3D glasses are an amazing tool, providing users with a sense of immersion when used in cinemas. But how do they work?
Today's 3D glasses use the most advanced "time division method", synchronizing with the display signal to achieve the desired effect. When the monitor outputs the left-eye image, the left eyeglass lens becomes translucent, while the right lens becomes opaque.
Conversely, when the monitor outputs the right-eye image, the right eyeglass lens becomes translucent, and the left lens becomes opaque. This process results in each eye receiving a slightly different image, creating the illusion of 3D.
The design of 3D glasses uses sophisticated optical components, and compared to passive glasses, each eye can achieve double the resolution and a wider perspective.
There are different types of 3D glasses, including:
1. Complementary color
Also known as chromatic aberration, this type of 3D glass uses common red and blue-tinted lenses.
Chromatic aberration uses color separation stereoscopic imaging technology, which prints two different views of the same image in two different colors. When viewed with the eye, this produces a blurred overlapping image.
Only through corresponding red and blue or other stereoscopic glasses can the 3D effect be seen. The filtering of the red and blue colors allows the red images to be seen through the red lens and the blue images to be seen through the blue lens. The brain then overlaps the two images to create a 3D stereoscopic effect.
2. Polarized light
Polarized 3D technology is commonly used in commercial theaters and other high-end applications. It uses a passive reception method and is therefore also known as a passive 3D technology. The cost of auxiliary equipment is lower, but the output device requirements are higher, making it suitable for commercial cinemas and other places with large audiences.
The left and right images are captured using two lenses, and then the image from the left lens is filtered by a transverse polarizer to get the transversely polarized light, while the image from the right lens is filtered by a longitudinal polarizer to get the longitudinally polarized light.
The left and right eyes of the stereoscope are fitted with a transverse and longitudinal polarizer respectively, so that the transversely polarized light can only pass through the transverse polarizer and the longitudinally polarized light can only pass through the longitudinal polarizer.
This ensures that what is captured by the left camera can only enter the left eye, and what is captured by the right camera can only enter the right eye, creating a stereoscopic effect.
3. Time division type
Also known as active shutter 3D glasses, shutter 3D technology provides home users with a high-quality 3D display. This technology requires a pair of active LCD shutter glasses, which alternate between the left and right eyes to see the image. The brain fuses the two images into one to create the illusion of a single image with a 3D sense of depth.
The refresh time of the human eye is used to achieve the desired frequency, increasing the fast refresh rate of the picture (at least 120Hz). The left and right eyes each receive 60Hz of fast refresh images to prevent any sense of jitter while maintaining the same number of frames as a 2D video. The audience's two eyes see the fast switching of different images, creating the illusion of a stereoscopic image.
4. Non-flash type
This technology uses a TV to separate the left and right images and sends them to the glasses at the same time. The glasses filter the separated left and right images to send them to each eye, and the brain synthesizes the two images to create the 3D stereoscopic sense.