The principles of holography are applicable to various forms of waves, such as X-rays, microwaves, sound waves, electronic waves, etc. As long as these fluctuations are coherent enough to form an interference pattern. Optical holography is expected to be used in three-dimensional movies, television, exhibitions, microscopy, interferometry, projection lithography, military reconnaissance and surveillance, underwater detection, metal internal detection, preservation of precious historical relics, artworks, information storage, and remote sensing. , it has been widely used in various aspects such as studying and recording instantaneous phenomena and instantaneous processes (such as explosions and combustion) that change physical states very quickly.
In life, we can often see the application of holographic photography technology. For example, on some credit cards and banknotes, there is a "rainbow" holographic image on polyester soft film produced using the full-color holographic image technology invented by Russian physicist Yuri Denisuk in the 1960s. . However, these holographic images are mostly used as a complex printing technology to achieve anti-counterfeiting purposes. Their sensitivity is low and the colors are not realistic enough, far from being realistic. Researchers are also trying to use dichromate glue as a photosensitive emulsion to make holographic identification devices. Some fighter jets are equipped with such devices, which allow the pilot to focus on the enemy. Using this technology to photograph some precious cultural relics, the cultural relics can be reproduced in a true three-dimensional manner for visitors to appreciate when on display. The original objects are properly preserved to prevent theft. Large holograms can display cars, satellites and various three-dimensional advertisements. , pulse holography can also be used to reproduce portraits and wedding photos. Small holograms can be worn around the neck to form beautiful decorations, recreating favorite animals, colorful flowers and butterflies. The rapidly developing molded rainbow holograms can not only become vivid cartoons, greeting cards, and three-dimensional stamps, but also appear as anti-counterfeiting marks on trademarks, ID cards, bank credit cards, and even banknotes. The holographic stereoscopic photos decorated in books and the holographic rainbow shining on gift packages allow people to experience the new leap in printing and packaging technology in the 21st century. The molded holographic logo, due to its three-dimensional layering, rainbow effect that changes with the viewing angle, and ever-changing anti-counterfeiting marks, coupled with its close integration with other high-tech anti-counterfeiting means, has pushed anti-counterfeiting technology into the new century. the culmination of glory.
In addition to optical holography, infrared, microwave and ultrasonic holography technologies have also been developed. These holographic technologies are of great significance in military reconnaissance and surveillance. We know that general radar can only detect the target orientation, distance, etc., while holography can give a three-dimensional image of the target, which is very useful for timely identification of aircraft, ships, etc. Therefore, it attracts people's attention. However, since visible light attenuates quickly when propagating in the atmosphere or water, it may even be impossible to work in adverse climates. In order to overcome this difficulty, infrared, microwave and ultrasonic holography technology has been developed, which uses coherent infrared light, microwave and ultrasonic waves to take holographic photos, and then uses visible light to reproduce the object image. This holographic technology has the same principle as ordinary holographic technology. The key to technology is finding sensitive recording media and appropriate reproduction methods. ?
Ultrasound holography can reproduce the three-dimensional pattern of objects lurking underwater, so it can be used for underwater reconnaissance and surveillance. Since objects that are opaque to visible light are often transparent to ultrasonic waves, ultrasonic holography can be used in underwater military operations, medical fluoroscopy, and industrial non-destructive testing.
In addition to using light waves to generate holograms, computers have been developed to generate holograms. Holograms are widely used and can be made into various thin-film optical components, such as various lenses, gratings, filters, etc. They can be overlapped in space and are very compact and lightweight, making them suitable for space flight. The use of holograms to store data has the advantages of large capacity, easy extraction, and anti-fouling.
