Topics in optics. Optics Definitions

Ancient scientists who lived in the 5th century BC suggested that everything in nature and this world is conditional, and only atoms and emptiness can be called reality. Today, important historical documents have been preserved confirming the concept of the structure of light as a constant flow of particles that have certain physical properties. However, the term “optics” itself will appear much later. The seeds of such philosophers as Democritus and Euclid, sown while comprehending the structure of all processes occurring on earth, have sprouted. Only at the beginning of the 19th century was classical optics able to acquire its characteristic features, recognizable by modern scientists, and appeared as a full-fledged science.

Definition 1

Optics is a huge branch of physics that studies and considers phenomena directly related to the propagation of powerful electromagnetic waves visible spectrum, as well as ranges close to it.

The main classification of this section corresponds to historical development doctrines about the specifics of the structure of light:

• geometric – 3rd century BC (Euclid);
• physical – 17th century (Huygens);
• quantum – 20th century (Planck).

Optics fully characterizes the properties of light refraction and explains phenomena directly related to this issue. The methods and principles of optical systems are used in many applied disciplines, including physics, electrical engineering, and medicine (especially ophthalmology). In these, as well as in interdisciplinary fields, the achievements of applied optics are extremely popular, which, along with precision mechanics, create a solid foundation for the optical-mechanical industry.

Nature of light

Optics is considered one of the first and main branches of physics, where the limitations of ancient ideas about nature were presented.

As a result, scientists were able to establish the duality of natural phenomena and light:

• the corpuscular hypothesis of light, originating from Newton, studies this process as a flow elementary particles-photons, where absolutely any radiation is carried out discretely, and the minimum portion of the power of a given energy has a frequency and magnitude corresponding to the intensity of the emitted light;
• The wave theory of light, originating from Huygens, implies the concept of light as a set of parallel monochromatic electromagnetic waves observed in optical phenomena and represented as a result of the actions of these waves.

With such properties of light, the absence of transition of the force and energy of radiation into other types of energy is considered a completely normal process, since electromagnetic waves do not interact with each other in the spatial environment of interference phenomena, because light effects continue to propagate without changing their specificity.

The wave and corpuscular hypotheses of electric and magnetic radiation have found their application in scientific works Maxwell in the form of equations.

This new concept of light as a constantly moving wave makes it possible to explain processes associated with diffraction and interference, including the structure of the light field.

Characteristics of light

The length of the light wave $\lambda$ directly depends on the overall speed of propagation of this phenomenon in the spatial medium $v$ and is related to the frequency $\nu$ by the following relation:

$\lambda = \frac(v)(\nu)=\frac (c)(n\nu)$

where $n$ is the refractive parameter of the medium. In general, this indicator is a basic function of the electromagnetic wavelength: $n=n(\lambda)$.

The dependence of the refractive index on wavelength manifests itself in the form of the phenomenon of systematic dispersion of light. A universal and still little-studied concept in physics is the speed of light $c$. Its special significance in absolute emptiness represents not only the maximum speed of dissemination of powerful electromagnetic frequencies, but also the maximum intensity of the dissemination of information or other physical effects on material objects. As the movement of the light flow increases in different areas, the initial speed of light $v$ often decreases: $v = \frac (c)(n)$.

The main features of the light are:

• spectral and complex composition determined by the scale of light wavelengths;
• polarization, which is determined by the general change in the spatial environment of the electric vector through wave propagation;
• the direction of dissemination of a light beam, which must coincide with the wave front in the absence of birefringence.

Quantum and physiological optics

The idea of ​​a detailed description electromagnetic field with the help of quanta appeared at the beginning of the 20th century, and was voiced by Max Planck. Scientists have suggested that the constant emission of light is carried out through certain particles - quanta. After 30 years, it was proven that light is not only emitted partially and in parallel, but also absorbed.

This provided the opportunity for Albert Einstein to determine the discrete structure of light. Nowadays, scientists call light quanta photons, and the flow itself is considered as an integral group of elements. Thus, in quantum optics, light is considered both as a stream of particles and as waves at the same time, since processes such as interference and diffraction cannot be explained by a single stream of photons.

In the middle of the 20th century research activities Brown–Twiss, made it possible to more accurately determine the area of ​​use of quantum optics. The scientist’s work has proven that a certain number of light sources that emit photons to two photodetectors and give a constant sound signal about the registration of elements can make the devices function simultaneously.

Implementation practical use non-classical light has led researchers to incredible results. In this regard, quantum optics is a unique modern field with enormous opportunities for research and application.

Note 1

Modern optics has long included many areas of the scientific world and development that are in demand and popularity.

These areas of optical science are directly related to the electromagnetic or quantum properties of light, including other areas.

Definition 2

Physiological optics is a new interdisciplinary science that studies the visual perception of light and combines information from biochemistry, biophysics and psychology.

Taking into account all the laws of optics, this section of science is based on these sciences and has a special practical direction. Elements of the visual apparatus are studied, and special attention is paid to unique phenomena, such as optical illusion and hallucinations. The results of work in this area are used in physiology, medicine, optical engineering and the film industry.

