Visible light. Wave ranges in descending order What is the wavelength range of visible radiation

Back in 1873, the famous British physicist D.K. Maxwell creates a general theory that describes the processes occurring in waves, which were presented in the form of vortex disturbances. Subsequently, most of his theoretical calculations were brilliantly confirmed. Currently, they have expanded, as the fields themselves began to be considered from the point of view of the processes of quantum physics. At the same time, it was suggested that even visible light is nothing more than a type of electromagnetic wave. In 2009, this was finally proven by physicists (the magnetic component of the light flux was measured). Its main difference from other varieties is the wavelength.

We are all accustomed to light, taking it for granted and rarely asking ourselves questions: what is the wavelength of light, what is it, etc. Even the Bible says that God created light on the first day of creation. This indirectly indicates the importance of this for all living things. Visible light is radiation of an electromagnetic nature that can be directly detected by the eye. However, the organ of vision does not record the entire spectrum of the wave, but only a certain interval: the lower limit is approximately 380 nm, and the upper limit is 780 nm. Why "approximately"? Because each person's visual sensitivity is different and these limits are approximate. The full spectrum is so vast that human visible light is only 0.04%.

If you mentally imagine two-dimensional coordinates, then the horizontal axis will indicate the wavelength of light in nanometers, and the vertical axis will indicate the sensitivity of the eyes. Accordingly, the wave begins at 780 and ends at 380. The peak is reached at 555 nm. In the range of 10 nm - 380 nm is located and infrared 780 nm - 1 mm. The total range of ultraviolet, visible and infrared radiation is the optical spectrum, although this does not mean that all of them can be seen with the naked eye. The wavelength of light is the most important characteristic for humans, since it is thanks to it that we can distinguish colors. It is easiest to capture color shades at the peak of the wave (555 nm), but at the edges, in the blue and red regions, it is more difficult. Therefore, it is when determining derivative shades that people sometimes have disagreements, since the sensitivity of eye receptors is different. Interestingly, 555 nm is the green spectrum that is most clearly visible. Is it a coincidence that the grass and leaves are green? By the way, you can see part of the infrared radiation if you point the camera of a mobile phone (or digital camera) at the LED of a working remote control for household appliances (TV, tuner, etc.).

The wavelength of red light corresponds to 700 nm, that is, almost from the very edge of the visible region. It follows that 10 conventional units of radiation in this range will be detected by the eye as one unit in green (555 nm). But the wavelength of yellow light, ranging from 560 nm to 590 nm, is located closer to the peak of the wave, so errors in determining shades by the human eye are less common.

In addition to various colors, in life you often come across white. In fact, there is no white in the spectrum. It is obtained by mixing three basic colors. It is believed that if you combine all seven colors of the rainbow with the same intensity, you will get pure white. At the same time, usually at least one of them predominates, which adds a certain shade. You can do it simpler and mix only three colors - red, blue and green. The existence of television screens based on ray tubes with three electrodes capable of displaying a white dot serves as direct proof of this.

The electromagnetic spectrum represents the range of all frequencies or wavelengths of electromagnetic radiation from very low energy frequencies such as radio waves to very high frequencies such as gamma rays. Light is the part of electromagnetic radiation that is visible to the human eye and is called visible light.

The sun's rays are much wider than the visible spectrum of light and are described as a full spectrum, including the range of wavelengths necessary to support life on earth: infrared, visible and ultraviolet (UV).

The human eye only responds to visible light, which lies between infrared and ultraviolet radiation and has tiny wavelengths. The wavelength of visible light is only 400 to 700 nm (nanometer-billionth of a meter).

The visible spectrum of light includes seven bands of color when the sun's rays are refracted through a prism: red, orange, yellow, green, cyan, indigo and violet.

The first person to discover that white is made up of the colors of the rainbow was Isaac Newton, who in 1666 directed a ray of sunlight through a narrow slit and then through a prism onto a wall - producing all visible colors.

Visible light application

Over the years, the lighting industry has rapidly developed electrical and artificial sources that mimic the properties of solar radiation.

