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Technical application of three-dimensional holographic imaging technology

The principle of holography is applicable to all kinds of waves, such as X-rays, microwaves, sound waves and electronic waves. As long as these fluctuations have sufficient coherence in forming the interference pattern. Optical holography is expected to be widely used in three-dimensional movies, televisions, exhibitions, microscopes, interferometry, projection lithography, military reconnaissance and surveillance, underwater detection, internal detection of metals, preservation of precious historical relics, works of art, information storage, remote sensing, research and recording of transient phenomena and transient processes (such as explosion and combustion) with extremely rapid changes in physical state.

In life, we can often see the application of holographic technology. For example, on some credit cards and banknotes, there is a kind of "rainbow" holographic image on polyester film, which is made by using the full-color holographic image technology invented by Russian physicist Yuri Denisuke in the 1960s. However, these holographic images are only used as a complex printing technology to achieve the purpose of anti-counterfeiting. Their sensitivity is low, their colors are not realistic enough, and they are far from the real state. The researchers also tried to use dichromate glue as emulsion to make holographic recognition equipment. Some fighters are equipped with this kind of equipment, which enables pilots to concentrate on the enemy. When some precious cultural relics are photographed by this technology, they can be truly reproduced in three dimensions for visitors to enjoy, while the original objects are properly preserved to prevent theft. Large holograms can not only display cars, satellites and various three-dimensional advertisements, but also copy portraits and wedding commemorative photos with pulse holography. Small holograms can be worn around the neck to form beautiful decorations, which can reproduce people's favorite animals, colorful flowers and butterflies. The rapid development of embossed rainbow holograms can not only become lifelike cartoons, greeting cards and three-dimensional stamps, but also appear as anti-counterfeiting marks on trademarks, ID cards, bank credit cards and even banknotes. Holographic stereo photo decorated on books and holographic rainbow shining on gift packaging make people realize the new leap of printing technology and packaging technology in 2 1 century. Molded holographic logo, because of its three-dimensional layering, rainbow effect changing with observation angle, ever-changing anti-counterfeiting logo, and the close combination with other high-tech anti-counterfeiting means, has pushed the anti-counterfeiting technology in the new century to a new brilliant peak.

In addition to optical holography, infrared, microwave and ultrasonic holography technologies have been developed, which are of great significance in military reconnaissance and surveillance. As we know, the general radar can only detect the direction and distance of the target, while holography can give three-dimensional images of the target, which plays a great role in identifying aircraft and ships in time. Therefore, people attach great importance to it. However, due to the rapid attenuation of visible light in the atmosphere or water, it can't even work in bad weather. In order to overcome this difficulty, infrared, microwave and ultrasonic holographic techniques have been developed, that is, coherent infrared, microwave and ultrasonic holographic photos are taken, and then the image of the object is reproduced by visible light. This holographic technology has the same principle as the ordinary holographic technology. The key of technology is to find sensitive recording media and suitable copying methods. ?

Ultrasonic holography can reproduce the three-dimensional pattern of underwater objects, so it can be used for underwater reconnaissance and surveillance. Because objects that are opaque to visible light are often transparent to ultrasonic waves, ultrasonic holography can be used in underwater military operations, medical perspective and industrial nondestructive testing.

In addition to using light waves to generate holograms, it has also developed into using computers to generate holograms. Holograms are widely used and can be made into various thin film optical elements, such as various lenses, gratings, filters, etc. , can overlap in space, very small and light, suitable for space flight. Using hologram to store data has the advantages of large capacity, easy extraction and pollution prevention.

The method of holography has expanded from the optical field to other fields. Such as microwave holography and acoustic holography, have been greatly developed and successfully applied to industrial medical care. Holography of seismic waves, electronic waves and X-rays is also under in-depth study. Holograms are widely used. Such as shock wave used to study rocket flight, nondestructive testing of honeycomb structure of aircraft wing, etc. Now there are not only laser holography, but also white light holography, rainbow holography and panoramic rainbow holography, so that people can see all sides of the scene. Holographic three-dimensional display is developing towards holographic color stereoscopic TV and movies.

Holographic technology is not only widely used in real life, but also has a large number of descriptions and applications in science fiction literature that rose and developed rapidly in the last century. You can go and have a look if you are interested. It can be seen that the future development prospect of holographic technology will be very bright.

[Edit this paragraph] The history of technology was long before the appearance of laser. In 1948, dennis gabor put forward the concept of holography in order to improve the resolution of electron microscope, and began the research work of holography. After 1960, laser appeared, which provided high brightness and high coherence light source for holography. Since then, holographic technology has entered a new stage. Various holographic methods have appeared one after another, constantly opening up new fields of holographic application. Gabor also won the 197 1 year Nobel Prize in Physics for his research on holography.

Whether holographic photography or the earliest silver disk photography, their mystery lies in the recording of light. All light has three properties, namely its intensity, color and direction. Early silver photography and black-and-white photographs can only record the changes of light and shade, while color photographs can also reflect their colors by recording the wavelength changes of light. Holography is the only photography that can capture three properties of light at the same time. Through laser technology, it can record the direction of light incident on the object, and then refract it to reproduce the real scene of the object in three-dimensional space realistically.

However, before the Ghent brothers' works came out, the so-called true reproduction was only theoretical. Perhaps it is because good holographic images are rare and difficult to generate, or because the scientific principle of holography is too profound. After half a century of invention, holography is still a mysterious technology.

When some media reported the achievements of Yves Ghent and his brothers, some people described them as "the only people who truly realized the function of holographic photography to reproduce nature", while others said that their works were "a part of nature" as Morse said. These comments may be exaggerated, because there are actually many other people in the world who are engaged in holographic research. The International Holographic Manufacturers Association is an organization that has gathered experts and enthusiasts from all over the world. However, Yves Ghent is undoubtedly the best among these experts. In the winter of 200 1, the Federation awarded Yves two most important awards: "the best holographic work of the year" and "the latest holographic technology".

In the following years, Yves Ghent taught himself the relevant chemical principles in his humble laboratory and practiced them repeatedly. Philip's joining helped him a lot. Later, they finally invented a photographic emulsion called "Ultimate". Like other photographic emulsions, the main component of Ultimate is silver bromide particles with excellent photographic performance, but the diameter of silver bromide particles in Ultimate is only 10 nm, which is110 to100 of the photosensitive particles on ordinary film. It is these tiny particles that enable "Ultimate" to record every detail, down to the smallest detail, and simultaneously record three colors of red, green and blue on the same photosensitive layer.

Eve found what he called "the emulsion that people have been looking for for for 30 years", but he still has a long way to go. He made the whole plan to copy the murals of Little Wei Yan Cave, but he had no recourse because he could not find the authority of the government. He also suggested building a holographic portrait gallery for visiting celebrities for Disneyland in Paris, but the negotiations were postponed. Everyone who has seen his works admits that it is a perfect hologram, but French investors are too cautious. Not only do they want geese that lay golden eggs, but also a group of such geese lay golden eggs on a large scale in an industrialized way before they are willing to pay for themselves. In order to seek investors, the Ghent brothers and their father even thought about immigrating to Quebec.

The earliest holographic works took a turn for the better after an American partner joined them. The machine he owns can copy the holographic image on the "ultimate" master to a polymer material made by DuPont. Although these images are not up to the image level of "ultimate" film, they are far superior to holographic images on polymer materials. With the large-scale production of holographic images on this DuPont material, industrial production using "ultimate" film is just around the corner. [ 1]