Optics

Optics. Branch of physics that is in charge of studying the behavior of light , as well as its characteristics and main manifestations.

Summary

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  • 1 History of optics
    • 1 Ancient age
    • 2 Middle ages
  • 2 Main topics of study covered by the discipline
  • 3 Scientific theories
    • 1 electromagnetic spectrum
  • 4 Modern optics
    • 1 Laser
      • 1.1 Applications of lasers
    • 5 Sources

History of optics

Old age

Long before methodical and formal studies of optical phenomena began, mirrors and lenses were built to improve vision. For example, the mirrors were already used by women of ancient Egypt to see themselves in them (1900 BC), as was found when finding one near the pyramid of Sesostris II. Naturally, these mirrors were just bits of metal with a very imperfect polish.

In the ruins of Nineveh , the ancient Assyrian capital, a piece of rock crystal was found that had all the appearance of a converging lens. One of the oldest references to lenses is found in the writings of Confucius (500 BC), who said that lenses improved vision, although he probably did not know anything about refraction.

Another very early mention of them is found in the book of Aristophanes , The Clouds, a comedy written in 425 BC, where he describes transparent stones, with which you can light the fire by means of sunlight . It was probably he who built the world’s first lens, with a blown glass globe, filled with water, in 424 BC. However, it was not built for the purpose of amplifying images, but to concentrate sunlight.

The first mention of the phenomenon of light refraction is found in Plato’s book , The Republic. Euclid first established (300 BC) the law of reflection and some properties of spherical mirrors in his book Catoptrica. Herón de Alejandría (250 AD) almost discovered Fermat’s Principle when he said that when reflected, light follows the minimum possible trajectory.

Middle Ages

During the Middle Ages , optics, like the other sciences, progressed very slowly. This advance was in the hands of the Arabs. The Arab philosopher Abu Ysuf Yaqub Ibn Is-Hak, better known as Al-Kindi , who lived in Basra and Baghdad (813-880 AD), wrote a book on optics called De Aspectibus. In it he makes some general considerations about the refraction of light, but he also contradicts Plato when he affirms, like Aristotle , that vision is due to rays that emanate from the luminous bodies, and not from the eye, from where they travel. in a straight line and then penetrate the eye, where they produce the visual sensation.

Another very important Arabian scientist, Ibn al-Haitham, better known by his Latinized name Alhazen (965-1038 AD), did research on astronomy, mathematics, physics, and medicine. Alhazen wrote a book called Kitab-ul Manazir (Treatise on Optics), where he exposes his studies on the subject. Among his main results is the discovery of the camera obscura, through which he was able to form an inverted image of a luminous object, passing light through a small hole.

Alhazen also made the first truly scientific study of refraction, testing Ptolemy’s approximate law, and he also found a law that gave the relative positions of an object and its image made up of a lens or a converging mirror. Without a doubt this scientist was the greatest authority of the Middle Ages, and had a great influence on the researchers who followed him, including Isaac Newton .

The Byzantines had discovered the need to use very high purity chemicals to obtain good transparency, at the same time that they had acquired great skill in carving and polishing glass. During the Fourth Crusade, in 1204 , the Venetians decided to plunder Constantinople instead of going to the Holy Land, so they discovered its secrets. Upon returning to Venice , the invaders of Constantinople took with them a large number of artisans specialized in the handling of glass , which later allowed them to acquire a great reputation throughout Europe. To date, the glass crafts of Venice are famous worldwide.

After carving the first lenses, the natural next step was to mount them on a frame to fit a lens to each eye , to improve the vision of people with visual defects. As expected, this was done in Italy , almost a century later, between 1285 and 1300 AD, although there has always been doubt as to whether it was Alexandro della Spina, a Dominican monk from Pisa, or his friend Salvino de Armati, in Florence. The first known portrait of a person with glasses is that of a fresco painted by Tomaso da Modena, in 1352 .

Main topics of study covered by the discipline

Refraction

Reflection, refraction, interference, diffraction, the interaction of light with matter and the formation of images.