Today, the word optics is more often used as the name of a store. Naturally, at such specialized points it is possible to purchase a variety of technical optics devices - lenses, glasses, vision-protecting mechanisms. At this stage, stores have modern equipment that allows them to accurately determine visual acuity on the spot, as well as identify existing problems and ways to eliminate them.

- History of the development of optics.

- Basic provisions of Newton's corpuscular theory.

- Basic provisions of Huygens' wave theory.

- Views on the nature of light in XIX – XX centuries.

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- Basic principles of optics.

- Wave properties of light and geometric optics.

- The eye as an optical system.

- Spectroscope.

- Optical measuring device.

- Conclusion.

- List of used literature.

History of the development of optics.

Optics is the study of the nature of light, light phenomena and the interaction of light with matter. And almost its entire history is the story of a search for the answer: what is light?

One of the first theories of light, the theory of visual rays, was put forward by the Greek philosopher Plato around 400 BC. e. This theory assumed that rays emanate from the eye, which, when meeting objects, illuminate them and create the appearance of the surrounding world. Plato's views were supported by many ancient scientists and, in particular, Euclid (3rd century BC), based on the theory of visual rays, founded the doctrine of the straightness of light propagation and established the law of reflection.

During those same years, the following facts were discovered:

– straightness of light propagation;

– the phenomenon of light reflection and the law of reflection;

– the phenomenon of light refraction;

– focusing effect of a concave mirror.

The ancient Greeks laid the foundation for the branch of optics, which later became known as geometric.

Most interesting work on optics, which has come down to us from the Middle Ages, is the work of the Arab scientist Algazen. He studied the reflection of light from mirrors, the phenomenon of refraction and transmission of light in lenses. Algazen was the first to suggest that light has a finite speed of propagation. This hypothesis was a major

step in understanding the nature of light.

During the Renaissance, many different discoveries and inventions were made; The experimental method began to be established as the basis for studying and understanding the surrounding world.

Based on numerous experimental facts, in the middle of the 17th century, two hypotheses about the nature of light phenomena arose:

– corpuscular, which assumed that light is a stream of particles ejected at high speed by luminous bodies;

– wave, which argued that light is represented by longitudinal oscillatory movements a special luminiferous medium - ether - excited by vibrations of particles of a luminous body.

The entire further development of the doctrine of light up to the present day is the history of the development and struggle of these hypotheses, the authors of which were I. Newton and H. Huygens.

The main provisions of Newton's corpuscular theory:

1) Light consists of small particles of matter emitted in all directions in straight lines, or rays, by a luminous body, such as a burning candle. If these rays, consisting of corpuscles, fall into our eye, then we see their source (Fig. 1).

2) Light corpuscles have different sizes. The largest particles, when entering the eye, give a sensation of red color, the smallest – violet.

3) White- a mixture of all colors: red, orange, yellow, green, blue, indigo, violet.

4) Reflection of light from the surface occurs due to the reflection of corpuscles from the wall according to the law of absolute elastic impact (Fig. 2).

5) The phenomenon of light refraction is explained by the fact that corpuscles are attracted by particles of the medium. The denser the medium, the smaller the angle of refraction is the angle of incidence.

6) The phenomenon of light dispersion, discovered by Newton in 1666, he explained as follows. Every color is already present in white light. All colors are transmitted through interplanetary space and the atmosphere together and give the effect of white light. White light - a mixture of various corpuscles - undergoes refraction after passing through a prism. From the point of view of mechanical theory, refraction is due to forces from glass particles acting on light corpuscles. These forces are different for different corpuscles. They are largest for violet and smallest for red. The path of the corpuscles in the prism will be refracted differently for each color, so the white complex ray will split into colored component rays.

7) Newton outlined ways to explain double refraction, hypothesizing that light rays have “different sides” - special property, causing their different refrangibility when passing through a birefringent body.

Newton's corpuscular theory satisfactorily explained many optical phenomena known at that time. Its author used scientific world enormous authority, and soon Newton's theory gained many supporters in all countries.

Basic principles of Huygens' wave theory of light.

1) Light is the propagation of elastic periodic impulses in the ether. These impulses are longitudinal and similar to sound impulses in air.

2) Ether is a hypothetical medium that fills celestial space and the gaps between particles of bodies. She is weightless, does not obey the law universal gravity, has great elasticity.

3) The principle of propagation of ether vibrations is such that each of its points, to which excitation reaches, is the center of secondary waves. These waves are weak, and the effect is observed only where their envelope passes

surface – wave front (Huygens principle) (Fig. 3).

Light waves coming directly from the source cause the sensation of vision.

A very important point in Huygens' theory was the assumption that the speed of light propagation is finite. Using his principle, the scientist was able to explain many phenomena of geometric optics:

– the phenomenon of light reflection and its laws;

– the phenomenon of light refraction and its laws;

– the phenomenon of total internal reflection;

– the phenomenon of double refraction;

– the principle of independence of light rays.

