How 3D glasses work

When considering a purchase of a 3D TV or Projector, people often neglect to research what type of 3D technology their prospective purchase uses.

Here at Optoma we thought we’d break-down the two 3D glasses technologies available and give you a run-down on what each technology is called and what they do to produce a 3D image.

3D glasses work by displaying a different image to each eye. Our brain then merges each image into one, but with 3D characteristics. This, in turn, “dupes” our brains into thinking that it is seeing an image in 3D, so it creates an image with depth for you.

3D-enabled TVs and projectors work by receiving a 3D signal that gets encoded and sent in a few different ways. The TV or projector has a decoder that takes the 3D signal and shows the left and right eye information as one image that looks slightly blurry when viewed without 3D glasses. The image is an overlapped image of the left and right eye signal. When you wear the appropriate glasses, they separate each image to the corresponding eye to deliver a 3D image.


Types of 3D Glasses

There are two types of 3D glasses – Passive Polarized & Active Shutter. Both achieve their 3D visuals in a different way.

Passive Polarized glasses look a lot like sunglasses, not unlike what you get when you visit the movies. They are lightweight and have ample space to accommodate normal glasses underneath if the viewer requires them.

The TV or projector has a special filter that polarizes each line of pixels. This filter makes the odd lines on the screen only visible to the left eye, and the even lines only visible to the right. Your brain then interprets the image as a 3D image. Without the glasses, the image looks normal. One caveat to this system is that the image is not full 1080p as it halves the amount of pixels visible.

Active Shutter glasses use batteries and a transmitter that syncs with the rapidly moving shutters for each eye with the on-screen display.

The 3D image resolution is the same as the 2D image displayed on the same screen. This is because the left and right eye images are shown in sequence rather than at the same time. The 3D glasses sync with the TV or projectors refresh rate to sequence the images that produce a 3D image to the viewer.


Optoma 3D Glasses

All of the projectors we produce at Optoma are active 3D. They can however be converted to passive 3D if required with the use of a silver screen and a passive 3D filter.

At Optoma, we manufacture two different types of Active 3D glasses:

ZD302 – These glassed incorporate DLP Link™ technology which use line of sight to the screen to produce a 3D image. If you look away and then back to the screen, the glasses will display a very slight stutter as they re-sync with the projector.

ZF2300 – These 3D glasses use RF (Radio Frequency) technology to sync with the projector. RF synchronization eliminates any potential sync issues and many glasses can be paired to the same projector. As these glasses need an RF emitter to function you will need a “ZF2300 starter kit” that includes an emitter and a pair of glasses.