What is a holographic image?

The ordinary image only records the light intensity information (reflected in the amplitude) of each point of the object, and loses the position image information, thus obtaining a two-dimensional plane image with no stereoscopic effect. Holography is based on the principle of interference caused by the superposition of coherent light. With the help of the interaction between the so-called reference light wave and the original light wave, the interference fringes of the two light waves on the recording medium are recorded. This interference fringe not only preserves the amplitude information of the object light wave (the light wave reflected from the object), but also preserves the phase information of the object light wave, which can only be observed under a high-power microscope. The hologram with interference fringes can be regarded as a complex diffraction grating. When the grating is irradiated with the same light as the original reference light wave, its diffraction wave can reproduce the original object light wave, and the three-dimensional image of the original illuminated object can be observed at the position of the original object after the photo.