History of optics – Mueller Check Valve Manufacturer – China Wafer Valve by jekky
Early history of optics The earliest known lenses were made from polished crystal often quartz and have been dated as early as 700 160 BC for Assyrian lenses such as the Layard Nimrud lens There are many similar lenses from ancient Egypt Greece and Babylon The ancient Romans and Greeks filled glass spheres with water to make lenses However glass lenses were not thought of until the Middle Ages Some lenses fixed in ancient Egyptian statues are much older than those mentioned above There is some doubt as to whether or not they qualify as lenses but they are undoubtedly glass and served at least ornamental purposes The statues appear to be anatomically correct schematic eyes citation SPIE In ancient India the philosophical schools of Samkhya and Vaisheshika from around the 6th5th century BC developed theories on light According to the Samkhya school light is one of the five fundamental subtle elements tanmatra out of which emerge the gross elements In contrast the Vaisheshika school gives an atomic theory of the physical world on the non atomic ground of ether space and time See Indian atomism The basic atoms are those of earth prthiv water apas fire tejas and air vayu that should not be confused with the ordinary meaning of these terms These atoms are taken to form binary molecules that combine further to form larger molecules Motion is defined in terms of the movement of the physical atoms Light rays are taken to be a stream of high velocity of tejas fire atoms The particles of light can exhibit different characteristics depending on the speed and the arrangements of the tejas atoms Around the first century BC the Vishnu Purana refers to sunlight as the the seven rays of the sun In the fifth century BC Empedocles postulated that everything was composed of four elements fire air earth and water He believed that Aphrodite made the human eye out of the four elements and that she lit the fire in the eye which shone out from the eye making sight possible If this were true then one could see during the night just as well as during the day so Empedocles postulated an interaction between rays from the eyes and rays from a source such as the sun In his Optics Greek mathematician Euclid observed that things seen under a greater angle appear greater and those under a lesser angle less while those under equal angles appear equal In the 36 propositions that follow Euclid relates the apparent size of an object to its distance from the eye and investigates the apparent shapes of cylinders and cones when viewed from different angles Pappus believed these results to be important in astronomy and included Euclid s Optics along with his Phaenomena in the Little Astronomy a compendium of smaller works to be studied before the Syntaxis Almagest of Ptolemy In 55 BC Lucretius a Roman who carried on the ideas of earlier Greek atomists wrote The light and heat of the sun these are composed of minute atoms which when they are shoved off lose no time in shooting right across the interspace of air in the direction imparted by the shove ucretius 160 On the nature of the Universe citation needed Despite being similar to later particle theories of light Lucretius s views were not generally accepted and light was still theorized as emanating from the eye In his Catoptrica Hero of Alexandria showed by a geometrical method that the actual path taken by a ray of light reflected from a plane mirror is shorter than any other reflected path that might be drawn between the source and point of observation In a twelfth century translation assigned to Roman mathematician Claudius Ptolemy a study of refraction including atmospheric refraction was described It was suggested that the angle of refraction is proportional to the angle of incidence Later in 499 Aryabhata who proposed a heliocentric solar system of gravitation in his Aryabhatiya wrote that the planets and the Moon do not have their own light but reflect the light of the Sun The Indian Buddhists such as Dignga in the 5th century and Dharmakirti in the 7th century developed a type of atomism that is a philosophy about reality being composed of atomic entities that are momentary flashes of light or energy They viewed light as being an atomic entity equivalent to energy similar to the modern concept of photons though they also viewed all matter as being composed of these light energy particles The beginnings of geometrical optics See also Geometrical optics 160 and Ray optics The early writers discussed here treated vision more as a geometrical than as a physical physiological or psychological problem The first known author of a treatise on geometrical optics was the geometer Euclid c 325 BC265 BC Euclid began his study of optics as he began his study of geometry with a set of self evident axioms Lines or visual rays can be drawn in a straight line to the object Those lines falling upon an object form a cone Those things upon which the lines fall are seen Those things seen under a larger angle appear larger Those things seen by a higher ray appear higher Right and left rays appear right and left Things seen within several angles appear clearer Euclid did not define the physical nature of these visual rays but using the principles of geometry he discussed the effects of perspective and the rounding of things seen at a distance Where Euclid had limited his analysis to simple direct vision Hero of Alexandria c AD 1070 extended the principles of geometrical optics to consider problems of reflection catoptrics Unlike Euclid Hero occasionally commented on the physical nature of visual rays indicating that they proceeded at great speed from the eye to the object seen and were reflected from smooth surfaces but could become trapped in the porosities of unpolished surfaces This has come to be known as emission theory Hero demonstrated the equality of the angle of incidence and reflection on the grounds that this is the shortest path from the object to the observer On this basis he was able to define the fixed relation between an object and its image in a plane mirror Specifically the image appears to be as far behind the mirror as the object really is in front of the mirror Like Hero Ptolemy c 90 168 considered the visual rays as proceeding from the eye to the object seen but unlike Hero considered that the visual rays were not discrete lines but formed a continuous cone Ptolemy extended the study of vision beyond direct and reflected vision he also studied vision by refracted rays dioptrics when we see objects through the interface between two media of different density He conducted experiments to measure the path of vision when we look from air to water from air to glass and from water to glass and tabulated the relationship between the incident and refracted rays His tabulated results have been studied for the air water interface and in general the values he obtained reflect the theoretical refraction given by modern theory but the outliers