Holographic technology is a technology that uses the principles of interference and diffraction to record and reproduce real three-dimensional images of objects. The first step is to use the principle of interference to record the lightwave information of the object, that is, the shooting process; the second step is to use the principle of diffraction to reproduce the lightwave information of the object, that is, the imaging process. Advantages of holographic technology: The reconstructed three-dimensional image is conducive to the preservation of precious art materials for collection; every point is recorded on any point of the hologram when shooting; the holographic photo has a strong three-dimensional sense and vivid image, and it can be displayed with the help of a laser. Display in various exhibitions. There are three types of projection technology: 1. Air projection and interactive technology: This was invented by a 29-year-old graduate student in science and engineering named Chad Dyne in Massachusetts, USA. It is a milestone in display technology. It can project on the wall formed by airflow. Produce interactive images. This technology is derived from the principle of the mirage. The image is projected on the water vapor. Due to the unbalanced molecular vibration, it can form an image with strong layers and a strong sense of three-dimensionality. 2. Laser beam technology: Japanese Science and Technology company invented a 3D image that can be projected with a laser beam. This technology uses nitrogen and oxygen to disperse in the air, and the mixed gas becomes hot Paste-like substance and forms a short-lived 3D image in the air. This method is mainly achieved by continuous small blasting in the air. 3. 360-degree display of the entire department: It is currently announced by the researchers of the Institute of Innovation and Technology of the University of Southern California that they have successfully developed this technology to project the image on a high-speed rotating mirror to achieve a three-dimensional image, but it is somewhat dangerous . It can be said that these technologies are being developed in many countries. It is no exaggeration to say that this technology includes the future. Whoever uses this technology first will be the first to enter the ranks of advanced technologies in the future. Holographic projection technology is a reverse display of holographic photography, essentially forming a three-dimensional image on the air or on a special three-dimensional lens. Unlike flat screen projection that only achieves a three-dimensional effect on a two-dimensional surface through perspective, shadow and other effects, holographic projection technology truly presents 3D images, which can view different sides of the image from any angle of 360°. Technical Application The principle of holography is applicable to various forms of fluctuations, such as X-rays, microwaves, acoustic waves, and electronic waves. As long as these fluctuations have sufficient coherence when forming interference patterns. Optical holography is expected to be used in three-dimensional movies, television, exhibitions, microscopy, interferometrics, projection lithography, military reconnaissance and surveillance, underwater detection, metal internal detection, preservation of precious historical relics, artworks, information storage, and remote sensing , The research and recording of transient phenomena and transient processes (such as explosions and combustions) with extremely rapid physical state changes have been widely used.