Huygens' theory gave the following expression for the refractive index of a medium:

From the formula it is clear that the speed of light should depend inversely on the absolute value of the medium. This conclusion was the opposite of the conclusion arising from Newton's theory. The low level of experimental technology in the 17th century made it impossible to establish which theory was correct.

Many doubted Huygens' wave theory, but among the few supporters of wave views on the nature of light were M. Lomonosov and L. Euler. From these studies scientists theory Huygens' theory began to take shape as a theory of waves, and not just aperiodic oscillations propagating in the ether.

Views on the nature of light in XIX - XX centuries.

In 1801, T. Jung performed an experiment that amazed world scientists(Fig.4)

S – light source;

E – screen;

B and C are very narrow slits, spaced 1-2 mm from each other.

According to Newton's theory, two light stripes should appear on the screen; in fact, several light and dark stripes appeared, and a light line P appeared directly opposite the gap between slits B and C. Experience has shown that light is a wave phenomenon. Jung developed Huygens' theory with ideas about particle vibrations and the frequency of vibrations. He formulated the principle of interference, based on which he explained the phenomenon of diffraction, interference and color of thin plates.

The French physicist Fresnel combined Huygens' principle of wave motions and Young's principle of interference. On this basis, he developed a rigorous mathematical theory of diffraction. Fresnel was able to explain all optical phenomena known at that time.

Basic principles of Fresnel wave theory.

– Light – propagation of vibrations in the ether at a speed where is the modulus of elasticity of the ether, r– ether density;

– Light waves are transverse;

– Light ether has properties elastic-rigid body, absolutely incompressible.

When moving from one medium to another, the elasticity of the ether does not change, but its density changes. Relative refractive index of a substance.

Transverse vibrations can occur simultaneously in all directions perpendicular to the direction of wave propagation.

Fresnel's work has won recognition from scientists. Soon appeared a whole series experimental and theoretical works confirming the wave nature of light.

IN mid-19th century, facts began to be discovered indicating a connection between optical and electrical phenomena. In 1846, M. Faraday observed rotations of the planes of polarization of light in bodies placed in a magnetic field. Faraday introduced the idea of ​​electricity and magnetic fields, as about peculiar overlays on the air. A new “electromagnetic ether” has appeared. The English physicist Maxwell was the first to draw attention to these views. He developed these ideas and built a theory of the electromagnetic field.

The electromagnetic theory of light did not cross out the mechanical theory of Huygens-Young-Fresnel, but put it on a new level. In 1900, the German physicist Planck put forward a hypothesis about the quantum nature of radiation. Its essence was as follows:

– light emission is discrete in nature;

– absorption also occurs in discrete portions, quanta.

The energy of each quantum is represented by the formula E = h n, Where h is Planck’s constant, and n is the frequency of light.

Five years after Planck, the work of the German physicist Einstein on the photoelectric effect was published. Einstein believed:

– light that has not yet interacted with matter has a granular structure;

– structural element discrete light radiation is a photon.

Thus, a new quantum theory of light appeared, born on the basis of Newton’s corpuscular theory. A quantum acts as a corpuscle.

Basic provisions.

– Light is emitted, propagated and absorbed in discrete portions - quanta.

– Quantum of light – a photon carries energy proportional to the frequency of the wave with which it is described by electromagnetic theory E = h n .

– A photon has mass (), momentum and angular momentum ().

– A photon, as a particle, exists only in motion whose speed is the speed of light propagation in a given medium.

– For all interactions in which a photon participates, the general laws of conservation of energy and momentum are valid.

– An electron in an atom can only be in some discrete stable stationary states. Being in stationary states, an atom does not radiate energy.

– When transitioning from one stationary state to another, an atom emits (absorbs) a photon with a frequency (where E1 And E2– energies of the initial and final states).

With the emergence of quantum theory, it became clear that corpuscular and wave properties are only two sides, two interrelated manifestations of the essence of light. They do not reflect the dialectical unity of discreteness and continuity of matter, expressed in the simultaneous manifestation of wave and corpuscular properties. The same radiation process can be described using mathematical apparatus for waves propagating in space and time, and with the help statistical methods predicting the appearance of particles in a given place and at a given time. Both of these models can be used simultaneously, and depending on the conditions, one of them is preferred.

Achievements recent years in the field of optics were made possible thanks to the development of both quantum physics, and wave optics. Nowadays, the theory of light continues to develop.

Optics is a branch of physics that studies the properties and physical nature of light, as well as its interaction with matter.

The simplest optical phenomena, for example the appearance of shadows and the production of images in optical instruments, can be understood within the framework of geometric optics, which operates with the concept of individual light rays that obey the known laws of refraction and reflection and are independent of each other. To understand more complex phenomena, physical optics is needed, which considers these phenomena in connection with the physical nature of light. Physical optics makes it possible to derive all the laws of geometric optics and establish the limits of their applicability. Without knowledge of these boundaries, the formal application of the laws of geometric optics can, in specific cases, lead to results that contradict the observed phenomena. Therefore, one cannot limit oneself to the formal construction of geometric optics, but must look at it as a branch of physical optics.

