Mitsubishi Electric

Before you begin to understand how a 3D movie works, you must first understand how your eyes work. In real life, our left and right eye see two separate images that are processed by the brain to see depth, or 3D. To see an example of this, hold your index finger out an arms length in front of you. Now as you're looking at your finger, alternately close one eye at a time. Your left eye sees a different image than your right eye. Your brain uses a process called stereopsis to translate these two images into depth perception. Watch How Stereopsis Works

Now that we know how our eyes see 3D in real life let's learn how this can be simulated on a flat surface like a movie screen or television. It's done by using a technique called stereoscopy (also called stereoscopic or 3D imaging). Two separate images, one representing your left eye and the other your right eye, are displayed or shown on the flat surface. Watch Stereoscopic Imaging

Ever wonder why 3D images look blurry or doubled without glasses. That's because you're seeing two images simultaneously. Now, somehow, we have to allow your left eye to only see one image and your right eye the other. Sounds difficult, huh? Not really. Remember ViewMasters, those big red binocular looking things that allowed you to see 3D images? Because of it's binocular design, when you look through the toy, the ViewMaster shows your left eye one image and the right eye the other. 3D glasses are designed to do the same thing. Watch Binocular Vision

Back in the days

I'm sure you remember those red and blue 3D books that amazed us as kids. These books separated the left and right images by using a method called Anaglyph (or color filtering). The anaglyph glasses (usually red and blue) would filter out the other image. The red lens blocks the red image on the page and blue lens blocks the blue image on the page, allowing your right eye to see the right image and the left eye to see the left image. This method works, but turns your world red and blue. Plus, it can give you a pretty big headache if you have to sit through a whole movie like that. Watch Anaglyph Glasses

Today's movie theaters

Most of today's movie theaters use a method of filtering called polarization. This technique blocks the left and right eye images without discoloring the image. Polarized 3D glasses block left and right eye images in the same way your polarized sunglasses filter or block out glare. The theater projects two separate images onto a special polarized movie screen and the glasses separate the two images. How does this work? Well, the glasses use lenses that filter out light waves projected at certain angles. Each lens only allows light through that is polarized in the same way. Left and right lenses are polarized differently, each lens only allowing light through that contains the correct angle of polarization. Simple. Watch Polarized 3D Glasses

3D in the home

So, can you take your polarized movie theater glasses home to use on your 3D television? Unfortunately, with the majority of 3D TVs in the market, you cannot. Remember that special polarized screen that's needed to use polarized glasses? Well, designing a television with a polarized glass screen would be really expensive. So, most 3D TVs use active shutter glasses, which are made with LCD lenses that can block out light completely. Your 3D capable television alternately displays the left and right eye images. Then a synchronization signal is sent to your active 3D glasses to alternately close the opposite lens. This way, your left eye only sees the left image and your right eye only sees the right image, giving you 3D. Now, why can't you see the glasses flickering on and off? Because the glasses are "shuttering" at 120 times per second. Now that's fast! Watch Active Shutter Explained