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How do 3D Glasses Work?

Team StoryWeavers|May 19, 2022, 08:52 IST| 2

From watching superheroes in action up close, to seeing iconic sets and locations jump out of the screen, 3D movies have become a huge part of modern cinema. But did you know that this popular cinematic technique is not a new, modern invention? In fact, the first 3D movie came out almost a century ago in 1922! How did 3D movies exist at a time when film-making technology was still in its nascent stages? It’s because the concept behind 3D movies is relatively simple – manipulating binocular vision in humans. Let’s look at how 3D glasses, an important component of 3D viewing, help us watch our favourite characters up close.

How do 3D glasses work?

Human vision is rich, colourful and finely detailed. A huge part of this is because we have what is called binocular vision i.e. we use two eyes to see the world around us. However, since the eyes are placed roughly two inches away from each other, the image picked up by each eye is slightly different too. These images are combined in the brain to help us see what is in front of us clearly. This is why we are able to perceive depth and can tell which object is closer to us and which one is farther away.

Due to the space between the eyes, each eye captures a slightly different image. Image source: Wikimedia Commons

Due to the space between the eyes, each eye captures a slightly different image. Image source: Wikimedia Commons

3D glasses make use of this quality about the human eyes and show each eye a slightly different image which is filtered by the lens in the glasses. When these images are combined in the brain, we feel like what we are seeing on a 2-dimensional screen is in fact 3 dimensional or 3D!

Types of 3D glasses

There are mainly two types of 3D glasses, passive glasses and active glasses.

While using passive glasses, the image being projected on the screen is slightly distorted so that when you view them through 3D glasses, your brain combines them into a 3-dimensional image. The glasses do this by filtering out light of certain wavelengths so only a portion of what is projected on the screen is shown to each eye. While watching a 3D movie at the theatre, if you remove your glasses in the middle of the movie you’ll notice that what is on the screen is in fact blurry! The movie appears clearly only when the light from the screen is filtered from the 3D glasses and reaches your eyes. There are two types of passive 3D glasses – polarised glasses and anaglyph glasses.

Polarised 3D glasses that are today commonly used in movie theaters. Image source: Wikimedia Commons

Polarised 3D glasses that are today commonly used in movie theatres. Image source: Wikimedia Commons

On the other hand, active 3D glasses can make any video appear 3D. These glasses can communicate with LCD screens via infrared signals and accordingly darken the lenses to make your brain think that it is viewing a 3 dimensional image. Active 3D glasses are much more expensive when compared to passive glasses.

Differences between active and passive 3D glasses

Active 3D Glasses Passive 3D Glasses
Expensive to make and obtain Made out of cheaper materials and is easily available
Does not need image distortion on screen to work Needs image distortion on screen to work
Creates a high quality clear image Creates a slightly lower quality image
Communicates with an LCD screen via infrared signals to create 3D image Doesn’t communicate with the screen but simply filters the light to create a 3D image

How do red and blue 3D glasses work?

Red and blue 3D glasses are anaglyph 3D glasses. These glasses have one red lens and one blue lens.

Red and blue 3D glasses in a bowl. Image source: Wikimedia Commons

Red and blue 3D glasses in a bowl. Image source: Wikimedia Commons

The video designed for these glasses is tinted with red and blue hues. When you see the video through the glasses, the coloured lenses filter the red and blue light out. The final images that reach your eyes makes the brain think the image is in 3D.

How does 3D glasses work on TV?

3D televisions use active 3D glasses. These glasses receive signals from the LCD TV and alternately make the lens opaque or transparent so that the final images reaching your eye appear to be in 3D. Therefore the actual image on the television is not modified for 3D viewing, but the active glasses do the work to make the image appear 3D.

Speaking of 3D glasses want to know how to make a projector?

If you could innovate the movie experience further, what would you do? Let us know in the comments!

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About the Author

Deepthi is an ambivert who is on a steady diet of good food, filter coffee, and self-improvement. Being an ardent reader, storytelling has been her first love and she enjoys exploring how to convey stories compellingly. Having studied psychology and experienced the learning and development field, Deepthi is driven to understand human behavior and to know what makes each of us unique. You are most likely to find her tucked into a cozy corner at a local cafe with a Kindle or a book in hand. If you find her there, stop by and say hello, she'd be eager to learn your story too. Until then, you can ping her at for anything you may like to share.

Leave a Comment




October 11, 2021

i would do like for movies the glasses should be replaced by the vr headsets but they will get hurt so they should be like buttons on the vr hands to move so people stay in their seat and feel like theyre moving. Image of vr headsets : .

Alokendra Mandal

October 9, 2021

If I could innovate the movie experience further, I would make pair of smart eye lenses, a computer chip (to be installed inside the brain and could detect what we are thinking) and micro speakers (which can be installed inside the ear). And all this will work in synchronization and could be connected to the internet; to make human life much more advance in all aspects including movie experience!


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