Optics is a science that studies the generation, propagation, reception and display of electromagnetic radiation and its interaction with matter in a wide range of microwave, infrared, visible light, ultraviolet to X-ray and γ-ray, focusing on the range from infrared to ultraviolet.
Research direction of optics specialty
The research direction of this major mainly includes: quantum optics and quantum information, photoelectron science and technology, optical information processing and calculation design, intense laser and laser biology.
Training objectives of optics specialty
This major has a solid optical theory foundation and basic experimental skills, and has strong innovation ability; Understand the development status and research trends in this field, and be familiar with the international frontier trends of optical development; Senior talents who can engage in scientific research, teaching or undertake specialized technical work and have strong comprehensive ability, language expression ability and written expression ability.
Employment direction of optics specialty
In addition to a certain proportion of graduates, they can go to colleges and universities to engage in related teaching and research, or engage in research and development, engineering technology, sales and other work in photoelectric enterprises.
Development history of optics specialty
Optics is a discipline with a long history, which can be traced back to more than 2000 years ago. At first, humans mainly tried to answer questions such as "how can people see the objects around them". About 400 BC, the earliest optical knowledge in the world was recorded in Mo Jing, China. It has eight records about optics, describing the definition and generation of shadows, linear propagation of light and pinhole imaging, and discussing the relationship between objects and images in plane mirrors, concave spherical mirrors and convex spherical mirrors with rigorous words (see History of Physics in China).
In the historical period of more than 2,000 years from the Book of Mohism, after 1 1 century, Al-Haisam invented and made the convex lens. From 1590 to1the beginning of the 7th century, H. Zhan Sen and H. Lipski independently invented the microscope at the same time until/kloc-0.
Newton experimented with sunlight in 1665. It can decompose sunlight into simple components and form a light distribution with colors arranged in a certain order-spectrum. It makes people come into contact with the objective and quantitative characteristics of light for the first time, and the spatial separation of monochromatic light is determined by the properties of light. Newton also found that when a convex lens with a large radius of curvature is placed on an optical flat glass, a group of colored concentric annular stripes appear at the contact between the lens and the glass plate when it is irradiated with white light; When irradiated with a monochromatic light, a group of concentric annular stripes alternating light and dark appear, which is called Newton's ring by later generations. Using this phenomenon, the corresponding monochromatic light can be quantitatively characterized by the air gap thickness of the first dark ring.
When Newton discovered these important phenomena, according to the linear propagation of light, he thought that light was a particle flow, and particles flew out of a light source and made uniform linear motion in a uniform medium, and explained the phenomena of refraction and reflection with this view. Huygens is an opponent of the particle theory of light. He founded the wave theory. 1690, in his book On Light, he wrote: "Like the simultaneous light, light propagates as a spherical wave surface." It is pointed out that every point reached by light vibration can be regarded as the vibration center of secondary wave, and the envelope surface of secondary wave is the wavefront of propagation wave. In the whole18th century, the particle flow theory of light and the wave theory of light have been put forward, but they are not complete.
/kloc-at the beginning of the 0/9th century, wave optics was initially formed, among which T. Young and A. Fresnel were the representatives. Yang satisfactorily explained the "color of film" and the phenomenon of double-slit interference. Fresnel supplemented Huygens' principle with Young's interference principle in 18 18, thus forming Huygens-Fresnel principle which is widely known today. It can be used to explain the interference and diffraction of light and the linear propagation of light. In further research, we observed the deflection of light and the interference of polarized light. In order to explain these phenomena, Fresnel assumes that light is a shear wave propagating in a continuous medium (ether). However, it is inconceivable that the characteristics of elastic solids should be imposed on the ether, and even if the ether is admitted, it is impossible to link optical phenomena with other physical phenomena.
1846 Faraday found that the vibration plane of light rotates in a magnetic field; 1856 W Weber found that the speed of light in vacuum is equal to the ratio of electromagnetic unit to electrostatic unit of current intensity. They show that there is a certain internal relationship between optical phenomena and electromagnetic phenomena.
