Parabolic reflector. Simulation of parallel beams of light striking a parabolic reflector (concave mirror) whose curvature increases with time. The light beams are brought to a focus in front of the reflector. As the curvature increases, so the focal point approaches the reflector. The ability of parabolic reflectors to concentrate parallel rays to a single focus is crucial in reflecting telescopes (which use huge parabolic mirrors to collect distant starlight). Satellite dishes (and radio telescopes) use parabolic collectors to collect radio waves, with the detector at the focus.