are distorted to represent Ptolemy s a priori model of the nature of refraction citation needed Optical revolution in the Islamic world Main articles Physics in medieval Islam and Book of Optics Reproduction of a page of Ibn Sahl s manuscript showing his discovery of the law of refraction now known as Snell s law Al Kindi c 801873 was one of the earliest important optical writers in the Islamic world In a work known in the west as De radiis stellarum al Kindi developed a theory that everything in the world emits rays in every direction which fill the whole world This theory of the active power of rays had an influence on later Western scholars such as Robert Grosseteste and Roger Bacon Ibn Sahl c 940 1000 was a Persian mathematician associated with the court of Baghdad About 984 he wrote a treatise On Burning Mirrors and Lenses in which he set out his understanding of how curved mirrors and lenses bend and focus light In his work he discovered a law of refraction mathematically equivalent to Snell s law He used his law of refraction to compute the shapes of lenses and mirrors that focus light at a single point on the axis The beginnings of physical optics Ibn al Haytham known in as Alhacen or Alhazen in Western Europe 9651040 often regarded as the father of modern optics formulated the first comprehensive and systematic alternative to Greek optical theories He initiated a revolution in optics and visual perception also known as the Optical Revolution and laid the foundations for a physical optics Ibn al Haytham s key achievement was twofold first to insist that vision only occurred because of rays entering the eye and that rays postulated to proceed from the eye had nothing to do with it the second was to define the physical nature of the rays discussed by earlier geometrical optical writers considering them as the forms of light and color He developed a camera obscura to demonstrate that light and color from different candles passed through a single aperture in straight lines without intermingling at the aperture He then analyzed these physical rays according to the principles of geometrical optics Ibn al Haytham also employed the experimental scientific method as a form of demonstration in optics He wrote many books on optics most significantly the Book of Optics Kitab al Manazir in Arabic translated into Latin as the De aspectibus or Perspectiva which disseminated his ideas to Western Europe and had great influence on the later developments of optics Ibn al Haytham proved that light travels in straight lines using the scientific method in the Book of Optics Another aspect associated with Ibn al Haytham s optical research is related to systemic and methodological reliance on experimentation i tibar and controlled testing in his scientific inquiries Moreover his experimental directives rested on combining classical physics ilm tabi i with mathematics ta alim geometry in particular in terms of devising the rudiments of what may be designated as a hypothetico deductive procedure in scientific research This mathematical physical approach to experimental science supported most of his propositions in Kitab al Manazir The Optics De aspectibus or Perspectivae and grounded his theories of vision light and colour as well as his research in catoptrics and dioptrics His legacy was further advanced through the reforming of his Optics by Kamal al Din al Farisi d ca 1320 in the latter s Kitab Tanqih al Manazir The Revision of Ibn al Haytham s Optics The Book of Optics established experimentation as the norm of proof in optics and gave optics a physico mathematical conception at a much earlier date than the other mathematical disciplines of astronomy and mechanics The book was influential in both the Islamic world and in Western Europe Avicenna 980 1037 agreed with Alhazen that the speed of light is finite as he observed that if the perception of light is due to the emission of some sort of particles by a luminous source the speed of light must be finite Ab Rayhn al Brn 973 1048 also agreed that light has a finite speed and he was the first to discover that the speed of light is much faster than the speed of sound Abu Abd Allah Muhammad ibn Ma udh who lived in Al Andalus during the second half of the 11th century wrote a work on optics later translated into Latin as Liber de crepisculis which was mistakenly attributed to Alhazen This was a short work containing an estimation of the angle of depression of the sun at the beginning of the morning twilight and at the end of the evening twilight and an attempt to calculate on the basis of this and other data the height of the atmospheric moisture responsible for the refraction of the sun s rays Through his experiments he obtained the value of 18 which comes close to the modern value In the late 13th and early 14th centuries Qutb al Din al Shirazi 1236 1311 and his student Kaml al Dn al Fris 1260 1320 continued the work of Ibn al Haytham and they were the first to give the correct explanations for the rainbow phenomenon Al Fris published his findings in his Kitab Tanqih al Manazir The Revision of Ibn al Haytham s Optics In 1574 Taqi al Din 15261585 wrote the last major Arabic work on optics entitled Kitab Nr hadaqat al ibsr wa nr haqqat al anzr Book of the Light of the Pupil of Vision and the Light of the Truth of the Sights which contains experimental investigations in three volumes on vision the light s reflection and the light s refraction The book deals with the structure of light its diffusion and global refraction and the relation between light and colour In the first volume he discusses the nature of light the source of light the nature of the propagation of light the formation of sight and the effect of light on the eye and sight In the second volume he provides experimental proof of the specular reflection of accidental as well as essential light a complete formulation of the laws of reflection and a description of the construction and use of a copper instrument for measuring reflections from plane spherical cylindrical and conical mirrors whether convex or concave The third volume analyses the important question of the variations light undergoes while travelling in media having different densities i e the nature of refracted light the formation of refraction the nature of images formed by refracted light He also describes what may be a rudimentary telescope The beginnings of physiological optics Ibn al Haytham discussed the topics of medicine and ophthalmology in the anatomical and physiological portions of the Book of Optics and in his commentaries on Galenic works He accurately described the process of sight the structure of the eye image formation in the eye and the visual system He also discovered the underlying principles of Hering s law of equal innervation vertical horopters and binocular disparity and improved on the theories of binocular vision motion perception and horopters previously discussed by Aristotle Euclid and Ptolemy He
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