9. Other techniques

9.1 Ultrasonic detection

The principle consists in generating sonar echoes on the product surface. The particulate product is distributed by a vibrating distributor on the surface of a rigid (metallic) contact zone, which is set in ultrasonic vibration by a sonicator. A set of microphonic detectors measures the echo returned by the contact surface. If a product comes into physical contact with the vibrating surface, the echo is modified.

Depending on the hardness or elasticity of the object's surface, ultrasound is reflected or absorbed...