Are holograms the same as holographic projections?

Holographic projection is a technology that uses optical technology to project a three-dimensional image into the air to form a three-dimensional image. It uses light sources such as lasers or LEDs to decompose the image into many tiny light tremor points, and reconstructs these light points into a three-dimensional image through optical principles such as interference and diffraction, so that people can see realistic three-dimensional images in the air. The vertical holographic projection technology has a wide range of applications in display, advertising, education, medical and other fields.

Holographic projection is a technology that can simultaneously present the light wave intensity and phase information of the object, so that the projection presents a 3D stereoscopic effect.

Holographic projection is a type of 3D technology, which originally refers to the technology that uses the principle of interference to record and reproduce the real three-dimensional image of an object. Later, with the guidance of science fiction films and commercial promotion, the concept of holographic projection gradually extended to commercial activities such as stage performances and exhibitions.

"Holo" comes from the Greek word "holo", which means "complete information", that is, it contains information about the amplitude and phase of the light waves. Ordinary photographic techniques only record the intensity (amplitude) of the light, while the depth information (phase) is lost. In the interference process of holographic technology, the superposition of wave peaks and peaks will be higher, and the superposition of peaks and troughs will be flattened, so a series of irregular, light and dark stripes will be generated, so that the phase information will be converted into intensity information and recorded on the photosensitive material.

The technical principle of holographic projection

Holographic projection technology, also known as virtual imaging technology, is a technology that uses the principle of interference and diffraction to record and reproduce the real three-dimensional image of an object.

The first step is to use the principle of interference to record the light wave information of the object, which is the shooting process: the photographed object forms a diffuse object beam under laser irradiation; The other part of the laser is used as a reference beam to shoot on the holographic negative, and the object beam is superimposed to produce interference, and the phase and amplitude of each point on the object light wave are converted into the intensity of spatial variation, so as to record all the information of the object light wave by using the contrast and spacing between the interference fringes. The negative recording of interference fringes becomes a hologram, or holographic**, after being developed and fixed.

The second step is to use the principle of diffraction to reproduce the light wave information of the object, which is the imaging process: the hologram is like a complex grating, and under the irradiation of a coherent laser, the diffraction light wave of a linearly recorded sinusoidal hologram can generally give two images, namely the original image (also known as the initial image) and the conjugated image.

The reproduced image has a strong sense of three-dimensionality and has a realistic 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, and can record a number of different images on the same negative by multiple times, and can be displayed separately without interfering with each other.