To benefit from the world around you and avoid its dangers, you need to know at least something about this world. Therefore, even primitive sessile animals, motionless and identical on all sides, have sensitive cells or entire organs. They collect data about environment, and based on this data, animals perform the most appropriate actions.

Organisms learned to distinguish light from darkness a long time ago. For many animals, including humans, vision is the main source of information about the world around them. How does this process work?

To a first approximation, the eye of vertebrates and cephalopods (one of the most advanced creatures in the “parallel” branch of evolution with us) is designed like a camera. There is a lens (lens), there is an opening through which light enters the lens (pupil). Finally, there is a photographic plate (or matrix in modern cameras) - the retina. Sensitive cells (photoreceptors) in its composition are activated when light of a certain wavelength falls. Each type of retinal cell has a different range of optimal wavelengths.

The eye is a very complex structure, and for full vision All its elements need to work well. Photo: Alexilus/shutterstock

There are two large groups photoreceptors - rods and cones. The sticks are easy to activate and do not require strong lighting. But they also provide poor image clarity. This is easy to verify if you go into the forest at night without a flashlight: something is visible, but only in general outline. It’s also completely unclear what color the surrounding objects are. To recognize colors and their shades, cones are needed. These receptors are more difficult to activate and only work in good light.

Different types of cones are responsible for recognizing different colors by responding to light within a narrow range of wavelengths. Therefore, it is pointless to have any one type of cones: “rod twilight” will simply take on one shade or another. This is impractical and dangerous: with such vision, for example, it will be impossible to distinguish ripe fruits from unripe ones, and unripe fruits can be poisonous. So sighted animals have acquired at least two types of cones.

“Human beings have three types of cones and one type of rods,” explains Pavel Maksimov, Candidate of Biological Sciences, senior researcher at the Laboratory of Sensory Information Processing at the Institute of Applied Physics of the Russian Academy of Sciences. “Even if we only had one type of cone and rod, we might be able to distinguish colors, but only in dim light, in which both rods and cones function.” In addition to the receptors themselves, appropriate signal processing is needed. For example, if signals from receptors different types just fold it, no information about the color will remain. The visual system must be able to compare signals from different receptors to determine whether the signal from short-wavelength (“blue”) cones is stronger or weaker than that from long-wavelength (“red”) cones.”

Rods (left) and cones are very small: their length does not exceed 0.06 millimeters. Photo: Designua/shutterstock

Cones and evolution

If an animal relies primarily on vision, it would be good for it to be able to distinguish between many different shades, and this requires more than two types of cones.

Male and female

Despite the fact that the topic of gender equality has become very fashionable, men and women differ markedly in their perception of colors. For example, color vision disorders are more common in men. And the point here is not only that the genes, mutations in which cause the loss of some type of cones, are located on the X chromosome, which is the only one in the stronger sex.

The perception of colors, like sounds, depends on the level of testosterone in the body. The most feminine men have many times more receptors for this hormone than the strongest women. And in particular, there are a lot of them on the neurons of the brain, especially in the occipital lobe of the cortex - where visual signals come. As a result, men form more connections between neurons visual cortex And visual areas thalamus, from where signals travel to the occipital lobes. In addition, for reasons that are not entirely clear, men are better at tracking rapidly changing small details, while women are good at distinguishing shades of similar colors. Perhaps these features developed in men due to the fact that in ancient society they hunted, and the women collected plants and mushrooms.

Hunting required ancient men to be able to discern fast-moving details. Photo: Dieter Hawlan/shutterstock

A 2001 study showed that among women, individuals with four (rather than three) types of pigments—the molecules that underlie the work of cones—are much more common (rods also have pigments, but they are different). This is one of the reasons why a woman, on average, can name more different shades than a man. Finally, the cones of men are tuned to light of slightly longer wavelengths than the visual receptors of women: apparently, the stronger sex, all other things being equal, sees the world more red.

