The first 3D movie “The Power of Love” was released in the year 1922, but the world experienced a striking view of 3D technology in the movie “Avatar” released in the year 2009 and after that every now and then a 3D movie is released. 3D movie’s gives you depth perception; when you equip your eyes with 3D glasses they makes you feel like as you are in the movie. A bullet fired seems coming right in your direction and scary characters coming to hunt you, this amazing experience is made possible by 3D glasses. But what is 3D and how 3D glasses work??
What is 3D
3D (Three Dimensional) is the term which has similar meanings when related to Mathematics and Films.
3D related to Mathematics:
An object that is represented in three axis Cartesian co-ordinate system (on a graph) i.e., X- axis which represents Horizontal, Y-axis which represents Vertical and Z-axis which represents depth.
3D related to Movies:
3D in relation to movies is a motion picture that provides depth perception which makes you feel like you can touch the things that are popping out of the screen.
How 3D works and why do we see the world in 3D
The key thing is we got two eyes separated with some distance (2 inches or 5 centimeters), so each eye sees a slightly different scenes and the brain which is unbelievably clever combines and correlates those two different scenes and gives you the depth perception. The brain has the remarkable binocular vision system, by seeing an object we can easily notice how far away the image is.
The binocular vision system even works with one eye but the accuracy decreases. Catching a ball with one eye closed is difficult but it is easier with two eyes open. You can also see this yourself, just stick out your thumb in front of your face, and see how your thumb seems to jump if you look at it only with your right eye and then look at it only with your left eye. You might also notice unless and until you look the thumb with your both eyes it’s difficult to know how far it is from you.
How 3D glasses work
Each of your eyes needs to see the correct image in order for you to see it in 3D. This is the task that 3D movie makers had to complete. 3D movie makers need to show the correct image to each of your eyes and lets the brain combine the two images into a 3D picture. To do this, the movie makers must ensure that the image that is intended to the right eye must be seen only by the right eye and vice versa.
This is where 3D glasses come into play. Each of the lenses on the glasses ensures that the image intended for that eye passes through it, and the other image does not. The first way movie makers showed 3D movies was using different colors for the left and right images. One lens would only let in red light, and the other lens would only let in blue light. The viewer’s brain would combine the two images– the blue one seen by one eye, and the red one seen by the other–into a 3D picture. This was not ideal, because the image that resulted was not in full color.
To make it perfect, 3D movie makers started using a property of light called polarization. As we know light is a wave and it can wave in horizontal, vertical or in some other direction. This orientation of wave is called “Polarization of Light”.
A polarizer is a material that only lets through light polarized in one direction. For example, a horizontal polarizer lets through horizontally polarized light, and blocks vertically polarized light. It’s a special material that absorbs the light in one polarization, and let’s through light in the other.
A 3D movie made using linear polarization projects two images onto the movie screen– one horizontally polarized, and one vertically polarized. Each lens in your 3D glasses has a differently oriented polarizer. So, for example, your right eye only sees the horizontally polarized image, and your left eye only sees the vertically polarized image.
There’s still a problem with these kinds of glasses, though. If your glasses are horizontally and vertically polarized, when you tilt your head– to lean it on your friend’s shoulder, perhaps– the glasses lenses turn into diagonal polarizer’s. But now the light from the screen is not lined up with a polarizer, so the movie doesn’t look right to you. To solve this problem, many 3D glasses today use a different kind of polarization in their lenses– circular polarization. In this type of polarization, the light wave travels towards you in a circular pattern. We can describe circularly polarized light based on the direction in which the wave is rotating– either clockwise, or counterclockwise. There are polarizer’s that work to only let in one orientation of circularly polarized light.
A 3D movie, therefore, could be made with clockwise polarization for your right eye, and counterclockwise for your left. The two different movies, one for each eye, will be visible only through the correct lens, with the correct polarizer, in your 3D glasses. The point of these circularly polarized glasses is that you can tilt your head without distorting the picture.
Today, most of the 3D movies that you actually see in theaters are, in fact, made using circular polarization.
3D glasses types
Let us know about the main types of 3D glasses and technology being used today
Anaglyph 3D glasses:
The lenses of these glasses use two different colors. The colors of these lenses are usually Red and Cyan, Green and Magenta, Red and Blue. If you choose Red and Cyan colored glasses, the red lens only absorbs the images that are intended for red color and Cyan lens only absorbs the images that are intended for cyan color. The price of these lenses is pretty low along with the 3D quality and no special display is required.
Active Shutter 3D glasses:
The lenses contain transparent liquid crystal which turns black when voltage is applied. It works as ON/OFF state. When the image is intended to right lens, the left lens becomes black (or OFF) and vice versa. The glasses works on instructions given by emitter or screen to darken (or OFF) each lens at right time, while the other unblocked (or ON) lens is presented with a different movie to complete illusion. The glasses are communicated using infrared emitter, a radio frequency emitter or DLP link. 3D effect of these glasses is awesome but is expensive and commonly used in 3D TVs, 3D Projectors and cinemas.
Polarized 3D glasses:
Polarized 3D glasses are the most common and popular glasses used in cinemas today. Each lens in your 3D glasses has a differently oriented polarizer. So, for example, your right eye only sees the horizontally polarized image, and your left eye only sees the vertically polarized image, as already discussed. These glasses are cheaper and provide a good 3D effect and works with special silver screen with a projector.
Infitec 3D glasses:
Infitec 3D glasses also called as Super Anaglyph glasses. Each image for each eye is encoded with slightly different red, green and blue colors. The differences are so slight that our brain hardly notices that but they’re strong enough to be filtered by the glasses lenses and each slightly different image is filtered to the intended eye. These are mostly used in cinemas.
3D without glasses
3D without glasses is possible with Auto Stereoscopic Displays which displays stereoscopic images. The technology is still under experiments but it will be available soon. The companies like Toshiba, LG, and Sony got a prototype during Consumer Electronics Show in 2011. Sharp in Consumer Electronics Show 2014 came up with glasses free 3D and got some drawbacks as you can’t sit at any sweet spot if you do, the image turns blurry. As the technology never stops its advancements, definitely a glass free 3D experience will be available soon.