What is the principle of holographic projection technology?

The principle of holographic projection technology:

Photography principle:

The first step is to use the interference principle to record the light wave information of the object. This is the shooting process: the subject is photographed The object forms a diffuse object beam under laser irradiation; the other part of the laser is used as a reference beam and is irradiated onto the holographic film, superimposing with the object beam to cause interference, converting the phase and amplitude of each point on the object's light wave into a spatially changing Intensity, thereby using the contrast and spacing between interference fringes to record all the information of the object's light waves. After the negative film recording the interference fringes undergoes development, fixation and other processing procedures, it becomes a hologram, or hologram.

The second step is to use the principle of diffraction to reproduce the object's light wave information. This is the imaging process: the hologram is like a complex grating. Under coherent laser irradiation, a linearly recorded sinusoidal hologram is Diffracted light waves generally give two images, namely the original image (also called the initial image) and the yoke image. The reproduced image has a strong three-dimensional sense and has a real visual effect. Each part of the hologram records the light information of each point on the object, so in principle, each part of it can reproduce the entire image of the original object. Through multiple exposures, multiple different images can also be recorded on the same negative. And they can be displayed separately without interfering with each other.

Before 3D projection, a 120° 3D photography of the object is required. Readers who have watched 3D movies should know that if you take off the 3D glasses to watch, the picture will be double and blurry. This is because the picture on the screen is not one, but the superposition of two pictures with different angles.

In order to simulate the "binocular effect", we must shoot the picture to the left and the picture to the right. During the shooting, there are actually two 3D cameras working at the same time. One is tilted to the left side of the actor and records the left image; the other is tilted to the right side of the actor and records the right image. The two images are then superimposed through computer processing. It became a 3D movie source.

Visual principle:

Note: This is the visual principle of 3D imaging. What is slightly different from this is that holographic projection actually presents a 3D image.

Everyone has two eyes, and the visual angle of each eye is about 80 degrees, but the visual angle of the two eyes together is only 120 degrees, which means that 40 degrees of visual angle overlap, so we The things seen by the left and right eyes are actually different. For example, if you close the left eye and look with the right eye or vice versa, you can test the effect. The objects received by the left and right eyes are forwarded to the brain to judge the distance of the object. In order to form a three-dimensional sense. 3D stereoscopic technology is formed by simulating this process.

After completing the photography, in the screening room, the 3D movie source is placed on the screen at a certain angle, and the audience needs to wear 3D glasses to watch. If we look closely at the 3D glasses, we will find that there are dense and thin stripes with different directions on the left and right lenses. The left lens has vertical stripes and the right lens has horizontal stripes. It is these stripes that we can see the wonderful 3D stereoscopic image.

After completing the photography, the image is decomposed according to the "binocular effect", so that the left eye only sees the left side of the picture, and the right eye only sees the right side of the picture, so that the brain can make judgments about distance. And give birth to a three-dimensional sense. During projection, the projection light used for the left-side picture and the right-side picture are different. Although the color of the picture is the same, the propagation direction of the projection light is different. The left-side picture uses longitudinal wave light (light wave along the edge). (Longitudinal transmission), the picture on the right uses transverse wave light (light waves are transmitted transversely). Due to the characteristics of polarized light, longitudinal wave light can only pass through vertical lines and cannot pass through horizontal lines. Therefore, through the left lens, we can only see The picture on the left is the same as the right lens.

As a result, the overlapping pictures are decomposed. The left eye only sees the picture on the left side, and the right eye only sees the picture on the right side. Due to the binocular effect, we have a sense of distance and three-dimensionality. .