Fiber optic test equipment is used to detect the signal loss or change through a fiber optic cable. The demand for fiber optic products has grown considerably in recent years, as advances within the telecommunications industry require the use of fiber optic testing equipment to test the strength of these signals. Fiber optic test equipment is used with fiber optic cables which contain thin, transparent threads of glass that are used to transmit signals. When bundled together, these glass threads form a fiber optic cable that can transmit light in the form of signals. This is done by the use of a fiber optic transmitter which produces light for encoding and transmission. The optical fibers then carry the light signal to a fiber optic receiver for decoding. Throughout this process, fiber optic test equipment is used to monitor signal loss or change. There are many different types of fiber optic test equipment. Common examples include optical fiber checkers and fiber optic test kits. An optical fiber checker is a type of fiber optic test equipment used to verify the signal loss or change through single-mode fibers and multiple mode fibers. Single-mode fibers are only 9 – 10 microns in diameter. Multiple mode fibers are usually 62 - 63 microns in diameter. Typically, single-mode optical fibers are used to transmit infrared (IR) laser light. Multi mode optical fibers are used to transmit infrared from a light emitting diode (LED) light. A fiber optic test kit includes all of the components needed for optical fiber testing. Common components of this type of fiber optic test equipment include a power meter and an optical light source. Advanced fiber optic test are fiber optic test equipment that may include a carrying case, rubber boots, straps, and software, along with standard fiber optic test equipment. There are many applications for fiber optic cables and fiber optic test equipment. Some products are used in medical imaging applications. Others are used in telephone, networking, and telecommunication applications. Fiber optic test equipment manufacturers are located across the United States and around the world. They may comply with voluntary guidelines established by the Electronics Industries Alliance / Telecommunications Industry Association (EIA/TIA).