Polaroid (polarizer) Polaroid (polarizer) Polaroid is a type of synthetic plastic sheet which is used as a polarizer or polarizing filter. A trademark of the Polaroid Corporation, the term has since entered common use. The original material, patented in 1929 and further developed in 1932 by Edwin H. Land, consists of many microscopic crystals of iodoquinine 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 is dichroic: it tends to absorb light which is polarized parallel to
Keystone Camera Company internal management structure led to many quality problems in the early 1970s and serious losses. Keystone later added its instant picture Everflash camera using Polaroid film again stressing the Everflash feature rather than Polaroid's use of the Flash Bar. From 1970 to 1977, Berkey accounted for 8.2% Of the sales in the camera market in the United States, reaching a peak of 10.2% In 1976. In 1978, Berkey sold its camera division and thus abandoned this market. <br> Keystone Camera Company The Keystone Camera Company was an American manufacturer of consumer photographic equipment. Notable products were Movie cameras, 126 and