Principles of holographic photos

Principles of holographic photos  Holographic photography is to use laser technology for photography, recording all the light information of an object on the negative film. Unlike normal photography, it only records a projection of an object. Therefore, when the weight of a negative film is present, it seems extremely lifelike In the viewer's eyes. The visual effects produced by the film are exactly the same as those when watching the object.

The principle of holographic photography, simply put, mainly utilizes the characteristics of pure laser color. In fact, the holographic theory was proposed by British scientist gabo as early as 1947. However, it was not until the advent of high brightness, pure color, and good coherence laser that truly took a holographic photograph.

Holographic photography and stereoscopic photography are two different things. Although a three-dimensional color photo looks colorful, hierarchical, and stereoscopic, it is still a single-sided image, and even a good three-dimensional photo cannot replace real objects. For example, no matter how we change the angle of observation, we can only see the picture on a square block. However, holographic images are different. We only need to change the angle of observation to see the six aspects of this square block. Because holographic technology can record all the geometric features of an object on a negative film, this is also the most important feature of holographic photography.

The second feature of holographic photography is to see the full picture. When the holographic photo is damaged, even if it is mostly damaged, we can still see the entire picture of the original object from the remaining half. This is not suitable for normal photos. Even if a corner is lost, the image on the corner will not be seen.

The third feature of a holographic photograph is that multiple holographic images can be recorded on a holographic negative, and they do not interfere with each other when they are displayed. This hierarchical record enables holographic photos to store a large amount of information.

Why do holographic photos have such characteristics? Why do ordinary photos do not have these features? This is from the shooting principle.

If a laser is used to illuminate a tiny particle. The light waves reflected from small particles are basically ball waves that are constantly expanding outward. We look at small particles as bright. When a camera is used to take a photo of this small particle, light waves form a bright spot on the negative film through the lens. The brightness is related to the light intensity reflected by the small particles. The photo negatives can record the highlights of this point, but do not remember the position of small particles in three-dimensional space. The printed photos only have one highlight. It looks like there is no three-dimensional feeling. When taking a holographic photo, you don't need to take a photo. Instead, you need to take a laser with a plane wave and a ball wave reflected by a small particle together to take a photo. The whole negative film is illuminated. It records not a bright spot, but a group of concentric circles. When the concentric circles are separated by hours, it looks like using a knife to cut a round radish into slices, stacked together to form a group of concentric rings. After the negative film is rinsed, it is placed in the original position. Then, when shooting, the plane wave laser will be sent to the negative film from the shooting angle, we can see that there is a bright spot in the position where the small particles were originally placed. Note! This highlight is in space, not in the negative film. The light we see is like from this highlight. Therefore, a holographic photo records not only the highlights, but also the space locations of the highlights, or the whole light wave from the highlights. All of the mysteries are that this novel shooting method lies in this parallel (plane wave) laser beam. This laser beam is called a reference beam.

Therefore, any object can be regarded as a three-dimensional image composed of countless bright spots. The holographic photos taken using the above method are complex images composed of countless concentric circles, and they look gloomy. Similarly, this holographic photo not only records the light and shade of each point of the object, but also records the space position of each point. When a reference beam is used to illuminate a dry film, the light we see is like being sent from the original object. Therefore, we say that it records all the light information sent from the object, and the name of the holographic photo is obtained accordingly. However, laser holographic photos only show a three-dimensional image in the eyes under laser radiation. laser is a expensive device, and a photo must be equipped with a laser, in addition to the possible settings of scientific research departments and specialized places, it is impossible to make a universal and extensive application. To address this disadvantage. Scientists continue to study and finally invented a holographic photo that can be seen in the incandescent light. It is called White holographic or rainbow holographic.

Laser Holographic photo negatives can be special glass, latex, crystals or thermoplastic. A small special glass can store all the contents of millions of books in a large library.

If you pay attention to the photos in the newspaper, you can find that they are composed of small ideas. Each small idea is called a pixel, and its density is about several points per square millimeter. The special glass Film Used for holographic photography has a thickness of about 10 microns, and the image point density is more than 2000 points per square millimeter. In this type of negative film, a 310 cm²-square-millimeter photo can be attached to it. You can install a 5mm-page-thick book on a small film of 200 square meters.

The invention of holographic cameras does not mean photography. As an aspect of laser technology, holographic cameras have extensive practical value in the fields of industry, agriculture, and scientific research.

In terms of photography, this is a brand new technology. Because holographic photos have a realistic stereoscopic effect, they are used to replace ordinary photos with unique effects. In foreign countries, some people have used holographic photos as book inserts, trademarks, and three-dimensional advertisements. museums use these photos to represent precious cultural relics. A foreign machine tool manufacturing company opened a commodity presentation in another country and used holographic photos instead of physical materials to hold a machine tool exhibition. The exhibition hall is full of holographic photos of various machine tools. These photos seem to be the same as the real machine tools, but they are more interesting to visitors.

A well-conceived holographic photo is also an exquisite work of art. The U. S., France, and other countries all have holographic photo museums, which are the most exquisite works in the world.

