How optics from physics helps people. Optics as a branch of physics. Quantum and physiological optics

Scientists of antiquity, 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. To date, important historical documents have survived, confirming the concept of the structure of light as a constant stream of particles that have certain physical properties. However, the very term "optics" will appear much later. The seeds of such philosophers as Democritus and Euclid, sown during the comprehension of the structure of all processes occurring on earth, gave their shoots. Only at the beginning of the 19th century, classical optics was 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 in the visible spectrum, as well as in the ranges close to it.

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

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

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

The 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 stream of 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 value corresponding to the intensity of the emitted light;
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 presented as a result of the actions of these waves.

With such properties of light, the absence of the transition of the strength 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.

Wave and corpuscular hypotheses of electric and magnetic radiation found their application in Maxwell's scientific works in the form of equations.

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

Light characteristics

The length of the light wave $ \ lambda $ directly depends on the general speed of propagation of this phenomenon in the spatial medium $ v $ and is related to the frequency $ \ nu $ as follows:

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

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

The dependence of the refractive index on the wavelength is manifested in the form of the phenomenon of systematic dispersion of light. The universal and still poorly understood concept in physics is the speed of light $ c $. Its special significance in absolute emptiness is not only the maximum rate of dissemination of powerful electromagnetic frequencies, but also the maximum intensity of the dissemination of information or other physical impact on material objects. With an increase in the movement of the stream of light 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 by wave propagation;
the direction of dissemination of the light beam, which should coincide with the wavefront in the absence of birefringence.

Quantum and physiological optics

The idea of a detailed description of the electromagnetic field using quanta appeared at the beginning of the 20th century, and was voiced by Max Planck. Scientists suggested that the constant emission of light is carried out by means of certain particles - quanta. Thirty years later, it was proved that light is not only emitted partially and in parallel, but also absorbed.

This made it possible for Albert Einstein to define the discrete structure of light. Nowadays, scientists call quanta of light photons, and the flux 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 only one stream of photons.

In the middle of the 20th century, the research activities of Brown-Twiss made it possible to more accurately determine the territory of the use of quantum optics. The scientist's work proved that a certain number of light sources, which emit photons to two photodetectors and send a constant sound signal about the registration of elements, can make the devices operate simultaneously.

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

Remark 1

Modern optics has long included many areas of the scientific world and developments 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 on biochemistry, biophysics and psychology.

Taking into account all the laws of optics, this branch of science is based on the indicated 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 technology 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, the 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.

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

WHITE LIGHT- complex electromagnetic radiation , a sensation in the eyes of a person that is neutral in color.

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

FORCED RADIATION, induced radiation - the emission of electromagnetic waves by particles of matter (atoms, molecules, etc.), which are in excited, i.e. nonequilibrium state under the influence of external stimulating radiation. In and. coherently (Cf. coherence) with forcing radiation and under certain conditions can lead to the 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 of obtaining volumetric images of objects, based on the registration and subsequent restoration of the front of the wave reflected by these objects. The hologram acquisition is based on.

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

LIGHT PRESSURE - pressure, produced by light on the illuminated surface. Plays a large role in cosmic processes (the formation of comet tails, the balance of large stars, etc.).

REAL IMAGE- cm. .

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

DISPERSION OF LIGHT- dependence of the absolute refractive index substances on the frequency of light. Distinguish between normal D., in which the speed of the light wave decreases with increasing frequency, and anomalous D., 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, decomposes into a dispersion spectrum, forming a rainbow strip on the screen.

DIFFRACTION GRATING- a physical device, which 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, D. a diffraction spectrum is formed - an alternation of 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 during its propagation 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 light bending around small obstacles, i.e. deviation from the laws of geometric optics. Plays an important role in the operation of optical devices, limiting them resolution.

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

NATURAL LIGHT- a set of incoherent light waves with all possible vibration planes and with the same vibration intensity 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 vibration of which can take on all possible values. see also polarization of light, coherence.

MIRROR OPTICAL- a body with a surface that is polished or coated with a reflective layer (silver, gold, aluminum, etc.), on which a reflection is close to specular (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 an object. Distinguish between real (obtained on the screen or retina of the eye when the rays that have passed through the optical system intersect) and imaginary. . (obtained at the intersection of ray extensions).

