One of the ancient and voluminous branches of physics is optics. Its achievements are applied in many sciences and fields of activity: electrical engineering, industry, medicine and others. From the article you can find out what this science is studying, the history of the development of ideas about it, the most important achievements, and what optical systems and devices exist.
What optics study
The name of this discipline is of Greek origin and translates as "the science of visual perceptions." Optics is a branch of physics that studies the nature of light, its properties, laws related to its propagation. This science explores the nature of visible light, infrared and ultraviolet radiation. Since it is thanks to light that people are able to see the world around them, this branch of physics is also a discipline related to the visual perception of radiation. And no wonder: the eye is a complex optical system.
The history of science
Optics originated in ancient times, when people tried to understand the nature of light and find out how to manage to see objects around the world.
Ancient philosophers believed that visible light was either rays coming out of a personβs eyes or a stream of tiny particles scattering from objects and falling into an eye.
In the future, the nature of light was studied by many prominent scientists. Isaac Newton formulated the theory of corpuscles - tiny particles of light. Another scientist, Huygens, advanced a wave theory.
The nature of light continued to be studied by physicists of the 20th century: Maxwell, Planck, Einstein.
At present, the hypotheses of Newton and Huygens are combined in the concept of wave-particle duality, according to which, light has the properties of both particles and waves.
Sections
The subject of research in optics is not only light and its nature, but also instruments for these studies, the laws and properties of this phenomenon, and much more. Therefore, in science there are several sections devoted to individual aspects of research.
It:
- geometric optics;
- wave;
- quantum.
Each section will be discussed in detail below.
Geometric optics
In this section, the following laws of optics exist:
The law on the straightness of the propagation of light passing through a homogeneous medium. A light ray is considered as a straight line along which light particles pass.
Law of reflection:
The incident and reflected rays, as well as the perpendicular to the interface between two media, restored at the point of incidence of the beam, lie in the same plane ( plane of incidence). The reflection angle Ξ³ is equal to the angle of incidence Ξ±.
Law of Refraction:
The incident and refracted rays, as well as the perpendicular to the interface between two media, restored at the point of incidence of the beam, lie in the same plane. The ratio of the sine of the angle of incidence Ξ± to the sine of the angle of refraction Ξ² is a constant for two of these media.
A means of studying the properties of light in geometric optics are lenses.
A lens is a transparent body that is capable of transmitting and modifying light rays. They are divided into convex and concave, as well as collecting and scattering. The lens is the main component of all optical devices. When its thickness is small compared to the radii of the surfaces, it is called thin. In optics, the formula of a thin lens looks like this:
1 / d + 1 / f = D, where
d is the distance from the subject to the lens; f is the distance to the image from the lens; D is the optical power of the lens (measured in diopters).
Wave optics and its concepts
Since it is known that light has all the properties of an electromagnetic wave, a separate section of physics studies the manifestations of these properties. It is called wave optics.
The basic concepts of this section of optics are dispersion, interference, diffraction, and polarization.
The phenomenon of dispersion was discovered by Newton, thanks to his experiments with prisms. This discovery is an important step towards understanding the nature of light. He found that the refraction of light rays depends on their color. This phenomenon has been called dispersion or scattering of light. It is now known that color depends on the wavelength. In addition, it was Newton who proposed the concept of spectrum to denote the rainbow strip obtained by dispersion through prisms.
Confirmation of the wave nature of light is the interference of its waves, discovered by Jung. This is the name of the overlapping of two or more waves. As a result, one can see the phenomenon of amplification and attenuation of light vibrations at various points in space. Beautiful and familiar manifestations of interference are soap bubbles and a rainbow colored film of spilled gasoline.
Any wave process is characterized by the phenomenon of diffraction. This term is translated from Latin as "broken." Diffraction in optics is the enveloping by waves of light of the edges of obstacles. For example, if a ball is placed in the path of a light beam, then alternating rings β light and dark β will appear behind it on the screen. This is called a diffraction pattern. The phenomenon was studied by Jung and Fresnel.
The last key concept of wave optics is polarization. Light is called polarized if the direction of oscillation of its wave is ordered. Since the light is a longitudinal and not a transverse wave, the oscillations occur exclusively in the transverse direction.
Quantum optics
Light is not only a wave, but also a stream of particles. On the basis of this component, a branch of science such as quantum optics arose. Her appearance is associated with the name of Max Planck.
Quantum is called any portion of something. And in this case we are talking about radiation quanta, that is, portions of light emitted from it. For the designation of particles, the word photons is used (from the Greek ΟΟΟΟΟ - "light"). This concept was proposed by Albert Einstein. In this section of optics, Einstein's formula E = mc 2 is also used to study the properties of light.
The main task of this section is to study and characterize the interaction of light with matter and study its propagation in atypical conditions.
The properties of light as a stream of particles are manifested in such conditions:
- thermal radiation;
- photo effect;
- photochemical processes;
- stimulated emission, etc.
In quantum optics, there is the concept of non-classical light. The fact is that the quantum characteristics of light radiation cannot be described in terms of classical optics. Non-classical light, for example, two-photon, compressed, is used in various fields: for calibrating photodetectors, for accurate measurements, etc. Another application is quantum cryptography - a secret way of transmitting information using binary codes, where the vertically directed photon is assigned 0 and the horizontally directed - 1.
The importance of optics and optical instruments
In which areas of optics technology have found major application?
First, without this science there would be no optical devices known to every person: a telescope, a microscope, a camera, a projector, and others. Using specially selected lenses, people got the opportunity to explore the microworld, the universe, celestial objects, as well as capture and broadcast information in the form of images.
In addition, thanks to optics, a number of important discoveries were made in the field of the nature of light, its properties, the phenomena of interference, polarization, and others were discovered.
Finally, optics gained widespread use in medicine, for example, in the study of X-ray radiation, on the basis of which an apparatus was created that saved many lives. Thanks to this science, a laser has also been invented, which is widely used in surgical interventions.
Optics and Vision
The eye is an optical system. Due to the properties of light and the capabilities of the organs of vision, you can see the world around us. Unfortunately, few people boast of perfect vision. With this discipline, it has become possible to restore the opportunity for people to see better with glasses and contact lenses. Therefore, medical institutions involved in the selection of vision correction tools also received the corresponding name - optics.
You can summarize. So, optics is a science about the properties of light, affecting many areas of life and having wide application in science and in everyday life.