The concept of a light beam can be obtained from considering a real light beam in a homogeneous medium, from which a narrow parallel beam is isolated using a diaphragm. The smaller the diameter of these holes, the narrower the isolated beam, and in the limit, going to holes as small as desired, it would seem that a light beam can be obtained as a straight line. But such a process of isolating an arbitrarily narrow beam (beam) is impossible due to the phenomenon of diffraction. The inevitable angular expansion of a real light beam passed through a diaphragm of diameter D is determined by the diffraction angle j ~ l / D. Only in the extreme case when l=0, such an expansion would not take place, and one could speak of the ray as a geometric line, the direction of which determines the direction of propagation of light energy.

Thus, a light ray is an abstract mathematical concept, and geometric optics is an approximate limiting case into which wave optics goes when the wavelength of light tends to zero.

The eye as an optical system.

The human organ of vision is the eyes, which in many respects represent a very advanced optical system.

In general, the human eye is a spherical body with a diameter of about 2.5 cm, which is called the eyeball (Fig. 5). The opaque and durable outer layer of the eye is called the sclera, and its transparent and more convex front part is called the cornea. On the inside, the sclera is covered with a choroid, consisting of blood vessels that supply the eye. Opposite the cornea, the choroid passes into the iris, which is unequally colored different people, which is separated from the cornea by a chamber containing a clear, watery mass.

The iris has a round hole called the pupil, the diameter of which can vary. Thus, the iris plays the role of a diaphragm, regulating the access of light to the eye. In bright light the pupil becomes smaller, and in low light it enlarges. Inside the eyeball behind the iris is the lens, which is a biconvex lens made of a transparent substance with a refractive index of about 1.4. The lens is surrounded by a circular muscle, which can change the curvature of its surfaces, and therefore its optical power.

The choroid on the inside of the eye is covered with branches of the photosensitive nerve, especially dense in front of the pupil. These branches form a reticular membrane on which it turns out real image objects created by the optical system of the eye. The space between the retina and the lens is filled with a transparent vitreous body, which has a gelatinous structure. The image of objects on the retina is inverted. However, the activity of the brain, which receives signals from the photosensitive nerve, allows us to see all objects in natural positions.

When the ring muscle of the eye is relaxed, the image of distant objects is obtained on the retina. In general, the structure of the eye is such that a person can see objects located no closer than 6 meters from the eye without strain. In this case, the image of closer objects is obtained behind the retina. To obtain a clear image of such an object, the annular muscle compresses the lens more and more until the image of the object appears on the retina, and then holds the lens in a compressed state.

Thus, “focusing” of the human eye is carried out by changing the optical power of the lens using the annular muscle. The ability of the optical system of the eye to create distinct images of objects located at different distances from it is called accommodation (from the Latin “accommodation” - adaptation). When viewing very distant objects, parallel rays enter the eye. In this case, the eye is said to be accommodated to infinity.

The accommodation of the eye is not infinite. With the help of the annular muscle, the optical power of the eye can increase by no more than 12 diopters. When looking at close objects for a long time, the eye gets tired, and the annular muscle begins to relax and the image of the object blurs.

Human eyes allow us to see objects clearly not only in daylight. The ability of the eye to adapt to varying degrees of irritation of the endings of the photosensitive nerve on the retina, i.e. to varying degrees of brightness of observed objects is called adaptation.

The convergence of the visual axes of the eyes at a certain point is called convergence. When objects are located at a considerable distance from a person, then when moving the eyes from one object to another, the axes of the eyes practically do not change, and the person loses the ability to correctly determine the position of the object. When objects are very far away, the axes of the eyes are parallel, and a person cannot even determine whether the object he is looking at is moving or not. The force of the annular muscle, which compresses the lens when viewing objects located close to the person, also plays a certain role in determining the position of bodies. sheep

Spectrum oscop.

A spectroscope is used to observe spectra.

The most common prismatic spectroscope consists of two tubes, between which a triangular prism is placed (Fig. 7).

In pipe A, called a collimator, there is a narrow slit, the width of which can be adjusted by turning a screw. A light source is placed in front of the slit, the spectrum of which must be examined. The slit is located in the plane of the collimator, and therefore the light rays from the collimator exit in the form of a parallel beam. After passing through the prism, the light rays are directed into tube B, through which the spectrum is observed. If a spectroscope is intended for measurements, then an image of a scale with divisions is superimposed on the image of the spectrum using a special device, which allows you to accurately determine the position of the color lines in the spectrum.

An optical measuring device is a measuring instrument in which sighting (alignment of the boundaries of a controlled object with a hairline, crosshair, etc.) or size determination is carried out using a device with an optical operating principle. There are three groups of optical measuring instruments: devices with an optical sighting principle and a mechanical method for reporting movement; devices with optical sighting and movement reporting; devices that have mechanical contact with the measuring device, with an optical method for determining the movement of the contact points.

The first devices to become widespread were projectors for measuring and monitoring parts with complex contours and small sizes.

