U.S. Army did it see Biometric Army), my hope is that after reading this post you will never make the same mistake.  

So let’s start by defining what an iris is as compared to the retina.  I found a picture that is a good representation of this.  If you look at someone’s eye, the colored section you see is the iris.  That is what is scanned using an iris scanner.  Behind someone’s eye is the retina, and this cannot be seen with the naked eye.  That is why retinal scanners use IR rays in order to generate an image of the retina.

Now you know the major difference between the two technologies.  However I am not going to stop there.  I will tell you how you can easily distinguish between the two technologies if you saw someone using them. 

A retinal scanner is considered more intrusive and is also slower.  For a retinal scan the subject’s eye generally has to be within 3 inches of the scanner and the subject has to focus on a point of green light that he/she would see in the scanner.  The retinal scanner scans about 400 reference points that it uses for identification processes and it takes about twenty seconds.  

As compared to the retinal scanner an iris scanner is a lot faster taking only about two seconds.  The iris scanner can be used from a much farther distance of up to two feet and uses about 240 reference point.  

So basically if the scan is taken at a very short distance and if the scan takes a little while then it is a retinal scan, and if it is done at a longer distance and is instantaneous then it is an iris scan.  Now hopefully you will never make the mistake of misidentifying the two technologies. 

Iris scan sounds better doesn’t it? It is faster and cheaper but also less accurate.  As I described in King of Biometrics retinal scanners are basically foolproof, which leads to an interesting post that is coming up (stay tuned).

Nowhere to HIIDE

Last Post I talked about the HIIDE device being used in Afghanistan and I was able to find a video that shows it in use.

Biometric Army

You’ve seen it done in movies a thousand times, the bad/good guy steals an identity badge and gains access to an installation and wreaks havoc/saves the day.  How can such a thing be stopped? Biometrics of course! And this is exactly what the Army thought as well.

Currently in use in operations Enduring Freedom and Iraqi Freedom is the Hand Held Interagency Identity Detection Equipment or HIIDE for short.  According to the Army this system is used for a lot of different uses and has given great results, and it better have seeing as the Army gave a $71 million dollar contract to the manufacturer.  

HIIDE in Action in Iraq

One example of how this program has helped was given by the Army and boy is it impressive.

Every day hundreds of people access U.S. military facilities; most are U.S. Army personnel, but some are employees of local contractors.  And before these employees can enter they are biometrically scanned for fingerprints, iris and facial recognition.  Today an employee comes to work as normal but one thing very different happens, he is detained for questioning instead of getting to work.  How did this happen? Let’s look back one day. 

The Army received intelligence of a suspected insurgent safe house that was immediately raided by a U.S. Army patrol.  All of the family members were evacuated and their fingerprints, irises, and faces were scanned using the HIIDE, while the house was searched.  Everything in the house appeared normal until the patrol discovered a hidden room with evidence of bomb making activity.  The family was questioned about it and everyone claimed they had no knowledge of the hidden room. 

Unfortunately for one of the “family” members, two sets of fingerprints were found in the hidden room and one belonged to one of the detained “family” members.  As soon as the insurgent was removed from the rest of the family, they tell the Army interrogators that two insurgents were using the room and threatened to kill them if they said anything.  And now one insurgent was in custody.  But what about the other one? Remember that employee that was detained?

Since the employee had access to a U.S. military facility, his fingerprints were in the database and were quickly matched with those scanned at the bomb making site and thus he was detained the next time he went to work. 

That is a major situation avoided by use of biometrics.  It’s great that the Army recognized the value of Biometrics and started using them to ensure the safety of their bases and installations.  

Quick side note: the site where I found the image states “Sgt. Nike Ferzacca is obtaining a retinal scan of an Iraqi.”  See anything wrong with that statement? I mentioned that the HIIDE has iris scanning not retinal scanning.  It is interesting to see that even on “The Official Homepage of the United States Army” they make a mistake between iris and retinal scanners.  The distinction between the two will be addressed in the future, so you never make the same mistake.

Source

The King of Biometrics

There is an old English proverb that states “You get what you pay for,” and this is definitely true of Biometrics.  Biometrics includes many technologies from fingerprint scans, to voice recognition, to facial recognition, but none are as reliable and foolproof as the Retina Scan.

Quick disclaimer here, the retina scan is not to be confused with the iris scan, although both scan they eye they are very different and this will be the subject of a future post.

So the retina scanner like the name implies scans your retina.  But what is your retina? I’m glad you asked.  Retina is just a fancy name for the light-sensitive tissue that lines the inner surface of the eye.  This tissue required blood to function properly and thus has an intricate blood vessels system that is called the choroidal vasculature.  This vasculature is what is scanned by a retina scanner.  

Take a look at the picture below.  The part on the left is a cross section of an eye with the retina being what you can see the blood vessels on.  The ring that you see in the picture is what is scanned by a retina scanner.  This ring can be seen more clearly on the right image which is just a cross section of the eye straight up and down.  Everyone has a unique blood vessel pattern and thus it is perfect for biometrics.

Cool, so now we know what a retina scanner scans, but how does it do it? The actual scanning process is very complicated but I will try to give you a basic run down of how it works.  Take a look at the following image and don’t freak out, a lot of things are pointed out that are not important to us so just ignore them and pay attention to what I circled in blue that I will talk about.

For simplicity the red arrows you see are how the light would travel from the source through the scanner disk and back to the detector.   

So basically, the eye of the person being scanned would be on the left facing inward.  That person would look into the camera and would focus on what would look like a pinhole illuminated by a krypton bulb (1).  The scanner disk (2) would begin to rotate, creating an infrared (IR, high wavelength non-visible light) scanning beam.  The IR beam would be reflected by the choroidal vasculature on the retina to a beam splitter (3) and into a detector (4) that generates the image of the retina.

