Holographic reality

Holographic reality

Photo report from the Museum of Optics

One of the important qualities of the museum, designed to tell about the structure of the surrounding world and captivate young and adult visitors, is interactivity. This is what distinguishes the Museum of Optics, an interactive educational exhibition created on the basis of the St. Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO University).

In the museum of optics, you can touch everything, expose various illusions of vision, freeze shadows, learn a lot of interesting things about holograms and opto-clones, and get acquainted with the phenomena of interference, diffraction and polarization of light.

Photo: Ivan Gorshunov / Chrdk.

The museum is located at first glance, as is usually the case in St. Petersburg, in a building that is not very suitable for it - on Vasilyevsky Island in the former home of the famous merchants Eliseev with preserved main interiors and rich refined decoration. But the place was not chosen by chance. In the middle of the 20th century, the State Optical Institute was located here under the leadership of the founder of the scientific school of physical optics, Sergey Ivanovich Vavilov.And now this building belongs to ITMO University.

Photo: Ivan Gorshunov / Chrdk.

This is the last holographic portrait of Yuri Nikolayevich Denisyuk - one of the founders of optical holography. He worked for many years at the optical institute in the very building where the museum is located now.

English physicist Dennis Gabor invented holography in 1947, he also invented a name for a new photographic method that reproduced three-dimensional images similar to real objects, and in 1971 Gabor received the Nobel Prize in Physics for the invention and development of the holographic principle.

The first holograms were of poor quality due to imperfect lighting systems, and they quickly lost interest. But that all changed in the 60s, after the creation of the laser - thanks to this new research began in this area. And the work of Yu.N. Denisyuk was of great importance for the development of graphic holography - he developed his own hologram recording scheme, which made it possible to obtain high-quality images.

Photo: Ivan Gorshunov / Chrdk.

How it works?

The hologram captures not the image of the object itself, but the structure of the light waves reflected from it, their amplitude and phase.To get a hologram, you need to divide the beam of light into two waves: the reference, which comes from the light source, and the object, which is reflected from the removed object. And then in the area where the waves overlap each other, place the photographic plate and record the interference of the waves - the redistribution of the light intensity.

It is only necessary that the light source has the property of coherence: this is when the waves flow in time and space in a consistent and synchronous manner and we can predict both the amplitude and phase. It is for coherent radiation that a laser is needed.

But this is not all: there is no image on the plate, it is only encrypted in the system of interference fringes. The three-dimensional image of the captured object will appear if the plate is illuminated with laser light of the same frequency as the reference wave.

Photo: Ivan Gorshunov / Chrdk.

Photo: Ivan Gorshunov / Chrdk.

Yuriy Nikolayevich Denisyuk owned the idea of ​​creating reflective holograms, they are known by the name of their creator. In his method, the reference and object waves using an expanding lens and a mirror fall on a photographic plate from two different sides.The main property of such holograms is that they can be seen with the help of a white light source, a lamp or the sun, because a wavelength selector is built into the hologram and it selects the wavelength from the entire spectrum that was used during the recording. That is, the image will be restored in the color in which it was recorded. If a ruby ​​laser was used, for example, the image will be red.

Photo: Ivan Gorshunov / Chrdk.

Three holograms of one object can be recorded with one red, green, and blue lasers on a single plate and a color hologram can be obtained that will be difficult to distinguish from the object itself.

Photo: Ivan Gorshunov / Chrdk.

“Lizards”, created in 1994, is one of the first two-color reflective holograms recorded according to the classical Denisyuk scheme using a red and green laser.

Ultra-realistic full-color holograms recorded using the Denisyuk method using the most modern technologies — the latest generation of compact lasers, photographic materials with enhanced diffraction efficiency and innovative lighting systems — have even been given a special name — opto-clones.

Photo: Ivan Gorshunov / Chrdk.

Optoclone "Hedgehog".Hologram removed in 2013 from a stuffed European comb hedgehogErinaceus europaeusprovided by the Museum of Zoology at University College London.

Photo: Ivan Gorshunov / Chrdk.

Yury Nikolaevich Denisyuk is considered the founder of artistic holography. Since the 1990s, under his leadership, the museum facilities of the Hermitage, the Artillery and Russian museums have been holographic. The Optics Museum presents a collection of opto-clones with images of historical objects from the collections of the Diamond Fund of the Russian Federation and the State Fund of Precious Metals and Gems of the Russian Federation.

In the photograph is a hologram of the rattles-whistle of the boys of the royal family. It was made by order of Anna Ioannovna for the baby emperor Ioan Antonovich, and later donated by Catherine II to her grandson Alexander.

Photo: Ivan Gorshunov / Chrdk.

Digital hologram of geological layers of soil, synthesized according to a mathematical model. You can look at it from different sides, look at both the bottom and the top.

Photo: Ivan Gorshunov / Chrdk.

Photo: Ivan Gorshunov / Chrdk.

The brightest exhibit of the museum is the collection of optical glass (catalog Abbe), iridescent with all the colors of the rainbow in time with the music.The collection consists of 144 glass samples of various formulations and brands from the lightest crowns to super-heavy flints, created in the second half of the last century under the guidance of Academician Guriy Timofeevich Petrovsky.

Photo: Ivan Gorshunov / Chrdk.

The second part of the exhibition is interactive. Here you can touch and learn everything yourself. For example, immerse yourself in the prescale math epoch and see how different optical instruments and toys worked. With the help of the praxinoscope, the pictures come to life: when the cylinder rotates, an animated effect of smooth movement appears.

Photo: Ivan Gorshunov / Chrdk.

Or you can try to solve the riddles of multiple mirrors.

Photo: Ivan Gorshunov / Chrdk.

Or - to get lost in a multi-colored light corridor, as in the more often magical forest.

Photo: Ivan Gorshunov / Chrdk.

Photo: Ivan Gorshunov / Chrdk.

And you can touch the lightning, sharpened in a plasma ball, the first analogue of which was invented by Nikola Tesla. The ball is a glass sphere with an electrode inside, to which high voltage is applied, which is why it is filled with lightning of various colors.

Finally, we can draw here ... with light! One of the walls is covered with a layer of photoluminescent phosphor capable of absorbing light energy and giving it away.Using a flashlight or some other light source (your smartphone, for example), you can draw any pictures or text - however, such a picture is completely short-lived.

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    Holographic reality