Optical microscope image of dacron fibers. Dacron or polyethylene terephthalate (pet) is a thermoplastic polymer and is used in synthetic fibers and beverage containers. The identification of different types of fibers is critical to investigating a crime scene. The magnification is 200 times when printed 10 inches wide. This fiber is also sold under trade names Arnite, Impet , Rynite, Ertalyte, Hostaphan, Melinex , Mylar films, Dacron, Diolen, Terylene , Trevira fibers. The identification of different types of fibers is critical to investigating a crime scene. The magnification is 200 times when printed 10 inches wide.