In the 1960s, scientists coined the term "full spectrum lighting" to describe sources that emit a semblance of full natural light, which included the ultraviolet and visible spectrum necessary for the health of humans, animals and plants.

Artificial lighting for a home or office involves natural lighting in a continuous spectral power distribution that represents the power of the source as a function of wavelength with a uniform level of radiant energy associated with and halogen lamps.

Visible light is part of electromagnetic radiation (EM), like radio waves, infrared radiation, ultraviolet radiation, X-rays and microwaves. Generally, visible light is defined as being visually detectable to most human eyes

The spectrum is generally divided into seven bands in order of decreasing wavelength and increasing energy and frequency. The general designation represents radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), x-rays, and gamma rays.

The wavelength of visible light lies in the range of the electromagnetic spectrum between infrared (IR) and ultraviolet (UV).

What is color

Perhaps the most important characteristic of visible light is explanation of what color is. Color is an integral property and artifact of the human eye. Oddly enough, objects “do not have” color - it exists only in the head of the beholder. Our eyes contain specialized cells that form the retina, which acts as receivers tuned to wavelengths in this narrow frequency band.

Star Betelgeuse

Star Rigel

Astronomers can also tell which objects are made of what because each element absorbs light at specific wavelengths, called an absorption spectrum. Knowing the absorption spectra of elements, astronomers can use spectroscopes to determine the chemical composition of stars, gas and dust clouds and other distant objects.

Visible light is the energy of that part of the spectrum of electromagnetic radiation that we are able to perceive with our eyes, that is, see. It's that simple.

Wavelength of visible light

And now it's more difficult. The wavelengths of light in the visible region of the spectrum range from 380 to 780 nm. What does it mean? This means that these waves are very short and high-frequency, and “nm” is a nanometer. One such nanometer is equal to 10 -9 meters. And in human terms, this is one billionth of a meter. That is, a meter is ten decimeters, one hundred centimeters, a thousand millimeters or... Attention! One billion nanometers.

How we see colors within the visible light spectrum

Our eyes can not only perceive these tiny waves, but also distinguish between their lengths within the spectrum. This is how we see color - as part of the visible spectrum of light. Red light, one of the three primary colors of light, has a wavelength of approximately 650 nm. Green (second main) - approximately 510 nm. And finally, the third one is blue - 475 nm (or so). Visible light from the Sun is a kind of cocktail in which these three colors are mixed.

Why is the sky blue and the grass green?

Actually, these are two questions, not one. And so we will give two different but related answers. We see a clear sky at midday blue because short wavelengths of light are scattered more efficiently when they collide with gas molecules in the atmosphere than long wavelengths. So the blueness we see in the sky is blue light scattered and reflected many times by atmospheric molecules.

But at sunrise and sunset the sky can take on a reddish color. Yes, this happens, believe me. This is because when the Sun is close to the horizon, light has to travel a longer distance through a much denser (and dustier) layer of atmosphere to reach us than when the Sun is at its zenith. All short waves are absorbed, and we have to be content with the long ones, which are responsible for the red part of the spectrum.

But with grass everything is slightly different. It appears green because it absorbs all wavelengths except green. She doesn't like green, you see, so she reflects them back into our eyes. For the same reason, any object has its own color - we see that part of the light spectrum that it could not absorb. Black objects appear black because they absorb all wavelengths without reflecting anything, while white objects, on the contrary, reflect the entire visible spectrum of light. This also explains why black heats up much more in the sun than white.

The sky is blue, the grass is green, a dog is man's friend

And what is there beyond the visible region of the spectrum?

As the waves get shorter, the color changes from red to blue to violet and finally visible light disappears. But the light itself did not disappear - but moved into the region of the spectrum called ultraviolet. Although we no longer perceive this part of the light spectrum, it is what makes fluorescent lamps, some types of LEDs, and all sorts of cool glow-in-the-dark things glow. Next comes X-ray and gamma radiation, with which it is better not to deal at all.

At the other end of the visible light spectrum, where red ends, infrared radiation begins, which is more heat than light. It could very well fry you. Then comes microwave radiation (very dangerous for eggs), and even further - what we used to call radio waves. Their lengths are already measured in centimeters, meters and even kilometers.

