optics (original) (raw)
Author: the photonics expert (RP)
Definition: the science and technology dealing with the properties and the propagation of light
general optics- optics
- geometrical optics
- wave optics
- Fourier optics
- quantum optics
- Gaussian optics
- technical optics
- aspheric optics
- adaptive optics
- diffractive optics
- integrated optics
- fiber optics
- flat optics
- micro-optics
- freeform optics
- laser optics
- nonlinear optics
- ultrafast optics
- infrared optics
- ultraviolet optics
- (more topics)
Related: lightgeometrical opticswave opticsphotonicslaser physicsquantum opticsdiffractioninterferencemicroscopescleaning of optics
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DOI: 10.61835/vwj Cite the article: BibTex BibLaTex plain textHTML Link to this page! LinkedIn
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Contents
Summary:
This article provides a comprehensive overview of optics, the branch of physics concerning the properties and propagation of light. It explains the main sub-fields, starting with classical optics, which is divided into geometrical optics (describing light with rays) and wave optics (treating light as electromagnetic waves to explain phenomena like diffraction and interference).
The text further introduces quantum optics, which deals with the particle nature of light (photons) and quantum effects. Finally, it covers technical optics, which focuses on the design and fabrication of optical components and systems for various practical applications.
(This summary was generated with AI based on the article content and has been reviewed by the article’s author.)
What is Optics?
Optics is a part of the discipline of physics. It began many centuries ago as the science dealing with the properties of light and its propagation. Its origins trace back to ancient civilizations, with early practical use of lenses by Egyptians and Mesopotamians, and foundational theoretical development from Greek, Islamic, and later European and American scientists.
Optics also became increasingly important for practical applications and can therefore now also be regarded as an important field of technology. As the properties of light have already been known quite precisely for several decades, much of current optics research focuses on applications. For example, one can study technical optics, which focuses on the operation principles and further optimization of various optical components and devices.
Optics plays a crucial role in the area of photonics, mainly concerning various properties of light, its propagation e.g. through transparent optical materials, and its reflection under various circumstances. (The generation of light and its detection are by some authors also considered as parts of optics, or alternatively as belonging only to the wider field of photonics.) Optics and photonics also have a very substantial economic importance as enablers for a very wide range of other modern technologies, with vital applications in diverse areas like astronomy, Earth observation, visual correction, medical diagnosis, microscopy, military observation and weapon guidance, and many others. Photonics contains other important fields like laser physics which interface with optical physics.
Nowadays, optics deals not only with visible light, but also with infrared and ultraviolet light, as these have been recognized as similar electromagnetic phenomena (only with different frequency ranges). These have many properties in common with visible light, and are often utilized with similar optical components.
Classical Optics
Geometrical Optics
Geometrical optics describes the propagation of light with geometrical light rays which (in homogeneous media) propagate along straight lines. There are laws describing the reflection and refraction of light at optical interfaces. The effects of optical components on light rays is often described with an ABCD matrix algorithm.
Figure 1: Reflection of light rays at a spherically curved mirror.
Although geometrical optics has serious limitations — it cannot describe various important physical phenomena involving diffraction, interference or polarization of light, for example — it is still useful. For example, many properties of optical imaging systems containing mirrors, lenses, prisms etc. can be well understood with geometrical optics, e.g. with ray tracing techniques, although their performance limitations (some kinds of optical aberrations) cannot be completely explained and analyzed with ray optics.
See the article on geometrical optics for more details.
Physical Optics, Wave Optics
Figure 2: Intensity profiles at the end of a multimode fiber for a variable input beam position, shown as animated graphics. Such calculations need to be based on wave optics; ray optics are not sufficient. The image is from a case study with the software RP Fiber Power.
Some physical phenomena show quite clearly that light has properties of waves, although the rather short wavelengths of light do not always make that obvious. However, interference and diffraction processes in particular are hard to explain without optical waves. Around 1865, James Clerk Maxwell managed to demonstrate that light can indeed be identified with transverse electromagnetic waves with frequencies of the order of hundreds of terahertz. This quickly explained many phenomena e.g. in the context of diffraction and polarization. Some of the first practical results were explanations for the limited optical performance e.g. of microscopes and telescopes, and hints towards further optimization of their performance.
Light propagation in optical fibers can also be well described only with wave optics; see Figure 2 for an example.