The most common second device is a universal measuring microscope, in which the part being measured moves on a longitudinal carriage, and the head microscope moves on a transverse carriage.

Devices of the third group are used to compare measured linear quantities with measures or scales. They are usually combined under the general name comparators. This group of devices includes an optimeter (opticator, measuring machine, contact interferometer, optical range finder, etc.).

Optical measuring instruments are also widespread in geodesy (level, theodolite, etc.).

Theodolite is a geodetic instrument for determining directions and measuring horizontal and vertical angles during geodetic work, topographical and mine surveying, in construction, etc.

Level - a geodetic instrument for measuring elevations of points on the earth's surface - leveling, as well as for setting horizontal directions during installation, etc. works.

A sextant is widely used in navigation - a goniometric mirror-reflective instrument for measuring heights. heavenly bodies above the horizon or angles between visible objects in order to determine the coordinates of the observer’s location. The most important feature of the sextant is the ability to simultaneously combine two objects in the observer’s field of view, between which the angle is measured, which allows the sextant to be used on an airplane or on a ship without a noticeable decrease in accuracy, even during pitching.

A promising direction in the development of new types of optical measuring instruments is to equip them with electronic reading devices that make it possible to simplify the reading and sighting, etc.

Conclusion.

The practical significance of optics and its influence on other branches of knowledge are extremely great. The invention of the telescope and spectroscope opened up before man the most amazing and richest world phenomena occurring in the vast Universe. The invention of the microscope revolutionized biology. Photography has helped and continues to help almost all branches of science. One of the most important elements of scientific equipment is the lens. Without it there would be no microscope, telescope, spectroscope, camera, cinema, television, etc. there would be no glasses, and many people over 50 would be unable to read and do many jobs that require vision.

The range of phenomena studied by physical optics is very extensive. Optical phenomena are closely related to phenomena studied in other branches of physics, and optical research methods are among the most subtle and accurate. Therefore, it is not surprising that optics has for a long time played a leading role in many basic research and the development of basic physical views. Suffice it to say that both main physical theories of the last century - the theory of relativity and the theory of quantum - originated and developed to a large extent on the basis of optical research. The invention of lasers has opened up vast new possibilities not only in optics, but also in its applications in various branches of science and technology.

Moscow Education Committee

World O R T

Moscow Technological College

Department of Natural Sciences

Final work in physics

On the topic :

Performed by student of group 14: Ryazantseva Oksana

Teacher: Gruzdeva L.N.

- Artsybyshev S.A. Physics - M.: Medgiz, 1950.

- Zhdanov L.S. Zhdanov G.L. Physics for intermediates educational institutions- M.: Nauka, 1981.

- Landsberg G.S. Optics - M.: Nauka, 1976.

- Landsberg G.S. Elementary physics textbook. - M.: Nauka, 1986.

- Prokhorov A.M. Great Soviet Encyclopedia. - M.: Soviet encyclopedia, 1974.

- Sivukhin D.V. General course Physics: Optics - M.: Nauka, 1980.

We come across the word “optics”, for example, when we pass by a retail outlet that sells glasses. Many also remember that they studied optics in school. What is optics?

Optics is a branch of physics that studies the nature of light, its properties, patterns of propagation in different environments, as well as the interaction of light with substances. To better understand what optics is, you need to understand what light is.

Ideas about light in modern physics

Physics considers the light we are used to as a complex phenomenon with a dual nature. On the one hand, light is considered a stream of tiny particles - light quanta (photons). On the other hand, light can be described as a type of electromagnetic waves that have a specific wavelength.

Separate branches of optics study light as a physical phenomenon from various angles.

Optics sections

• Geometric optics. Examines the laws of light propagation, as well as the reflection and refraction of light rays. Represents light as a ray propagating rectilinearly in a homogeneous medium (this is its similarity to a geometric ray). Does not take into account the wave nature of light.
• Wave optics. Studies the properties of light as a type of electromagnetic waves.
• Quantum optics. Studies the quantum properties of light (studies the photoelectric effect, photochemical processes, laser radiation etc.)

Optics in human life

By studying the nature of light and the patterns of its distribution, a person uses the acquired knowledge to his advantage. Most common in surrounding life optical instruments are glasses, a microscope, a telescope, a photographic lens, as well as a fiber-optic cable used for laying a LAN (you can find out about this in the article

- (Greek optike the science of visual perceptions, from optos visible, visible), a branch of physics in which optical radiation (light), the processes of its propagation and phenomena observed during the influence of light and in va are studied. Optical radiation represents... ... Physical encyclopedia

- (Greek optike, from optomai I see). The doctrine of light and its effect on the eye. Dictionary foreign words, included in the Russian language. Chudinov A.N., 1910. OPTICS Greek. optike, from optomai, I see. The science of the propagation of light and its effect on the eye... ... Dictionary of foreign words of the Russian language

optics- and, f. optique f. optike vision science. 1. outdated Raek (a type of panorama). Poppy. 1908. Or through the glass of optics I look at picturesque places of my estates. Derzhavin Evgeniy. Features of vision, perception of something. The optics of my eyes are limited; everything is in the dark... Historical Dictionary of Gallicisms of the Russian Language