And how does all this relate to lighting?

Very relevant! Since we have learned a lot about the spectrum of visible light and how we perceive it, lighting equipment manufacturers are constantly working to improve quality to meet our ever-growing needs. This is how “full spectrum” lamps appeared, the light of which is almost indistinguishable from natural light. The color of the light has become available to have real numbers for comparison and marketing gimmicks. Special lamps began to be produced for various needs: for example, lamps for growing indoor plants, giving more ultraviolet and light from the red region of the spectrum for better growth and flowering, or “heat lamps” of various types, which settled in household heaters, toasters, and grills in "Shaurma from Ashot."

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visible radiation, visible radiation application
- electromagnetic waves perceived by the human eye. The sensitivity of the human eye to electromagnetic radiation depends on the wavelength (frequency) of the radiation, with the maximum sensitivity occurring at 555 nm (540 terahertz), in the green part of the spectrum. Since sensitivity gradually decreases to zero as one moves away from the maximum point, it is impossible to indicate the exact boundaries of the spectral range of visible radiation. Usually, the region of 380-400 nm (750-790 THz) is taken as the short-wave boundary, and 760-780 nm (385-395 THz) as the long-wave boundary. Electromagnetic radiation with these wavelengths is also called visible light, or simply light (in the narrow sense of the word).

Visible radiation also falls into the "optical window", a region of the electromagnetic radiation spectrum that is practically not absorbed by the earth's atmosphere. Clean air scatters blue light much more strongly than light with longer wavelengths (towards the red side of the spectrum), so the midday sky appears blue.

Many animal species are capable of seeing radiation that is not visible to the human eye, that is, not in the visible range. For example, bees and many other insects see light in the ultraviolet range, which helps them find nectar on flowers. Plants pollinated by insects are in a more favorable position from the point of view of procreation if they are bright in the ultraviolet spectrum. Birds are also able to see ultraviolet radiation (300-400 nm), and some species even have markings on their plumage to attract a mate, visible only in ultraviolet light.

• 1. History
• 2 Characteristics of visible radiation boundaries
• 3 Visible spectrum
• 4 See also
• 5 Notes

Story

The first explanations of the spectrum of visible radiation were given by Isaac Newton in his book “Optics” and Johann Goethe in his work “The Theory of Colors,” but even before them, Roger Bacon observed the optical spectrum in a glass of water. Only four centuries after this, Newton discovered the dispersion of light in prisms.

Newton was the first to use the word spectrum (Latin spectrum - vision, appearance) in print in 1671, describing his optical experiments. He made the observation that when a ray of light hits the surface of a glass prism at an angle to the surface, some of the light is reflected and some passes through the glass, forming multi-colored stripes. The scientist suggested that light consists of a stream of particles (corpuscles) of different colors, and that particles of different colors move at different speeds in a transparent medium. According to his assumption, red light moved faster than violet, and therefore the red beam was not deflected by the prism as much as the violet one. Because of this, a visible spectrum of colors arose.

Newton divided light into seven colors: red, orange, yellow, green, blue, indigo and violet. He chose the number seven out of the belief (derived from the ancient Greek sophists) that there was a connection between colors, musical notes, objects in the solar system and days of the week. The human eye is relatively sensitive to indigo frequencies, so some people cannot distinguish it from blue or violet. Therefore, after Newton, it was often proposed that indigo should not be considered an independent color, but only a shade of violet or blue (however, it is still included in the spectrum in the Western tradition). In the Russian tradition, indigo corresponds to the color blue.

Goethe, unlike Newton, believed that the spectrum arises from the superposition of different components of light. By observing wide beams of light, he discovered that when passed through a prism, red, yellow and blue edges appear at the edges of the beam, between which the light remains white, and a spectrum appears if these edges are brought close enough to each other.

