Hello everyone. My name is Teppei of KOYO Orient JAPAN’s Product Division.
We receive many inquiries about our super light absorption sheet "FineShut” regarding its effectiveness in the prevention of internal reflection caused by Near-Infrared (NR) light. “FineShut” has mainly been utilized in Single-Lens Reflex (SLR) cameras so I asked myself, “What exactly is Infrared?” I immediately began to research about it. I’ve attended seminars and asked our customers about it and the more I learn about the world of Infrared, the more interesting it becomes. Today, I would like to share what I have learned with you.
So right off the bat, for those of you who are familiar with Infrared light please raise your hand…I see there are many. Great!
Next, for those of you who are familiar to how Infrared light is being used around us, please speak at your monitor…ok, I heard “TV Remotes”, “Heaters”, and “Security Cameras”. Yes, you are all correct!
Now as you can see here, there’s a broad range of uses for Infrared light to the point where you may get confused to what exactly Infrared light is.
Well don’t worry because in this blog, we’ll go over how Infrared light works and its uses!
What is Infrared light?
So, what exactly is Infrared light? Please refer to the chart below.
This is the Visible Spectrum. It’s the part of the Electromagnetic Spectrum that our eyes can visually recognize. The wavelengths of the Visible Spectrum range from 380 to 750 nanometers (nm). The shorter wavelength on the left-hand side of the spectrum (380nm) is recognized as Purple and the longer wavelength on the right-hand side of the spectrum (750nm) is recognized as Red. We can’t see anything above or below this range. Anything under 380 nanometers is known as Ultravoilet (UV) and anything above 750 nanometers is known as Infrared (IR).
*Image from Wikipedia page "Visible Spectrum"*
There are different categories of Infrared. There’s Near-Infrared (750-2500nm), Mid-Infrared (2500-4000nm), and Far-Infrared (4000nm~). We’ll go over this more in detail in other blogs however the important thing is that Near-Infrared and Far-Infrared have completely different properties and uses.
For this blog, let's deepen our understanding of "Near-Infrared" using a very familiar example.
Introducing the state-of-the-art "Near-Infrared" device...the iPhone!
Surprised? First off, let’s briefly go over Near-Infrared. The characteristics of Near-Infrared include “having properties close to visible light” and “invisible to human eyes.” Since the wavelength of Near-Infrared is close to visible light, large-volume, expensive devices such as sensors and cameras can be used as is and can be manufactured at low cost. Also, because we can’t see NR light, we won’t be irritated by it.
To give an idea of Near-Infrared applications in our daily lives, we have prepared an iPhone XR and a Near-Infrared camera.
We call this camera a “Near-Infrared” camera but we took a regular digital camera and modified it. Digital cameras have silicon sensors that can pick up electromagnetic waves longer than 750nm up to 1000nm. Remember, we can’t see anything above 750nm long. For that reason, these cameras also have a filter called an “IR Cut Filter” that doesn’t allow waves longer than 750 nm through in order to better match our eyes' ability.
So, we modified this camera by removing the IR cut filter and installed an
"IR Transmission Filter" that only allows wavelengths longer than 760 nm through. Ta-da! We have made an infrared camera.
Now back to the main subject. First, let’s unlock this iPhone using Face ID. The moment we touch the power button, the iPhone has already been unlocked. It was as if there weren’t any process of authentication. However, if we look at the iPhone through our NR camera…
FLASH! FLASH! FLASH!
You can see lots of flashing from the bezel on the top side of the phone! What is that?
If we project this flashing towards a wall, it turns out the identity of the flashing is a pattern made up of countless dots.
This flashing occurs when the iPhone is running facial recognition software or when creating Memojis.
This is the identity of the iPhone’s TRUE DEPTH. Its function is to measure the exact distance of the subject from the camera, that is, the three-dimensional shape of the subject.
We monitored the Dot Projector using our NR camera. More than 30,000 Infrared dots are emitted from the dot projector. Because the iPhone’s IR camera and the dot projector are located separately, the dots will be projected slightly off from the camera. As a result, each dot captured by the IR camera shifts horizontally depending on the distance of the subject. By calculating the degree of this shift, the distance of each dot can be determined. This 3D measurement method is known as the Active Stereo Method.
This method is used to grasp the three-dimensional shape of the subject's face and to improve the accuracy of the iPhone’s face authentication. Even if you are wearing sunglasses, you can pass the authentication as long as it’s something that transmits infrared rays to some extent. Have you ever used Memoji? This function can read the facial muscles of the subject in front of the camera, another technique that “True Depth” is capable of.
I’ll leave a video here for you to get a better idea. Here we are monitoring the iPhone using our NR camera.
Incredible, isn’t it? This distance recognition technology based on dot pattern projection can perform as well if used with visible light. However, if the flashing was visible, then it would just be an unpleasant experience for everyone.
Because this technology uses Near-Infrared light, state-of-the-art optical sensing can be implemented without anyone noticing.
Cheers to Apple's technology!
That's it for this one, be sure to check out our next blog, as we have some exciting news for the new iPad Pro!