INTERFERENCE OF LIGHT- the phenomenon of overlapping 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 IS observed on a screen or photographic plate is called an interference pattern. I. white light leads to the formation of an iridescent pattern (the color of thin films, etc.). It is used in holography, in optical antireflection, etc.

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

QUANTUM OF LIGHT- the same as photon.

COLLIMATOR- an optical system designed to obtain a beam of parallel beams.

COMPTON EFFECT- the phenomenon of scattering of electromagnetic radiation of short wavelengths (X-ray and gamma radiation) by 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 location, for processing solid and refractory materials, in surgery, spectroscopy and holography, for plasma heating. Wed Maser.

LINEAR SPECTRA- spectra, consisting of individual narrow spectral lines. Emitted by substances in an atomic state.

LENS optical - a transparent body, limited 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. Distinguish between collecting (converting a parallel beam of rays into converging) and scattering (converting a parallel beam of rays into diverging) lenses. They are used in optical, optical-mechanical, photographic devices.

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

RAY- an imaginary line along which the radiation energy propagates in the approximation geometric optics, i.e. if diffraction phenomena are not observed.

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

MICHAELSON'S EXPERIENCE- an experiment designed to measure the effect of the Earth's motion on the value speed of light... Negative result of M.o. became one of the experimental foundations 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.

IMAGE IMAGE- cm. .

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

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

OPTICAL AXIS- 1) MAIN - the straight line on which the centers of the refractive or reflecting surfaces that form 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... Measured in diopters (diopters).

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

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

- the phenomenon observed when light passes 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 Is the refractive index of the second medium relative to the first. In this case, the light is completely reflected from the interface between the media.

REFLECTION WAVES LAW- the incident ray, the reflected ray, and the perpendicular 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 true for mirroring.

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

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

LIGHT POLARIZATION- a phenomenon leading to the ordering of the vectors of the electric field strength and magnetic induction of a light wave in a plane perpendicular to the light beam. Most often occurs when light is reflected and refracted, as well as when light propagates in an anisotropic medium.

REFRACTION OF LIGHT- a phenomenon consisting in a change in the direction of propagation of light (electromagnetic wave) during the transition from one medium to another that differs from the first refractive index... For refraction, the law is fulfilled: the incident ray, the refracted ray and the perpendicular 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. Refraction is caused by the difference in phase velocities in different media.

OPTICAL PRISM- a body made of transparent material, limited by two non-parallel planes, on which light refraction occurs. It is used in optical and spectral devices.

STROKE DIFFERENCE- a physical quantity equal to the difference in optical path lengths of two light beams.

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 inhomogeneity of the medium and the interaction of light with particles of matter, in which the direction of propagation, the frequency and plane of oscillation of the light wave change.

LIGHT, light radiation - which can cause visual sensation.

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

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

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

SPECTRUM OPTICAL- the frequency (or wavelength) distribution 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). Distinguish S.O .: ruled, consisting of separate spectral lines; striped, consisting of groups (stripes) close spectral lines; solid, corresponding to radiation (emission) or absorption of light in a wide frequency range.

SPECTRAL LINES- narrow areas in the optical spectra, corresponding to practically the same frequency (wavelength). Each S. l. responds to a certain quantum transition.

SPECTRAL ANALYSIS- a physical method for the qualitative and quantitative analysis of the chemical composition of substances, based on the study of their optical spectra. Differs in high sensitivity and is used in chemistry, astrophysics, metallurgy, geological exploration, etc. The theoretical basis of S. and. is an .

SPECTROGRAPH- an optical device for obtaining and simultaneous registration of the radiation spectrum. The main part of C. - optical prism or .

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

SPECTROSCOPY- a section of physics studying optical spectra in order to clarify the structure of atoms, molecules, as well as substances in its various states of aggregation.

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

ULTRAVIOLET 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 the 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 phase angle 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 - 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 investigated by A. G. Stoletov. The basic laws of f. explained on the basis of quantum concepts by A. Einstein.

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

Shemyakov N.F.

Physics. Part 3. Wave and quantum optics, the structure of the atom and nucleus, the physical picture of the world.

The physical foundations of wave and quantum optics, the structure of the atom and nucleus, the physical picture of the world are presented in accordance with the program of the general course of physics for technical universities.

Particular attention is paid to the disclosure of the physical meaning, the content of the main provisions and concepts of statistical physics, as well as the practical application of the phenomena under consideration, taking into account the conclusions of classical, relativistic and quantum mechanics.

