Ideas how to use the big piezoelements for the gauge with the small aperture
作者:A Sh
1. a wave guide with refracting focusing surfaces
1.1. Fresnel lens
2. use of effect of diffraction
2.1. ultrasonic holography
3. Hammer method: to neglect geometrical accuracy and to deduce an energy stream through a small window somehow
4. a wave guide with focusing mirrors
4.1. a paraboloid
4.2. heart mirrors
5. diaphragm use
6. the classical acoustic concentrator
7. phased array