Modern encyclopedia

Optics- OPTICS, a branch of physics that studies the processes of light emission, its propagation in various media and its interaction with matter. Optics studies the visible part of the spectrum of electromagnetic waves and the adjacent ultraviolet... ... Illustrated Encyclopedic Dictionary

OPTICS, a branch of physics that studies light and its properties. Key aspects include the physical nature of LIGHT, covering both waves and particles (PHOTONS), REFLECTION, REFRACTION, POLARIZATION of light and its transmission through various media. Optics... ... Scientific and technical encyclopedic dictionary

OPTICS, optics, many. no, female (Greek optiko). 1. Department of Physics, a science that studies the phenomena and properties of light. Theoretical optics. Applied optics. 2. collected Devices and instruments, the action of which is based on the laws of this science (special). Intelligent... ... Dictionary Ushakova

- (from the Greek optike, the science of visual perception) a branch of physics that studies the processes of light emission, its distribution in various media and the interaction of light with matter. Optics studies a wide range of the electromagnetic spectrum... ... Big Encyclopedic Dictionary

OPTICS, and, women. 1. A branch of physics that studies the processes of light emission, its propagation and interaction with matter. 2. collected Devices and instruments whose action is based on the laws of this science. Fiber optics (special) section of optics,... ... Ozhegov's Explanatory Dictionary

OPTICS- (from the Greek opsis vision), the study of light, an integral part of physics. O. is partly included in the field of geophysics (atmospheric O., optics of the seas, etc.), partly in the field of physiology (physiology). Basically physical. content O. is divided into physical... ... Great Medical Encyclopedia

Books

• Optics, A.N. Matveev. Approved by the Ministry of Higher and Secondary Education of the USSR as a teaching aid for students of physical specialties at universities. Reproduced in the original author’s spelling of the publication...

ABSOLUTELY BLACK BODY– a mental model of a body that, at any temperature, completely absorbs all electromagnetic radiation incident on it, regardless of the spectral composition. Radiation A.h.t. is determined only by its absolute temperature and does not depend on the nature of the substance.

WHITE LIGHT- complex electromagnetic radiation , causing a color-neutral sensation in a person’s eyes.

VISIBLE RADIATION- optical radiation with wavelengths of 380 - 770 nm, capable of causing a visual sensation in human eyes.

Stimulated EMISSION, induced radiation - the emission of electromagnetic waves by particles of matter (atoms, molecules, etc.) located in an excited state, i.e. nonequilibrium state under the influence of external driving radiation. V.i. coherently (See coherence) with forcing radiation and under certain conditions can lead to amplification and generation of electromagnetic waves. See also quantum generator.

HOLOGRAM- an interference pattern recorded on a photographic plate, formed by two coherent waves (see. coherence): a reference wave and a wave reflected from an object illuminated by the same light source. When reconstructing G., we perceive a three-dimensional image of an object.

HOLOGRAPHY- a method for obtaining three-dimensional images of objects, based on the registration and subsequent reconstruction of the wave front reflected by these objects. Obtaining a hologram is based on.

HUYGEN'S PRINCIPLE- a method that allows you to determine the position of the wave front at any time. According to g.p. all points through which the wave front passes at time t are sources of secondary spherical waves, and the desired position of the wave front at time t+Dt coincides with the surface enveloping all secondary waves. Allows you to explain the laws of reflection and refraction of light.

HUYGENS - FRESNEL - PRINCIPLE- an approximate method for solving problems of wave propagation. G.-F. p. states: at any point located outside an arbitrary closed surface covering a point source of light, the light wave excited by this source can be represented as the result of the interference of secondary waves emitted by all points of the specified closed surface. Allows you to solve simple problems.

LIGHT PRESSURE - pressure, produced by light on an illuminated surface. Playing big role in cosmic processes (formation of comet tails, equilibrium of large stars, etc.).

ACTUAL IMAGE- cm. .

DIAPHRAGM- a device for limiting or changing the light beam in an optical system (for example, the pupil of the eye, lens frame, camera lens).

DISPERSION OF LIGHT- dependence of absolute refractive index substances from the frequency of light. A distinction is made between normal radiation, in which the speed of the light wave decreases as the frequency increases, and anomalous radiation, in which the speed of the wave increases. Due to D.s. A narrow beam of white light, passing through a prism made of glass or other transparent substance, is decomposed into a dispersive spectrum, forming a rainbow stripe on the screen.

DIFFRACTION GRATING- a physical device that is a collection of a large number of parallel strokes of the same width, applied to a transparent or reflective surface at the same distance from one another. As a result, on D.r. A diffraction spectrum is formed - alternating maxima and minima of light intensity.

DIFFRACTION OF LIGHT- a set of phenomena that are caused by the wave nature of light and are observed when it propagates in a medium with pronounced inhomogeneities (for example, when passing through holes, near the boundaries of opaque bodies, etc.). In the narrow sense, under D.s. understand the bending of light around small obstacles, i.e. deviation from the laws of geometric optics. Plays an important role in the operation of optical instruments, limiting them resolution.

