Optics - Wikipedia, the free encyclopedia. Optics is the branch of physics which involves the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X- rays, microwaves, and radio waves exhibit similar properties. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces. Physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be accounted for in geometric optics. Historically, the ray- based model of light was developed first, followed by the wave model of light. Progress in electromagnetic theory in the 1. Some phenomena depend on the fact that light has both wave- like and particle- like properties. Explanation of these effects requires quantum mechanics. When considering light's particle- like properties, the light is modelled as a collection of particles called . PROPAGATION OF LIGHT 2.1 Huygens’ Principle In the 1670’s Christian Huygens proposed a mechanism for the propagation of light, nowadays known as Huygens’ Principle: All points on a wavefront act as sources. Geometrical Optics / Mirror and Lenses Outline Reflection Plane Mirrors Concave/Convex Mirrors Refraction Lenses Dispersion. Quantum optics deals with the application of quantum mechanics to optical systems. Optical science is relevant to and studied in many related disciplines including astronomy, various engineering fields, photography, and medicine (particularly ophthalmology and optometry). Practical applications of optics are found in a variety of technologies and everyday objects, including mirrors, lenses, telescopes, microscopes, lasers, and fibre optics. History. The earliest known lenses, made from polished crystal, often quartz, date from as early as 7. BC for Assyrian lenses such as the Layard/Nimrud lens. UCLA Physics & Astronomy. Instructional Resource Lab. Experiment 4 - Physical Optics.These practical developments were followed by the development of theories of light and vision by ancient Greek and Indian philosophers, and the development of geometrical optics in the Greco- Roman world. The word optics comes from the ancient Greek word . With many propagators including Democritus, Epicurus, Aristotle and their followers, this theory seems to have some contact with modern theories of what vision really is, but it remained only speculation lacking any experimental foundation. Plato first articulated the emission theory, the idea that visual perception is accomplished by rays emitted by the eyes. He also commented on the parity reversal of mirrors in Timaeus. The rays were sensitive, and conveyed information back to the observer. He summarised much of Euclid and went on to describe a way to measure the angle of refraction, though he failed to notice the empirical relationship between it and the angle of incidence. One of the earliest of these was Al- Kindi (c. In the early 1. 1th century, Alhazen (Ibn al- Haytham) wrote the Book of Optics (Kitab al- manazir) in which he explored reflection and refraction and proposed a new system for explaining vision and light based on observation and experiment. Grosseteste's most famous disciple, Roger Bacon, wrote works citing a wide range of recently translated optical and philosophical works, including those of Alhazen, Aristotle, Avicenna, Averroes, Euclid, al- Kindi, Ptolemy, Tideus, and Constantine the African. Bacon was able to use parts of glass spheres as magnifying glasses to demonstrate that light reflects from objects rather than being released from them. The first wearable eyeglasses were invented in Italy around 1. He was also able to correctly deduce the role of the retina as the actual organ that recorded images, finally being able to scientifically quantify the effects of different types of lenses that spectacle makers had been observing over the previous 3. In the late 1. 66. Isaac Newton expanded Descartes' ideas into a corpuscle theory of light, famously determining that white light was a mix of colours which can be separated into its component parts with a prism. In 1. 69. 0, Christiaan Huygens proposed a wave theory for light based on suggestions that had been made by Robert Hooke in 1. Introductory Physics II Electricity, Magnetism and Optics by RobertG.Brown Duke University Physics Department Durham, NC 27708-0305 [email protected]. Ch.1 A brief history : optics By Joonghoe Dho 1 . Looking for books on Optics? Check our section of free e-books and guides on Optics now! This page contains list of freely available E-books, Online Textbooks and Tutorials in Optics. Qualifying Questions and Solutions - Physics > Problems and Solutions on Optics This Book. 204pp Feb 1991 ISBN: 978-981-02-0438-9 (hardcover) USD98.00; Buy Now. PDF (1190 KB) 51: WAVE OPTICS. General Physics 1 Optics 1 Condensed Matter Physics 2 Particle and Nuclear Physics 4 Theoretical and Mathematical Physics 6. General Physics / Optics 1. Hooke himself publicly criticised Newton's theories of light and the feud between the two lasted until Hooke's death. In 1. 70. 