Plastic Fiber

Light guides conduct the flow of light from a light source to a point of use. They are used to illuminate areas that are too small or too hazardous to permit the installation of a light bulb. There are two basic types of light guides: Plastic light guide and Glass light guide .Plastic light guides have a flexible outer sheath and a light-conducting core. Fiber optic light guides consist of non-coherent bundles of optical fibers. The fibers at each end of the bundle are tightly compressed, cut perpendicular to the axis of the fibers, and polished to permit light to pass into and out of the bundle. Plastic or PMMA(Poly methyl methacrylate) F.O light guides are less flexible than flexible Glass F.O. but are well-suited for the transmission of light in the visible and near-infrared range .Plastic light guides have little luminous loss over distance and are better suited for the transmission of UV light. Most plastic and fiber optic light guides are rigid and straight, rigid and bent, or flexible. Multi-leg devices are split along the length of the light guide so that the ends of the fibers extend separately to illuminate different points from a single light source

Selecting light guides requires an analysis of physical and performance specifications. Physical specifications include length, diameter, and termination method. Some light guides are terminated with a threaded or unthreaded ferrule, a tube-like mechanical fixture that confines the stripped end of a fiber bundle. Others are unterminated devices. Performance specifications for light guides include wavelength, acceptance angle, bend angle, and numerical aperture. Acceptance angle is the maximum angle measured from the axis within which light is accepted or emitted by the light guide and transmitted along its length. Bend radius is the smallest bend that fibers can withstand before fracture. Numerical aperture is a calculated, optical value that indicates a device’s ability to collect light over a range of input angles. It is equal to the sine of the acceptance angle. For fiber optic light guides, numerical aperture depends upon the core and cladding indexes of refraction.