DOPPLER EFFECT– change phenomenon vibration frequencies sound or electromagnetic waves perceived by an observer due to the mutual movement of the observer and the source of the waves. When approaching, an increase in frequency is detected, and when moving away, a decrease is detected.

NATURAL LIGHT- a set of incoherent light waves with all possible planes of vibration and with the same intensity of vibration in each of these planes. E.s. almost all natural light sources emit, because they consist of a large number of differently oriented radiation centers (atoms, molecules) emitting light waves, the phase and plane of vibrations of which can take on all possible values. See also polarization of light, coherence.

OPTICAL MIRROR– a body with a polished or coated with a reflective layer (silver, gold, aluminum, etc.) surface on which close to specular reflection occurs (see. reflection).

IMAGE OPTICAL– an image of an object obtained as a result of the action of an optical system (lenses, mirrors) on light rays emitted or reflected by the object. There is a distinction between real (obtained on the screen or retina of the eye when rays passing through the optical system intersect) and imaginary information. . (obtained at the intersection of the continuations of the rays).

INTERFERENCE OF LIGHT- the phenomenon of superposition of two or more coherent light waves linearly polarized in one plane, in which the energy of the resulting light wave is redistributed in space depending on the relationship between the phases of these waves. The result of the I.S., observed on a screen or photographic plate, is called an interference pattern. I. white light leads to the formation of a rainbow pattern (colors of thin films, etc.). Finds application in holography, for clearing optics, etc.

INFRARED RADIATION - electromagnetic radiation with wavelengths from 0.74 microns to 1-2 mm. Emitted by all bodies with a temperature above absolute zero (thermal radiation).

QUANTUM OF LIGHT- the same as photon.

COLLIMATOR- an optical system designed to produce a beam of parallel rays.

COMPTON EFFECT– scattering phenomenon electromagnetic radiation short wavelengths (X-ray and gamma radiation) on free electrons, accompanied by an increase wavelength.

LASER, optical quantum generator - quantum generator electromagnetic radiation in the optical range. Generates monochromatic coherent electromagnetic radiation, which has a narrow directivity and significant power density. It is used in optical ranging, for processing solid and refractory materials, in surgery, spectroscopy and holography, for heating plasma. Wed. Maser.

LINE SPECTRA- spectra consisting of individual narrow spectral lines. Emitted by substances in the atomic state.

LENS optical - a transparent body bounded by two curved (usually spherical) or curved and flat surfaces. A lens is called thin if its thickness is small compared to the radii of curvature of its surfaces. A distinction is made between converging (converting a parallel beam of rays into a converging one) and diverging (converting a parallel beam of rays into a diverging one) lenses. They are used in optical, optical-mechanical, and photographic instruments.

MAgnifying glass- collecting lens or a lens system with a short focal length (10 - 100 mm), gives 2 - 50x magnification.

BEAM– an imaginary line along which the radiation energy propagates in the approximation geometric optics, i.e. if no diffraction phenomena are observed.

MASER - quantum generator electromagnetic radiation in the centimeter range. It is characterized by high monochromaticity, coherence and narrow radiation directivity. It is used in radio communications, radio astronomy, radar, and also as a generator of stable frequency oscillations. Wed. .

MICHAELSON EXPERIENCE- an experiment designed to measure the influence of the Earth's movement on the value speed of light. Negative result M.o. became one of the experimental grounds relativity theory.

MICROSCOPE- an optical device for observing small objects invisible to the naked eye. The magnification of the microscope is limited and does not exceed 1500. Cf. electron microscope.

VIMARY IMAGE- cm. .

MONOCHROMATIC RADIATION– mental model electromagnetic radiation one specific frequency. Strogogo M.I. does not exist, because any real radiation is limited in time and covers a certain frequency range. Sources of radiation close to m. - quantum generators.

OPTICS- a branch of physics that studies the patterns of light (optical) phenomena, the nature of light and its interaction with matter.

OPTICAL AXIS- 1) MAIN - straight line on which the centers of refractive or reflective surfaces forming the optical system are located; 2) SIDE - any straight line passing through the optical center of a thin lens.

OPTICAL POWER lenses - a quantity used to describe the refractive effect of a lens and the inverse focal length. D=1/F. It is measured in diopters (Dopters).

OPTICAL RADIATION- electromagnetic radiation, the wavelengths of which are in the range from 10 nm to 1 mm. K o.i. include infrared radiation, , .

REFLECTION OF LIGHT– the process of the return of a light wave when it falls on the interface between two media having different refractive indices. back to the original environment. Thanks o.s. we see bodies that do not emit light. There are specular reflection (a parallel beam of rays remains parallel after reflection) and diffuse reflection(the parallel beam is converted into a divergent beam).

– a phenomenon observed during the transition of light from an optically denser medium to an optically less dense one, if the angle of incidence is greater than the limiting angle of incidence, where n – refractive index of the second medium relative to the first. In this case, the light is completely reflected from the interface between the media.