Color therapy

This section alternative medicine teaches that various diseases, even cancer, can be treated by having the patient look at a certain color depending on what hurts. But the recommendations for treatment in many clinics are different, there is no general standard. And this is the first signal that color therapy is an untested method. Of course, the colors that a person sees regularly can influence his emotions and perception of the world. But this is true for any other elements of the environment. And changing your mood is not a cure, although in most cases it is a useful thing.

Some psychologists actively use color therapy in practice, but serious scientific justification this approach does not. Photo: Olimpik/shutterstock

Although visual system- one of the most studied sensory systems, evaluate how the perception of colors has changed during evolution and how it differs among animals different types and within species, it is not easy. We also have to take into account the number various types visual pigments, and the structure of the retina and visual areas of the brain, and gender, and even native language- if we are talking about people. Verbal descriptions of the same object under the same lighting from different authors may differ noticeably. And if you test color vision, without resorting to words (for example, identifying a “special square” from dozens of identical ones), it turns out that two people can distinguish two colors, but we will never know what exactly they see at the same time. And of course, the neural signals that arise in the brain in response to any color are completely individual.

Svetlana Yastrebova

Ultraviolet is part of the spectrum electromagnetic radiation, which is beyond the boundaries of our perception. Simply put - no visible radiation. But not really. The light we see is limited to wavelengths between 380 nm and 780 nm (nanometers). The wavelengths of ultraviolet or ultraviolet radiation range from 10 nm to 400 nm. It turns out that we can still see ultraviolet light - but only a small part of it, located in a small interval between 380 and 400 nm.

All. Dry facts are over, interesting facts begin. The fact is that this barely visible radiation actually plays a huge role not only in the biosphere (we will definitely talk about this separately), but also in lighting. Simply put, ultraviolet helps us see.

Ultraviolet and lighting

Ultraviolet has found its main use in lamps. Electrical discharges cause the gas inside a fluorescent lamp (or compact fluorescent lamp) to glow in the ultraviolet range. In order to obtain visible light, a special coating of material is applied to the walls of the lamp that will fluoresce - that is, glow in the visible range - under the influence of ultraviolet radiation. This material is called a phosphor, and manufacturers are constantly working to improve its composition to improve the quality of visible light produced. That is why today we have a good selection of fluorescent lamps, which not only outperform conventional incandescent lamps in energy efficiency, but also produce light of an almost full spectrum that is quite pleasant to the eye.

What other uses can ultraviolet light have?

Exists a whole series materials that can glow in ultraviolet light. This ability is called fluorescence and many organic substances have it. In addition to it, there is also the so-called phosphorescence - its difference is that the substance emits light with a lower intensity, but continues to glow for some time (often quite long - up to several hours) after the cessation of exposure to ultraviolet radiation. These properties are actively used in the manufacture of various “glow in the dark” objects and jewelry.

Page 1

Visible and ultraviolet light is transmitted various samples mirror and optical glass up to wavelengths of 3200 - 3500 A, glass does not transmit shorter waves. Fused quartz transmits waves with a length of 2000 A, but its serious disadvantage is its low mechanical strength.  

The absorption of visible and ultraviolet light corresponds to energy quanta from 30 to 300 kcal/mol.  

For visible and ultraviolet light good results give transparent metallic layers of platinum, rhodium, antimony (4000 to 2000 A), deposited by evaporation on quartz plates.  

Radio waves, infrared, visible and ultraviolet light, x-rays and gamma rays are electromagnetic waves of different wavelengths. Planck proposed that the energy of electromagnetic radiation is quantized. The energy of a quantum of electromagnetic radiation is proportional to its frequency, E hv, where h is Planck’s constant, equal to 6 6262 - 10 34 J - s. The knocking out of electrons from a metal surface by light is called the photoelectric effect. A quantum of light is called a photon. The photon energy is equal to hv, where v is the frequency of the electromagnetic wave. The dependence of the absorption of light by an atom or molecule on wavelength, frequency, or wave number is the absorption spectrum. The corresponding emission of light by an atom or molecule is the emission spectrum. The emission spectrum of atomic hydrogen consists of several series of lines.  