Designed for 2nd year distance learning students, can be used by full-time students, graduate students and physics teachers.

From the heavens, cosmic showers streamed, Carrying streams of positrons on the tails of comets. Mesons, even bombs appeared, What kind of resonances there are just no ...

7. WAVE OPTICS

1. The nature of light

According to modern ideas, light has a corpuscular nature. On the one hand, light behaves like a stream of particles - photons, which are emitted, propagated and absorbed in the form of quanta. The corpuscular nature of light is manifested, for example, in the phenomena

photo effect, Compton effect. On the other hand, light has wave properties. Light is electromagnetic waves. The wave nature of light is manifested, for example, in phenomena interference, diffraction, polarization, dispersion, etc. Electromagnetic waves are

transverse.

V oscillations of vectors occur in an electromagnetic wave

electric field E and magnetic field H, and not a substance as, for example, in the case of waves on water or in a taut cord. Electromagnetic waves propagate in a vacuum with a speed of 3 108 m / s. Thus, light is a real physical object, which is not reduced to either a wave or a particle in the usual sense. Waves and particles are only two forms of matter in which the same physical entity manifests itself.

7.1. Elements of geometric optics

7.1.1. Huygens principle

	When waves propagate in a medium, including
	number and electromagnetic, to find a new
	wave front at any time
	use the Huygens principle.
	Each point of the wave front is
	a source of secondary waves.
	In a homogeneous isotropic medium, wave
	the surfaces of the secondary waves have the form of spheres
	radius v t,	where v is the propagation rate

	waves in the environment.	Conducting the envelope of the wave

fronts of secondary waves, we get a new front of the wave at a given time (Fig. 7.1, a, b).

7.1.2. Reflection law

Using Huygens' principle, one can prove the law of reflection of electromagnetic waves at the interface between two dielectrics.

The angle of incidence is equal to the angle of reflection. The incident and reflected rays, together with the perpendicular to the interface between the two dielectrics, lie in

to the SD is called the angle of incidence. If at a given moment in time the front of the incident wave OB reaches m. 0, then according to the Huygens principle this point

begins to emit a secondary wave. During		t = BO1 / v incident ray 2
	reaches point O1. During the same time, the front of the secondary
	waves, after reflection in t. O, propagating in
	the same environment, reaches the points of the hemisphere,
	radius ОА = v	t = BO1. New wave front
	is depicted by the plane AO1, and the direction
	spreading	ray OA. The angle is called
	angle of reflection. From the equality of triangles
	JSC1 and OBO1 follows the law of reflection: angle
	incidence is equal to the angle of reflection.

	7.1.3. Refraction law
	Optically homogeneous medium 1 is characterized by absolute
refractive index
refractive index

	the speed of light in a vacuum; v1		the speed of light in the first environment.




where v2
	Attitude	n2 / n1 = n21

called the relative refractive index of the second medium relative to the first.

frequencies. If the speed of propagation of light in the first medium is v1, and in the second v2,

medium (in accordance with the Huygens principle), reaches the points of the hemisphere, the radius of which is ОВ = v2 t. The new front of the wave propagating in the second medium is depicted by the BO1 plane (Fig. 7.3), and its direction

propagation by beams ОВ and О1 С (perpendicular to the wave front). The angle between the OF beam and the normal to the interface between two dielectrics in

point O called the angle of refraction. From triangles OJSC1

OBO1

it follows that AO1 = OO1 sin

OB = OO1 sin.

Their attitude and expresses the law

refraction (Snell's law):

n21.

The ratio of the sine of the angle of incidence to the sine of the angle

refractions

relative

the refractive index of the two media.

7.1.4. Total internal reflection

According to the law of refraction at the interface between two media, one can

observe total internal reflection if n1> n2, i.e.

7.4). Therefore, there is such a limiting angle of incidence

when

900. Then the law of refraction

takes the following form:

sin pr =

(sin 900 = 1)

Further

increasing

fully

reflected from the interface between the two media.

This phenomenon is called total internal reflection and is widely used in optics, for example, to change the direction of light rays (Fig. 7. 5, a, b). Used in telescopes, binoculars, fiber optics and other optical instruments. In classical wave processes, such as the phenomenon of total internal reflection of electromagnetic waves,

phenomena similar to the tunneling effect in quantum mechanics are observed, which is associated with the wave-particle properties of particles. Indeed, when light passes from one medium to another, refraction of light is observed, associated with a change in the speed of its propagation in different media. At the interface between two media, the light beam is divided into two: refracted and reflected. According to the law of refraction, we have that if n1> n2, then for> pr, total internal reflection is observed.

