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
Polaroid type 55 the edges, creating positive and negative images. A consequence of the process is an impression of a frame on the unprotected negative. The result (a perfect negative surrounded by imperfect frame-like image on three sides, the fourth showing an impression of connective mesh) creates a distinctive "Polaroid frame look" that became popular, so much so photographers who did not use large format cameras (or any kind of chemical process) graphically combine a conventional photographic image, however created, with a superimposed image of an original 'Polaroid frame' as a graphic effect. In 2001 Polaroid filed for bankruptcy protection, and in February