Visible and ultraviolet light absorption studies have long been used to obtain information about equilibrium in solution. However, since the optical density of the solution depends on specific factor intensity (extinction coefficient), as well as the concentration of each absorbing species, interpretation of measurements is often complicated if multiple complexes are present. The method of continuous variation (Job's method) and other unreliable methods that are still often used to calculate stability constants from spectrophotometric data are critically discussed in Sect. This chapter deals mainly with more precise methods processing absorption measurements in the visible and ultraviolet parts of the spectrum. This chapter also examines the use of the later developed fields of spectroscopy and the closely related polarimetric and magneto-optical techniques to study equilibrium in solution.  

Telomerization under the influence of visible and ultraviolet light, radioactive radiation and radioactive particles, proceeding through a radical mechanism, has been described.  

The window should be protected from visible and ultraviolet light.  

Organoaluminum compounds generally do not absorb visible or ultraviolet light. There is no doubt, however, that absorption can be caused by the introduction of certain substituents, for example aryl groups. As mentioned above, donor-acceptor complexes with aliphatic and cyclic aldimines (for example, with benzalaniline, pyridine and benzopyridines) are colored to a greater or lesser extent. This stain can be used for various quantitative determinations.  

As has been established, irradiation of polymers pre-irradiated with 1U radiation with visible and ultraviolet light will make it possible to obtain additional information about the nature and properties of paramagnetic particles. It turned out that paramagnetic formations in polymers absorb light in the visible and UV regions.  

Aromatic polycarbonates are very resistant to visible and ultraviolet light, even in the presence of air.  

Qualitative and quantitative spectroscopy methods in visible and ultraviolet light are widely used to determine some vitamins, hormones and other biologically active substances.  

Based on the study of absorption spectra in infrared, visible and ultraviolet light, as well as the study of Raman scattering, an organic molecule, as mentioned above, should not be represented as a static system. Atoms in molecules are not stationary, but undergo vibrations that approach harmonics. The degree of deviation of atomic vibrations from vibrations of the harmonic type - the so-called antiharmonicity - determines the ability of molecules to disintegrate into their component parts.  

In Fig. Figure 16 shows the SF-4 spectrophotometer for visible and ultraviolet light.  

Kronig showed that in the region of visible and ultraviolet light these ideas lead to consequences regarding dispersion and absorption that qualitatively coincide with the results of experiment.  

February 15, 2012 at 01:30

Patient with artificial lens began to see ultraviolet light. How?

• Biotechnology

Today a post appeared on slashdot by a certain author, who, after implanting an artificial lens, began to see in the ultraviolet range, more precisely, approximately 365 nm - this is at the average upper limit for ordinary person at 400nm. I was interested in this topic, and I decided to find out what was happening there, and whether there was a ghost looming here Chris Carter.

So, a short excursion into ophthalmic surgery. During the Second World War, a certain English ophthalmologist, who operated on pilots shot down in air combat, found that the plexiglass of an airplane canopy that got into the eye was not rejected by the tissues. Moreover, it traumatically changes the shape of the cornea - and since it is responsible for ~70% of refraction in eyeball(the rest falls on the lens), then a change in its shape leads to significant changes in the refraction of the eye. Naturally, the idea immediately came to treat myopia by reducing the optical power of the cornea by cutting it and reducing its curvature. By today's standards, this is reminiscent of trepanning a skull with a stone knife (and without precise measurements and calculations for accuracy, this is about the same) - but it was better than nothing.

Then they realized that if the plexiglass does not come off, then it can be placed there intentionally... after having been ground to the shape of a lens. For what? Because by the age of 45-50, the natural lens a) becomes hard and loses the ability to accommodate (which leads to the inability to refocus vision), and b) some time later it becomes cloudy, as a result of which vision slowly drops to almost zero. So, it can be replaced.

At first, instead of the natural lens, hard lenses were placed, which, quite naturally, caused mass discomfort, damaged inner fabrics, etc. Now in general terms the procedure looks like this. I will use English terminology in transliteration.

