Parabolic reflectors for solar applications are nice stuff, and making your own is ... vacuum is needed to force the film into parabolic shape. Extract the air from a little hole in the lid ...

Parabolic reflectors for solar applications are nice stuff, and making your own is ... vacuum is needed to force the film into parabolic shape. Extract the air from a little hole in the lid ...

Schematic diagram of a parabolic reflector. Incoming sound is directed to the microphone placed at the focus of the parabola-shaped reflector. The property of the parabolic shape to reflect all sound ...