The wavelengths corresponding to the different colors of visible radiation were first presented on November 12, 1801 in the Baker Lecture by Thomas Young, they were obtained by converting the parameters of Newton's rings measured by Isaac Newton himself into wavelengths. Newton obtained these rings by passing through a lens lying on a flat surface corresponding to the desired color of a part of the light decomposed by a prism into a spectrum, repeating the experiment for each of the colors: 30-31. Jung compiled the resulting wavelengths in the form of a table, expressing them in French inches (1 inch = 27.07 mm); when converted to nanometers, their values ​​correspond well to modern ones accepted for various colors. In 1821, Joseph Fraunhofer initiated the measurement of wavelengths of spectral lines, obtaining them from the visible radiation of the Sun using a diffraction grating, measuring diffraction angles with a theodolite and converting them into wavelengths. Like Jung, he expressed them in French inches, converted into nanometers, they differ from modern ones by units: 39-41. Thus, already at the beginning of the 19th century, it became possible to measure the wavelengths of visible radiation with an accuracy of several nanometers.

In the 19th century, with the discovery of ultraviolet and infrared radiation, understanding of the visible spectrum became more precise.

In the early 19th century, Thomas Young and Hermann von Helmholtz also explored the relationship between the visible light spectrum and color vision. Their theory of color vision correctly suggested that it uses three different types of receptors to determine eye color.

Characteristics of visible radiation boundaries

Visible spectrum

When a white beam is decomposed in a prism, a spectrum is formed in which radiation of different wavelengths is refracted at different angles. The colors included in the spectrum, that is, those colors that can be obtained using light of one wavelength (more precisely, with a very narrow range of wavelengths), are called spectral colors. The main spectral colors (which have their own names), as well as the emission characteristics of these colors, are presented in the table:

see also

• Spectral and complementary colors

Notes

1. 1 2 Gagarin A. P. Light // Physical encyclopedia / D. M. Alekseev, A. M. Baldin, A. M. Bonch-Bruevich, A. S. Borovik-Romanov, B. K. Vainshtein, S. V. Vonsovsky , A. V. Gaponov-Grekhov, S. S. Gershtein, I. I. Gurevich, A. A. Gusev, M. A. Elyashevich, M. E. Zhabotinsky, D. N. Zubarev, B. B. Kadomtsev , I. S. Shapiro, D. V. Shirkov; under general ed. A. M. Prokhorova. - M.: Soviet Encyclopedia, 1994. - T. 4. - P. 460. - 704 p. - 40,000 copies.
2. GOST 8.332-78. State system for ensuring the uniformity of measurements. Light measurements. Values ​​of relative spectral luminous efficiency of monochromatic radiation for daytime vision
3. GOST 7601-78. Physical optics. Terms, letter designations and definitions of basic quantities
4. Cuthill Innes C. Ultraviolet vision in birds // Advances in the Study of Behavior / Peter J.B. Slater. - Oxford, England: Academic Press. - Vol. 29. - P. 161. - ISBN 978-0-12-004529-7.
5. Jamieson Barrie G. M. Reproductive Biology and Phylogeny of Birds. - Charlottesville VA: University of Virginia. - P. 128. - ISBN 1578083869.
6. 1 2 Newton I. Optics or treatise on reflections, refractions, bendings and colors of light / Translation by S. I. Vavilov - 2nd ed. - M.: State. Publishing house of technical and theoretical literature, 1954. - P. 131. - 367 p. - (series “Classics of Natural History”).
7. Coffey Peter. The Science of Logic: An Inquiry Into the Principles of Accurate Thought. - Longmans, 1912.
8. Hutchison, Niels Music For Measure: On the 300th Anniversary of Newton's Opticks. Color Music (2004). Retrieved August 11, 2006. Archived from the original on February 20, 2012.
9. 1 2 John Charles Drury Brand. Lines Of Light: The Sources Of. - CRC Press, 1995.
10. Thomas Young (1802). "The Bakerian Lecture." On the Theory of Light and Colors". Philosophical Transactions of the Royal Society of London for the Year 1802: 39.
11. Fraunhofer Jos. (1824). "Neue Modifikation des Lichtes durch gegenseitige Einwirkung und Beugung der Strahlen, und Gesetze derselben." Denkschriften der Königlichen Akademie der Wissenschaften zu München für die Jahre 1821 und 1822 VIII: 1-76.
12. Thomas J. Bruno, Paris D. N. Svoronos. CRC Handbook of Fundamental Spectroscopic Correlation Charts. CRC Press, 2005.