Why is this happening? The solution of Maxwell's equations shows that the light intensity in the second medium is nonzero, but very quickly, exponentially, decays with distance from

interface.
	Experimental
observation		internal
reflection is shown in Fig. 7.6,
demonstrates		penetration
light into the "forbidden" area,
geometric optics.
		rectangular

of an isosceles glass prism, a beam of light falls perpendicularly and, without refraction, falls on face 2, total internal reflection is observed,

/ 2 from facet 2 to place the same prism, then the light beam will pass through facet 2 * and exit the prism through facet 1 * parallel to the ray incident on facet 1. The intensity J of the transmitted light flux decreases exponentially with an increase in the gap h between the prisms according to the law:

Therefore, the penetration of light into the "forbidden" region is an optical analogy of the quantum tunneling effect.

The phenomenon of total internal reflection is indeed complete, since in this case all the energy of the incident light is reflected at the interface between two media than when reflected, for example, from the surface of metal mirrors. Using this phenomenon, one more

an analogy between refraction and reflection of light, on the one hand, and Vavilov-Cherenkov radiation, on the other.

7.2. WAVE INTERFERENCE

7.2.1. The role of vectors E and H

In practice, in real environments, several waves can propagate simultaneously. As a result of the addition of waves, a number of interesting phenomena are observed: interference, diffraction, reflection and refraction of waves etc.

These wave phenomena are characteristic not only of mechanical waves, but also of electrical, magnetic, light, etc. Wave properties are also manifested by all elementary particles, which has been proven by quantum mechanics.

One of the most interesting wave phenomena that is observed when two or more waves propagate in a medium is called interference. Optically homogeneous medium 1 is characterized by

absolute refractive index
absolute refractive index

	the speed of light in a vacuum; v1 is the speed of light in the first environment.
Medium 2 is characterized by an absolute refractive index



where v2	the speed of light in the second medium.
Attitude
Attitude

called the relative refractive index of the second medium


	using Maxwell's theory, or


	where 1, 2 are the dielectric constants of the first and second media.
	For vacuum, n = 1. Due to dispersion (the frequency of light				1014 Hz), for example,

for water n = 1.33, and not n = 9 (= 81), as follows from electrodynamics for low frequencies. Light electromagnetic waves. Therefore, the electromagnetic

the field is determined by the vectors E and H, which characterize the strengths of the electric and magnetic fields, respectively. However, in many processes of interaction of light with matter, for example, such as the effect of light on the organs of vision, photocells and other devices,

the decisive role belongs to the vector E, which in optics is called the light vector.

All processes occurring in devices under the influence of light are caused by the action of the electromagnetic field of a light wave on charged particles that are part of atoms and molecules. In these processes, the main role

electrons play due to the high frequency

hesitation

light

15 Hz).

acting

per electron from

electromagnetic field,

F qe (E

0 },

where q e

electron charge; v

its speed;

magnetic permeability

the environment;

magnetic constant.

The maximum value of the modulus of the vector product of the second

term at v

H, taking into account

0 H2 =

0 E2,

it turns out

0 N ve =

ve E

the speed of light in

matter and in vacuum, respectively;

0 electric

constant;

dielectric constant of the substance.

Moreover, v >> ve, since the speed of light in matter v

108 m / s, a speed

electron in atom ve

106 m / s. It is known that

cyclic frequency; Ra

10 10

the size of the atom, plays a role

amplitudes of forced vibrations of an electron in an atom.

Hence,

F ~ qe E, and the main role is played by the vector

E and not

vector H. The results obtained are in good agreement with the experimental data. For example, in Wiener's experiments, the region of blackening of a photographic emulsion under

the action of light coincide with the antinodes of the electric vector E.

7.3. Conditions for maximum and minimum interference

The phenomenon of superposition of coherent light waves, as a result of which there is an alternation of light amplification at some points in space and attenuation at others, is called light interference.

A prerequisite light interference is coherence

stacked sine waves.

Waves are called coherent if the phase difference of the added waves does not change over time, i.e., = const.

