Gone are those days when we used to watch movies on a 2D screen. Now we can enjoy the depth of a movie using 3D glasses. It is a simple yet fascinating technology that lets us enjoy three dimensions of length at the same time even on a 2D screen. 3D glasses for movies are such a brilliant invention that dates back to 1922. It is quite surprising as the filmmaking technology itself was in a dormant stage at that time.
The prime foundation of a pair of 3D glasses is the binocular vision of the human eyes. To find out how 3D glasses work, let us study the mechanism in detail and learn to make one of them at home.
To understand the concept of 3D glasses, we need to understand what binocular vision is. Our eyes are present nearly two inches away from each other. Due to this, we see objects from two different angles. It helps us to understand the depth and distance of objects. With this natural phenomenon, we can understand the distance or depth of an object up to 20 feet away from us.
To understand the importance of binocular vision, close one of your eyes and try to meet a finger of your right hand with another finger of your left hand keeping your hands parallel to the ground. Most of the time, you will fail to judge the distance.
The binocular vision concept is used in making 3D glasses. Both the lenses used in a spectacle frame are made of two different colours or polarised glasses. Both the eyes impart two different images in your brain resulting in a 3D view. The two different feeds enable our brains to perceive the depth and distance of objects shown on a 2D screen. This is how 3D glasses work explained in a simpler way.
Mechanism of 3D Glasses for Movies
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The technological development of optics used in creating 3D films has given birth to the different types of 3D glasses mentioned below.
1. Active 3D Glasses
A pair of active 3D glasses make any video appear 3D. For this, a smart pair of glasses is chosen to communicate with a TV screen. The signals of communication are sent through infrared rays between the TV and the glasses. Hence, the TV responds by creating 3D pictures for 3D glasses to watch. It does not need any image distortion technology to create 3D images in the brain.
2. Passive 3 Glasses
Passive 3D glasses, on the other hand, depend on the slight distortion of images projected on a screen. It means two different images are projected on a screen. The two different lenses installed in a spectacle frame produce two different images. These images are then composed by the brain to form a single 3D image. If you remove these glasses, the screen will appear blurry as two images are projected on it.
Passive glasses are of two types, anaglyph and polarised. Anaglyph 3D glasses have two different coloured lenses installed. It can be either red/blue or red/green. Two different images with such colour combinations are projected on a screen. Polarised glasses, on the other hand, use two different polarised lenses for image distortion. It means two images with different polarisations are projected on a screen.
We can clearly understand that the passive 3D glasses use the binocular vision of the human eyes but the active glasses do not. Hence, the best 3D glasses will be the active ones. They are expensive and can be paired with 3D TV sets.
The most amazing part of wearing 3D glasses is that a pair can be worn by anyone. If a person uses spectacles, he can still use a pair of 3D glasses on them. The lenses of the 3D glasses will send the light rays following the same mechanism. These rays will be adjusted by spectacles in the usual way and the user will be able to watch a 3D movie.
Making a pair of polarised 3D glasses is not possible when you do not have the proper lenses. On the other hand, creating anaglyph glasses is easier. All you need is hard cellophane and a pair of empty spectacles with no lenses. You can also use a cardboard frame to make a frame.
Capture the shape of two lenses from the cardboard frame you have made on the hard cellophane. Colour one lens blue with a sketch pen and the other one red. Fix it on the backside of the cardboard frame. Make sure the frame fits well on your ears. Fold it accordingly to give it the shape of a pair of glasses and wear it. Yes! It is that simple. The view will be not as even as the commercial 3D glasses sold but you will enjoy the success of this experiment.
We actually fool our eyes by creating a pair of 3D glasses using the above-mentioned scientific principles. By using the binocular vision phenomenon, we create two images of different optic properties. Our eyes actually see two images of the same properties but from two different angles. The concept is quite fascinating and is almost 100 years old.
According to the discussion, 3D polarised glasses are the latest versions of this technology. We have smart screens that project images according to the glasses and the distance a viewer is sitting from the screen. Imagine how far we have to project 3D images into our brains. Active glasses are thus costlier than passive ones. This is, in a nutshell, how a pair of 3D glasses work.