What is optics?

We explain to you what is optics, its history, impact on other sciences and how physical, geometric and modern optics differ.

1. What is optics?

Optics is a branch of physics that is dedicated to the study of visible light : its properties and behavior. It also analyzes its possible applications in the life of the human being , such as the construction of instruments to detect or use it.

Light has been defined by optics as a strip of electromagnetic emissions , whose behavior is similar to other invisible (for us) forms of the electromagnetic spectrum , such as ultraviolet or infrared radiation.

This means that their behavior can be described according to wave mechanics (except in very specific contexts in which light acts as a particle) and the classical electrodynamic approaches of light.

Optics is a very important field of research that nourishes other sciences with tools , especially astronomy , engineering, photography and medicine (ophthalmology and optometry). To it we owe the existence of mirrors, lenses, telescopes, microscopes , lasers and fiber optic systems.

2. History of optics

The field of optics has been part of human concerns since ancient times. The first attempts at known lenses date from ancient Egypt or ancient Mesopotamia, such as the Nirmud lens (700 BC) manufactured in Assyria.

The ancient Greeks also worried about understanding the nature of light , which they understood based on two perspectives: their reception or vision , and their emission, since the ancient Greeks thought that objects emitted copies of themselves through light (called eidola ). Philosophers such as Deócritus, Epicurus, Plato and Aristotle profusely studied optics.

The relief of these scholars was made up of Islamic alchemists and scientists during medieval European times, such as Al-Kindi (c. 801-873) and especially Abu Ali-al-Hasan or Alhazén (965-1040), who is considered the Father of Optics for his Book of Optics (11th century), where he explored the phenomena of refraction and reflection.

The European Renaissance brought that knowledge to the West, especially thanks to Roberto Grosseteste and Roger Bacon. The first practical glasses were manufactured in Italy around 1286 . Since then, the application of optical lenses for different scientific purposes has not ceased.

Thanks to optics, geniuses such as Copernicus, Galileo Galilei and Johannes Kepler were able to carry out their astronomical studies. Later, the first microscopes allowed the discovery of microbial life and the beginning of modern biology and medicine. The entire Scientific Revolution is largely due to the contribution of optics .

3. Physical optics

Physical optics is one that considers light as a wave propagating in space . In other words, it is the branch of optics that is most faithful to the principles and reasoning of physics, using prior knowledge like Maxwell’s Equations, to cite an important example.

In that way, he worries about physical phenomena such as interference, polarization or diffraction . In addition, it proposes predictive models to know how light will behave in certain situations or in certain media, when not numerical simulation systems .

4. Geometric optics

Geometric optics is born from the geometric application of phenomenological laws around the refraction and reflection of Willebrord Snel van Royen (1580-1626), the Dutch scientist known as Snell.

For this, this branch of optics starts from the existence of a light ray, whose behavior is described by the rules of geometry to find formulas corresponding to lenses, mirrors and diopters. In this way it is possible to study phenomena such as rainbows , the propagation of light and prisms . All using the language of mathematics .

5. Modern optics

The contemporary branch of optics emerges with quantum physics and the new fields of knowledge that the latter made possible, as well as its possible applications by engineering. Thus, modern optics comprise a huge variety of new fields of research regarding light and its applications, which include:

• Laser mechanisms (amplification of light by simulated radiation emission).
• The photocells , and metamaterials LED lights.
• The optoelectronics , hand the computer , and digital image processing.
• The Illuminating Engineering , with applications in photography, film and other fields.
• Quantum optics and the physical study of the photon as a light particle and light wave at the same time.
• The atmospheric optical and lighting understanding of atmospheric processes.