4, Newton published Opticks and, at the time, partly because of his success in other areas of physics, he was generally considered to be the victor in the debate over the nature of light. Young's famous double slit experiment showed that light followed the law of superposition, which is a wave- like property not predicted by Newton's corpuscle theory. This work led to a theory of diffraction for light and opened an entire area of study in physical optics. The ultimate culmination, the theory of quantum electrodynamics, explains all optics and electromagnetic processes in general as the result of the exchange of real and virtualphotons. Reflection and refraction. Light waves can be bent and reflected to form new and sometimes altered images. Understanding how light rays can be manipulated allows us. Glauber, and Leonard Mandel applied quantum theory to the electromagnetic field in the 1. Classical optics. In geometrical optics, light is considered to travel in straight lines, while in physical optics, light is considered as an electromagnetic wave. Geometrical optics can be viewed as an approximation of physical optics that applies when the wavelength of the light used is much smaller than the size of the optical elements in the system being modelled. Geometrical optics. They can be summarised as follows: When a ray of light hits the boundary between two transparent materials, it is divided into a reflected and a refracted ray. The law of reflection says that the reflected ray lies in the plane of incidence, and the angle of reflection equals the angle of incidence. The law of refraction says that the refracted ray lies in the plane of incidence, and the sine of the angle of refraction divided by the sine of the angle of incidence is a constant: sin. If the first material is air or vacuum, n is the refractive index of the second material. The laws of reflection and refraction can be derived from Fermat's principle which states that the path taken between two points by a ray of light is the path that can be traversed in the least time. The mathematical behaviour then becomes linear, allowing optical components and systems to be described by simple matrices. This leads to the techniques of Gaussian optics and paraxial ray tracing, which are used to find basic properties of optical systems, such as approximate image and object positions and magnifications. Specular reflection describes the gloss of surfaces such as mirrors, which reflect light in a simple, predictable way. This allows for production of reflected images that can be associated with an actual (real) or extrapolated (virtual) location in space. Diffuse reflection describes non- glossy materials, such as paper or rock. The reflections from these surfaces can only be described statistically, with the exact distribution of the reflected light depending on the microscopic structure of the material. Many diffuse reflectors are described or can be approximated by Lambert's cosine law, which describes surfaces that have equal luminance when viewed from any angle. Glossy surfaces can give both specular and diffuse reflection. In specular reflection, the direction of the reflected ray is determined by the angle the incident ray makes with the surface normal, a line perpendicular to the surface at the point where the ray hits. The incident and reflected rays and the normal lie in a single plane, and the angle between the reflected ray and the surface normal is the same as that between the incident ray and the normal. The image size is the same as the object size. The law also implies that mirror images are parity inverted, which we perceive as a left- right inversion. Images formed from reflection in two (or any even number of) mirrors are not parity inverted. For mirrors with parabolic surfaces, parallel rays incident on the mirror produce reflected rays that converge at a common focus. Other curved surfaces may also focus light, but with aberrations due to the diverging shape causing the focus to be smeared out in space. In particular, spherical mirrors exhibit spherical aberration. Curved mirrors can form images with magnification greater than or less than one, and the magnification can be negative, indicating that the image is inverted. An upright image formed by reflection in a mirror is always virtual, while an inverted image is real and can be projected onto a screen. The simplest case of refraction occurs when there is an interface between a uniform medium with index of refraction n. In such situations, Snell's Law describes the resulting deflection of the light ray: n. For example, the propagation of light through a prism results in the light ray being deflected depending on the shape and orientation of the prism. In most materials, the index of refraction varies with the frequency of the light. Taking this into account, Snell's Law can be used to predict how a prism will disperse light into a spectrum. The discovery of this phenomenon when passing light through a prism is famously attributed to Isaac Newton. This effect is responsible for mirages seen on hot days: a change in index of refraction air with height causes light rays to bend, creating the appearance of specular reflections in the distance (as if on the surface of a pool of water). Optical materials with varying index of refraction are called gradient- index (GRIN) materials. Such materials are used to make gradient- index optics. In this case, no transmission occurs; all the light is reflected. This phenomenon is called total internal reflection and allows for fibre optics technology. As light travels down an optical fibre, it undergoes total internal reflection allowing for essentially no light to be lost over the length of the cable. Lenses are characterized by their focal length: a converging lens has positive focal length, while a diverging lens has negative focal length.
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