  • Reflection refers to the change in direction that a ray will have or, failing that, a wave, and that will occur on the surface of separation between two media, in such a way that it will end up returning to the initial medium.
  • Refractionwill be the change in direction that a wave undergoes when it passes from one material medium to another, meanwhile, it will only be carried out if the wave obliquely impinges on the separation surface of the two media and the refractive indices of the means turn out to be different. The clearest example to see and understand this that I tell you can be observed when immersing a pencil in a glass with water, it will appear as broken before our eyes, when its reality outside the glass of water indicates that it is not. This phenomenon of refraction can also occur when light passes through several layers of air of different temperatures.
  • Diffraction is a very characteristic phenomenon of waves, which consists of the dispersion and apparent bending when they meet an obstacle.

Scientific theories

From a physical point of view, light is an electromagnetic wave. According to the model used for light, a distinction is made between the following branches, in increasing order of precision (each branch uses a simplified model used by the following):

  • The geometrical optics: Treat light as a set of rays that meet Fermat’s principle. It is used in the study of light transmission by homogeneous means (lenses, mirrors), reflection and refraction.
  • Electromagnetic optics or physical optics: Considers light as an electromagnetic wave, thus explaining diffraction, interference, reflectance and transmittance, and the phenomena of polarization and anisotropy.
  • The quantum optics: quantum Study of the interaction between electromagnetic waves and matter, in which wave-particle duality plays a crucial role.

Electromagnetic spectrum

Although Optics began as a branch of physics other than electromagnetism, it is currently known that visible light starts from the electromagnetic spectrum, which is nothing more than the set of all the frequencies of vibration of electromagnetic waves. The colors visible to the human eye are grouped in the “Visible Spectrum” part.

Modern optics

Modern optics encompasses the areas of optical science and engineering that became popular in the 20th century . These areas of optical science normally refer to electromagnetics or the quantum properties of light, but do not include other topics.

An important subfield of modern optics, quantum optics, which deals with mechanical properties especially the quantum of light. Quantum optics is not just theoretical, some of the modern devices, like lasers, have their operating principles that depend on quantum mechanics. Light detectors, such as photomultipliers and channeltrons, respond to individual photons.

Electronic image sensors, such as CCDs, trigger noise exposure corresponding to the statistics of the various photon events. Light emitting diodes and photovoltaic cells cannot be understood without quantum mechanics either. In the study of these devices, quantum optics often overlaps with quantum electronics.

Specialized areas in optics research include the study of how light interacts with specific materials such as glass optics and metamaterials. Other research focuses on the phenomenology of electromagnetic waves, such as singular optics, imageless optics, nonlinear optics, and statistical optics, and radiometry. Additionally, computer engineers have taken an interest in integrated optics, machine vision, and photonic computing as possible components of the “next generation” of computers.

Today, the pure science of optics is called optical science or optical physics to distinguish it from the applied optical sciences, which are known as optical engineering. Featured subfields of optical engineering include lighting engineering, photonics, and optoelectronics, with practical applications targeting the design, manufacturing, and testing of optical and imaging components. Some of these fields overlap, with fuzzy boundaries between topic terms that mean different things in different parts of the world and in different areas of the industry.

To be

A laser is a device that emits light (electromagnetic radiation) through a process known as stimulated emission. The term laser is an acronym for Light Amplification by Stimulated Emission of Radiation.

Laser light is generally coherent, which means that the light is emitted in a narrow, low-beam divergence, or can be converted into one with the help of optical components such as lenses.

The first laser was demonstrated on May 16 , 1960 by Theodore Maiman at Hughes Research Laboratories. When it was first invented, they were called “a solution by looking for a problem.” Since then, lasers have become one of the industry’s millions of dollars, seeking utility in thousands of widely varied applications.

Laser applications

The first application of visible lasers in the daily life of the general population was the supermarket barcode scanner, introduced in 1974 . The laserdisc player, introduced in 1978 , was the first successful consumer product to include a laser, but the compact disc player was the first laser-equipped device to become truly common in consumer homes, beginning in from 1982 .

These optical storage devices use a semiconductor laser less than one millimeter wide to scan the surface of the disk for data recovery. Fiber optic communication relies on lasers to transmit large amounts of information at the speed of light.

Other common uses of lasers include laser printers and laser pointers. Lasers are used in medicine in areas such as “bloodless surgery”, laser eye surgery, and laser capture microdissection and in military uses such as missile defense systems, electro-optic countermeasures (EOCMs), and LIDAR . Lasers are also used in holograms, laser light sets, and laser hair removal.

 

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