visible radiation, visible radiation application, visible radiation scale, visible radiation is

Visible radiation Information About

SPECTRAL COMPOSITION OF LIGHT

The optical region of the spectrum of electromagnetic radiation consists of three sections: invisible ultraviolet radiation (wavelength 10-400 nm), visible light radiation (wavelength 400-750 nm), perceived by the eye as light, and invisible infrared radiation (wavelength 740 nm - 1- 2 mm).

Light radiation that affects the eye and causes the sensation of color is divided into simple (monochromatic) and complex. Radiation with a specific wavelength is called monochromatic.

Simple radiations cannot be decomposed into any other colors.

Spectrum is a sequence of monochromatic radiation, each of which corresponds to a certain wavelength of electromagnetic vibration.

When white light is decomposed by a prism into a continuous spectrum, the colors in it gradually transform into one another. It is generally accepted that within certain wavelengths (nm) radiation has the following colors:

390-440 – purple

440-480 - blue

480-510 – blue

510-550 – green

550-575 - yellow-green

575-585 - yellow

585-620 – orange

630-770 – red

The human eye is most sensitive to yellow-green radiation with a wavelength of about 555 nm.

There are three radiation zones: blue-violet (wavelength 400-500 nm), green (length 500-600 nm) and red (length 600-680 nm). These spectrum zones are also the zones of predominant spectral sensitivity of the eye receivers and three layers of color photographic film. Light emitted by conventional sources, as well as light reflected from non-luminous bodies, always has a complex spectral composition, that is, it consists of the sum of various monochromatic radiations. The spectral composition of light is the most important characteristic of lighting. It directly affects light transmission when shooting on color photographic materials.

Newton took the first step towards measuring color - he systematized color according to hue, constructing color circle

In addition, Newton conducted experiments on the addition of radiation of different colors, introducing the concept main And additional colors. He experimentally established that any color can be obtained as the sum of radiations of three colors - blue, green and red - which he named primary colors. This statement formed the basis of the color equation, where color is represented by the sum of the radiations of three primary colors (K, Z, S), taken in a certain proportion:

C = kK + zZ + sS,

Where s, z, k – coefficients corresponding to the mixed intensities of blue, green and red radiation. In foreign literature, these intensity values ​​are designated accordingly R, G, B.

Color circle- a scheme that systematizes color according to hue. In the spectrum, colors smoothly transition into one another, but there are no purple, lilac, or crimson tones in the spectrum. At the same time, in the color violet we clearly feel the presence of red. Therefore, Isaac Newton arranged all the color tones according to their similarity to each other in a circle. Newton arranged the colors so that complementary colors lay opposite each other. Subsequently, the color wheel changed somewhat

(Goethe's Color Wheel, Munsell's Color Wheel, etc.), where the condition of complementarity of opposite tones is not met.

WITH The next stage in the development of half-body colorimetry of the Ostwald color gamut was the CIE (International Commission on Illumination) schedule. The need for its creation was caused by the fact that not all saturated colors can be obtained from the three primary colors. Some colors obtained by adding primary colors have less saturation than pure spectral colors. And in order for truly any color to be obtained in an additive way, the original primary colors must have a saturation of more than 100%, that is, more saturated than spectral colors. In reality, such colors cannot exist, but such colors were introduced as mathematical abstractions. They were called X, Y, Z - red, green and blue, respectively.

In fact, the MKO chart is a modified color wheel on which colors of 100% saturation are placed. Towards the center, the saturation drops to 0. The CIE graph is often used to indicate the color of the radiation from various light sources.

In addition to the MKO schedule, other colorimetric systems are currently used, for example Lab. Magnitude L determines the brightness of the color, A– closeness of color to red or green color tone, b– color close to blue or yellow.

It should be noted that none of the existing colorimetric systems fully reflect all the phenomena of color vision. Therefore, colorimetric systems continue to develop and improve.