This condition is satisfied by monochromatic waves, i.e. the waves

E, the added electromagnetic fields were committed along the same or similar directions. In this case, there should be no coincidence

only vectors E, but also H, which will be observed only if the waves propagate along the same straight line, i.e. are equally polarized.

Let us find the conditions for the maximum and minimum of interference.

To do this, consider the addition of two monochromatic, coherent light waves of the same frequency (1 = 2 =), having equal amplitudes (E01 = E02 = E0), oscillating in a vacuum in one direction according to the sine (or cosine) law, i.e.

		E01 sin (		01),
		E02 sin (		02),
where r1, r2	distances from sources S1 and S2		to the observation point on the screen;
01, 02	initial phases; k =	wave number.
01, 02	initial phases; k =	wave number.

According to the principle of superposition (set Leonardo da Vinci) the vector of intensity of the resulting oscillation is equal to the geometric sum of the vectors of the intensity of the added waves, i.e.

E 2.

For simplicity, we assume that the initial phases of the added waves

are equal to zero, i.e. 01 =

02 = 0. In absolute value, we have

E = E1 + E2 = 2E0 sin [

k (r1

k (r2

In (7.16) the expression

r1) n =

optical path difference

folded waves; n

the absolute refractive index of the medium.

For media other than vacuum, for example, for water (n1, 1),

glasses (n2, 2), etc. k = k1 n1;

k = k2 n2;

1 n1;

2 n 2;

called the amplitude of the resulting wave.

The amplitude of the wave power is determined (for a unit surface of the wave front) Poynting vector, i.e. modulo

0 Е 0 2 cos2 [

k (r2

where П = с w,

0E 2

volumetric

density

electromagnetic field (for vacuum

1), i.e., P = c

0 E2.

If J = P

the intensity of the resulting wave, and

J0 = c

0 E 0 2

its maximum intensity, then taking into account

(7.17) and (7.18) intensity

the resulting wave will change according to the law

J = 2J0 (1+ cos).

Phase difference of the added waves

and does not depend on time, where

2 = t kr2 +

1 = t kr1 +

The amplitude of the resulting wave is found by the formula

K (r2

r1) n =

Two cases are possible:

1. Maximum condition.

If the phase difference of the added waves is equal to an even number


	1, 2, ..., then the resulting amplitude will be maximum,

	E 02 E 012 E 022 2E 01E 02
	E0 = E01 + E02.
Therefore, the amplitudes of the waves add up,		and if they are equal
(E01 = E02)	the resulting amplitude is doubled.
The resulting intensity is also maximum:
	Jmax = 4J0.

Amangeldinov Mustafa Rakhatovich
Student
Nazarbayev Intellectual School mustafastu[email protected] gmail. com

Optics. History of optics. Applications of optics.

The history of the development of optics.

Optics - the study of the nature of light, light phenomena and the interaction of light with matter. And almost all of her story is a story of searching for an 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. NS. This theory assumed that rays emanate from the eye, which, meeting with objects, illuminate them and create the appearance of the surrounding world. Plato's views were supported by many scientists of antiquity and, in particular, Euclid (3rd century BC), based on the theory of visual rays, founded the doctrine of the straightness of the propagation of light, established the law of reflection.

In the 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 action of a concave mirror.

The ancient Greeks laid the foundation for the branch of optics, which later received the name geometric.

The most interesting work on optics that 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. Alhazen was the first to express the idea 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 establish itself as the basis for the study and knowledge of the surrounding world.

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

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

– wave, which asserted that light is a longitudinal vibrational motion of a special luminiferous medium - ether - excited by vibrations of particles of a luminous body.

All further development of the theory 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 along straight lines, or rays, a luminous body, for example, a burning candle. If these rays, consisting of corpuscles, enter our eye, then we see their source.

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

3) White is a mixture of all colors: red, orange, yellow, green, light blue, blue, purple.

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.

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 less the angle of refraction is the angle of incidence.

6) The phenomenon of dispersion of light, 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 atmosphere together and produce a white light effect. White light - a mixture of various corpuscles - experiences refraction after passing through a prism. From the point of view of mechanical theory, refraction is due to the forces from the glass particles acting on the light corpuscles. These forces are different for different corpuscles. They are largest for purple and smallest for red. The path of the corpuscles in the prism for each color will be refracted in its own way, therefore the white complex ray will split into colored component rays.