Maxwell's theoretical research around 1860 points out that the changes of electric field and magnetic field cannot be confined to a certain part of space, but propagate at a speed equal to the ratio of electromagnetic unit to electrostatic unit of current, and light is such a electromagnetic phenomena. This conclusion was confirmed by Hertz experiment in 1888. According to Maxwell's theory, if c represents the speed of light in a vacuum and v represents the speed of light in a transparent medium with a dielectric constant of ε and a permeability of μ, there are:
c/v=(εμ) 1/2
Where c/v is only the refractive index of the medium, so there are:
n=(εμ) 1/2
The above formula gives the relationship between the optical constant n of transparent medium and the electrical constant ε and the magnetic constant μ. Maxwell's theory has taken a big step forward in understanding the physical properties of light.
However, this theory can't explain the nature of the electric oscillator with a frequency as high as that of light, nor can it explain the dispersion of light caused by the change of refractive index with the frequency of light. It was not until H. Lorenz founded the electronic theory in 1896 that the phenomena of light emission and absorption by matter and various characteristics of light propagation in matter were explained, including the explanation of dispersion. In Lorenz's theory, ether is an infinite and immovable medium, and its only feature is that the vibration of light in this medium has a certain propagation speed.
Lorenz theory can not give a satisfactory explanation for such an important problem as the distribution of energy by wavelength in hot blackbody radiation. Moreover, if Lorenz's concept of ether is correct, we can choose the moving ether as the frame of reference, so that people can distinguish absolute motion. In fact, in 1887, A. Michelson and others measured the "etheric wind" with an interferometer, and got a negative result, which shows that people still have a lot of one-sided understanding of the nature of light in Lorenz's electronic theory period.
1900, Planck borrowed the concept of discontinuity from the molecular structure theory of matter and put forward the quantum theory of radiation. He believes that electromagnetic waves of various frequencies (including light) can only be emitted from oscillators with their own discrete energy. This kind of energy particle is called quantum, and the quantum of light is called photon. Quantum theory not only naturally explains the distribution law of radiant energy of hot objects according to wavelength, but also puts forward the interaction between light and matter with a brand-new concept. Quantum theory provides a new concept not only for optics, but also for the whole physics, and its birth is usually regarded as the starting point of modern physics.
1905, Einstein applied quantum theory to photoelectric effect and made a very clear representation of photons. He pointed out in particular that when light interacts with matter, light also takes photons as the smallest unit. In addition, many experiments at the end of 19 and the beginning of the 20th century proved the quantum nature of light. 1905 In September, the German Yearbook of Physics published Einstein's Electrodynamics of Moving Media. The basic principle of special relativity was put forward for the first time. This paper expounds the classical physics that has been dominant since Galileo and Newton, and its application scope is limited to the case that the speed is much less than the speed of light, and his new theory can explain the characteristics of the process related to high-speed motion. He fundamentally abandoned the concept of ether and satisfactorily explained the optical phenomenon of moving objects.
In this way, at the beginning of the 20th century, on the one hand, the interference, diffraction and polarization of light and the optical phenomena of moving objects confirmed that light is electromagnetic wave; On the other hand, the quantum nature of light-particle nature, has been undoubtedly proved from the aspects of thermal radiation, photoelectric effect, light pressure and chemical action of light.
The Compton effect discovered in 1922, the Raman effect discovered in 1928, and the ultra-fine structure of atomic spectrum obtained by experiments at that time undoubtedly show that the development of optics cannot be independent of quantum physics.
The concept of light quantum in modern optics does not exclude the concept of light fluctuation, but requires the creation and development of quantum mechanics and quantum electrodynamics with the help of Heisenberg, Schrodinger, Dirac, Feynman, Schwinge and Asanaga Ichiro. , in order to unify them. Using their theory, atomic spectrum, molecular spectrum and ion spectrum can be clarified. Can explain the influence of electric field, magnetic field and sound field on the spectrum; The relationship between excitation conditions and spectral characteristics can be established. The history of optics shows that the two most important basic theories in modern physics, quantum mechanics and special relativity, were born and developed in the study of light.
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