The PROLITE-30B is a handheld, easy-to-use optical test instruments that identify fiber optics without any damage by detecting the optical signals being transmitted through the fibers. By non-destructive macroband detection technology and mechanism damp technology, it avoids opening the fiber at the splice point for identification and interrupting service. The PROLITE30B can accurately detect the optical signals, signal directions and the presence of 2 kHz modulated tone. It can test all kinds of fibers, including fibers of 250 um and 900 um as well as jacketed fibers of 2 mm and 3 mm. With its wide dynamic range, PROLITE-30B can efficiently identify the wide-spectrum signals, such as signals in CATV system and EDFA. Therefore it can be used in all the physical layer testing of SONET/SDH and DWDM systems.