Ultrasonic thickness gauges are designed to measure thickness of materials from one side using ultrasonic sound waves.
When an ultrasonic wave is sent through the material, this signal is reflected by the back wall of the material and received by the wall thickness gauge. The delay between sending and receiving the signal can be used to calculate the wall thickness of the material.
Common applications are thickness measurement in plastics, glass, ceramics and metal along with coating thickness. It also serves as a major corrosion testing equipment.