WAVE REFLECTIONS LAW- the incident ray, the reflected ray and the perpendicular raised to the point of incidence of the ray lie in the same plane, and the angle of incidence is equal to the angle of refraction. The law is valid for mirror reflection.

LIGHT ABSORPTION- a decrease in the energy of a light wave during its propagation in matter, occurring as a result of the conversion of wave energy into internal energy substances or energy of secondary radiation having a different spectral composition and a different direction of propagation.

1) ABSOLUTE - value equal to the ratio speed of light in vacuum to the phase speed of light in a given medium: . Depends on the chemical composition of the medium, its state (temperature, pressure, etc.) and the frequency of light (see. light dispersion).2) RELATIVE - (p.p. of the second medium relative to the first) a value equal to the ratio of the phase velocity in the first medium to the phase velocity in the second: . O.p.p. equal to the ratio of the absolute refractive index of the second medium to the absolute p.p. feather environment.

POLARIZATION OF LIGHT– a phenomenon leading to the ordering of tension vectors electric field and magnetic induction of a light wave in a plane perpendicular to the light beam. Most often it occurs during the reflection and refraction of light, as well as during the propagation of light in an anisotropic medium.

REFRACTION OF LIGHT– a phenomenon consisting in a change in the direction of propagation of light (electromagnetic wave) when moving from one medium to another, different from the first refractive index. For refraction, the law is satisfied: the incident ray, the refracted ray and the perpendicular raised to the point of incidence of the ray lie in the same plane, and for these two media the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant value called relative refractive index the second environment relative to the first. The reason for refraction is the difference in phase velocities in different media.

OPTICAL PRISM- a body made of a transparent substance, bounded by two non-parallel planes on which light is refracted. Used in optical and spectral instruments.

STROKE DIFFERENCE – physical quantity, equal to the difference in the optical path lengths of two light rays.

LIGHT SCATTERING- a phenomenon consisting in the deflection of a light beam propagating in a medium in all possible directions. It is caused by the heterogeneity of the medium and the interaction of light with particles of matter, during which the direction of propagation, frequency and plane of oscillations of the light wave changes.

LIGHT, light radiation - which can cause a visual sensation.

LIGHT WAVE - electromagnetic wave in the wavelength range of visible radiation. Frequency (set of frequencies) r.v. determines color, energy r.v. is proportional to the square of its amplitude.

LIGHT GUIDE- a channel for transmitting light, having dimensions many times greater than the wavelength of light. Light in the village propagates due to total internal reflection.

SPEED OF LIGHT in vacuum (c) - one of the basic physical constants, equal to speed propagation of electromagnetic waves in vacuum. s=(299 792 458 ± 1.2) m/s. S.s. - the maximum speed of propagation of any physical interactions.

OPTICAL SPECTRUM- distribution by frequency (or wavelength) of the intensity of optical radiation of a certain body (emission spectrum) or the intensity of absorption of light as it passes through a substance (absorption spectrum). There are S.O.: lined, consisting of individual spectral lines; striped, consisting of groups (stripes) of closely related spectral lines; solid, corresponding to radiation (emission) or absorption of light in a wide frequency range.

SPECTRAL LINES- narrow sections in optical spectra corresponding to almost the same frequency (wavelength). Each S. l. meets a certain quantum transition.

SPECTRAL ANALYSIS - physical method qualitative and quantitative analysis of the chemical composition of substances, based on the study of their optical spectra. It is highly sensitive and is used in chemistry, astrophysics, metallurgy, geological exploration, etc. Theoretical basis S. a. is .

SPECTROGRAPH- an optical device for obtaining and simultaneously recording the radiation spectrum. The main part of S. - optical prism or .

SPECTROSCOPE- an optical device for visual observation of the radiation spectrum. The main part of the lens is an optical prism.

SPECTROSCOPY- branch of physics that studies optical spectra in order to clarify the structure of atoms, molecules, as well as matter in its various states of aggregation.

INCREASE optical system - the ratio of the size of the image produced by the optical system to the true size of the object.

UV RADIATION- electromagnetic radiation with a wavelength in vacuum from 10 nm to 400 nm. They also cause luminescence in many substances. Biologically active.

FOCAL PLANE- a plane perpendicular to the optical axis of the system and passing through its main focus.

FOCUS- the point at which a parallel beam of light rays passing through the optical system is collected. If the beam is parallel to the main optical axis of the system, then the beam lies on this axis and is called the main one.

FOCAL LENGTH- the distance between the optical center of a thin lens and the focus. PHOTO EFFECT, photoelectric effect is the phenomenon of the emission of electrons by a substance under the influence of electromagnetic radiation (external f.). Observed in gases, liquids and solids. Discovered by G. Hertz and studied by A.G. Stoletov. Basic patterns f. explained on the basis of quantum concepts by A. Einstein.

COLOR- a visual sensation caused by light in accordance with its spectral composition and the intensity of the reflected or emitted radiation.