That is basically how a retina scanner works.  The biggest drawback to this technology is that certain diseases can affect your choroidal vasculature, thus causing you to not be authenticated by the scanner.  This is also a reason your eye doctor can detect a disease just by looking at your eye. 

So that is how the king of Biometrics works.  Retina scanning is the most accurate but also the most expensive biometric security tool.  

Source: Robert Hill. Retina Identification. Michigan State University. 2005.

Fetal Fingerprints (Continued)

Benito el Jefe, one of my awesome commenters posed an interesting question on my original Fetal Fingerprints post. The question was:

“To find out when they develop, did researchers have to look at miscarriages for signs of fingerprint development? How could they determine that otherwise, without possibly harming the child?”

I looked through the articles that were referenced and sure enough one of them mentions how they obtained the information. And Benito was actually spot on.  In the study they investigate 24 aborted or miscarriage human fetuses at different stages of development and they categorize how their fingerprints develop.  These technical name for these fetuses is abortuses.   

This type of study is under a field called Fetal Dermatoglyphics that basically studies how skin develops on fetuses. 

Thanks a lot for the question Benito and everyone keep them coming!

Source: Katznelson, Goldman. Fetal Dermatoglyphics.   

iPhone eyeD App Review

Here is a video I made reviewing a new app available for iPhone 4. Enjoy!

 

 Thanks a lot to my friend Matt Emmett for executive producing this video and lending me his iPhone.

Fetal Fingerprints

Ever wonder how fingerprints develop or why they are all different?  A couple of commenters on my blog did which got me researching the topic.  After looking through a lot of information on how and when fingerprints develop, I finally found a reputable source.  So without further ado I present to you how and when fingerprints develop.

A working theory of how they formed was developed by two scientist at the University of Arizona named Kucken and Newell.  They basically developed their theory by the use of springs.  

As some of you may know the skin has many layers.  It starts with the epidermis and works down to the dermis and others further down, but for the purposes of fingerprints only the top two layers are important.  The epidermis then has a lower layer (basal layer) and an upper layer.

For the model the scientists assumed that the basal layer of skin was an overdamped elastic sheet trapped between the upper epidermis layer and the lower dermis layer.  What this basically means is that the basal epidermis layer can be thought of as a sheet of plastic that does not oscillate (move up and down) much.     

As the basal layer grows, it is stressed (pushed on) by forces from the upper layer of the epidermis, the dermis, and also by inward pressure from the basal layer itself.  This phenomenon can be modeled by terms of elasticity (how much it can stress), and the solution the scientists found is actually the relatively well known von Karman equations.  Once the stress becomes too much, the basal layer “buckles” and produces the ridges in the epidermis that become your fingerprints.

Using the developed equation it was found that fingerprints develop starting in the nail furrow (top portion of the finger), and in the center of the volar pad (center of finger). These then stretch out until the entire finger is covered in fingerprints.  

The main reason everyone’s fingerprints are unique is that everyone had different stresses applied to their basal layer during fetal growth.  Everything from the orientation the fetus is in to the amount of movement the fetus experiences helps differentiate fingerprints.  Even identical twins grow in different orientations and experience different stresses, thus they have different fingerprints.  

Finally, when do the fingerprints develop? Surprisingly early in the fetal development process; fingerprints begin to develop at around the 10^th week of pregnancy and they are set in stone by the 17^th week of pregnancy.  That means that about four months into pregnancy the baby already has defined fingerprints that will be the same throughout their lifetime.  

I find this information to be fascinating and more proof of how amazing the human body is.  Did you know that fingerprints developed so early in the stages of pregnancy? That was shocking to me since I thought fingerprints would be one of the last things to develop.  Let me know if you have any questions and I will try to answer them as well as I can!   

Source:

M. Kucken, A. Newell. A model for fingerprint formation. Europhysics Letters. October 2004. Link

Why Fingerprints?

So I have been doing lots of research into fingerprints and how they form and I came across some interesting information that I thought I would post. 

Fingerprints are all about friction, which is a force that resists motion.  As animals that use our hands a lot to grip all sorts of objects, the little ridges on your palms, fingers and feet help you to grip on to surfaces.  If you did not have fingerprints you would have a very hard time holding on to that glass of beer as you went for a drink, because your fingers would be smooth and have a very small coefficient of static (no motion) friction.  

As far as animals that have fingerprints, all primates have fingerprints and toe prints, and some even have tail prints where their tail has grooves to grip on to things.  One interesting fact however is that koala bears (actually marsupials), also have fingerprints.  

Quick little quiz.  Look at the fingerprints below and guess what species they belong to.  There are three options, Human, Chimpanzee, and Koala. The answer is in the comments, don’t cheat and post how you did! 

 Be on the lookout for my next post that describes how and when fingerprints are formed!

Incredible Biometrics

The movie The Incredibles features a scene where Edna Mode gains access to her den by use of Biometrics.  The Biometric part can be seen starting 30 seconds in until about 45 seconds into the clip. 

The clip is actually quite realistic considering all the technologies she uses are currently available.  The first thing she uses is just a pin number.  Although Biometric technologies are seen by many to eliminate passwords and pins, this adds an extra layer of security to her lair.  Next Edna uses a hand scanner which are already in use in many different places.  Edna then goes on to use an Iris or Retina scanner, it is not exactly clear which one, but based on the fact that she lowers her glasses it was probably a Retina scanner.  Finally she finishes by using voice recognition of her name.  This four step security system is a little paranoid but it would provide excellent protection, since the odds of beating all four of these technologies are very, very slim (especially with the huge machine gun if you fail).