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
Instant camera their own takes on instant cameras. Polaroid cameras can be classified by the type of film they use. The earliest Polaroids (pre-1963) used instant roll film. Roll film came in two rolls (positive/developing agent and negative) which were loaded into the camera and was eventually offered in three sizes (40, 30, and 20 series). The next generation of Polaroid cameras used 100 series "pack film," where the photographer pulled the film out of the camera, then peeled apart the positive from the negative at the end of the developing process. Pack film initially was offered in a rectangular format (100