Apple was recently granted a patent for "Methods of biometric imaging of input surfaces" which explains an acoustic imaging system that would be used to map a high-res image of something on the surface, such as a fingerprint. The patent explains that an acoustic transducer could convert electricial signals into mechanical energy or vice versa. The mechanical wave would be the finger placed on the display, which would then be converted in to an electrical signal. Those signals would be reconstructed into an image of the fingerprint used for authentication. The patent even...