3D displays utilize the principle of binocular vision to transform two-dimensional images into three-dimensional images with depth perception through a series of optical technologies. Below is a detailed explanation of the main technologies involved:

1. Principle of Stereoscopic Vision:

   Human eyes are approximately 6.5 centimeters apart, which creates a disparity when observing objects—each eye perceives a slightly different image due to the difference in distance between the eyes and the object. The brain merges these two images and calculates the depth information based on the disparity, thereby forming stereoscopic vision.

2. Traditional 3D Display Technologies:

   - Anaglyph 3D: This method uses glasses with red and blue color filters to transmit different colored images to each eye. Since the red and blue filters only allow light of their respective colors to pass through, the images seen by each eye have different colors, creating a disparity. The brain merges these images to produce a stereoscopic effect. However, this technology has drawbacks such as color distortion and eye strain with prolonged viewing.

   - Liquid Crystal Shutter: This technology uses liquid crystal shutters in glasses to alternately block each eye, transmitting images separately to the left and right eyes. The opening and closing of the shutters are synchronized with the display’s refresh rate, so each eye sees a different image, creating disparity. The advantage of this technology is that it provides full-color stereoscopic vision, but the shutter glasses are relatively heavy and can cause eye strain for some users.

   - Polarization Glasses: This method uses polarized glasses to transmit images with different polarization directions to each eye. The polarizing filters only allow light with a specific polarization direction to pass through, so the images seen by each eye have different polarization, creating disparity. The brain merges these images to produce a stereoscopic effect. The advantage of this technology is its high color fidelity, making it suitable for prolonged viewing.

3. Advanced 3D Display Technologies:

   - Integral Imaging: This technology uses a microlens array to capture light information from an object, creating multiple two-dimensional images. Each microlens samples the object from a different angle, recording the shape and position information from various perspectives. These two-dimensional images are called Elemental Images. The Elemental Images are displayed on a two-dimensional screen and projected to their corresponding positions through the microlens array. All the light passes through the microlens array to form a three-dimensional image. Viewers perceive different Elemental Images from different angles, resulting in stereoscopic vision. The advantage of this technology is that it provides a more natural sense of depth without the need for special glasses.

   - Head-Mounted Display (HMD): This technology combines a miniature display with an optical system to create a virtual three-dimensional image. The miniature display presents different images to the left and right eyes, while the optical system enlarges the images and projects them into the viewer's eyes. Since the images seen by each eye have a disparity, the brain merges them to produce a stereoscopic effect. This technology is widely used in Virtual Reality (VR), offering an immersive experience.

   - Volumetric Light Field Display: This technology controls the direction of light propagation in space to create three-dimensional images. For example, static volumetric displays use light-emitting elements to form different patterns in different states, simulating the three-dimensional shape of an object. Surface scanning volumetric displays rapidly move a display surface, projecting different surface images of a 3D object from various angles to create a continuous three-dimensional image. This technology has great potential in Augmented Reality (AR) and Virtual Reality (VR) applications.

   - Holographic Display: This technology records light wave information from an object using the principle of light interference and reproduces three-dimensional images using the principle of diffraction. For example, a hologram records the interference patterns of light waves reflected from an object with a reference light wave, capturing the three-dimensional information of the object. When coherent laser light is shone onto the hologram, the interference patterns generate diffracted light waves, forming a three-dimensional image of the object. Although holographic displays provide highly realistic three-dimensional effects, current technology still faces limitations in resolution and viewing angles.

4. Trends in 3D Display Technology:

   - More Natural Disparity Images: By more accurately simulating the disparity perceived by the human eye, 3D displays can reduce visual fatigue and enhance viewing comfort.

   - Glasses-Free Viewing: The development of glasses-free 3D display technology increases convenience and reduces costs.

   - Higher Resolution and Wider Viewing Angles: These advancements provide more realistic visual effects, meeting users' demands for high-quality 3D content.

   - Lower Costs and Higher Production Capacity: These factors will drive the widespread adoption of 3D display technology, allowing more people to enjoy the visual experience it offers.

   - Light Field Display Technology: As a future trend, this technology can provide disparity-free 3D images, significantly reducing eye strain.