7) Newton outlined ways of explaining birefringence, hypothesizing that the rays of light have "different sides" - a special property that determines their different refraction when passing through a birefringent body.

Newton's corpuscular theory satisfactorily explained many optical phenomena known at that time. Its author enjoyed tremendous authority in the scientific world, and soon Newton's theory gained many adherents in all countries.

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

In 1801, T. Jung performed an experiment that amazed the world's scientists: S - light source; E - screen; B and C are very narrow slits spaced 1-2 mm apart.

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 the slots B and C. Experience has shown that light is a wave phenomenon. Jung developed Huygens' theory with ideas about the vibrations of particles, about 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 motion and Young's interference principle. On this basis, he developed a rigorous mathematical theory of diffraction. Fresnel was able to explain all the optical phenomena known at that time.

The main provisions of the Fresnel wave theory.

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

– Light waves are transverse;

– The light ether has the properties of an elastic-solid body, it is absolutely incompressible.

When passing from one medium to another, the elasticity of the ether does not change, but its density changes. The relative refractive index of the substance.

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

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

In the middle of the 19th century, facts began to emerge indicating a connection between optical and electrical phenomena. In 1846 M. Faraday observed the rotation of the planes of polarization of light in bodies placed in a magnetic field. Faraday introduced the concept of electric and magnetic fields as a kind of superposition in the ether. A new "electromagnetic ether" has appeared. The first to draw attention to these views was the English physicist Maxwell. He developed these ideas and built a theory of the electromagnetic field.

The electromagnetic theory of light did not eliminate the mechanical theory of Huygens-Jung-Fresnel, but raised it to 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;

– absorption also occurs in discrete portions, quanta.

The energy of each quantum is represented by the formulaE = hn , whereh 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 came out. Einstein believed:

– light that has not yet entered into interaction with matter has a granular structure;

– the structural element of discrete light radiation is a photon.

In 1913 the Danish physicist N. Bohr published the theory of the atom, in which he combined the theory of Planck-Einstein quanta with the picture of the nuclear structure of the atom.

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

Basic provisions.

– Light is emitted, distributed 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 the electromagnetic theoryE = hn .

– Photon, has mass (), momentum and angular momentum ().

– A photon, as a particle, exists only in motion, the speed of which is the speed of propagation of light 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 certain discrete stable stationary states. While in stationary states, the atom does not radiate energy.

– When passing from one stationary state to another, an atom emits (absorbs) a photon with a frequency, (whereE 1 andE 2 - energies of the initial and final states).

With the emergence of quantum theory, it became clear that the 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. One and the same radiation process can be described both with the help of a mathematical apparatus for waves propagating in space and time, and with the help of statistical methods for predicting the appearance of particles in a given place and at a given time. Both of these models can be used at the same time, and depending on the conditions, preference is given to one of them.

The achievements of recent years in the field of optics have become possible thanks to the development of both quantum physics and wave optics. The theory of light continues to evolve today.

Wave properties of light and geometric optics.

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, such as the appearance of shadows and the acquisition of images in optical devices, can be understood in the framework of geometric optics, which operates with the concept of separate light rays obeying the known laws of refraction and reflection and 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 confine oneself to the formal construction of geometric optics, but it is necessary to look at it as a section of physical optics.

The concept of a light beam can be obtained from the consideration of a real light beam in a homogeneous medium, from which a narrow parallel beam is extracted with the help of a diaphragm. The smaller the diameter of these holes, the narrower the emitted beam, and in the limit, passing to holes as small as you like, one would see the light beam as a straight line. But such a process of extracting an arbitrarily narrow beam (ray) is impossible due to the phenomenon of diffraction. The inevitable angular expansion of a real light beam transmitted through a diaphragm of diameter D is determined by the diffraction angle j~ l / D ... Only in the limiting case, when l = 0, such an expansion would not take place, and one could speak of a 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 geometrical optics is an approximate limiting case into which wave optics goes when the length of a light wave tends to zero.

The eye as an optical system.

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

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

The iris has a circular opening called the pupil, which can vary in diameter. Thus, the iris acts as a diaphragm that regulates the access of light to the eye. In bright light, the pupil decreases, and in low light, it increases. Inside the eyeball, behind the iris, the lens is located, which is a biconvex lens made of transparent material with a refractive index of about 1.4. The lens is surrounded by an annular muscle, which can change the curvature of its surfaces, and hence its optical power.