Holographic photography can also record precious historical cultural relics. In the event of serious damage to cultural relics and monuments, even if they do not exist, we can still reconstruct them based on holographic photography. For example, although the scenic spots like Beijing Yuanmingyuan were burned down by the eight-nation coalition forces in the past, although they intend to be rebuilt, it is difficult to completely restore the whole landscape. If holographic photography was invented in 100, it would be easy.

Inspired by the holographic photos of three-dimensional scenes, scientists think of holographic movies and holographic TVs. Experimental holographic film has already appeared in the former Soviet Union. When a movie is displayed, the audience does not see the scene on the screen, but in the audience, which gives people an immersive feeling. Holographic television is still being studied because of its complicated technical problems. In 1982, a German television station broadcast a Three-Dimensional TV, instead of a Laser Holographic TV. It works in the same way as an ordinary three-dimensional movie. It needs to wear a special pair of glasses when watching it. It is expected that by the end of this century, film and television will be replaced again. By that time, people's cultural and entertainment life may become more colorful due to the appearance of laser panoramic stereo movies and laser stereo TVs.

Another important application of holographic photography is to make holographic optical elements that can replace glass in some special cases. This special optical element has the advantages of convenient processing, small size, light and thin. A concave lens can make the beam divergence, and a bunch of parallel light waves are taken as spherical waves. The holographic photos we mentioned earlier use small particles to change the parallel light reference beam to spherical waves; such a holographic photo is a special concave lens. A similar method can be used to produce convex lens, cylindrical lens, and other optical elements. This kind of component is as thin and light as paper, and will not be broken. A telescope has been made of holographic optical elements, and its thickness is similar to that of myopia lenses. It was also reported that holographic optical elements were used as window glass. This strange window glass does not affect people's sight, but can reflect a lot of sunshine, with the curtain function; what's more interesting is, the reflected sunlight can be concentrated in a row of solar cells under the eaves of the window, which is converted into electric energy for indoor use.

Holographic photography technology has the ability to understand. Because holographic photos can accurately reproduce the original object, we can use it as a standard to check whether the original object has changed; in fact, as long as there is a 1 micron change, you can use holographic imaging technology to check the image. The Scientific Research and Production Department also enables Laser Holographic photography to serve as the "Examiner" of the internal quality of finished products ". During the inspection, add a little pressure or heat to the object to be inspected. If the object contains cracks and microholes, the surface of the object will change accordingly. Although the extent of such changes is extremely subtle and invisible to the naked eye, all these flaws and hidden dangers are exposed under the eyes of holographic photography. In addition to precision inspection of internal quality, this method also has the advantage of no loss to the inspected objects, especially suitable for the detection of valuable objects, such as precious cultural relics and ancient sculptures. Greek scientists used this method to identify the degree of weathering of ancient figures. This method is used in production to check the inherent quality of precision parts, aircraft skins, and aircraft tires. In Foreign Aircraft Tire factories, laser holographic "inspectors" have been used ". This method is also used for biological research, such as studying the deformation produced by the stress of the brain shell, and studying the growth rate of mushrooms.

Holographic Storage Technology is still being developed. The storage information we mentioned when talking about the characteristics of holographic photography, that is, the ability to record information. Theoretically, the information stored on a CD is about 106 bits per square centimeter, while the holographic storage can store 108 bits per square centimeter, 100 times higher! In addition, the time for reading information is only one second per million!

Now, we can store the information in the materials. The materials used for holographic photography are not a thin film, but the entire crystal can be stored in 0.1 million books, A library only needs to save several records of crystals. This seems to have a bit of fantasies, but it is promising. More importantly, the development of holographic storage will promote the development and replacement of computers.

Generally, only one holographic photo can be made at a very high price. In addition to the use of scientific research, it can only be used as a high-level art. In 1980s, a new holographic technology was introduced. To create a holographic photo in this way, we first need to make a metal micro-float Board; use it as a printing board, and compress a holographic photo on a special sheet coated with a metal film. This is more convenient than printing stamps. It can be produced in large quantities, greatly reducing the cost and increasing application scope.

This holographic photography not only has a stereoscopic effect, but also presents a variety of colors in the sun or light, lining the silver-white metal background, and looks more brilliant. People use it to decorate books, toys, and souvenirs.

This holographic photography also contains a wealth of information, and it depends entirely on the scene and shooting method used during production, just like adding a password. Unable to copy because there is no original printing plate. Therefore, it becomes an effective means to prevent forgery. All kinds of holographic marks have been displayed on the vouchers such as banknotes, credit cards, magnetic cards, and foreign visa to prevent forgery. In China, many manufacturers have used holographic photo trademarks to prevent counterfeit trademarks and deceive customers.

It is worth mentioning that holographic photography, a major technological achievement, was invented in Scientific Research Fields unrelated to normal photography. Inventor Garber studied this topic to improve the resolution of electron microscopy. He designed this new imaging method and published it in science in 1948. However, there was no such good monochrome light as laser at the time, and there were some technical difficulties. gabo did not make any achievements, and no one paid attention to his thesis.

It was not until more than a decade later that holographic photography technology began to develop due to the emergence of an ideal laser source in 1964. Soon, holographic photography has become a new technology that is widely used and has unlimited development potential. Gabo won the Nobel Physics Award in 1971 for his first holographic theory. He himself was recognized by the world as the "father of holographic photography ".