How is 3D glasses-free technology possible?

What is glasses-free 3D? 

Glasses-free 3D, in layman's terms, is that the naked eye can intuitively see the three-dimensional visual effect without the help of external equipment such as glasses and helmets. As we all know, our human brain is an extremely complex nervous system, in the visual system, due to the distance between our two eyes is about 60mm, when we look at objects, there will be a certain degree of horizontal difference in the imaging of objects on the retina of the left eye and the right eye, then this phenomenon is what we usually call parallax, and it is the existence of this parallax that our brain can judge the distance of the object. At the same time, the brain will reflect the two images with parallax into both eyes through the fusion reflection of the optic nerve center, as well as the visual psychological response to form a three-dimensional feeling, which is the basic principle of naked-eye 3D imaging.

In addition, glasses-free 3D visual effect ≠ glasses-free 3D technology, glasses-free 3D visual effect is more of a pseudo-three-dimensional effect formed by optical illusions, while glasses-free 3D technology is an imaging technology. Glasses-free 3D technology combines optics, image processing, and computer vision technologies to project images from different perspectives. Through special display technology and image processing methods, glasses-free 3D technology can project images from different perspectives on the screen at the same time, so that our left and right eyes can receive different images. In this way, when our brains process these images, they create a three-dimensional sense, as if the real world is unfolding right in front of our eyes.

Mainstream glasses-free 3D technology

1.Slit liquid crystal grating

The principle of this technology is to add a slit grating in front of the screen, these stripes are tens of microns wide, and through their light a vertical thin grating pattern is formed, which is called a "parallax barrier". When the image that should be seen by the left eye is displayed on the LCD screen, the opaque streak obscures the right eye; In the same way, when an image that should be seen by the right eye is displayed on an LCD screen, opaque stripes obscure the left eye, allowing the viewer to see the 3D image by separating the visual images of the left and right eyes.

2. Rod-lens technology

The greatest advantage of the cylindrical lens technology, also known as the biconvex lens or micropillar lens 3D technology, is that its brightness is not compromised. Its principle is to add a layer of cylindrical lens in front of the liquid crystal screen, so that the image plane of the liquid crystal screen is located on the focal plane of the lens, so that the pixels of the image under each cylindrical lens are divided into several sub-pixels, so that the lens can project each sub-pixel in different directions. So when you look at the display from different angles, you see different sub-pixels.

3. Point to the light source

In simple terms, this technology is to precisely control two sets of screens to project images to the left and right eyes respectively. By matching two sets of LEDs, with a fast-responding LCD panel and a driving method, the 3D content enters the viewer's left and right eye swap images in a sorted way to produce parallax, and then makes the eyes feel the 3D three-dimensional effect. The advantage of this technology is that it ensures the resolution, light transmittance and other factors, and does not affect the existing design architecture, and the 3D display effect is excellent. The disadvantage is that the technology is not yet mature and cannot be put into use on a large scale.

What are the applications of glasses-free 3D?

1.Education and training 

In the teaching of courses such as stereo geometry, the three-dimensional structure of the real object can be reproduced through naked-eye 3D technology to assist the teaching. In addition, in the field of culture, the processing and display of some art exhibits, naked-eye 3D display has a wide range of applications.

2.Medical and health field 

The use of naked-eye 3D vision training system can effectively help children with amblyopia to restore binocular stereoscopic vision function and improve visual acuity. Doctors can use glasses-free 3D technology to complete remote diagnosis and treatment, which can obtain more and more accurate diagnosis and treatment information compared with 2D image display, greatly improving the efficiency of diagnosis and treatment. At the same time, glasses-free 3D technology can also be a good auxiliary to medical teaching, surgical operation simulation and other application needs.

3.Military field 

3D display technology can be applied in national defense military teaching, flight simulation, military exercises, tank driving, training of submarine pilots in a simulated environment, stereo photography reconnaissance, interstellar remote sensing and telemetry imaging analysis, etc. At the same time, it can also be applied to weapon control, space exploration, space training, etc.