The method of holography has been extended from the field of optics to other fields. For example, microwave holography and acoustic holography have been greatly developed and successfully used in industrial medical and other aspects. Holograms such as seismic waves, electron waves, and X-rays are also being studied in depth. Holograms have an extremely wide range of applications. For example, it is used to study the shock waves of rocket flight and non-destructive testing of aircraft wing honeycomb structures. Now there is not only laser holography, but also white light holography, rainbow holography, and panoramic rainbow holography have been successfully researched, allowing people to see all sides of the scene. Holographic three-dimensional display is developing in the direction of holographic color stereoscopic TV and movies.
Holographic technology is not only being widely used in real life, but also has a large number of descriptions and applications in science fiction literature that emerged and developed rapidly in the last century. If you are interested, you can check it out. It can be seen that the future development prospects of holographic technology will be very bright.
[Edit this paragraph] Technical history Long before the emergence of lasers, Gaber proposed the concept of holography in 1948 in order to improve the resolution ability of electron microscopes and began research on holography. After 1960, laser appeared, providing a high-brightness and highly coherent light source for holography. Since then, holography technology has entered a new stage. A variety of holographic methods have emerged one after another, constantly opening up new areas of holographic applications. Gabor also won the 1971 Nobel Prize in Physics for his research on holography.
Whether it is holography or the earliest daguerreotype, their secret lies in the recording of light. All light has three attributes, which are the intensity of light and darkness, the color of light, and the direction of light. Early daguerreotypes and black-and-white photos could only record changes in light and dark, while color photos could also record changes in wavelength of light to reflect its color. Holography is the only photography technology that can capture the three properties of light at the same time. Through laser technology, it can record the direction in which light hits an object and is refracted, and realistically reproduces the true scene of the object in three-dimensional space.
However, until the advent of the works of the Ghent brothers, the so-called true representation has always been nothing more than theoretical. Perhaps because good holographic images are rare and difficult to generate, or perhaps because the scientific principles of holography are too esoteric, half a century after its invention, holography is still a technology full of mystery.
In some media reports on the achievements of Yves Gent and his brothers, some people described them as "the only people who have truly realized the function of reproducing nature in holography". Others said that their The work is, as Morse said, "a part of nature." These comments may be exaggerated, because in fact, there are many other people around the world who are engaged in holography research. The International Hologram Manufacturers Association is a gathering of holography experts and enthusiasts around the world. organization of the person. But Yves Gent is undoubtedly the leader among these experts. In the winter of 2001, the federation awarded the two most important awards for "Best Holographic Work of the Year" and "Latest Holographic Technology" to Yves.
In the following years, Yves Gent taught himself relevant chemical principles in his humble laboratory and practiced them repeatedly. The addition of Philip helped him a lot. Later, they finally invented a photosensitive emulsion called "Ultimate". Like other photosensitive emulsions, the main component of "Ultimate" is also extremely photosensitive silver bromide particles, but the diameter of the silver bromide particles in "Ultimate" is only 10 nanometers, which is 1/10 to 1/10 of the photosensitive particles on ordinary film. 1/100. It is these tiny particles that enable the "Ultimate" to record every detail down to the smallest detail, and simultaneously record red, green, and blue colors on the same photosensitive layer.
Yves found what he called "the photosensitive emulsion that everyone has been looking for for 30 years," but he still had a long way to go. He made the entire plan to copy the Chauvet cave paintings, but he was unable to find an authoritative person in the government. He also proposed building a hologram pavilion of visiting celebrities for Disneyland in Paris, but negotiations dragged on. Everyone who has seen his work admits that it is a perfect holographic image, but French investors are too cautious. They not only want geese that lay golden eggs, but also a group of such geese that can industrialize and lay golden eggs on a large scale. Only then are they willing to take money out of their own pockets. In search of investors, the Ghent brothers and their father even considered immigrating to Quebec.
The earliest turning point for holographic photography came after an American partner joined the company. He had a machine that copied the holographic image from the "ultimate" master onto a certain polymer material made by DuPont. While the images aren't quite as good as those on "ultimate" film, they are far better than previous holographic images on polymer materials. With the mass production of holographic images on this DuPont material, industrial production using the "ultimate" film is just around the corner. [1]