A TIR (total internal reflection) optic is a compound lens that combines the best of both a reflector and a lens to maximize the beam shaping capabilities. The compound lens consists of a refractive lens inside a reflector. The refractive lens collects and manages the light from an LED package. The reflector processes light and shapes the beam. The beam angle depends on the curvature of the TIR surface. The use of refractive and reflective elements allows for more optical aberrations to be corrected than it is possible with a single element. The characteristics unique to LEDs afford luminaire designers an opportunity to extract light directly efficiently from the source and precisely regulate it through key vertical and horizontal planes. Typically TIR lenses are rotationally symmetrical designs and can be designed in arrays to accommodate multiple LEDs. TIR optics are the optimum solution to produce smooth circular beams with small FWHM angular widths. TIR optics are generally injection-molded from polymers such as PMMA (polymethyl methacrylate) acrylic and polycarbonate.
