History of spherical mirrors in human civilization pdf

A first surface mirror history of spherical mirrors in human civilization pdf with aluminum and enhanced with dielectric coatings. Mirror image in a surveillance mirror, which reflects the person taking the photo.

A mirror is an object that reflects light in such a way that, for incident light in some range of wavelengths, the reflected light preserves many or most of the detailed physical characteristics of the original light, called specular reflection. The most familiar type of mirror is the plane mirror, which has a flat surface. Curved mirrors are also used, to produce magnified or diminished images or focus light or simply distort the reflected image. Mirrors are also used in scientific apparatus such as telescopes and lasers, cameras, and industrial machinery. This section does not cite any sources. There are many types of glass mirrors, each representing a different manufacturing process and reflection type.

An aluminium glass mirror is made of a float glass manufactured using vacuum coating, i. A low aluminium glass mirror is manufactured by coating silver and two layers of protective paint on the back surface of glass. A low aluminium glass mirror is very clear, light transmissive, smooth, and reflects accurate natural colors. This type of glass is widely used for framing presentations and exhibitions in which a precise color representation of the artwork is truly essential or when the background color of the frame is predominantly white. A safety glass mirror is made by adhering a special protective film to the back surface of a silver glass mirror, which prevents injuries in case the mirror is broken. This kind of mirror is used for furniture, doors, glass walls, commercial shelves, or public areas. A silkscreen printed glass mirror is produced using inorganic color ink that prints patterns through a special screen onto glass.

Various colors, patterns, and glass shapes are available. Such a glass mirror is durable and more moisture resistant than ordinary printed glass and can serve for over 20 years. A silver glass mirror is an ordinary mirror, coated on its back surface with silver, which produces images by reflection. This kind of glass mirror is produced by coating a silver, copper film and two or more layers of waterproof paint on the back surface of float glass, which perfectly resists acid and moisture. A silver glass mirror provides clear and actual images, is quite durable, and is widely used for furniture, bathroom and other decorative purposes. Decorative glass mirrors are usually handcrafted.

A variety of shades, shapes and glass thickness are often available. In a concave mirror, parallel beams of light become a convergent beam, whose rays intersect in the focus of the mirror. In a convex mirror, parallel beams become divergent, with the rays appearing to diverge from a common point of intersection “behind” the mirror. Spherical concave and convex mirrors do not focus parallel rays to a single point due to spherical aberration. However, the ideal of focusing to a point is a commonly used approximation. This article needs additional citations for verification.

Distortions in the image increase with the viewing distance. However, a mirror does not usually “swap” left and right any more than it swaps top and bottom. Looking at an image of oneself with the front-back axis flipped results in the perception of an image with its left-right axis flipped. When reflected in the mirror, your right hand remains directly opposite your real right hand, but it is perceived as the left hand of your image. Ancient Greek Attic red-figure lekythos, c. Adorning Oneself’, detail from ‘Admonitions of the Instructress to the Palace Ladies’, Tang dynasty copy of an original by Chinese painter Gu Kaizhi, c.

The first mirrors used by humans were most likely pools of dark, still water, or water collected in a primitive vessel of some sort. If well used, however, the mirror can aid moral meditation between man and himself. Socrates, we are told by Diogenes, urged young people to look at themselves in mirrors so that, if they were beautiful, they would become worthy of their beauty, and if they were ugly, they would know how to hide their disgrace through learning. Glass was a desirable material for mirrors. Because the surface of glass is naturally smooth, it produces reflections with very little blur. In addition, glass is very hard and scratch-resistant. However, glass by itself has little reflectivity, so people began coating it with metals to increase the reflectivity.

Parabolic mirrors were described and studied in classical antiquity by the mathematician Diocles in his work On Burning Mirrors. In China, people began making mirrors by coating metallic objects with silver-mercury amalgams as early as 500 A. This was accomplished by coating the mirror with the amalgam, and then heating it until the mercury boiled away, leaving only the silver behind. The problems of making metal-coated, glass mirrors was due to the difficulties in making glass that was very clear, as most ancient glass was tinted green with iron. The method of making flat panes of clear glass from blown cylinders began in Germany and evolved through the Middle Ages, until being perfected by the Venetians in the sixteenth century. The Venetians began using lead glass for its crystal-clarity and its easier workability. The invention of the silvered-glass mirror is credited to German chemist Justus von Liebig in 1835.

His process involved the deposition of a thin layer of metallic silver onto glass through the chemical reduction of silver nitrate. Vacuum deposition began with the study of the sputtering phenomenon during the 1920s and 1930s, which was a common problem in lighting in which metal ejected from the electrodes coated the glass, blocking output. Four different mirrors, showing the difference in reflectivity. All are first-surface mirrors except the chrome mirror.