Why is what the human eye sees three-dimensional (with one eye closed or three-dimensional), and why is holography three-dimensional?

1. What human eyes see is stereoscopic: this is because of binocular effect, and the distance between human eyes is about 10 cm. When watching an object, two eyes look at the same object and see two pictures reflecting different sides of the same object, which are integrated into a stereoscopic image by the brain.

2. Close your eyes or stereoscopic: When you look at an object with one eye, you see a plane and lack a sense of depth. Do not believe me, you can do a small experiment to prove it. As for seeing with one eye, it is still three-dimensional, which is due to the existing life experience.

3. As for holography, it is a photographic technique that uses the interference of waves to record the information (amplitude and phase) in the light waves reflected (or transmitted) by objects. Holography is formed by superimposing a beam of reference light and light reflected by an object on a photosensitive plate to produce interference fringes. Holography not only records the amplitude (intensity) of the reflected light wave of the photographed object, but also records the relative phase of the reflected light wave.