Optical fiber red light pen (i., optical fiber fault detector, optical fiber fault test pen) is a 650nm (± 20nm) semiconductor laser as a light-emitting device, which emits stable red light through a constant current source drive, and connects with the. Optical fiber red light pen (i. This compact and lightweight tool is an essential instrument for field technicians and. The LBTEK Fiber Optic Red Light Pen is a handheld visual fault locator used for testing fiber optic cables. The 650 nm visible red laser source identifies breaks, sharp bends, and bad splices in single-mode and multimode fibers. Home > Products > Instruments > Optical Ligh.