Abstract: A system is provided for estimating a condition of a non-conductive hollow structure exposed to a lightning strike. The structure has an internal cavity. The system includes a pressure transducer to measure a pressure of an acoustic wave generated within the internal cavity due to the lightning strike. The system further includes a controller coupled to the pressure transducer, to receive the measured pressure from the pressure transducer, and to process the condition of the structure, based on the measured pressure.

Abstract: A system is provided for estimating a condition of a non-conductive hollow structure exposed to a lightning strike. The structure has an internal cavity. The system includes a pressure transducer to measure a pressure of an acoustic wave generated within the internal cavity due to the lightning strike. The system further includes a controller coupled to the pressure transducer, to receive the measured pressure from the pressure transducer, and to process the condition of the structure, based on the measured pressure.

Abstract: The light-emitting device includes a light source and a gradient index (GRIN) element. The GRIN element has a cylindrical refractive index profile in which the refractive index varies radially and is substantially constant axially. The GRIN element includes a first end surface opposite a second end surface and is characterized by a length-to-pitch ratio. The GRIN element is arranged with the first end surface adjacent the light source to receive light from the light source, and emits the light from the second end surface in a radiation pattern dependent on the length-to-pitch ratio. Since the radiation pattern depends on the length-to-pitch ratio of the GRIN element, LEDs with different radiation patterns can be made simply by using GRIN elements of appropriate lengths.

Abstract: A cylindrical encoder has a cylinder with a coding surface that is disposed about a rotational axis. The coding surface has code lines that spiral along the cylinder about the rotational axis. Resolution depends on the pitch, or spacing, of the code lines, and on the angle at which the code lines are oriented to the rotational axis. An imaging system positioned for optical coupling to the coding surface senses a succession of moving code lines as the cylinder rotates about the rotational axis.