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Polaroid® (a trademark of the Polaroid Corporation) is the name of a type of synthetic plastic sheet which is used to polarise light. The original material, patented in 1929 and further developed in 1932 by Edwin H. Land, consists of many microscopic crystals of iodo quinine sulphate ( herapathite) embedded in a transparent nitrocellulose polymer film. The needle-like crystals are aligned during manufacture of the film by stretching or by applying electric or magnetic fields. With the crystals aligned, the sheet tends to absorb light which is polarised parallel to the direction of the crystal alignment, but transmits light which is polarised perpendicularly to it. This allows the material to be used as a light polariser.
This material, known as J-sheet, was later replaced by the improved H-sheet Polaroid, invented in 1938 by Land. H-sheet is a polyvinyl alcohol (PVA) polymer impregnated with iodine. During manufacture, the PVA polymer chains are stretched such that they form an array of aligned, linear molecules in the material. The iodine dopant attaches to the PVA molecules and makes them conducting along the length of the chains. Light polarised parallel to the chains is absorbed, and light polarised perpendicular to the chains is transmitted.
Polaroid sheets are used in liquid crystal displayFor other meanings of LCD, see LCD (disambiguation). polarize the light as it enters. Glass substrate with ITO electrodes. The shapes of these electrodes will determine the dark shapes that will appear when the LCD is turned on. Vertical ridges are etcheds, optical microscopeA microscope is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. The science of investigating small objects using such an instrument is called microscopy, and the term microscopic means minute or very small, nots and sunglassesSunglasses (also called sun spectacles see usage of words for eyepieces) are a kind of visual correction aid, variously termed spectacles or glasses, which feature lenses that are coloured or darkened to screen out strong light from the eyes. Many people.
Polaroid is also used as a trade name for a variety of products sold by the Polaroid Corporation, including sunglasses based on Polaroid polarisers, and instant-print photographic film and cameras.
1 See Also
- Polaroid Corporation
- Polaroid cameraA Polaroid camera is a type of camera with self-developing film usually called an " instant camera". The invention of modern instant cameras is generally credited to American scientist Edwin Land, who unveiled the first commercial instant camera, the Land
- Edwin H. Land
- Polarization
2 External links
Polaroid Corporation website
Optics