The choroid on the inner side of the eye is covered with branches of the photosensitive nerve, especially dense opposite the pupil. These ramifications form a reticular membrane on which the actual image of objects is obtained, created by the optical system of the eye. The space between the retina and the lens is filled with a transparent vitreous body with a gelatinous structure. The image of objects on the retina is inverted. However, the activity of the brain, which receives signals from the light-sensitive nerve, allows us to see all objects in natural positions.

When the annular muscle of the eye is relaxed, then the image of distant objects is obtained on the retina. In general, the structure of the eye is such that a person can see without tension objects located at least 6 meters from the eye. In this case, the image of closer objects is obtained behind the retina of the eye. To obtain a clear image of such an object, the annular muscle compresses the lens more and more until the image of the object is on the retina, and then holds the lens in a compressed state.

Thus, "aiming at the focus" of the human eye is carried out by changing the optical power of the lens with the help of the annular muscle.The ability of the optical system of the eye to create clear images of objects at different distances from it is called accommodation (from the Latin "accommodation" - device). When looking at very distant objects, parallel rays fall into 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 be increased by no more than 12 diopters. With a long examination of close objects, the eyes get tired, and the annular muscle begins to relax and the image of the object becomes blurred.

Human eyes allow you to see objects well, 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 the 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 between the axes of the eyes, it practically does 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 the person cannot even determine whether the object is moving or not, at which he is looking. The force of the annular muscle, which compresses the lens when examining objects located near a person, also plays a role in determining the position of the bodies.

Spectroscope.

A spectroscope is used to observe the spectra.

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

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

Optical measuring device.

Optical measuring device - a measuring instrument in which sighting (aligning the boundaries of the controlled object with a target line, crosshair, etc.) or determining the size is carried out using a device with an optical principle of operation. There are three groups of optical measuring instruments: instruments with an optical principle of sight and a mechanical way of reporting the movement; instruments with optical sighting and movement reporting; devices having mechanical contact with a measuring device, with an optical method for determining the movement of contact points.

Of the devices, projectors for measuring and controlling parts with a complex contour and small dimensions were the first to spread.

The second most common instrument is a universal measuring microscope, in which the part to be measured moves on a longitudinal carriage, and the head microscope - on a transverse one.

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

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

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

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

In navigation, a sextant is widespread - a goniometric mirror-reflective instrument for measuring the heights of celestial bodies above the horizon or the angles between visible objects in order to determine the coordinates of the observer's place. The most important feature of the sextant is the ability to combine two objects in the observer's field of view at the same time, between which the angle is measured, which makes it possible to use the sextant on an airplane and on a ship without a noticeable decrease in accuracy even during pitching.

A promising direction in the development of new types of optical measuring devices is equipping them with electronic reading devices, which 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 exceptionally great. The invention of the telescope and spectroscope opened before man the most amazing and richest world of 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 years old would be deprived of the opportunity to read and perform many of the work related to vision.

The field 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 for a long time optics played a leading role in very many fundamental research and the development of basic physical views. Suffice it to say that both the main physical theories of the last century - the theory of relativity and the theory of quanta - originated and largely developed on the basis of optical research. The invention of lasers opened up new vast possibilities not only in optics, but also in its applications in various branches of science and technology.

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

Zhdanov L.S. Zhdanov G.L. Physics for secondary educational institutions - Moscow: Nauka, 1981.

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

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

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

Sivukhin D.V. General course of physics: Optics - Moscow: Nauka, 1980.

- The history of the development of optics.

- The main provisions of the corpuscular theory of Newton.

- The main provisions of Huygens' wave theory.

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

- The main provisions of optics.

- Wave properties of light and geometric optics.

- The eye as an optical system.

- Spectroscope.

- Optical measuring device.

- Conclusion.

- List of used literature.

The history of the development of optics.

Optics - the study of the nature of light, light phenomena and the interaction of light with matter. And almost all of her story is a story of searching for an answer: what is light?

In the 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 action of a concave mirror.

The ancient Greeks laid the foundation for the branch of optics, which later received the name geometric.

a step in understanding the nature of light.

During the Renaissance, many different discoveries and inventions were made; the experimental method began to establish itself as the basis for the study and knowledge of the surrounding world.

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

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

- wave, which asserted that light is a longitudinal vibrational motion of a special luminiferous medium - ether - excited by vibrations of particles of a luminous body.