1. The patient lies under a microscope. The eyelids are fixed in an open position, in optic nerve Anesthesia is given.

2. A small incision, about 2mm in length, is made on the side of the eye, approximately at the border of the iris, using a super-sharp scalpel.

3. The lens is located inside the capsular bag. An instrument with which this bag is cut penetrates into the eye through this incision.

4. The phacoemulsifier probe penetrates into the bag through these two incisions. This device a) crushes the hardened natural lens with ultrasound, and b) simultaneously sucks out the crushed pieces. It is important here not to tear the capsular bag - this is fraught with a lot of problems and complications, and also not to hurt the iris. It has the consistency of a blotter, and its damage leads to vision problems - for example, the patient may begin to see halos around point light sources.

5. After phacoemulsification, viscoelastic gel is pumped into the capsular bag through a microsyringe so that this bag does not deflate, because the lens is no longer there.

6. Fanfares and drums - we implant the lens. The lens itself is made of materials like silicone and can be folded. That is why an incision of only 2 mm is sufficient, even though the lens is noticeably larger. It comes in a cartridge that is inserted into a syringe, which is carefully inserted through an incision into the eye, then into the capsular bag, and is simply squeezed out there. There she turns around and takes on her original appearance, with the surgeon helping her. In half a minute it is ready.

7. If the lens is aspherical, then it can also help with astigmatism. In this case, it must be turned to the desired angle. Subsequently, the tissues of the eye will grow together through certain protrusions on the outer, optically non-functional part of the lens, and fix it from rotation. There are often cases when the lens still rotates uncontrollably - this is corrected by repeated surgery.

8. The eye is moistened and covered with a bandage. The incision will heal on its own. The patient goes home.

Such an operation can cost from 3 to 20 thousand dollars, depending on various reasons. The recovery period before removing the bandage takes a day or two. Yes, it’s sometimes hard to believe, but in our practice there have been cases when 70-year-old grandmothers received 80% vision the day after the operation... I’ve never seen it myself, but, as they say, people start crying with happiness.

And now on topic. Why did that patient start seeing UV? Because the lens usually absorbs UV rays, preventing them from reaching the retina. Older lenses were made from materials that often allowed UV to pass through easily, and patients began to see in the UV range. But it didn’t last long, because... the retina is damaged by ultraviolet radiation. Therefore, new lenses contain additives that filter out UV rays. That patient was fitted with a Crystalens lens, which apparently contains a smaller amount of such additives (or does not contain them at all), hence the result. The chief once operated on a patient who various reasons One eye was wearing one lens and the other eye was wearing a different lens, and they had different UV absorption coefficients. The patient was then quite surprised that he could see UV with one eye, but not with the other. This did not bother him, and everyone was quite pleased.

P.S. The material was written after consultation with my boss, an ophthalmic surgeon with more than 10 years of experience. If there are errors in the text, I fully accept all responsibility for the crooked translation, and please point them out.

P.P.S. What do I do as a programmer to write such texts? Good question. Our company advises others regarding calculations the right lenses for each specific eye... and I am engaged in the implementation of calculation software. Incredible interesting topic, and very rewarding, especially when they write to us about grandparents who received eagle vision.

Good health to you, take care of your eyes :)

The concept of ultraviolet rays was first encountered by an Indian philosopher of the 13th century in his work. The atmosphere of the area he described Bhootakasha contained violet rays that cannot be seen with the naked eye.

Soon after it was discovered infrared radiation, German physicist Johann Wilhelm Ritter began searching for radiation at the opposite end of the spectrum, with wavelengths shorter than violet. In 1801, he discovered that silver chloride, which decomposes when exposed to light, decomposes more quickly when exposed to invisible radiation outside the violet region spectrum Silver chloride white within a few minutes it darkens in the light. Different areas spectrum have different effects on the rate of darkening. This happens most quickly in front of the violet region of the spectrum. Many scientists, including Ritter, then agreed that light consists of three distinct components: an oxidative or thermal (infrared) component, an illuminant (visible light) component, and a reducing (ultraviolet) component. At that time ultraviolet radiation also called actinic radiation. Ideas about the unity of three different parts of the spectrum were first voiced only in 1842 in the works of Alexander Becquerel, Macedonio Melloni and others.