Beyond an improved understanding, many new kinds of devices and operation principles have resulted from the evolution of physical optics and wave optics. For example, powerful spectrometers based on diffraction gratings have been realized, dielectric coatings (thin-film coatings) have become very important in various fields of photonics, and optical resonators play important roles e.g. as optical filters and as laser resonators.
In many cases, wave optics can be utilized without considering the physical foundations of electromagnetism in great detail. For example, light propagation can often be studied based on refractive indices of optical materials without considering how exactly these result from the interaction of electromagnetic waves with matter.
Large parts of physical optics require quite sophisticated and partly abstract mathematical methods, although greatly simplified mathematical methods are still sufficient for many purposes. Numerical computation methods have become very important, greatly simplifying the work in many cases. Interestingly, one can utilize quantities like components of ABCD ray matrices for calculations in wave optics, although it is conceptually so different from ray optics.
See the article on wave optics for more details.
Quantum Optics
Although the description of light as classical electromagnetic waves, as developed in the 19th century, has been extremely successful, it became apparent in the early 20th century that there are phenomena which are hard to explain on that basis. For example, Albert Einstein realized that the photoelectric effect seemed to suggest that light energy is not delivered continuously, but in certain discrete packages, which are nowadays called photons. The further development of quantum mechanics led to a physical description which reconciles quite well the wave nature and apparent particle properties of light, although the resulting physical model is hard to bring together with intuitive ideas, and some aspects of quantum physics are still a matter of debate, essentially concerning interpretations. Note, however, that there seem to be no logical flaws or gaps of understanding in the sense that phenomena could not be properly described or predicted.
The field of optics which is specifically dealing with quantum effects is called quantum optics. In recent years, quantum optics has led to interesting technological developments; important keywords are quantum cryptography (for secure data transmission based on physical principles) or more generally quantum communications, and quantum computing.
See the article on quantum optics for more details.
Technical Optics
Technical optics is based on optical physics, but focuses on optical components and systems for transforming and utilizing light, not on studying the properties of light itself. Some examples of areas of activity and technical optics are:
- Modeling and design methods for developing optical systems are still being further refined and optimized. While in the early times sophisticated mathematical methods were defined, numerical computational methods have become increasingly important. Partly, they are based on previously developed mathematical methods, and partly they replace analytical methods with numerical approaches, which are sometimes substantially more practical.
- Optical materials and methods of their fabrication are further optimized, and new optical materials are developed.
- Various optical components and devices as well as methods of optical fabrication are developed further, and new concepts are introduced. Some progress in optical technology is based on new materials or improved fabrication technologies, which can be utilized e.g. for improving the performance of optical systems or making them simpler, more compact and less expensive. For example, new fabrication techniques for aspheric optics, freeform optics and high-quality plastic optics allow one to realize extremely compact photo cameras with astonishing performance figures.
Much of technical optics is based on classical optics, i.e., not involving quantum effects.
Modern optics deals with light propagation not only in “simple” artificial media, but also for example in the atmosphere (atmospheric optics) and in strongly scattering biological materials.
Frequently Asked Questions
This FAQ section was generated with AI based on the article content and has been reviewed by the article’s author (RP).
What is optics?
Optics is a branch of physics that studies the properties and behavior of light, including its interactions with matter and the construction of instruments that use or detect it. It covers visible, infrared, and ultraviolet light.
What is the difference between optics and photonics?
Optics is a core part of photonics, focusing on light's properties and propagation. Photonics is a broader field that also includes the generation of light (e.g., in lasers) and its detection (photodetectors).
What are the main branches of classical optics?
Classical optics is primarily divided into geometrical optics, which describes light propagation using rays, and wave optics (or physical optics), which treats light as an electromagnetic wave.
What is geometrical optics?
Geometrical optics is a model of optics that describes light propagation in terms of rays traveling in straight lines. It is useful for understanding basic imaging with components like lenses and mirrors, but cannot explain phenomena like diffraction or interference.
Why is wave optics necessary?
Wave optics is necessary to explain phenomena that result from the wave nature of light, such as interference, diffraction, and polarization. These effects are critical for understanding the performance limits of optical instruments like microscopes and telescopes.
What is quantum optics?
Quantum optics is the field of optics dealing with quantum effects of light. It describes light in terms of discrete energy packets called photons and is essential for understanding phenomena like the photoelectric effect and for developing technologies like quantum cryptography.
What does technical optics focus on?
Technical optics focuses on the application of optical principles to design, fabricate, and optimize optical components and systems, such as lenses, coatings, and cameras. It aims to improve performance and create more compact and cost-effective optical devices.
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