Basic Principles and Applications of Holography

Ever since the movie of the Star Wars, we remember the amazing special effects with the sudden appearance of spaceships and various fairy-tale creatures. Over time, film directors increasingly resorted to new special effects and spoiled them to us - their viewers, and today we no longer think without them a single film.

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But we can state with confidence that the future of the films described in the events has already come. And not in any of the distant worlds of the Jedi conquered by the knights, but in our reality. Soon the first invented hologram will celebrate its 70th anniversary. Let us check about what this technology is like and how it works.

Basic concepts : Holography is an abstraction

Holography, a word that from Greek means a complete representation, is a special method of photographing, the principle of which is the laser scanning of the object, with the aim to restore it as clearly as possible in a 3D view.

When recording a holographic projection, at a certain point in space, two waves are formed, which are formed from the division of one and the same laser beam. The wave, called the reference wave, comes from the source, and the wave, called the object wave, is reflected from the model from which the scan is conducted. At the same place, a photosensitive plane is established, which captures the structure of the bands, which characterizes the interference of the waves.

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Approximately the same is obtained when using simple photographic film. But in the case with her, the resulting picture appears on paper, and with the hologram one has to act differently. In order to obtain an accurate three-dimensional copy of the scanned object, it is necessary simply to act on the photographic plate with a support type wave. After that, the viewer will see the light silhouette of the scanned object in space.

History

The first holographic projection was reproduced in 1947. This was done by Dennis Gabor in his series of studies on increasing the resolution of an electron microscope. He also named the word hologram, as he wanted to describe the complete light match of the modeled object, the original. The hologram obtained in the course of the experiment was very poor. The equipment, in which lamps with a very narrow light spectrum was used. But, in general, the experiment was undoubtedly a success, it was for him that the scientist received the Nobel Prize in 1971.

When two types of lasers were invented in 1960, holography began to develop intensively. Soon a scientist created an algorithm for recording reflected 2D holograms on plates, whereby it was possible to record in the highest quality.

Development of the industry : Scientists have come up with a 3D hologram to which you can touch

Scientist Lloyd Kross in 1977 became the author of the famous multiplex program, or known in our time 3D pictures. Its main difference from other holograms is that the object consists of a set of certain angles that can only be seen from the right angle. Such an approach deprives the parallax object vertically (that is, we can not see the hologram from below or from above), but now the size of the projected figure itself is not limited by the wavelength of the laser. Previously, this imposed a restriction on the projection of a maximum of several meters.

Thanks to such achievements, one can now safely leave everyday reality and plunge into the world of fairy tales, creating holograms of new characters and objects. In order to get any object, you just need to create it on your computer and save it as a file. Multiplex holography surpasses all other technologies in its capabilities, but for the time being it loses a little for the realism of the picture.

Information carriers : Currency with a hologram

In order to store information about the scanned hologram, plates of silver bromide are used. Such material makes it possible to obtain a very high-quality picture, a resolution of 500 lines per 1 cm. Also, bases made of bichromated gelatin are often used, which allows displaying even better models that almost completely repeat the original.

There is also an option in which the recording is conducted using alkali-halide crystals. Recently, recording of holograms using photopolymer materials has become increasingly popular. A mixture of photo-polymer powders is sprayed onto a glass plate. Recording devices built on this basis are cheaper, but the image quality suffers.

Holography is at home : 3D Hologram with your own hands

Thanks to the rapid development of technology, today any of us is able to record a fairly good hologram right at home, no expensive equipment is needed. All you need to do is install a tripod, on which the laser, a photographic plate and what we will scan will stand.

In order to create an object record, even a simple laser pointer will do. When we adjust the focus of the laser pointer, it starts behaving like a simple flashlight, which makes it possible to illuminate the plate and the part that is behind it. The laser pointer button must be locked in the on position, for which you can use a clothes clip or other clamp.

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But such dances are absolutely not necessary, now there is a smartphone with the ability to display holograms "Takee 1" which appeared in 2014. Using the technology we can monitor the position of the user's eyes through the sensor system and the front camera, and reproduce holographic objects for viewing which do not need any glasses.

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