All further development of the theory 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:

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

3) White is a mixture of all colors: red, orange, yellow, green, light blue, blue, purple.

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).

7) Newton outlined the ways of explaining birefringence, hypothesizing that the rays of light have "different sides" - a special property that determines their different refraction when passing through a birefringent body.

The main provisions 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 impulses of sound in air.

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

3) The principle of propagation of vibrations of the ether is such that each point, to which the 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 produce the sensation of seeing.

A very important point in Huygens' theory was the assumption that the speed of light propagation was finite. Using his principle, the scientist was able to explain many of the 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 birefringence;

- the principle of independence of light rays.

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

The formula shows that the speed of light should depend inversely on the absolute index of the medium. This conclusion was the opposite of the conclusion following 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. With the research of these scientists, the theory of Huygens 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 the world's scientists (Fig. 4)

S - light source;

E - screen;

B and C are very narrow slits spaced 1-2 mm apart.

The main provisions of the Fresnel wave theory.

- Light - the propagation of vibrations in the ether at a speed where the elastic modulus of the ether, r- the density of the ether;

- Light waves are transverse;

- The light ether has the properties of an elastic-solid body, it is absolutely incompressible.

When passing from one medium to another, the elasticity of the ether does not change, but its density changes. The relative refractive index of the substance.

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

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

- light emission is discrete;

- 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 the light.

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

- light that has not yet entered into interaction with matter has a granular structure;

- the structural element of discrete light radiation is a photon.

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

Basic provisions.

- Light is emitted, distributed 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 the electromagnetic theory E = h n .

- Photon, has mass (), momentum and angular momentum ().

- A photon, as a particle, exists only in motion, the speed of which is the speed of propagation of light in a given environment.

- 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. While in stationary states, the atom does not radiate energy.

- When passing 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).

The achievements of recent years in the field of optics have become possible thanks to the development of both quantum physics and wave optics. The theory of light continues to evolve today.

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

The concept of a light beam can be obtained from the consideration of a real light beam in a homogeneous medium, from which a narrow parallel beam is extracted with the help of a diaphragm. The smaller the diameter of these holes, the narrower the emitted beam, and in the limit, passing to holes as small as you like, one would see the light beam as a straight line. But such a process of extracting an arbitrarily narrow beam (ray) is impossible due to the phenomenon of diffraction. The inevitable angular expansion of a real light beam transmitted through a diaphragm of diameter D is determined by the diffraction angle j ~ l / D... Only in the limiting case when l= 0, such an expansion would not take place, and one could speak of a 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 geometrical optics is an approximate limiting case into which wave optics goes when the length of a light wave tends to zero.

The eye as an optical system.

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

In general, the human eye is a spherical body about 2.5 cm in diameter, which is called the eyeball (Fig. 5). The opaque and durable outer shell of the eye is called the sclera, and its transparent and more convex anterior part is called the cornea. On the inside, the sclera is covered with a choroid, which consists of blood vessels that feed the eye. Against the cornea, the choroid passes into the iris, differently colored in different people, which is separated from the cornea by a chamber with a transparent watery mass.

Thus, the "focusing" of the human eye is carried out by changing the optical power of the lens with the help of the annular muscle. The ability of the optical system of the eye to create clear images of objects located at different distances from it is called accommodation (from the Latin "accommodation" - adaptation). When looking at very distant objects, parallel rays fall into the eye. In this case, the eye is said to be accommodated to infinity.

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 between the axes of the eyes, it practically does 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 the person cannot even determine whether the object is moving or not, at which he is looking. The force of the annular muscle, which compresses the lens when examining objects located near the person, also plays a role in determining the position of the bodies. sheep.

Spectrum oskop.

A spectroscope is used to observe the spectra.

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

Of the devices, projectors for measuring and controlling parts with a complex contour and small dimensions were the first to spread.

The second most common instrument is a universal measuring microscope, in which the part to be measured moves on a longitudinal carriage, and the head microscope - on a transverse one.

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

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

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

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

Conclusion.

Moscow Education Committee

World About R T

Moscow technological college

Department of Natural Sciences

Final work in physics

On the topic :

Performed by a 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 secondary educational institutions - Moscow: Nauka, 1981.

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

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

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

- Sivukhin D.V. General course of physics: Optics - Moscow: Nauka, 1980.