3D-technology use the operation principle of our brain that perceives three-dimensional image when the eyes see the different image projections. Today, there are several 3D technologies. Many know them as passive, active and anaglyph 3D-technologies.
Polarization or passive technology uses the image separation on the screen with the help of a special film. The images on the screen have the left and right polarization. Filter of eyepiece in special glasses transmits only one type of circular polarization (left or right). Thus, each eye sees through the glasses corresponding light wave (image).
Active shutter 3D technology
Active shutter 3D technology uses a different principle. The left and right eyepiece alternately is closed in special glasses. Wherein, the flashing frequency reaches 60 times per second. TV, in its turn, alternately shows the image for both eyes, opening the right filter for right eye and then the left filter for the left eye. Wherein, the synchronization of Glasses and TV uses a radio channel.
Eyepiece lock uses liquid crystals. In fact, each eyepiece of shutter glasses is a miniature LCD screen.
Today, active shutter 3D technology is considered the most innovative. It provides the high depth of 3D-image and the opportunity of its control. But almost all modern 3D TVs have adjustable depth of three-dimensional image. Moreover, the quality of the 3D-effect depends mainly from the content.
Unfortunately, it also has drawbacks. Firstly, active 3D technology partially obscures the image, that causes eye fatigue at prolonged viewing due to the constant flicker. Additionally, batteries in the glasses creates electromagnetic radiation. Some experts consider these factors unsafe for health. Some users even experience such discomfort, as dizziness and eye fatigue while watching 3D. Batteries also make heavier the weight of glasses, reducing comfort during watching. Additionally, these glasses have relatively high price. This technology also has limitations for distance. The visible lines disappear at a distance of more than two diagonals. Technology provides the large vertical viewing angles (170°) and small horizontal viewing angles (90-100°). This also negatively affect on perception.
Anaglyph 3D technology
Anaglyph technology uses more simple blue-red glasses, but it has a significant drawback. The color filters absorb colors and shades of spectrum in range beside with red and blue. Therefore, this three-dimensional image is paler compared to other 3D technologies.
Polarization 3D technology
Polarization linear technology also has one drawback. Rotating the head relative to the screen destroys the perception of the volumetric image. Additionally, the watching 3D video on a small screen and at a short distance substantially amplifies it. But the big screen in the cinema compensates for this shortcoming.
Cinema 3D technology also uses passive polarization. It was developed and implemented by LG Company. This technology forms a 3D image into TV. Therefore, it eliminates the dependence from visual angle and provides the perception of the volumetric image in the any comfortable position. Additionally, the eyeglasses design is simple and they are cheap. Unfortunately, today this technology is only available in LG models.
This video convincingly demonstrates the pros and cons of passive and active 3D technology.