Subtypes

Degradation of polymers and dyes

Scope of application

Black light

Chemical analysis

UV spectrometry

UV spectrophotometry is based on irradiating a substance with monochromatic UV radiation, the wavelength of which changes over time. Substance in varying degrees absorbs UV radiation from different lengths waves A graph, the ordinate axis of which shows the amount of transmitted or reflected radiation, and the abscissa axis the wavelength, forms a spectrum. The spectra are unique for each substance, which is the basis for the identification of individual substances in a mixture, as well as their quantitative measurement.

Mineral Analysis

Many minerals contain substances that, when illuminated by ultraviolet light, begin to emit visible light. Each impurity glows in its own way, which makes it possible to determine the composition of a given mineral by the nature of the glow. A. A. Malakhov in his book “Interesting about Geology” (Moscow, “Young Guard”, 1969. 240 pp) talks about it this way: “An unusual glow of minerals is caused by cathode, ultraviolet, and x-rays. In the world of dead stone, those minerals that light up and shine most brightly are those that, once in the zone of ultraviolet light, tell about the smallest impurities of uranium or manganese included in the rock. Many other minerals that do not contain any impurities also flash a strange “unearthly” color. I spent the whole day in the laboratory, where I observed the luminescent glow of minerals. Ordinary colorless calcite became miraculously colored under the influence of various light sources. Cathode rays made the crystal ruby ​​red; in ultraviolet light it lit up with crimson-red tones. The two minerals, fluorite and zircon, were indistinguishable in X-rays. Both were green. But as soon as the cathode light was connected, the fluorite became purple, and the zircon turned lemon yellow.” (p. 11).

Qualitative chromatographic analysis

Chromatograms obtained by TLC are often viewed under ultraviolet light, which makes it possible to identify a number of organic matter by glow color and retention index.

Catching insects

Ultraviolet radiation is often used when catching insects with light (often in combination with lamps emitting in the visible part of the spectrum). This is due to the fact that in most insects the visible range is shifted, compared to human vision, to the short-wave part of the spectrum: insects do not see what humans perceive as red, but see soft ultraviolet light.

Artificial tanning and “Mountain sun”

At certain dosages, artificial tanning can improve the condition and appearance human skin, promotes the formation of vitamin D. Fotaria are currently popular, which in everyday life are often called solariums.

Ultraviolet in restoration

One of the main tools of experts is ultraviolet, x-ray and infrared radiation. Ultraviolet rays make it possible to determine the aging of a varnish film - fresher varnish looks darker in ultraviolet light. In the light of a large laboratory ultraviolet lamp, restored areas and hand-written signatures appear as darker spots. X-rays are retained by the heaviest elements. IN human body This bone tissue, and in the picture there is whitewash. The basis of white in most cases is lead; in the 19th century, zinc began to be used, and in the 20th century, titanium. All these are heavy metals. Ultimately, on film we get an image of the whitewash underpainting. Underpainting is the individual “handwriting” of the artist, an element of his own unique technique. To analyze the underpainting, a database of X-ray photographs of paintings by great masters is used. These photographs are also used to determine the authenticity of a painting.

Notes

1. ISO 21348 Process for Determining Solar Irradiances. Archived from the original on June 23, 2012.
2. Bobukh, Evgeniy On animal vision. Archived from the original on November 7, 2012. Retrieved November 6, 2012.
3. Soviet encyclopedia
4. V. K. Popov // UFN. - 1985. - T. 147. - P. 587-604.
5. A. K. Shuaibov, V. S. Shevera Ultraviolet nitrogen laser at 337.1 nm in frequent repetition mode // Ukrainian Physical Journal. - 1977. - T. 22. - No. 1. - P. 157-158.
6. A. G. Molchanov